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This is to certify that the

thesis entitled

The Economic Potential of On-Farm Biomass
Gasification for Corn Drying

presented by

Otto John Loewer

has been accepted towards fulfillment
of the requirements for

M.S. degree in Agr. Econ.

 

    

ajor professor

Date May 12, 1980

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THE ECONOMIC POTENTIAL OF ON-FARM BIOMASS

GASIFICATION FOR CORN DRYING

By

Otto John Loewer

A THESIS
Submitted to
Michigan State University
in partial fulfillment of the requirements

for the degree of

MASTER OF SCIENCE

Department of Agricultural Economics

1980

ABSTRACT
THE ECONOMIC POTENTIAL OF ON-FARM BIOMASS
GASIFICATION FOR CORN DRYING
By

Otto John Loewer

Computations indicate that sufficient energy exists in grain,
cobs and stover so that the gasification process may be used to dry
corn over the range of moisture contents typical at harvest. It was
found that as much as 38.9c and 23.5c per U.S. No. 2 bushel could be
invested in gasification equipment when using cobs and stover, re-
spectively, as sources of energy when removing 10 points of moisture
and using representative values for essential physical and economic
parameters. Grain could be used as an economical fuel source only
if it were subsidized by the equivalent of 37.6¢ per bushel dried.
This analysis indicated that cobs would be the best source of biomass
fuel for grain drying followed by stover and grain. However, it is
unlikely that grain could ever compete with cobs or stover as an

energy source.

ACKNOWLEDGEMENTS

The author wishes to especially thank the following:

Dr. John Walker, Chairman, Agricultural Engineering
Department, University of Kentucky, who assisted in
making my sabbatical leave possible.

Dr. Lester Manderscheid, Associate Chairman, MSU Agricultural
Economics Department, who helped greatly in arranging
for my graduate study at MSU.

Dr. Roy Black, who served as major professor.

Drs. Roger Brook, Earl Erickson and Gerald Schwab, who
served as members of my graduate committee.

Mr. Fred Payne and Dr. I. J. Ross, Agricultural Engineering
Department, University of Kentucky, who served as

consultants for the study.

ii

TABLE OF CONTENTS

CIIAPTER I "' INTRODUCTION AND OBJECTIVES o o o o o o o o o o 0

CHAPTER II - CORN DRYING: ECONOMIC AND ENERGY CONSIDERATIONS

CHAPTER

A. Historical Perspective . . . . . . .

B. Biomass Conversion Processes . . . . . .
CHAPTER IV - THE AVAILABILITY OF BIOMASS . . .
CHAPTER V - THE AVAILABILITY OF ENERGY FOR DRYING

A. Cross Energy . . . . . . . . . . . . . .

B. Bomb Calorimeter Adjustments . . . . . .

C. Moisture Content Adjustments . . . . . .

D. Example 0 0 O O O I O O O O O O O O 0 O O

E. Efficiency of Gasification Process . . .

F. Efficiency of Drying . . . . . . . . . .
CHAPTER VI — ECONOMIC CONSIDERATIONS . . . . . .

A. LP Gas 0 O I O I C C O O O O O O O O O O

B. Harvesting and Transportation Costs . .

Grain I O O O O O O O O O O O I O O O
CObS O O O O O O O O I O O O O O O O
stover O O O O O O O O O O O O O O I

C. 8011 PrOductiVity Q o O I O O O O O O O O

D. Alternative Uses . . . . . . . . . . . .

E. Gasification Equipment Costs . . . . .

F o Break-even Investment 0 o o o o o o o o o

G. Concluding Remarks . . . . . . . . . .
CHAPTER VII - ECONOMIC FEASIBILITY OF GASIFICATION

A. IntrOduction O O O O O O O O O O O O O O

B. Base Condition . . . . . . . . . . . . .

C. Sensitivity Analysis . . . . . . . . . .

D. Physical Factors . . . . . . . . . . . .

III - THE GASIFICATION PROCESS . . . . .

Gasification Efficiency . . . . . . .
LP Gas Burner Efficiency . . . . . .
Drying Efficiency . . . . . . . . . .

iii

\1

15
22

22
23
24
26
30
34

39

39
41
41
43
45
46
52
53
55
62

65

65
65
67
67
67
69
69

Adjustment to Bomb Calorimeter Data .
Nitrogen Retention Rate . . . . . . .
E. Economic Factors . . . . . . . . . . . . .
Life of the Gasification Equipment . .
Moisture Content of Grain to be Dried
Interest Rate . . . . . . . . . . . .
Annual Operation and Maintenance . . .
Harvesting Costs . . . . . . . . . . .
Market Value of Biomass . . . . . . .
Cost of Nitrogen . . . . . . . . . . .
Increases in LP Gas Price . . . . . .
F. Summary . . . . . . . . . . . . . . . . . .

CHAPTER VIII - SUMMARY AND CONCLUSIONS . . . . . .

APPENDIX - BIOMASS COMPUTER PROGRAM LISTING,
DATA AND SAMPLE OUTPUT . . . . . . . .

BIBLIOGRAPIIH O O 0 O O O O O O O O O O O O O O O 0

iv

69
73
73
73
73
77
77
80
80
85
85
96

102

106

118

Table

Table

Table

Table

Table

Dry matter distribution (Z of total dry matter)

LIST OF TABLES

within corn plant (Ayres, 1973). . . . .

Nutrient content of corn biomass (Crampton and

Harris, 1969).

Base values of inputs used in sensitivity

analysis.

Linear sensitivity of break-even investment to

changes in physical and economic parameters. .

Modification to the base condition values given

in Table 3.

16

48

66

97

104

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

10.

11.

LIST OF FIGURES

Thermochemical process for biomass
conversion (Payne, 1979). . . . . . . . . . . . . . .

Schematic of the biomass gasification-combustion
process for grain drying (Payne, et a1., 1979).

Schematic of the three basic types of mobile
gasifiers (Payne, et a1., 1979). . . . . . . . . . .

Schematic of the gasification combustion equipment
used at the University of Kentucky (Payne, et a1.,
1979). O C O O O I O O O O I O O O C O O C O C O O O 0

Relative percentage of above ground biomass as a
function of grain moisture content (Ayres, 1973). . .

Relative dry weights of biomass components as a
function of grain moisture content (grain, cabs and
stover are measured simultaneously and in the

same units). . . . . . . . . . . . . . . . . . . . . .

Ratios of the weights of biomass components under
field conditions as a function of grain
moisture content. . . . . . . . . . . . . . . . . . .

Gross and net energy content per wet pound of
biomass as a function of the moisture content
of the grain to be dried . . . . . . . . . . . . . . .

Net energy available for drying one pound of wet
grain based on relative field quantities
Of biomass. O O O O O I O O O I O O I O O O O O 0 O

Ratios of gross and net energy availability based
on grain moisture content. . . . . . . . . . . . . . .

The percentage of the available biomass required

to dry one bushel of U.S. No. 2 wet grain
(gasification efficiency = 60%; drying

efficiency = 45%). . . . . . . . . . . . . . . . . . .

vi

11

13

14

17

19

20

27

31

32

38

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

Effects of gasification efficiency on break-
even investment per bushel of dry grain
(U.S. No.2). 0 O I O O O I O C O O O O O O O 0

Effects of LP gas burner efficiency on
break-even investment per bushel of dry
grain (U.S. No.2). . . . . . . . . . . . . . .

Effects of drying efficiency on break-even
investment per bushel of dry grain (U.S. No.2).

Effects of adjusting bomb calorimeter data
on break-even investment per bushel of
dry grain (U.S. No.2). . . . . . . . . . . . .

Effects of the nitrogen retention rate on
break-even investment per bushel of dry
grain (U.S. No.2). . . . . . . . . . . .

Effects of gasification equipment life on
break—even investment per bushel of dry
grain (U.S. No.2). 0 O O O O O O O O O O O O 0

Effects of moisture content on break-even
investment per bushel of dry grain (U.S. No.2).

Effects of interest rate on break-even investment

per bushel of dry grain (U.S. No.2). . . . . .

Effects of annual operation and maintenance
on break-even investment per bushel of dry
grain (U.S. No.2). . . . . . . . . . . . . . .

Effects of grain harvesting cost on break-even
investment per bushel of dry grain when using
grain as a fuel source (U.S. No.2). . . . . .

Effects of cob and stover harvesting costs on
break-even investment per bushel of dry grain
when using cobs and stover as a fuel source
(U.S. No.2). . . . . . . . . . . . . . . . . .

Effects of the market price of grain on break—
even investment per bushel of dry grain when
using grain as a fuel source (U.S. No.2). . . .

Effects of the cob and stover market value on
break-even investment per bushel of dry grain
when using cobs or stover as sources of

fuel (U.S. No.2). . . . . . . . . . . . . . . .

vii

68

70

71

72

74

75

76

78

79

81

82

83

84

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

25.

26.

27.

28.

29.

30.

31.

32.

33.

34.

Effects of nitrogen cost on break-even
investment per bushel of dry grain (U.S.No.2). . .

Effects of a constant LP gas price on the
break—even investment per bushel of dry grain
when grain is the fuel source (U.S. No.2). . . . .

Effects of a constant LP gas price on the break-
even investment per bushel of dry grain when
cobs are the fuel source (U.S. No.2). . . . . . . .

Effects of a constant LP gas price on the break-
even investment per bushel of dry grain when
stover is the fuel source (U.S. No.2). . . . . . .

Effects of annual percentage increase in LP gas
price on break-even investment per bushel of dry

grain when using grain as a fuel source (U.S. No.2).

Effects of annual percentage increase in LP gas
price on break-even investment per bushel of dry
grain when using cobs as a fuel source (U.S. No.2).

Effects of annual percentage increase in LP

gas price on break-even investment per bushel

of dry grain when using stover as a fuel

source (U.S. No.2). . . . . . . . . . . . . . . . .

Effects of a constant increase per year in

LP gas prices on break-even investment per bushel
of grain dried when using grain as a fuel

source (U.S. No. 2). . . . . . . . . . . . . . . .

Effects of a constant increase per year in LP
gas prices on break-even investment per bushel
of grain dried when using cobs as a fuel

source (U.S. No.2). . . . . . . . . . . . . . . .

Effects of a constant increase per year in LP

gas prices on break-even investment per bushel

of grain dried when using stover as a fuel

source (U.S. No.2). . . . . . . . . . . . . . . . .

viii

86

87

88

89

9O

91

92

93

94

95

CHAPTER I

INTRODUCTION AND OBJECTIVES

Early harvesting of corn reduces the field losses associated
with adverse weather and insects, and may enhance the price received
at harvest time. In most areas of the country, early harvested corn
must be dried if it is to be stored safely. The primary fuel sources
for corn drying are liquid petroleum (LP) gas and natural gas, both
of which burn cleanly and are utilized in directly fired systems.
The returns to heated air drying are inversely proportional to the
cost of LP and natural gas. Should the prices of these fuels become
sufficiently high, substitute energy sources and technologies may
develop. One such alternative is the gasification of crop residue.

Gasification is the process by which biomass is burned while
controlling the air supply to the material. This process results in
a combustible gas that may be ignited and mixed with ambient air to
provide the heated air necessary for grain drying.

Biomass gasification equipment is not currently being manu-
factured for use in crop drying. How much can manufacturers charge
or farmers afford to pay for this equipment? The primary objective
of this study is to answer this question by determining the break-
even investment for biomass gasification equipment used in corn

drying. For this study only corn grain, stover and cobs will be

evaluated as sources of energy, and uses of the gasification
equipment for purposes other than grain drying will not be consid-
ered. The break-even investment will be determined for one bushel
of U.S. No. 2 corn defined as 56 pounds of grain at 15.5 percent
moisture content. Storage of biomass will not be evaluated.

The study begins by presenting an overview of the economic and
energy considerations associated with corn drying followed by a dis-
cussion of biomass gasification technology. The break-even invest—
ment for gasification equipment is partially a function of biomass
and energy availability; thus, Chapters III and IV investigate the
technical feasibility of using biomass as an energy source for corn
drying. This portion of the analysis is structured so as to deter-
mine the quantities of biomass and energy available and required for
drying one bushel of corn over a range of moisture contents and energy
conversion efficiencies. Chapter V addresses the economic considera—
tions associated with gasification of corn biomass including gross
return, harvesting and transportation costs, soil productivity,
alternative uses for biomass, gasification equipment costs and break-
even investment determination. In Chapter VI the sensitivity of
break-even investment to changes in technology and prices is computed.
The summary and conclusions from the study are given in Chapter VII.
An example drying situation is periodically used in Chapters IV-VI
to demonstrate the procedures used for determining the break—even

investments reported in Chapter VII.

CHAPTER II

CORN DRYING: ECONOMIC AND ENERGY CONSIDERATIONS

The drying of corn enables the farmer to significantly reduce
his harvest and storage losses. This gain in physical production
efficiency is obtained by extensive use of fossil energy, primarily
liquid petroleum (LP) gas.

In 1974, the United States produced approximately 4.7 billion
bushels of corn (Statistical Reporting Service, USDA). Nelson (1975)
reported that nearly one billion gallons of LP gas were used that
year in drying feed and food grains, primarily corn. This translates
to approximately 0.2 gallons of LP gas to dry each bushel, and would
be sufficient to remove 10 points of moisture. Using 1977 corn pro-
duction levels (6.4 billion bu), and assuming the same energy usage
per bushel, LP gas consumption for drying would have increased to
1.27 billion gallons.

Although agricultural production accounts for only 2.2 percent
of the total fossil energy used in the United States (Hirst, 1974),
it uses 17 percent of the LP gas that is consumed (Walker, 1975).
Drying accounts for 6.5 percent of the total energy used in all U.S.
agricultural production (Nelson, 1975). However, drying would
account for 22 percent of the energy required in a non-irrigated no-
tillage corn production system where 10 points of moisture are removed,

second only to the energy input in fertilization (Walker, 1975).

3

Drying allows for earlier harvesting of corn, thus significantly
reducing harvest losses. Byg et a1. (1966) reported that for har-
vesting conditions in Ohio, total machine losses for combines aver-
aged 6.4, 6.5 and 9.3 bushels per acre in 1964, 1965 and 1966,
respectively. The losses over all samples ranged from a low obser-
vation of 2.3 to a high of 29.4 bushels per acre in 1964. Similar
but somewhat less extreme conditions were reported for 1965 and 1966.
Data compiled by Johnson and Lamp (1966) for picker-shellers indicated
a range of 7 to 26 percent for harvest losses depending on harvester
speed, number of calendar days required for harvesting, moisture
content at the beginning of harvest, and weather. If drying could
account for a 5 percent saving in total yield by permitting earlier
harvesting, the gross dollar gain would $12.50 per acre assuming 100
bushels per acre corn at a price of $2.50 per bushel.

Grain must also be dried if it is to be safely stored for future
sale, the final moisture content depending primarily on average out-
side temperature and relative humidity (Ross et a1., 1973; Loewer
et a1., 1979). This is especially important when there is a possi-
bility of aflatoxin contamination (Ross et a1., 1978).

Another consideration is that farmers can avoid discounts for
excess moisture by drying the grain before delivering it to a com-
mercial elevator. Using a "2 percent of selling price per point of
moisture above 15.5 percent" dockage method for 25.5 percent moisture
corn, the gross returns for on-farm drying would be 8.74c per dollar
of selling price less expenses for fuel, labor and equipment (Loewer

and Hamilton, 1974).

Electricity is used as a source of heat in most low temperature
drying processes. This drying method is very slow and in some geo-
graphic areas may lead to unacceptable storage risk (Ross et a1.,
1978). If the price of LP or natural gas is sufficiently high or
if these fuel sources are not available for drying because of allo-
cation policies, electricity would presently be the primary substi-
tute. In all likelihood, a shift to electrical drying would result
in a greatly increased demand for peak load power, not a situation
welcomed by utility companies. There would be production pattern
shifts in corn production away from the warmer areas of the United
States,because of storage risks,accompanied by an increase in ear
corn production. Harvest losses would increase dramatically because
of additional field drying required when using low temperature dry-
ing, and there would be a shift in the types of equipment and struc-
tures used for harvesting, handling and storing the corn. In essence,
the elimination of an economical energy source for medium to high
temperature grain drying could result in a corn production system
similar to that of 30-40 years ago.

From the above discussion, the drying of corn is an important
energy and economic consideration for both the grain farmer and
consumer. The thrust of this analysis is directed toward the econo-
mic examination of a new energy technology for grain drying, the

gasification of biomass.

CHAPTER III

THE GASIFICATION PROCESS

A. Historical Perspective

 

The gasification process is not a new technology. Horsfield and
Williams (1976), Horsfield (1977), G035 and Williams (1977b) and Payne
(1978) have traced the development of gasification. The first record
of a gasification process was in 1839 when Bischaf patented a simple
process for gasifying coke. Since that time many different types of
cellulosic material have been used including rice hulls, olive pits,
corn cobs, straw, walnut shells and animal manure.

The gasification process has been used for both stationary and
mobile sources of energy, the most common sources of fuel being either
coal or coke. Research into the use of portable gas generators in-
creased into the war years of the 1940's and nearly 700,000 vehicles
in Europe were powered by "producer" gas (the term used for the gas
output). However, development of the process ceased after World
War II when plentiful supplies of petroleum became available. In
fact, gasification never attracted wide attention in the United States.

The Suez crisis in 1957 triggered a long term research program
in producer gas systems in Sweden, as they realized their total de—
pendence on foreign oil. Presently, Duvant Motors in France manu-
factures diesel engines that can operate in the dual fuel mode with

producer gas.

In the early 1970's, as petroleum became more expensive and
supplies less certain, the United States became more involved in
evaluating alternative fuel sources. Initially, the agricultural
research community focused on the technology for direct collection
of solar energy. More recently, the potential of biomass utilization,
especially in the production of alcohol, has received attention.

Much of the interest in gasification and direct combustion has been
directed toward large scale systems such as the substitution of agri-
cultural biomass for coal in electrical power generating stations
(Bailie and Richmond, 1976; Emrri-Ames Laboratory, 1976; Horsfield,
Jenkins and Becker, 1977).

There are several companies that are presently involved in
biomass gasification projects. Likewise, agricultural engineering
departments at several universities are conducting research in the
area of converting biomass to a heat source suitable for drying.
These include projects at the University of California at Davis
(Case, 1978), Iowa State University (Buchele et a1., 1977), Purdue
University (Peart et a1., 1979) and the University of Kentucky

(Payne et a1., 1979).

B. Biomass Conversion Processes

 

There are three thermochemical processes that may be used to
convert dry biomass into an energy form suitable for grain drying:
pyrolysis, combustion and gasification (Payne, 1978). In an actual
thermochemical conversion process, a combination of all three pro-
cesses may occur. The energy source and by-products of each process

are shown in Figure 1.

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Pyrolysis is destructive distillation in the absence of oxygen
in which the biomass is decomposed to yield char, organic liquids
and gas. The char is composed primarily of mineral ash and fixed
carbon. The organic liquids include resin oils, turpentine, cre—
osote oils, etc. The gas is of relatively low energy value, 20 to
40 percent the energy content of natural gas. The major U.S. research
on this process has been conducted at Georgia Tech (Knight et a1.,
1974).

Combustion is the most direct method of obtaining thermal
energy from biomass and has been used extensively by man since his
beginning. In the combustion process, the moisture is first evapo-
rated from the biomass. Then the volatile matter is distilled and
burned. ’Lastly, the fixed carbon is burned. If sufficient oxygen
is available, the resulting product is composed mainly of heat,
carbon dioxide and water vapor.

Gasification is the conversion of the carbonaceous solids in
biomass into a combustible gas by controlling or limiting the rate
of oxygen or air admitted to the fuel bed. The combustible com-
ponents in the gas are primarily carbon monoxide and hydrogen with
traces of methane. The energy value of this gas is 15 percent of
natural gas.

Of the three techniques mentioned above, the concensus of past
research is that for grain drying a combination of gasification-
combustion offers the best biomass energy alternative to LP gas.
The advantages are that the exhaust gases from the combination are

free from odor and smoke and require no pollution control equipment.

10

This may allow the heated exhaust to be passed directly into the grain
mass just as occurs with present day LP gas burner units. University
of Kentucky researchers are currently investigating the properties

of the exhaust gases to determine if pollution hazards exist. The
direct application of heat would eliminate the need for a heat ex-
changer, thus reducing equipment costs. Estimated efficiencies of

the gasification process range from 60 to 80 percent.

The disadvantages of this technique are that a closed air-tight
mechanical system is required, and the gasification of loose biomass
such as corn fodder and straw is not a proven technology. Possible
contamination of grain by the exhaust gas may also prove to be a
disadvantage (Payne et a1., 1979).

For grain drying, Payne et al. (1979) states "The combustion
takes place in two stages (Figure 2). The first stage is gasifica—
tion, in which the volatiles are driven off and the char is oxidized
primarily to carbon monoxide. In the second stage, the gas is trans-
ferred into the secondary combustion chamber where additional air
is used to complete the combustion of the gas. The products of.
combustion (exhaust) are then mixed with air in roughly one part by
weight of exhaust to 20 parts by weight of outside air. .... Two
major factors distinguish this type of burning from ordinary com-
bustion. First, only 30 percent of the air required to complete
the combustion passes through the fire zone. This reduces the
amount of particulates that are carried into the exhaust. And
second, the gases are burned, before any heat is removed, in an in—
sulated secondary combustion chamber with sufficient time, tempera-

ture, turbulence and oxygen to complete the burning reactions".

11

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Mobile gas producers are usually classified as one of three
types: updraft, downdraft and crossdraft (Figure 3). The differ-
ences in the types lie in the relative directions of fuel and air
flow. The fuel and gases flow counter current to each other in the
updraft gasifier. The products of combustion and air move con-
currently through the restricted fire zone in the updraft gasifier.
The crossdraft producers are characterized by small fire zone volumes
and require high temperatures to produce a high quality gas. Payne
et a1. (1979) carefully evaluated the relative advantages and dis-
advantages of each of these types and concluded that the updraft
gasification process was best suited for corn drying. A schematic

of his design, currently in operation, is shown in Figure 4.

13

 

 

 

 

 

 

 

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DRYING

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aeoucruon
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OXIDATION

 

GASIFIER ZONES

(c) CROSSORAFT

Figure 3. Schematic of the three basic types of mobile
gasifiers (Payne, et al., 1979).

14

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CHAPTER IV

THE AVAILABILITY OF BIOMASS

The first consideration in using corn biomass for drying is to
determine the quantity of material available and the relative pro—
portions of the components. Buchele (1975), in reporting on the
harvesting and utilization of corn stalks from Iowa farms, presented
data from an earlier study by Ayres (1973). This information relates
the dry matter distribution of the above ground plant parts as a
function of grain moisture content (Table 1 and Figure 5). The data

may also be expressed in equation form as follows:

Grain dry matter, Z = 70.4 — 0.8*MC (1)
Cobs dry matter, Z = 12.4 - 0.035*MC (2)
Stalks dry matter, Z = 6.7 + O.525*MC (3)
Leaves dry matter, Z = -0.1 + O.38*MC (4)
Husks dry matter, Z = 10.4 - 0.065*MC (5)
Stover dry matter, Z = 17.0 + 0.84*MC (6)

where MC 8 percentage moisture content of the grain,
wet basis.

For purposes of this study, stover includes stalks, leaves and husks.
The quantity of dry matter per unit area may be computed using
the following equations:

. YWB (100-MC)

F (70.4-0.8*MC) (7)

 

15

16

Table 1. Dry matter distribution (Z of total dry matter) within
corn plant (Ayres, 1973).

 

. Kernel Moisture (Z)
Plant Part 40 35 30 25 20

Grain 38.4 42.4 46.4 50.5 54.4
Cobs 11.0 11.1 11.3 11.5 11.7
Stalk 27.7 25.1 22.5 19.9 17.2
Leaf 15.1 13.2 11.3 9.4 7.5

Husk 7.8 8.1 8.5 8.8 9.1

 

17

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18

100-MC

Dry weight of grain/unit area = YWB*__T00— (8)

Dry weight of cobs/unit area = F*(12.4-0.035*MC)/1OO (9)

Dry weight of stalks/unit area = F*(6.7+0.525*MC)/100 (10)

Dry weight of leaves/unit area = F*(-O.1+0.38*MC)/100 (11)

Dry weight of husks/unit area = F*(10.4-0.065*MC)/100 (12)

Dry weight of stover/unit area B F*(17.0+0.84*MC)/100 (13)

where F = total above ground dry matter yield/unit area

MC = percent moisture content of the grain, wet basis
YWB = yield of grain per unit area at MC, and

computed dry weights are measured in the
same units as YWB.

See Figure 6 for a graphical presentation of Equations 8, 9 and 13.
Using Equations 1 and 2 or 8 and 9, the ratio of cobs to grain is
0.2150 at a grain moisture content of 20 percent. If Equations 1 and
2 were linearly projected to moisture contents of 10 and 0 (well
beyond the range for which they were developed), the ratios of cobs
to grain would be 0.193 and 0.176, respectively. This is to be come
pared with a ratio of 0.186 given by Horsfield, Doster and Peart (1977);
thus, the difference might be explained by the relative plant part
composition at different grain moisture contents. Likewise, Roller
et al. (1975) gave data from several sources that compared favorably
with results obtained from Equations 1 - 6.
The following equations may be used to determine the dry weight
ratios of the major biomass components (Figure 7):

COB _ (12.4 - 0.03S*MC)
GRAIN (70.4 - 0.8*MC)

 

(14)

srovra g (17.0 + O.84*M§)
GRAIN (70.4 - 0.8*MC)

 

(15)

19

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COB = (12.4 - 0.035*MC) (16)
STOVER (17.0 + O.84*MC)

 

GRAIN a (70.4 - 0.8*MC), (17)
cos (12.4 - 0.035*MC)

 

GRAIN . (70.4 - 0.8*MC) (18)
STOVER (17.0 + O.84*MC)

 

STOVER = (17.0 + 0.84*MC) (19)
COB (12.4 - 0.035*MC)

 

where MC - percent moisture content of the
grain, wet basis.

The results shown in Figure 7 indicate that there are sufficient
differences in the dry weight ratios of grain, cobs and stover over
a range of moisture contents to influence the relative costs of har-
vesting and transporting a given quantity of energy demanded for dry-
ing. This will be explored in greater detail in the following chapter
on energy availability. Note also, Equations 7-19 do not consider
any production, varietal or environmental factors that might alter

the relative proportions of grain, cobs and stover.

CHAPTER V

THE AVAILABILITY OF ENERGY FOR DRYING

A. Cross Energy

 

The National Research Council (NRC) provides information
concerning the energy content of feedstuffs (Crampton and Harris,
1969). The heat of combustion of gross energy (GE) is defined as
the amount of heat, measured in calories, that is released when a
substance is completely oxidized in a bomb calorimeter containing
25 to 30 atmospheres of oxygen. The CE for corn kernels is given as
5553 kilogram-calories (kcal) per kilogram (kg) or 9995 British
thermal units (Btu) per pound (lb) of dry weight. The CE for cobs
is 4423 kcal/kg (7961 Btu/lb) dry weight. No GE value is given in
the NRC tables for corn stover. Kajewski et al., (1977), reports
that cornstalks contain 1.66 x 107 joules (J) per kg (3972 kcal/kg;
7150 Btu/lb) dry weight. For purposes of this study, the energy
value for cornstalks will also be used for stover.

Not all of the biomass will be converted to energy; some ash
will remain. However, this is considered when computing the gross
energy values. The dry weight percentages of ash for kernels, cabs
and stover are 1.2, 1.7 and 7.6 percent, respectively (Crampton and
Harris, 1969), and there is a slight variation in these values

depending on feedstuff description.

22

23

B. Bomb Calorimeter Adjustments

 

Only 93 percent of bomb calorimeter values should be considered

as useful energy for grain drying (Payne, 1980). This is because

bomb calorimeter measurements

include the latent heat used to vapor-

ize the water resulting from the combustion process which is not

available for grain drying.
basis then becomes:

GRAIN - 5164
2.16
9295

COBS - 4113
1.72
7404

STOVER - 3694
1.54
6650

Similarly, the following

COB

 

GRAIN = 0.796
13% = 0.715
Efg—icgi = 1.113
E‘s—3% = 1.256
fig = 1.399
m = 0.898

COB

The net energy content on a dry weight

kcal/kg,
x 107 J/kg, or
Btu/1b

kcal/kg,
x 107 J/kg, or
Btu/1b

kcal/kg,
x 107 J/kg, or
Btu/1b

dry weight gross energy ratios apply:

(20)
(21)
(22)
(23)
(24)

(25)

24

C. Moisture Content Adjustments

 

The energy availability computed thus far has been on a dry
matter basis. However, when biomass is gasified, part of the energy
must be used in removing the moisture contained within the material.
The latent heat of evaporation for water is approximately 589 kcal/kg
(2.46 x 106 J/kg; 1060 Btu/1b). Thus, for each kg of moisture in the
biomass, 589 kcal of energy will be used for vaporization rather than
as a source of energy for grain drying.

The moisture contents of each of the biomass components must be
known if the net energy available for drying is to be computed.
Buchele (1975) reports that the stover contains approximately twice as
much moisture as the kernels during the harvest season. Bargiel et a1.
(1979) confirms Buchele's observation for cobs when kernel moisture
content is above 25 percent. However, he states that cob moisture
content rapidly approaches the grain moisture content in the range of
15 to 20 percent and is essentially the same at 12.5 percent moisture
content wet basis. Using these estimates, the following relationships
have been established:

Stover moisture content = 2.0*GMC) (26)
For GMC greater than 25 percent,
Cob moisture content = 2.0*GMC (27)

For GMC in the range of 12.5 to 25 percent,

Cob moisture content = —25.0 + 3.0*GMC (28)
For GMC less than 12.5 percent,
Cob moisture content = GMC (29)

where GMC = grain moisture content, and
all moisture contents are measured
as a percentage, wet basis.

25

The net energy that is available for grain drying is a function
of moisture content after adjustments for the bomb calorimeter data
have been made. The following general equation may be used:

Energy available _ 100-MC * MC *
per unit weight, - 100 ECD ' {65 HVAP (30)

wet basis

where MC = percentage of moisture content of biomass
component, wet basis

ECD = adjusted gross energy content per unit
of biomass component, dry basis

HVAP = heat of vaporization of water
Equation 30 can also be written as follows for the adjusted
energy content based on the wet weight of the biomass components

using values presented previously for the different biomass com-

ponents:
GRAIN = (5164) - (57.53)*MC (31)
(kcal/kg)
GRAIN = (2.16 x 107) - (2.406 x 105)*MC (32)
(J/kg)
GRAIN = (9295) - (103.55)*MC (33)
(Btu/lb)
cons = (4113) — (47.02)*MC (34)
(kcal/kg)
cons = (1.72 x 107) — (1.966 x 105)*MC (35)
(J/kg)
cons = (7404) - (84.64)*MC (36)
(Btu/lb)
sroer = (3694) - (42.83)*MC (37)
(kcal/kg)
sroer = (1.54 x 107) - (1.786 x 105)*MC (38)
(J/kg)
sroer = (6650) - (77.1)*MC (39)

(Btu/1b)

26
where MC = moisture content of the biomass component,
percent wet basis, and all computed values
are based on the wet basis of the material.
Equations 31-39 are presented graphically in Figure 8.

In the previous discussion, the ratios of dry weights, energy
values and moisture contents were presented. It has been shown that
moisture content affects the available energy for drying in two ways.
First, the higher the moisture content of a given weight of biomass,
the less the proportion of dry matter to provide energy. Secondly,
the greater the moisture content the greater the energy requirements
to vaporize the water, thus leaving less energy available for grain
drying. Therefore, the field moisture content will be an important

consideration if the biomass component is to be utilized directly at

the time of harvest.

D. Example

The relationship between the grain moisture content and energy
availability among the biomass components can be computed using the
following equations:

GIVEN: 1 unit of wet grain (kg or 1b), GWWT, @ GMC percent

moisture content, wet basis.
Step 1. Use Equation Nos. 26, 27, 28 and 29 as appropriate to
compute:
GMC - cob moisture content, percent wet basis
SMC - stover moisture content, percent wet basis
Step 2. Use Equation Nos. 7, 8, 9 and 13 to compute:
GDWT - dry weight of grain

CDWT - dry weight of cobs

SDWT - dry weight of stover

27

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28
Step 3. Use the following equations to compute the wet weight of

cobs and stover:

CDWT*100

cwwI (100_CMC) (40)
_ SDWT*100

SWWT ' (1oo-smc) (41)

Step 4. Use Equation Nos. 31—39 as appropriate to determine:

GEPWWT = available grain energy per wet weight
unit considering GMC

CEPWWT = available cob energy per wet weight
unit considering CMC

SEPWWT = available stover energy per wet weight
unit considering SMC.

Step 5. Compute the total energy available for drying during harvest

using the following relationships:

TGE = GEPWWT*WTUGI (42)
TCE = CEPWWT*CWWT (43)
TSE = SEPWWT*SWWT (44)

where TGE = the total net energy available for drying
from one wet unit of grain

TCE = the total net energy available for drying
from cobs

TSE = the total net energy available for drying
from stover

WTUGI = initial wet weight units of grain
Step 6. The available energy for drying ratios may then be
expressed:

cob energy a TCE
grain energy TGE

 

(45)

stover energy.‘ TSE
grain energy TGE

 

(46)

29

 

cob energy = TCE

 

 

 

stover energy TSE (47)

grain energy = TGE (48)
cob energy TCE

grain energy = TGE (49)

stover energy TSE

stover energy = TSE (50)

cob energy TCE
For purposes of illustration, consider at harvest 1 kg of grain
at 30.5 percent moisture, wet basis. From Equations 26 and 27, the
stover and cob moisture contents are:

SMC

2.0*GMC = 2.0*30.5

61.0 percent

CMC 2.0*GMC = 2.0*30.5

61.0 percent
The moisture content of the grain may be used to determine the dry

weight of material that is available (Equations 7, 8, 9 and 13).

 

F = YWB(100-GMC) = (1)*(69.5)7 =
(70.4-0.8*GMC) (70.4-O.8*30.5) 1-510
GDWT = YWB*199:§!9-= (1)*lQQ:§Q;§.= 0.695 kg
100 100
cnwr = F*(12.4-0.035*GMC)/100 = 0.171 kg
SDWT = F*(17.0+0.84*GMC)/100 = 0.644 kg

The initial wet weight of the grain, GWWT, was given as 1 kg. The
wet weights for cobs and stover are computed from Equations 40 and 41.

CDWT*100 3 (0.171)§(100)

 

 

CWWT = (IOO-CMC) (100-61) ‘ 0'439 kg
8 san*100 _ (9.644)*(100) =
SWWT (IOO-SMC) ‘ (100-61) 1'651 kg

At this point, the net energy available for drying per wet unit
of biomass may be calculated using Equations 31, 34, and 37.
GEPWWT = 5164 - 57.53*GMC = 3409 kcal/kg

CEPWWT = 4113 - 47.02*CMC = 1245 kcal/kg

30
SEPWWT = 3694 - 42.83*SMC = 1081 kcal/kg
The net energy per wet unit of biomass may be converted to total

energy available for drying per unit of wet grain by using Equations

42, 43 and 44.

TGE = GEPWWT*WTUGI = (3409)*(1) = 3409 kcal
TCE = CEPWWT*CWWT = (1245)*(0.439) = 547 kcal
TSE = SEPWWT*SWWT = (1081)*(1.651) = 1785 kcal

The energy ratios are calculated from Equations 45-50.

cob energy a 292., _§fil.= o 160
grain energy TGE 3409 .

 

stover energy TSE 1785
grain energy TGE 3409

 

= 0.524

cob energy TCE 547

 

 

 

stover energy = TSE = 1785 = 0.306
grain energy =.I§§ -.§£92-= 6 232
cob energy TCE 547 .
_grain energy = E§§_= 2392.: 1 910
stover energy TSE 1785 °
stover energy = E§§.=111§2-= 3.263

 

cob energy TCE 547
See Figures 9 and 10 for a graphical representation of the effects

of kernel moisture content on energy availability.

E. Efficiency of Gasification Process

Thus far, the total energy available for drying has been com-
puted. The previous discussion assumed complete combustion and
100 percent efficiency in removing the internal moisture from the
biomass. However, in physical systems, the process of converting
stored energy into thermal energy for drying will not be 100 percent

efficient. There are several references to the efficiency of

31

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32

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33

gasifiers (Payne et al., 1079; 6033 and Williams, 1977a; Horsfield
and Williams, 1976; Williams and Horsfield, 1977). The efficiency
values typically range from 65 to 80 percent. Williams and Horsfield
(1977), in a detailed report of their efficiency calculations,
included such items as initial moisture content; sensible heat in

the air and dry gas; heat losses in solid refuse, condensate and

the steam in the gas; and radiant losses from the gasifier. Their
comments, along with that of Payne et a1. (1980), would indicate that
a minimum efficiency of 60 percent could be obtained. Likewise, they
suggest that gasification efficiency could be much higher, perhaps

80 percent, when using a well-engineered system. This would be com—
parable to the 80 percent conversion efficiency of LP gas to thermal
energy for drying.

Although the total energy available per unit of wet grain must
be further reduced by the conversion efficiency of the gasification
process, there was no mention in the literature of efficiency dif—
ferences among grain, cobs and stover. If the process efficiency is
assumed to be the same for each biomass component, the energy delivered

to the grain is:

EDGRC = TGE * GEFF/IOO (51)
EDGRC = TCE * GEFF/IOO (52)
EDGRS = TSE * GEFF/IOO (53)

where EDGRC = grain energy available for each unit of
wet grain to be dried

EDGRC = cob energy available for each unit of
wet grain to be dried

EDGRS 8 stover energy available for each unit of
wet grain to be dried

34

TGE, TCE and TSE = the total energy available
per unit of wet grain from the grain,
cobs and stover, respectively

GEFF = percent efficiency of the gasification
process.

Using the example in the previous chapter, the total energy avail-
able for drying one wet unit of grain, when adjusted for a 60 percent
gasification efficiency,would be 2045, 328 and 1071 kcal respectively
for grain, cobs and stover, when beginning with 1 kg of grain at

30.5 percent moisture, wet basis.

F. Efficiency of Drying

 

There are many factors that influence the efficiency of evapora-
ting and removing moisture during the drying process. However, these
items all involve the utilization of available thermal energy and
would be indifferent as to whether the heat source was biomass or
LP gas. The typical values used in estimating drying fuel efficiency
is the units of energy required to remove a unit weight of moisture
from the grain. The theoretical lower limits are 589 kcal/kg of
water (2.46 x 106 J/kg; 1060 Btu/lb). The lower limit expected in
on—the-farm drying systems would be approximately 778 kcal/kg of
water (3.25 x 106 J/kg; 1400 Btu/lb). Likewise, the expected upper
limit would approach 1945 kcal/kg of water (8.14 x 106 J/kg; 3500
Btu/1b). This would indicate a drying efficiency range of from 30
to 76 percent. It should be noted that overall harvesting efficiency
may be lowered by a high drying fuel efficiency. For example, the
farmer may have a very fuel efficient dryer that creates a bottle-
neck in his harvesting operation. This may result in excessive

field and hence economic losses, greater than his fuel savings.

35

A typical drying efficiency that will be used in this study as

a basis for comparison is 45 percent (1308 kcal/kg of water; 5.46 x

106 J/kg; 2356 Btu/lb). Equations for relating the energy and the

quantity of wet biomass needed for drying are:

WATERU

where WATERU

GIMC

GFMC

GRAINU

NOTE:

ENERNU

where ENERNU

HVAP

DEFF

NOTE:

(GRAINU)*(GIMC-GFMC)

 

(IOO-GIMC) (54)

the units of water to be removed during
drying per unit of grain, GFMC base

initial moisture content of the grain,
percent wet basis

final (or desired) moisture content of
the grain after drying, percent wet basis

units of grain to be dried, GFMC base

GRAINU and WATERU are measured in the
same units.

WATERU * HVAP * 100

 

DEFF (55)

energy required per unit of grain dried,
GFMC base

heat of vaporization of water
drying efficiency, percent

(a) If WATERU is measured in kg and HVAP equals
589 kcal/kg, then ENERNU will be measured
in kcal.

(b) If WATERU is measured in kg and HVAP equals
2.46x106 J/kg, then ENERNU will be measured
in J.

(c) If WATERU is measured in pounds and HVAP
equals 1060 Btu/lb, then ENERNU will be
measured in Btu's.

Equations 56, 57 and 58 may be used to determine the percentage

of the available energy required for drying one unit of grain,

measured at the final moisture content, GFMC.

36

ENERNU

= *
PCWTGU EDGRC 100 (56)
ENERNU
= —-—— *
ENERNU
= —— *
PCWTSU EDGRS 100 (58)

where PCWTGU, PCWTGU, PCWTSU = the percent of the wet
grain, cobs and stover, respectively,
required to dry the grain unit, GRAINU.

EDGRC, EDGRC, EDGRS = the energy available for each
unit of grain (at the final moisture content)
to be dried from grain, cobs and stover,
respectively.
Referring back to the previous example, what fraction of the
biomass units must be utilized in drying 1 kg of 15.5 percent moisture
grain (U.S. No. 2) from 30.5 to 15.5 percent? The quantity of water

that must be removed is computed using Equation 54:

(1 kg)*(30.5-15.5)
(ICC-30.5)

 

WATERU = = 0.216 kg

The energy requirements for one unit of 15.5 percent moisture
grain may be estimated from Equation 55 using a drying efficiency of

45 percent.

(0.216 kg)*(589 kcal/kg)*(100)=

45 283 kcal

ENERNU =

In the previous example for grain at 30.5 percent moisture con-
tent, the energy to the dryer from each wet biomass component was 2045,
328 and 1071 kcal/kg for grain, cobs and stover, respectively. The
percentage of the wet biomass components needed for drying is the
ratio of energy requirements to energy availability. Using Equations

56, 57 and 58:

_ 283 kcal * =
PCWTGU "264§‘EEZI 100 13.8 percent

283 kcal

PCWTGU ‘ 328 kcal

* 100 = 86.3 percent

37

_ 283 kcal * =
PCWTSU - I67T7EE§I 100 26.4 percent

In other words, for the conditions given, either 13.8 percent of the
grain, 86.3 percent of the cobs, or 26.4 percent of the stover would
be required to dry one unit of 15.5 percent moisture grain from 30.5
percent. This would be equivalent to 11.4 percent of the grain, 70.8
percent of the cobs, and 21.7 percent of the stover based on 30.5
percent moisture grain rather than the 15.5 percent base. The rela-
tionships between moisture content of the grain and the proportion

of biomass needed for drying are shown in Figure 11.

To this point, an engineering analysis of biomass energy avail-
ability has been completed. The example problem indicates that suffi-
cient energy exists in each category of biomass to dry the grain when
using conservative estimates of system performance. The next question
involves the economic feasibility of gasification. The following
chapter addresses this topic by examining gross return as determined
by LP gas replacement cost, harvesting and transportation costs, soil
productivity changes, alternative uses of biomass, and gasification
equipment cost estimates. The chapter concludes by presenting the

procedure used for determining break-even investment.

38

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CHAPTER VI

ECONOMIC CONSIDERATIONS

At this point in the analysis, the economic question becomes one
of determining if biomass can be used as a fuel source for grain dry—
ing for less money than the value of the LP gas saved. Initially,
gross return from LP gas savings will be presented followed by a

discussion of biomass cost considerations.

A. Cross Return from Savings of LP Gas

The dominant fuel used from grain drying in the U.S. is LP gas.
LP gas prices have increased rapidly following the upward spiral of
energy costs in general. Presently, U.S. farmers are paying 50 to
60 cents per gallon of LP gas, which contains approximately 6125
kcal/1 (2.56 x 107J/1; 92,000 Btu/gal).

Referring back to the example in Chapter V, Section F, the dry-
ing efficiency assumed was 45 percent. When using LP gas, the effi-
ciency of converting the gas to thermal energy available for drying
must also be considered. The usual value given for this efficiency
is 80 percent. The quantity of energy in LP gas needed to remove
the specified quantity of water from the grain is obtained using
Equation 54, repeated below, and a modified version of Equation 55.

(GRAINU)*(§IMC-GFMC)
(lOO-GIMC)

where WATERU = the units of water to be removed during
drying per unit of grain, GFMC base

WATERU .. (54)

39

GIMC

GFMC

GRAINU

NOTE:

ENERNU

where ENERNU

HVAP
DEFF

THEFF

The quantity of LP

QLPG -

where QLPG

EPQLPG

40

initial moisture content of the grain,
percent wet basis

final (or desired) moisture content of the
grain after drying, percent wet basis

units of grain to be dried, GFMC base

GRAINU and WATERU are measured in the
same units.

WATERU * HVAP * 10000

 

The cost for this quantity of gas is:

COSTLP

where COSTLP

PPULPG

= THEFF * DEFF (59)
= energy required per unit of grain dried,
GFMC base
= heat of vaporization of water
= drying efficiency, percent
= thermal conversion efficiency for LP gas
burners, percent
gas needed is:
_ ENERNU
EPQLPG (60)
= quantity of LP gas needed per unit of
grain to be dried, GFMC base
= energy per quantity of LP gas
= QLPG * PPULPG (61)

cost of LP gas per unit of grain
dried, GFMC base

price per unit of LP gas

In the example problem, the water to be removed from 1 kg of

15.5 percent moisture grain being dried from 30.5 to 15.5 percent

moisture content was computed to be 0.216 kg.

Using Equation 59:

ENERNU 8 (0.216_kg) * (589 kcal/kg) * (10000)

(80) * (45)

353 kcal/kg of grain, 15.5 percent base

41

The quantity of LP gas needed for drying one kg of 15.5 percent

moisture grain is computed from Equation 60:

353 kcal/kg
6125 kcal/l

 

QLPG = = 0.057 1/kg

The cost equivalent of $0.50/gallon LP gas is approximately $0.132
per liter. Therefore from Equation 61, the total cost of drying per
kg of 15.5 percent moisture grain is:

COSTLP = (0.057 l/kg grain)*($0.132/l) = $0.00752
This would be equivalent to a cost of $0.192 per 15.5 percent moisture
bushel for 15 points of moisture removal, and represents the gross

return for using biomass gasification equipment.

B. Harvesting and Transportation Costs

 

Grain

The form of biomass most often collected on grain farms is grain
itself. The primary advantages of using grain as a source of fuel
are (1) no additional machinery is required for gathering and hand-
ling, (2) the material is easily transported, marketed and stored for
future use, (3) the material is flowable, and (4) the grain contains
relatively high levels of energy per unit weight when compared to
cabs and stover.

The cost of harvesting might be considered either the custom
charge or the average ownership cost. Schwab (1975) stated that the
average custom charge for a combine-sheller in Michigan was $13.03 per
acre. The average yield in Michigan that year was 80 U.S. No. 2
bushels per acre which would correspond to $0.163 per bushel for har-
vesting. Custom rates for delivery to the grain facility would cost

approximately $0.02 per bushel based on delivering 400 bushels per

42

hour and an $8.00 rental charge for the truck bringing the total custom
charge to $0.183 per bushel. Hinton and Walker (1971) reported on cus-
tom rates in Illinois. When adjusted to 1975 prices by the Consumer
Price Index (CPI), the cost for combining and hauling corn was $0.173
per bushel which would compare favorably with the value computed pre-
viously. Schlender and Figurski (1975) reported an average custom har-
vesting rate of $0.18 per bushel for Kansas, not including hauling.
From these studies, a custom combining charge for corn of $0.18 per
bushel, including hauling, seemed to be representative for 1975. If
the CPI were 224, somewhat representative of 1980, the custom rate
would be $0.25 per bushel ($0.00446/1b; $0.00984/kg). The moisture
content of the bushel was not specified in any of the above studies.

The cost of combine ownership may be approximated using the
following parameters (Campbell, 1978):

Average annual interest - 7.5% of purchase price (PP)

Annual depreciation (7 yr life, - 14.3% of PP
zero salvage, straight line method)

Repair and maintenance - 8.6% of PP
Taxes, insurance, housing - 2.0% of PP

32.4% of PP

 

Estimated fixed cost

Estimated life, total in 7 yr - 2000 hours
Estimated purchase price - $60,000
Harvesting rate — 400 bu/hr

Operator labor $5.00 per hour

Fuel and lube cost $6.25 per hour

(diesel @ $1.25/gal)

These figures indicate an annual cummulative charge of 32.4 per-
cent of purchase price or $19,440. This equals $68.04 per hour of

machine life. The fixed cost per bushel is $0.17. To this is added

43

the total variable cost of $11.25 or $0.028 per bushel for a total
ownership cost of approximately $0.20 per bushel.
The same assumptions apply for a farm delivery truck except for
the following:
Purchase price - $14,000.00

Fuel and lube — $ 1.56 per hour
(operating 25% of time)

Hauling rate - 400 bu/hr
The fixed cost is $15.88 per hour and the variable cost is $6.56 per
hour for a total of $22.44 per hour or $0.0561 per bushel.

From these calculations, the total per bushel cost of combining
and hauling the grain is about $0.26 per bushel or essentially the
same as the custom rate computed previously. Of course, the com-
puted cost could vary considerably with changes of the input assump—
tions. Likewise, the present interest rate and fuel charges have

risen considerably faster than the general CPI.

Cobs
Cobs may be gathered in several ways including:
1. Harvesting the cobs in broken form and mixing the
material with the grain during harvesting (Horsfield,
Doster and Peart, 1977).
2. Collecting cobs in a separate wagon during the
harvesting operation (Bargiel et al., 1979).
3. Harvesting ear corn and separating the cobs from
the corn at the drying site.
The first method would involve some modification of present-day

harvesting machinery with regard to the mechanisms involving separation

44

of cob and grain after shelling occurs. This would probably not be
a major problem. The addition of broken cob to the grain was esti-
mated by Horsfield et al. (1977) to require an increase in harvest-
ing volume of 15 percent. Using this figure, the estimated total
cost of harvesting and transportation would also increase to $0.30
from $0.26 per bushel of grain. This would translate to an addi-
tional charge of $0.04 per harvested bushel if cobs were collected
with grain.

The method presented by Bargiel et al. (1979) utilized an
attachment much like a straw spreader to direct cobs to a wagon
being pulled by the combine. No estimates of cost were given, but
the power requirements were similar to a straw spreader and the
device was reasonably simple in design. The additional cost would
be for combine design modifications, a forage wagon, transportation,
and the added fuel needed for the combine. This cost should be no
greater than the cost of transporting the grain, $0.06 per bushel
equivalent. Another cost estimate is $13.33/dry ton of cobs collected
behind a combine (Williams, McAniff and Larson, 1979). This assumes
a 25 percent moisture content and is equivalent to $0.85 per million
Btu's of cob energy value.

All of the equipment needed to harvest ear corn is available.
The question is whether it is more economic to do the shelling at
a central location where drying occurs, or separate the grain from
the cob in the field using the present technology. Custom rates
given by Schwab and Gruenwald (1978) indicated that rates for har—

vesting ear corn were $3.12 per acre less than combine harvesting.

45

The custom rate for shelling ear corn from the crib averaged $0.09
per bushel. For a yield of 90 bushels per acre, the ear corn har—
vesting system would cost nearly $0.06 per bushel more than the

conventional combine system.

Stover

Stover may be collected from the field using standard baling
equipment. Schwab and Gruenwald (1978) stated that the average
custom charge per bale for hauling and baling straw was $0.27, the
bales weighing 40-55 pounds each. The custom rate for big bale
balers was $5.79 for straw bales, each weighing 1000 to 1500 pounds.
When using mechanical long hay stackers, the custom rate for straw
stacks weighing not over 2 tons was $20.00. If over 2 tons, the
charge was $25.00.

Hillman and Logan (1979) estimated the total harvesting and
feeding cost per ton for several different forage systems over a
range of yearly capacities. The cost per ton varied from $9.77 to
$14.68 per ton, the average being $11.82 for an annual capacity of
500 tons. The average was $8.91 per ton when 1000 tons per year
were harvested. These values would compare favorably with those
presented in other studies (Fairbanks et al., 1977; Stout, 1979).
Stout gives the average cost per ton in the mid-west to be $16.01
but this includes a uniform haul distance of 15 miles.

Stout (1979) provides a rather detailed analysis of cost compu-
tations involving labor, diesel fuel and equipment costs. The

following equations apply:

46

For large round bales,

10.85

= *
TCPTNR 6.30 + RESIDU + 0.182 DIST (62)
For large stacks,
TCPTNS = 2.61 + 133— + O.276*DIST (63)
RESIDU

where TCPTNR total cost per ton (dry) for large

round bales

TCPTNS = total cost per ton (dry) for large
stacks
RESIDU = harvestable residue, tons (dry)
per acre
DIST = one-way haul distance, miles.

For example, if the grain is a 30 percent moisture, there would be
42.3 percent stover per acre (Equation 6). Assuming a dry weight
yield of 100 bushels per acre, the dry stover present is 5105 pounds,
or 2.55 tons. If the one-way hauling distance is 1 mile, the cost
per dry ton for large round bales is:

TCPTNR = 6.30 + 313% + 0.182*1 = $10.74
For large stacks, the cost per dry ton is:

TCPTNS = 2.61 + 32%? + 0.276*1 = $6.70
When converted to a 60 percent wet basis, the cost per wet ton is

$6.72 and $4.20 for large round bales and large stacks, respectively.

C. Soil Productivity

There are many arguments to be made both against and in favor of
biomass removal (Robertson and Mokma, 1978). First, it should be
remembered that approximately half of the biomass, in terms of dry
matter, is already removed in the form of grain. The remaining cabs

and stover are the primary source of organic matter which aids in

47

the formation of a stable soil structure. In addition, the stover
and cobs add to soil fertility levels and help reduce soil erosion.
How are important are these factors? Soil organic matter levels
influence the physical condition of the soil and in turn are associ-
ated with power requirements for tillage, water infiltration levels,
and oxygen diffusion rates. However, the effects would appear to be
more long-run, hence part of the difficulty in assigning short term
economic costs. For example, Robertson and Mokma (1978) stated that
root growth rates were slow and crop yields were less than optimum
when bulk density values were less than 1.3 gms/cc, a condition already
prevalent on most of Michigan's soils. This bulk density is approxi-
mately equivalent to a 3 percent organic matter level. The upper
6 inches of soil weighs approximately 2 million pounds per acre. If
9000 pounds of residue from 150 bushel per acre corn are incorporated
into the soil and if all of it were converted to organic matter with
no losses, this would change the organic matter level by 0.45 per-
cent. If only 25 percent of the residue was used for drying, the
difference would be approximately 0.11 percent per year in organic
matter. This says nothing about the normal disappearance of organic
matter from the soil.
The nutrient contents of the biomass components are presented
in Table 2. Of these items, only nitrogen is really affected in
that the remaining nutrients may be recovered after the gasification
process and again applied to the soil as with fertilizer. Even
with nitrogen, the situation is not clearly stated because over the

winter the losses from the stover and cobs to the air, through

.eoeumeeoasemea oaz ou mememak

 

48

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m~.H uw>oum :uoo

Ammaumoua .oz .wmavk
me.o meou anoo

mma1~oue ens
Hmmnwoue .oz .eemvk
oe.~ cameo anon

 

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auwouuwz
unmoumm

 

.AoooH .mwuumm was souaEmuov mmmaown :uoo mo uamuaou unmauuaz .N oases

49

the soil, and from run-off may totally negate any benefits from this
source of nitrogen.

Crop residue reduces soil losses from both wind and water
erosion. The relative importance of erosion varies with climate
and soil type. For Michigan conditions, water erosion is the more
important. Data presented by Robertson and Mokma (1978) showed that
the potential soil loss was greatest when fall plowing with a mold-
board plow. The second greatest soil losses occurred on land used
for silage and plowed in the spring. Chisel plowing in the fall
resulted in the third greatest soil loss. The best practice to
follow in terms of reducing water erosion was to leave the residue
standing in the field and spring plow. However, in all instances the
expected soil losses exceeded the tolerable loss, the magnitude of
the difference being primarily a function of soil type and the length
of the slope. In the case of spring plowing, there was no differ-
entiation as to the proportion of losses that occurred before plowing
as compared to afterwards.

A study by Mannering and Meyer (1963) suggested that one ton
of uniformly distributed crop residue per acre would be sufficient
to control water erosion. Buchele (1975) reported that 1 to 1.5
tons of cornstalk residue per acre could control erosion under Iowa
conditions if the material were managed correctly. In addition,
he suggested that the removal of some of the residue might reduce
the need for tillage operations specifically geared to incorporating
the cornstalks into the soil. When considering the cost for
nitrogen replacement and harvesting, and the savings associated

with reduced tillage requirements, Buchele's cost estimates showed

50

only an increased cost of $1.07 per acre for removing one ton of
material per acre, not considering transportation. For a yield of
100 bushels per acre, the equivalent cost would be approximately
$0.01 per bushel.

Considering all factors, it would appear that soil erosion can
be minimized using currently available cultural practices so long as
1 to 1.5 tons of the crop residue remain. For the earlier example of
drying 30.5 percent moisture corn to 15.5 percent, only 26.4 percent
of the available stover was used, much less than the minimum needed
for erosion control. Therefore, the cost of reduced erosion control
will be neglected in so far as this study is concerned.

The value of the nutrients lost due to gasification may be ignored,
except for nitrogen, assuming they will be replaced in the soil after
gasification. The value of the lost nitrogen may be estimated using

the following equations:

CSTNRG . 1.6*GDWT*RNSPC*CSTUN*GUGPC*10’6 (64)
CSTNRC - 0.45*CDWT*RNSPC*CSTUN*CUGPC*10'6 (65)
CSTNRS . 1.15*SDWT*RNSPC*CSTUN*SUGPC*10‘6 (66)

where CSTNRG, CSTNRC, CSTNRS = cost of nitrogen
replacement because of biomass removal,
for grain, cobs and stover, respectively

GDWT, CDWT and SDWT 8 dry weight units per unit
of wet grain for grain, cobs and stover,
respectively, in relative proportion to
each other (Equations 7, 8, 9, 13)

RNSPC = percentage of nitrogen retained by the
soil and available for crops the
following year

CSTUN = cost of nitrogen per unit

CUGPC, CUGPC, SUGPC = the percentage of grain, cabs
and stover, respectively, that are utilized
in drying

51

In the example used previously, corn was to be dried from 30.5
11115.5 percent moisture.The moisture contents of both the cobs and
stover was computed to be 61 percent. The proportional dry weights
for grain, cobs and stover were 0.695,0.171 and 0.637 kg, respective-
ly. Likewise, the percentages of grain, cobs and stover required to
dry the grain were 13.8, 86.3 and 26.4 percent, respectively. A
representative cost for nitrogen is $.44/kg ($0.20/lb), and expected
losses over the winter would be approximately 20 percent, or an
80 percent retention factor (Vitosh, Lucas and Black, 1979). Using

these values in Equations 64, 65 and 66:

CSTNRG = 1.6*O.70kg*80%*$0.44/kg*13.8*10’6
= $0.00054/kg or $0.0137/bu

CSTNRC = 0.45*0.171kg*80%*$0.44/kg*86.3%*10‘6
= $0.00023/kg or $0.0058/bu

CSTNRS = 1.15*0.637kg*80%*$0.44/kg*26.4%*1O‘6

$0.00068/kg or $0.0173/bu

From these calculations, the removal of biomass from the soil for
purposes of grain drying would have sufficient economic impact with
regard to nitrogen replacement to be included in the study.

In summary, the effects of biomass removal in the quantities
required for drying do not seem to have significant short term costs
for erosion control. Instead, it appears that management practices,
such as plowing and residue distribution are more important con-
siderations than residue removal alone. From this analysis, no
opportunity costs will be assigned to gasification in this study
based on erosion control. This is not to say, however, that the long

term effects under improper management might not be important. Only

52

nitrogen loss will be considered with regard to nutrient loss and
then only for cobs and stover for reasons stated in the following

section.

D. Alternative Uses

 

In the previous section, the opportunity cost of biomass was
defined in terms of soil productivity. However, greater opportunity
cost would typically be reflected in the market value of the material.
In the case of grain, the market value is approximately $2.50 per
bushel. However, for the grain farmer, cobs and stover have tra-
ditionally had no market value, except in those cases where indivi-
duals were able to use this material for animal feed. Therefore,
for the boundaries of this study, only the grain will be considered
to have a non—zero opportunity cost, recognizing that in the longer
run stover and cobs may develop into valuable energy sources that
may compete with gasification for grain drying.

Using the previous example and corn at $2.50 per bushel
($0.10/kg) the Opportunity costs for grain, cobs and stover may
be computed using the following general equation:

MVBU*PCBUGA/ 100 (67)

OPCST

where OPCST opportunity cost per unit of grain dried

MVBU = market value of the biomass per unit
of material

PCBUGA percent of biomass used per unit of

grain dried
For our example, the opportunity cost of gasification when 13.8 per-
cent of the grain is required to dry the remaining portion is:

OPCST = $0.10/kg*13.8%/100 - $0.0138/kg

53

This would be equivalent to $0.35 per bushel, or nearly twice as
much as the cost of LP gas computed earlier for 15 points of moisture

removal.

E. Gasification Equipment Costs

 

There is little data on which to estimate the capital cost of
a farm size gasification unit in that they are not produced on a large
scale. Goss and Williams (1977a) estimated the cost of a commercial
gasification unit to be $3000/(ton-day) plus additional cost for
piping, burners and controls, bringing the capital cost to approxi-
mately $4400/(ton-day). Typical burners for farm dryers range from
approximately 2 to 5 million Btu/hr capacity (0.5-12.6 kcal/hr;
2.1 x 103 - 5.3 x 103 J/hr). In the example problem, the quantities
of wet biomass needed to dry 1 kg of grain was found to be 13.8 per-
cent of the grain, 86.3 percent of the cobs and 26.4 percent of the
stover. For each kg of 30$5percent moisture grain, there is 0.439 kg
of wet cobs and 1.651 kg of wet stover. Therefore, the drying of 1
kg of 30.5 percent grain each day requires approximately 0.14 kg of
grain or 0.36 kg of cobs or 0.42 kg of stover. This would translate
to an estimated capital cost per kg of wet grain of $0.68, $1.74 and
$2.04 for a gasification unit processing grain, cobs and stover,
respectively. On a per wet bushel basis, the corresponding capital
costs are $17.25, $44.35 and $51.74.

Perhaps the closest comparison to a gasification unit would be
an incinerator (Rubel, 1974). Using the same basic information as
above, the 1969 incinerator cost for a unit that could dispose of

1 kg of grain, 0.36 kg of cobs and 0.42 kg of stover each day would

54

be $0.31, $0.80, and $0.91, respectively, when adjusted to 1977 prices.
On a per wet bushel dried basis, the corresponding costs would be
$7.87, $20.32 and $23.12.

The above two references do give some range of prices that one
might expect for a gasification unit. Both sets of prices are based
on 24 hours of operation. In grain drying, the time of operation
per day may be considerably less than 24 hours. If, for example, the
dryer was to operate only 12 hours per day, the cost of the unit would
double due to the doubling of the required hourly capacity.

In that there is no exact cost information, the maximum amount
of money that may be invested in a gasification unit will be calcu-
lated using present value analysis. This requires that certain
annual costs be considered including interest, taxes, insurance,
maintenance, repair and depreciation.

The following annual costs would be typical for a machine of
this type:

1. Interest: 15 percent of purchase price com-
pounded yearly for an average annual
rate of 7.5 percent considering no

salvage value.

2. Taxes and Insurance: 1 percent of purchase
price per year.

3. Maintenance and Repair: 4 percent of purchase
price per year.

4. Depreciation: 10 percent of purchase price per
year based on straight line depreci—
ation and a 10-year machine life.
Other items of consideration are investment credit and the tax

bracket of the particular individual. Investment credit would be

nearly equivalent to a 10 percent reduction in purchase price

55
assuming present law and a lO—year life for the gasification unit.
The income tax bracket tends to reduce both the profits and the

losses associated with the investment.

F. Break-even Investment

 

The major objective of this study is to determine the break-
even capital investment in gasification equipment for grain drying.
For purposes of this analysis, cost considerations that may be unique
to an individual will not be considered, i.e. tax bracket, investment
credit, and depreciation. In that way, the results apply more readi—
ly to all individuals although each would have to make modifications
to reflect his unique situation.

Break-even capital investment is defined as the amount of money
that may be invested in equipment so that the gross return will equal
the gross expenses. Gross return is defined as the annual equivalent
cost of LP gas if used as a source of energy for drying. Annual
gross expenses include the cost of harvesting and transportation;
replacement value of nitrogen lost due to gasification; opportunity
costs of the biomass as a function of market price; and repair,
operation and maintenance costs of the gasification equipment.

The following equations are used to determine the break-even
investment cost per unit of wet grain dried where "wet" grain is

referenced to either its initial or final moisture content.

ENERNU*PPULPG
EPQLPG

 

CQLPQ = (68)

where CQLPQ = cost of the quantity of LP gas needed
per unit of wet grain to be dried

ENERNU = efficiency adjusted energy requirements
per unit of wet grain dried by LP gas
(determined using Equation 59)

PPULPG

EPQLPG

QWWT

where QWWT

ENERNX

ENPWTU

GEFF

HTCST

where HTCST

HTCPU

VNREM

where VNREM

PCN

QDRYB

RNSPC

QUGPC

56

price per unit of LP gas
energy per quantity of LP gas

ENERNX*100

 

ENPWTU*GEFF (69)

quantity of wet biomass needed to
dry one wet unit of grain

adjusted energy requirements per unit
of wet grain dried by biomass
(determined from Equation 55)

energy available for drying one wet
unit of grain after adjusting for
internal moisture

(determined by Equations 31-39)

efficiency of the gasification process,
percent

HTCPU*QWWT (70)

harvesting and transportation cost per
unit of wet grain dried

harvesting and transportation cost per
unit of wet biomass

PCN*QDRYB*RNSPC*QUGPC*10‘6 (71)

value of the nitrogen removed per unit
of wet grain dried
(see Equations 64-66)

percent of the dry biomass composed of
nitrogen

dry weight of biomass available for
gasification per unit of wet grain
(see Equations 7, 8, 9 and 13)

percentage of nitrogen retained by the
soil and available for crops the next year

percentage of biomass available that is
utilized in drying one wet unit of grain
(see Equations 56, 57 and 58)

MARVAL

where MARVAL

MPRICU

GROSAV

where GROSAV

PWF

where PWF

SPWF

where SPWF

GPVAL

where GPVAL

BEGASE

where BEGASE

AMAIN

AMGASE

57

MPRICU*QUGPC/100 (72)
market value of biomass per unit of
wet grain dried

market price per unit of biomass

CQLPQ-HTCST-MAX(VNREM,MARVAL) (73)
gross savings per year associated with

using the gasification process, on a

per wet unit of grain dried basis

1.0/(1.0+I)**n (74)
present worth factor for a given year

that when multiplied times a future

return will give its present value

annual interest rate, decimal

years from present

((1.0+I)**L-1.0)/(I*(1.0+I)**L) (75)
present worth factor that will give the
present value of a uniform series of
payments when multiplied by the annual
return

life of the gasification equipment in

years

n
2 PWF(j)GROSAV (j)
3‘1

(76)

gross present value of the annual stream

of gross savings
GPVAL/(1.0+(AMAIN/100.0)*SPWF) (77)
break-even investment cost per wet unit

of grain dried for gasification
equipment

annual charge for maintenance, repair
operation of gasification equipment,
percent

BEGASE*AMAIN/100.0 (78)

58

where AMGASE = annual charge per wet unit of grain
dried for maintenance, repair and
operation of gasification equipment
However, if "BEGASE" is negative, another alteration is required
to show that if the gasification equipment is purchased, the mainten-
ance and operation expense decreases the break-even investment even

more. This is discussed in greater detail later in this section.

BEGASE = BEGASE + SPWF * AMGASE (79)
(new value) (Equation 77 value)

Using Equations 68-78, the break-even investment cost for
gasification equipment may be calculated for the previous example.
The cost of LP gas is calculated using the value obtained in Equation
59 for ENERNU and converted to Btu's per dry bushel. An LP gas price
of $.50 per gallon is used and a fuel energy content of 92,000 Btu/gal
is assumed. A dry bushel is defined as 56 pounds of corn that is at
15.5 percent moisture content after drying (U.S. No. 2).

ENERNU*PPULPG
EPQLPG

= 35280 Btu/bu*$.50/gal
92000 Btu/gal

 

CQLPQ =

 

$0.1917 per dry bushel dried

The quantity of wet grain, cobs and stover needed to dry one
dry bushel of grain are computed using values determined previously
and converted to a Btu per dry bushel dried basis.

ENERNX*100
ENPWTU*GEFF

 

war=

28224 Btu/bu*100

6188 Btu/lb*60 = 7.60 wet pounds per

dry bushel dried

For grain: QWWT =

28114 Btu/bu*100

For cobs: QWWT ‘ 2326 Btu/b1*60

- 20.22 wet pounds per
dry bushel dried

59

28224Btu/bu*100
20238tu/1b*60

 

For stover: QWWT = = 23.25 wet pounds per

dry bushel dried
The cost of harvesting and transporting the biomass can be
calculated using Equation 70. Assume that a 56 lb bushel may be har-
vested for $0.26 and that similar costs are $5.00 and $10.00 per ton

of wet material for cobs and stover, respectively.

For grain: HTCST 26¢/bu*7.601b/56lb/bu

3.53¢ per dry bushel dried

For cobs: HTCST 500c/ton*20.221b/20001b/ton

= 5.06c per dry bushel dried

For stover: HTCST 1000c/ton*23.251b/20001b/ton
= 11.63c per dry bushel dried
The value of the nitrogen lost from the field has previously

been calculated using Equations 64, 65 and 66.

For grain: VNREM

1-37¢ per dry bushel dried

For cobs: VNREM

0.58¢ per dry bushel dried

For stover: VNREM

1.70¢ per dry bushel dried
A typical market value for grain would be $2.50 per bushel based
on 15.5 percent moisture content. This would be equivalent to $2.07 per
bushel for 30.5 percent moisture grain. For purposes of this
study, cobs and stover have no market value.

For grain: MARVAL = 207c/bu*7.60lb/56lb/bu = 28.09¢ per dry
bushel dried

For cobs: MARVAL = 0
For stover: MARVAL = 0
There is now sufficient information to compute the gross savings

using Equation 73. Note that the maximum cost of either the nitrogen

60

removed or the market value will be considered but not both. This

is to say that the market value reflects the total worth of the

biomass including the nitrogen removed from the soil. One would

usually expect the market price to exceed the nitrogen value con-

tained with the material.

and stover, the nitrogen
In the example problem:

For grain: GROSAS

For cobs: GROSAS

For stover: GROSAS

If not, as is the case assumed for cobs

loss is the opportunity cost considered.

19.17¢-3.53¢-MAX(1.37¢, 28.09¢)
-12.45¢ per dry bushel dried
19.17¢-5.06¢-MAX(0.58¢, 0)
13.53¢ per dry bushel dried
19.17¢-11.63¢-MAX(1.73¢, 0)

5.82c per dry bushel dried

For purposes of this example, the life of the gasification equip-

ment will be 10 years and the interest rate 15 percent per year. From

Equation 74, PWF may be determined for each year.

Year 1: PWF =
Year 2: PWF =
Year 3: PWF a
Year 4: PWF =
Year 5: PWF =
Year 6: PWF =
Year 7: PWF =
Year 8: PWF =
Year 9: PWF =
Year 10: PWF =

From Equation 75:

SPWF =

0.8696
0.7561
0.6575
0.5718
0.4972
0.4323
0.3759
0.3269
0.2843
0.2474

((1.0+0.15)**10-1.0)/(0.15*(1.0+0.15)**10)

5.019

The gross present value is computed using Equation 76.

61

For grain: GPVAL

0.8696*(-12.45¢)+0.7561*(-12.45¢)+0.6575
*(-12.45¢)+0.5718*(-12.45¢)+0.4972*(-12.45¢)
+0.4323*(-12.45¢)+0.3759*(-12.45¢)+0.3269
*(-12.45¢)+0.2843*(-12.45¢)+0.02474*(-12.45¢)

= -62.49¢ per dry bushel

Similarly,

For cobs: GPVAL 67.90¢ per dry bushel dried

For stover: GPVAL

29.16¢ per dry bushel dried

These values can be calculated somewhat easier than in the above
example for situations where the annual return is constant over the
life of the equipment. However, this will not always be the case
as with escalating real energy prices.

Part of the gross present value must be used to maintain and
operatethe gasification equipment if it is purchased. For this
example, 4 percent of the purchase price will be charged each year
for maintenance and operation. The break-even investment can be
calculated using Equation 77:

For grain: BEGASE = -6Z.49¢/(1.0+(4.0/100)*5.019)
= -52.04¢ per dry bushel dried

For cobs: BEGASE

67.90¢/(1.0+(4.0/100)*5.019)
= 56.55c per dry bushel dried

For stover: BEGASE

29.16¢/(1.0+(4.0/100)*5.019)
= 24.28¢ per dry bushel dried
The annual charge for maintenance and operation may now be
computed using Equation 78:
For grain: AMGASE = -52.04¢*4.0/100

= —2.08¢ per dry bushel dried

62

56.55¢*4.0/100

For cobs: AMGASE

= 2.26c per dry bushel dried

For stover: AMGASE 24.28¢*4.0/100
= 0.97c per dry bushel dried
Because BEGASE has a negative value, an adjustment must be made

by using Equation 79.

For grain: BEGASE

-52.04+(5.019)*(-2.08)
= -62.49¢ per dry bushel dried

Notice that this value is actually the same as the gross present
value calculated previously using Equation 76.

For our example, there is a negative break-even investment for
using grain as a source of fuel for grain drying. There are several
ways in which the negative value should be interpreted. First, a
negative investment simply reflects a negative annual return which
means the machine will not pay for itself. Another interpretation is
that the negative investment is the present value of the annual losses.
The annual losses include the gross savings (actually gross losses)
and the maintenance and operation charges for the equipment. The
annual losses perchsr bushel times the number of dry bushels dried
yield the total value per year that must be returned by other uses
of the equipment besides grain drying if the investment is to break

even .

G. Concluding Remarks
At this point in the analysis, both the technological and
economic implications have been examined. The following represents

a descriptive summary of the evaluation:

63

The relative and absolute quantities of grain, cobs and

stover may be determined based on the grain moisture con-

tents for which the grain is considered mature enough for

harvesting.

The energy available for drying can be estimated based

on biomass moisture content, and gasification and drying

efficiency.

The present value of the annual gross return to gasification

is defined as the present value of the cost savings from

not using LP gas in grain drying.

The annual net return available for purchase of gasifica-

tion equipment may be determined by subtracting from the

annual gross return the following items:

(a) harvesting and transportation costs of the biomass;

(b) opportunity costs, i.e. market value of the biomass,
or the value of the nitrogen losses, whichever is
greater; and

(c) maintenance, insurance and operational costs for
gasification equipment.

The cost for harvesting grain, cobs and stover is usually

based on the weight of wet material rather than dry material.

In fact, moisture content is not usually considered at all

when establishing custom rates.

The effects of biomass removal on soil productivity are

somewhat site specific; that is, nutrient removal may be

calculated easily but the effects of erosion and losses

64

in organic matter will not have the same effect on yield
in every location.
The same example problem has been presented through the text.
How representative is this example? The initial moisture content of
the grain, 30.5 percent wet basis, would be considered close to the
upper bound for normal grain harvesting operations. The drying
efficiency of 45 percent would be typical of a high temperature
(180-2200 F) drying system. The energy supplied by LP gas would
represent over 95 percent of the energy required for drying, the
remainder being for electricity to power the fans. However, fan
operation would be required regardless of the energy source for heat-
ing the air.
The problem now becomes one of determining the influence of the

various physical and economic factors on break-even investment.

CHAPTER VII

ECONOMIC FEASIBILITY OF GASIFICATION

A. Introduction

 

In the preceding chapters, 3 series of equations have been
presented that may be used to determine the physical and economic
feasibility of gasifying corn grain, cobs and stover for purposes of
drying grain. Either single or a range of values have been given
for the physical and economic parameters considered. In this chap-
ter, the sensitivity of the gasification system to changes in certain
physical and economic conditions will be explored. The mechanism
for doing this is a computer program which incorporates the equations

and concepts presented in previous chapters. (See Appendix.)

B. Base Condition

 

A base condition is defined as the set of parameters considered
most representative for determining the break-even investment cost
for gasification equipment. For this study, the base conditions are
given in Table 3. All values presented in the following analyses
are determined by changing one of the base conditions while holding
the remaining values constant. This is commonly referred to as a
sensitivity analysis. Again, a dry bushel is defined as 56 pounds of

corn at 15.5 percent moisture (U.S. No. 2).

65

66

 

 

Table 3. Base values of inputs used in sensitivity analysis.

No. Input Description New Value
1 Initial grain moisture, percent 25.50
2 Desired final grain moisture, percent 15.50
3 Gross energy in grain, Btu/dry 1b 9995.00
4 Gross energy in cobs, Btu/dry lb 7961.00
5 Gross energy in stover, Btu/dry lb 7150.00
6 Percent adjustment for bomb calorimeter 93.00
7 Percent efficiency of LP gas burner 80.00
8 Percent efficiency of drying process 45.00
9 Percent efficiency of gasification process 60.00

10 Nitrogen content in grain, percent of dry weight 1.60

11 Nitrogen content in cobs, percent of dry weight 0.45

12 Nitrogen content in stover, percent of dry weight 1.15

13 Heat of vaporization of water, Btu/lb 1060.00

14 Price of LP gas in year No. 1, c/gal 50.00

15 Constant change per year in LP gas price, c/gal 0.00

16 Change in LP gas price, percent from previous year 0.00

17 Price of nitrogen, ¢/lb 20.00

18 Percent/year for maintenance of gasification

equipment based on purchase price 4.00

19 Annual interest rate, percent 15.00

20 Economic life of gasification equipment, years 10.00

21 Harvest-transport cost for grain, c/bu @ 56lb/bu 26.00

22 Harvest-transport cost for cobs in field,

$/ton of wet material 5.00

23 Harvest-transport cost for stover in field,

$/ton of wet material 10.00
24 Market value of grain at 15.5 percent moisture,
$/bu 2.50

25 Market value of cobs in field, $/wet ton 0.00

26 Market value of stover in field, $/ wet ton 0.00

27 Retention rate of biomass nitrogen by soil, percent 80.00

 

Computed base break-even investment costS, ¢/dry bushel (U.S. No.2)

Grain
Cobs

Stover

-37.56
38.88
23.49

 

67

C. Sensitivity Analysis

 

The objective of the sensitivity analysis is to determine the
relative importance of an exogenous variable with respect to endo-
genous variables. For this study, the sensitivity analysis is used
primarily to determine the effects of changing a "base condition"
variable with regard to the break-even investment for gasification
equipment. Generally, the base condition changes are broad and are
not intended to reflect normally expected input values but rather
extreme input differences. Radical changes permit the vigorous test-
ing of equation logic and tend to expose errors more readily than

when using "typical" input values.

The base conditions may be categorized into two broad categories
of factors: physical and economic. An estimate of the net effects of
simultaneously changing more than one base condition may be obtained

by summing the effects of each separate change.

D. Physical Factors

 

Gasification Efficiency (Figure 12)

The efficiency of the gasification process has moderate economic
implications. References cited previously indicate that gasification
efficiency may reach 80 percent. An 80 percent efficiency, as compared
to the base condition efficiency of 60 percent, increases the break-
even investment for cobs, stover and grain by approximately 3, 7 and
14¢, respectively. The effect is more pronounced when using grain as
a fuel source because it has a relatively high market value. Note,
as the efficiency of the gasification process nears 100 percent, the

break-even investment cost becomes positive for using grain as fuel.

68

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69

LP Gas Burner Efficiency (Figure 13)

The efficiency of converting LP gas to heat energy through a
conventional burner is usually estimated to be 80 percent and it is
unlikely that it deviates greatly from that value. However, it does
have significant economic implications in that it directly influences
the quantity of LP gas required for drying. In fact, the break-even
investment cost for using grain as a fuel source nears a positive

value when the burner conversion efficiency apporaches 50 percent.

Drying Efficiency (Figure 14)

As drying efficiency increases, the break-even investment cost
narrows between using LP gas and biomass. The narrowing occurs
because the relative quantities of fuel needed for drying increase
with a decrease in drying efficiency. Thus, the relative break-even
investments for using cobs or stover tend to decrease with an increase
in drying efficiency. If the fuel source is grain, the break-even

investment tends to increase.

Adjustment to Bomb Calorimeter Data
(Figure 15)

The base condition for adjustment of the biomass energy content
is 93 percent of the gross energy reported from bomb calorimeter data.
In reality, this percentage is assumed to vary very little. However,
a reduction in the value of this parameter is effectively the same
as reducing the energy content of the biomass. In this context, the
break-even investment cost for stover remains positive so long as

approximately 58 percent of the gross energy content is available

70

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72

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73
for gasification. At approximately 53 percent of the gross energy
value, all the available cobs are required to dry the corn from

25.5 to 15.5 percent.

Nitrogen Retention Rate (Figure 16)

The percentage of nitrogen retained by the soil from biomass has
no effect on the economics of using grain as a fuel. This is because
the market value of the grain exceeds its value as a source of nitro-
gen. Cobs contain less than half the percentage of nitrogen found
in stover, the nitrogen content being low in both instances. Hence,
the break-even investment cost when using stover is somewhat more
sensitive to the nitrogen retention rate than when using cobs.
Regardless, the nitrogen retention rate does not appear to be over-

whelmingly important.

E. Economic Factors

 

Life of the Gasification Equipment (Figure 17)

As the economic life (assumed to be the same as the physical
life) increases, the potential for using either cobs or stover
increases at a moderate but diminishing rate as would be expected.
Likewise, the potential for using grain decreases. This really says
that for the base conditions selected, using grain for fuel to dry
grain is a bad investment and the longer the life of the investment,

the worse it becomes but at a decreasing rate.

Moisture Content of Grain to be Dried
(Figure 18)

As initial moisture content increases, the break-even investment

cost also increases when using cobs or stover. However, the rate of

74

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‘ II.‘ ‘\‘
lmmém
[00.1w
lmN.Nw

 

(nq/s) nuamnsaAul uaAa-xeaiq

76

chwza awn unusuww>cw :w>woxmwnb co “coucoo wuzuwwos mo muowwww .w~ wuswwh

N~

    

 

mm>OHm

”My
lllllwlmmoo

.~m

mm.~m

77

increase decreases and in fact becomes negative in the case of

stover. The reduction in increase is because both cobs and stover
collection costs are based on wet rather than dry material. Thus,

the cost of collection (harvesting and transportation) increases
faster than the savings associated with expanded use of LP gas at

the higher moisture content. This effect is compounded when using
grain as a fuel source in that it becomes a progressively poorer
investment as moisture content increases. Note that drying efficiency

is held constant over the entire range of moisture contents.

Interest Rate (Figure 19)

The break-even investment cost for cobs and stover decreases as
the interest rate increases. However, the effects are less when
moving from the base condition to higher values than when moving to
lower values. In other words, future increases will have a relatively
lower effect than past increases. In the case of grain, the higher
interest rates reduce the return that must be obtained from other
sources nasubsidize the losses resulting from using grain as a fuel

source .

Annual Operation and Maintenance (Figure 20)

Annual operation and maintenance are expressed as a constant
annual percentage of purchase price. It has no effect on situations
where the expected return is negative as when using grain as a source
of fuel. It has a moderate effect on break-even investment when

using cobs and stover.

78

.A~.oz.m.=v eneuw see no
Hmcmsn Mme unwEumw>cfi am>mlxmoun co mums ammuwuaa mo muommmm .aH munwfim

unwound .mumm ummumucH Honca<

 

G.“ e e a. e e e e e .. .6 a N. 04...-
Iooému
Imm.0ml

\\ .698-

 

 

- 1| .II‘IWMIm‘\
1...... 1 0 13:8:
loo.ow
II: .I .I ll 1 MESS 1 '2 o...
mmoul/ Iomdm
all
lmm.0m
.IOO.~m

 

Imm.aw

(nq/g) nuamnsaAuI uaAa-neelg

79

.AN.oz.m.:v :Nmpw New mo Hmnmon non ucoEumo>cfl cm>m

 

 

 

 

 

Ixmmuo so mucmcmuswms mam cowumumao Hmnccm mo muomwmm .oN muswwm
umo%\moaue mmmzouse mo unmoume
.mucmswucamz was :owumumao Hmscc<
m N o m c m N H o
T b p . b b b _ 3.3..
[00.31
13.0w:
13.8-
zH<mU
lmN.Om1
18.8
egos Immém
mmO'U" '.', I.
Iomdw
13.3
log;

 

[mNQm

(nq/s) nuamnsaAuI uana—xealg

80

Harvesting Costs (Figures 21 and 22)

Large changes in the cost of harvesting grain have only a
moderate effect on break-even investment cost. Certainly the changes
are not sufficient to make grain a viable source of fuel. However,
the costs of harvesting cobs and stover are very important factors
to consider when computing the break-even investment cost of gasi-
fication equipment. In fact, harvesting costs of approximately
$20 and $25 per ton of wet material for stover and cobs, respectively,

would result in a zero break-even investment.

Market Value of Biomass (Figures 23 and 24)

The primary reason that grain is not an economic source of fuel
is its high opportunity cost; that is, grain can be sold and the
resulting funds used to buy more energy in the form of LP gas than
the grain itself contains. However, if grain were to sell for
approximately $1.45 per bushel (15.5 percent moisture), it would be
competitive with LP gas as a fuel source for the values used in the
base conditions.

The same logic applies to the use of cobs and stover for energy.
The higher the market value, the less desirable they are as sources
of energy, all other things constant. The base conditions assume a
market value of zero. However, a positive market value could reflect
the equivalent worth of cobs or stover as animal feed or as a source
of erosion control. For this analysis, a zero value for break-even
investment would be obtained if the market value of cobs and stover

were approximately $20 and $11 per ton of wet material, respectively.

81

.AN.oz.m.Dv mouzom Hwnw m mm :Hme mcfims :wzz awmuw has NO Hmcmnn

 

 

 

 

 

poo unmaumw>cfi cm>wuxmmun so umoo wnwumm>ums cwmuw mo wuowwmm .HN wuswfim
o .m:wamm>um= Ham Hmsmnm umz nae umoo

oe mm 0m mN 0N m~ ON

_ — - — P — P mN.HwI
looéml
I mm.Om|
18.8-

l ' l

2361. I11 1

I mN.ow|
loo.0w
I mN.Om
Iomdm
I mN.Ow
Iooéw
lmNJm

(nq/s) JuamnseAuI uaAa—x'eaig

82

.Acfimuw N.oz.m.:v mounom Hmsm 6 mm um>oum
paw mnoo wean: coca samuw hum mo Hmnmnn you unmEumm>ca
cm>wuxmoun co mumoo wcwumw>um£ um>oum new poo mo muomwmm .NN Gunman

Hmfiumume uma mo aou\w .umou wcaumm>umm

mN ON ma OH m o
p - P1 b -

mm.smu
Iooému
IWN.OWI

Iom.oml

ImNdmI

mm>OHm

  

v8.8
ImN.om
(113.8
fined...

food

 

lmN.Hm

(nq/g) nuamasanul uaAa-nealg

83

.Aoamuw N.oz.m.:v wounom Hoam o no camuw wean: cmg3 cfimuw
app mo Hosmsn use unwEumm>ca aw>muxmoun no :«muw mo mofiua umxuma man mo muommwm .MN onswfim

munumwofi Nm.m~ ® nn\w .awmuo mo moaum

 

00...}. ow.mm oemm cmflNm oobNm om-Jw oo-ém omom oodMNJma
loo.HwI
Ill
llllllllll ImN.OmI
A!

It lOm.Oml

/ 13.8-
/ foods

/IITmN.om

Iom.0m
Imm.om

loo.Hm

 

ImN.~w

(nq/s) nuamnsaAuI uaAa—xeazg

84

.AN.oz.m.Ov Mona mo mmounom mm pm>0um no mnoo
magma coca Camuw zuv uo Hmsman hoe ucmEumm>CH sm>m

Ixmmue co mo~m> umxums um>0um was nou wsu mo muummmm .QN muswwm

mmmEown ups mo c0u\w .mnam> umxumz

Om we Oq mm Om mN ON mfi OH
- p p p p b p p -

 

pm
0

mN.HmI

IOO.#wI

rmadmu

IOm.OmI

ImN.Ow1

IOO.Hm

 

lmN.Hm

(nq/s) nuamnsanul uaAa-xealg

85

Cost of Nitrogen (Figure 25)
The cost of nitrogen is not important when considering grain as
a fuel source. It is relatively more important when using stover
as compared to cobs because stover contains a larger percentage of
nitrogen, hence having a larger opportunity cost. Regardless, the

price of nitrogen is not an extremely important factor.

Increases in LP Gas Price (Figures 26-34)

The break-even investment cost increases as the base price of
LP gas increases. In fact, a base price greater than approximately
84¢ per gallon would result in a positive break-even investment cost
when using grain as a fuel source. Likewise, increases in the
amount of drying amplifies the gains or losses in break-even invest-
ment .

All increases in LP gas prices are considered real; that is, the
price increase is relative to all other costs which are assumed to
remain constant. This is especially important when considering that
investment in capital goods occur at one point in time with proposed
returns being prorated over the life of the investment. This may
result in losses during the early years of the investment only to be
offset by gains in the later years.

From the figures, a real increase in LP gas prices of approxi-
mately 15 percent over each previous year would result in a positive
break-even investment for grain as a fuel source. It would also
approximately double the break-even investment for cobs and stover

for 10 points of moisture removal.

86

.AN.oz.m.Ov :wmuw mew mo Hmnmsn “we

 

 

 

 

ucwEumw>=N cw>mlxmmun co umoo cowouufia mo muommwm .mN muzwwm
u .vcsom you :mwouuwz mo moaum
on 00 om OQ Om ON

P . . - - . mN.~m|
IOO.HmI
13.8-
lends-
2:3.” ImN.OwI

18.0.6.

Mme/8m 1 Immdm

l"ll||'lmfl5l.|||ll|ll|'l'|l lOmOm

13.8

15.;

FT;

("Q/S) nuamnssAul uaAs—xealg

87

.AN.oz.m.=v mounom Noam mnu mH :Hmuw awn? :fimuw hum mo

 

 

 

Honmsn Hoe ucmEumm>cH co>onxmouo ecu so mowua mow m4 usmumcoo m mo muommmm .ON Gunman
coaamw\m .mmO mg no oUHHm
OO.Nw OOJ» ooém 3.; 8.3 093 OOOm oodm
. . F b b . . p . p . b . p . 3.8:
Iooéwn
lOmOmI
.593
10nd...“
111 km
IOO.$
«ON
.69;
km.
TOO.Nm
OQ>CEom mpsumwoz mo mucflomk jlOmNm
Cameo ”mounom Noam
Ioo.mm
Foméw

(UQ/S) nuamnsaAuI usaa-xealg

88

.AN.oz.m.Ov mounom Noam mnu mum mnoo :653 :«muw hum mo
Hmcmsn you usosuww>cfi cm>01xmmun ecu so mowue mow m4 uamumcou m mo muommmm .NN muswwm

aoHHmw\m .mmO mg mo wowum
Om.~m OO.~w Oc.~w ON.~m OO.~m
P L — -

OO.Nm
p b p -

O0.0m O0.0m
L p

. om.sm-

TOOJwI
lOmOmI

IOO.Om

 

OmOm

 

1 km roogm

1Om.~m

«OH
182%

woe/086x ousumwoz mo mucflomk TOmNm
«ma mnoo "mousom Noam

lOO.mm

 

IOm.mm

(nq/g) JUBmJSBAUI uaAa-xealg

89

.AN.oz.m.Ov mounom Hmnm ecu ma uw>oum c053 afimuw mac mo

 

 

Hmnmsn you ucmEumm>sw cm>mlxmmun may no mowua mmw ma ucwumcoo m mo muo¢mmm .wN munwfim
soHHmw\m .wmo ma «0 moaum
OO.Nm OO.Hw OO.Hm Oq.~m ON.Hw OO.Hm O0.0w O0.0m
- p p p p p p p p - 1P1 - b (PIIIII . I
lOm Ow
IOO.HmI
IOm.OmI
or;
toms...
111. «m IOO.~w
lOm.Hm
«OH
IOO.Nm
m~ Om>OEmm menumwoz mo mu:womk lOm.Nm
ya
no>oum "wouoom Hose
looém
Iomém

 

(nq/s) nuamnsanul uaAa-xeaig

90

.AN.oz.m.Ov mouaom Hmaw m mm :wmuw mean: :053 awmuw
xup mo Hmsmsn use unwaumm>cw cm>mlxmwun so dogma
mmw m4 ca mmmmuocw mwmucmoumn amazes mo muommmm

new» use N .moaum mmO mg a“ wmmmuocH

mN ON mg OH
P

m
p - p .P

.mN enemas

Om.~m|
Iooému

IOm.OwI

 

km

«mg

pm>o€mm ounumwoz we wu:wom«

awmuo "mousom Noam

fiO0.0m

rOm.Om
roo.Hm
IOm.~w
IOO.Nm

lem.Nm

 

IOO.mm

(nq/S) nuamnssAul uaAa-xsalg

91

.AN.oz.m.Ov sounom asom s ms woos waumn :sss ausuw
eup mo asesnn use unsEums>cu cs>s1xssun so souue
ssw e4 cu smssuucu swsuasouse assess mo suosmmm .Om suswue
usse use N .ssuue use eg cu smssusaH

mN ON me OH m
- . p p —

o
enem.am1
loo.am-
Ion.0m-
noo.0a

18.8

111. km

IOO.~m
«O~

ems nom.sm

rOo.Nm

Os>oEsm susumuoz mo mucuoek fiO
m.Nm

mnoo ussuaom fisse

 

lOO.mm

(nq/s) nusmqsaAuI uaAa-xealg

92

.AN.oz.m.OO sousom assw s ms us>ous mafia: csna cusuw

huh mo asnmsn use ucsEums>au cs>slxssun so souue
ssw e4 cu smssusau swsucssuse assess mo mussmmm .Hm suawue

ussm use N .suuue ssO ea cw smssuonH
mN ON mu O“ m O
- 1P - - Om.~ml
IOO.~m1
IOm.OmI
1.8.8
‘11 *m 'OM.OW
*OH Iooofiw
«me
ref;
IOO.Nm

UQ>OE®M MHDumMOZ wO WUCHOQ% 'Omon

us>oum "sousom asse

 

IOO.mm

(nq/s) nuamnsaAul uaAa-xeelg

93

.AN.oz.m.Dv souaos Hs=u s ms :Hsuw mews: aspa csuuv
:«suw mo HsSmno use ucsEums>cu ss>slxssua so ssswue
msw e4 cu usse use smssuocu unsumcos s mo musswmm .Nm sunwue

usse use 0 .souue msO e4 cu ssssuocH
N ON O OH m O .
Ioo.umu

lOm.Om1

 

IOO.Om

 

IOm.Om

 

roo.em

IOm.Hm

IOO.Nw

vs>oEsm susumuoz No manuoek

IOm.Nw
Cusuu "sousom asoe

 

IOO.mm

(nq/s) nuamnsenul uaAa-xealg

94

.AN.oz.m.Ov sousom assw s ms mnoo wags: use: Osuuv
:Nsuw mo asewsn use ucssums>au as>slxssun no ssouue
msm eA :H usse use ssssuusu unsuscos s mo muosmwm .mm suswue

usse use 0 .suuue msO ea cu smssussH

ON ON we OH m O
. p p . . 8.3-

loo.$..
lOm.OmI
IOO.Om
IOm.Om

IOO.Hw
«OH

lOm.~w
«we

IOO.Nw

Os>OEsm susumuoz mo manuoek

lOm.Nw
meow “sousom asse

 

IOO.mm

(nq/s) nuamasenul usAa-xeezg

95

.AN.oz.m.Dv sousos asnm s ms us>0um wsumn asea usuuv
swsuw mo asnmsn use unsEums>cw cs>slxssun so mssuue
ssw e4 cu usse use smssuoau unsumcoo s mo mussmwm .qm suswue

usse use 0 .ssuue msO ea cu smssussH

mN ON me O_ m O

p n p P - Om.~wl

lOO.~wI

IOm.Om1

IOO.Ow

 

111 «m IOm.Om

Roe Ioo.um

kme
lOm.Hw

too.~w

Os>ossm susumuoz mo mucuoek
iom.Nm
us>0um "sounom Hsae

 

IOO.mm

(nq/S) JuamnsaAul uaAa-xealg

96

Constant real increases in LP gas prices would be equivalent
to diminishing percentage increases. A constant real price increase
of approximately 10 cents per year would result in positive break-
even costs for grain as a fuel source. It would also approximately
double the break-even investment for using cobs and stover at 10

points of moisture removal.

F. Summary

Thus far, the sensitivity analysis has shown the effects of
altering one variable while holding the remaining base conditions
constant. In order to gain some insight into the relative importance
of changing a parameter, the average effects were computed as shown
in Table 4. In this analysis, the break-even investment was deter-
mined for the low and high values of the parameter used in the
sensitivity analysis. The average change in the break—even invest-
ment was then computed over this range using only the end point
values. Within the limits of the linearity assumption, certain com-
parisons may be made concerning the relative importance of certain
parameters.

For the set of physical factors when using grain as a fuel
source, the most important factor was the bomb calorimeter adjustment
followed in descending order by the efficiencies of gasification,

LP gas burner and drying. The least important factor was the soil
retention rate for nitrogen. For cobs, the most important physical
factor was LP gas burner efficiency followed by the efficiencies for
drying, bomb calorimeter adjustments and gasification. Of least

importance was the soil retention rate for nitrogen. For stover, the

97

 

Amussev

 

 

 

 

ue\omee.o o.uu m.wN n.0H us>oum ucsseusvm
u»\oow~.u N.mu m.ee e.u~ meoo eouomuusummo
ue\ooeq.e1 m.HNI ~.n<1 N.mN1 we ON m nwsuu mo smug .O

Ausssusev

N\oumo.ou H.e . e.m~ u.u~ um>oum amwouuuz
N\om~O.O1 q.~ 1 “.mm m.O¢ snoo u0m susm
N\0OOO.O O N.Nm1 N.nm1 ON OO O awsuu couuasusx Huom .m
N\emeu.o u.mN e.m~ u.e 1 uo>oum Aeemuumev
N\omeN.O N.~H ~.mm «.NN snow ucsaus3nv<
N\smmm.u w.mm m.nm1 m.n-l Oq mm mm cusuu ususauuoaso neon .q
N\onoq.O1 ¢.¢N1 m.m~ m.mm us>oum Aucssusev
N\smeo.O1 <.Oq1 m.NN N.NO mnoo esasusumwm
N\on0.0 H.mm m.HN1 0.001 Oo mm mm anuO waaeun .m
N\0OOO.OI c.Oq1 m.m~ m.mm us>0um Aucsousev
N\ewom.ou e.oe- o.o~ e.ee meoo sensuoussm
N\oqNO.H N.Hm m.ee m.~ I Om OOH Om cusuo uscusm msu e4 .N
N\onO¢.O m.qN c.8m “.0“ us>oum Aucsousev
N\o~uu.o m.ou e.me m.mm meoo sensuousum
N\oONq.H N.Ow m.H m.ow1 OO OON cc cfisuo coaussumumsu .u
saas> socsuswwua emu: 304 socsusmmwa awe: BOA sousom ususasuse

ususesuse ucsEums>cu os>slxssum ususasuse asne

cw swcsss mauvcoemsuuoo

own: use msSHs> mo swemm

unsaums>cu

fi0>0|¥wmhm

 

.mususasuse oqusoss was Assamese cu mswcssu ou unsEuss>nu as>s1xssun mo euu>uuumasm ussaua

.e «Hemu

98

 

 

 

 

 

neu\ev\omo~.o1 N.» 1 e.mu e.m~ um>oem Aee\ev
Aeu\ev\omuo.o1 o.~ 1 ~.em u.am meoo cowouuuz
Aoa\oV\o o o n.5m1 ~.Nm1 oq co om cumuo mo souue .NH
Au\mv\omsu.m 1 m.moH1 e.moa1 m.e oe om on ue>oum A063 .eou\wv
Ae\mv\owom.~ 1 m.~s1 a.uu1 e.o~ as on on meoo Aum.maese\wv
A:n\wv\om-.~m1 m.m~u1 o.om1 m.wm e e o cumuo souue assumz .uu
Ao\mv\eom~.~1 e.me1 m.o e.ee om ow o uo>oum Aeoo\m1se\ov
Au\wv\omoo.~1 H.041 o.m u.oe ON em 0 when umoo
A=h\ov\oemm.o1 m.oa1 o.~e1 e.~m1 em on ma humus meuemm>umm .OH
Aucsousev
N\om~o.e1 H.m 1 N.ON m.wN us>oum ssasssuausz a
N\omno.u1 «.mun m.mm e.oq mnoo couususeo uom
N\0 o o n.5m1 5.5m1 m w o ausuo swumno Hmaaq< .e
N\omwe.01 n.m~1 O.N~ m.mm us>oum
N\eoom.u1 o.e~1 ~.m~ «.mm heoo Auamuumev some
N\oocm.u N.Hm m.ON1 H.wm1 ON mN m ausuo umsususH asssq< .O
Auasousev
N\oNNm.u e.e~ N.NN w.N us>oum msuue sn
N\ouom.m o.~m m.om o.m mnoo on cumuu so
N\ooeo.q1 o.oe1 u.mo1 u.m 1 we m.om m.oH cumus assumes suaumuoz .N
snas> socsuswwuo emu: 304 sscsuswmuo zwum 30A souaom ususEsuse
ususEsuse unseums>sw cs>s1xssum ususEsuse Hsne
:u swcsno wcuwcoemsuuou
sun: use mssas> mo swcsm
uGsEums>cu

:s>slxssum

 

.A.e.ueoov e seems

99

 

 

 

 

 

Aus\00\ooNe.m «.mw i.eo3 e.m~ u6>oum Auu\ev
Aua\ev\eeue.m «.mm n.emu a.sm heoo muuum was me
Auu\ev\emee.m u.um o.em u.um1 mm mm o humus cu washes .mu
Aua\uv\oe-.m e.ow N.eOu e.m~ u6>oem Aua\NO
Aua\Nv\oowm.m m.ow e.asu H.8m meoo mouse 660 ma
Auu\Nv\e~ue.m m.em n.ms u.um1 mm mm o aueuo cu mmameo .eu
Aemw\ev\oaeo.u e.mmu N.ao~ e.m~ ue>oum Aumm\ev
Au6w\ev\eeeo.u ~.emu m.m- H.mm meoo m<o so so
Aumm\ov\emmo.u m.awu m.umu u.um1 mus mNN om humus soups when .mu
snas> sscsusmmua :wum 304 socsusmwua awu: 304 sousom ususasuse
ususEsuse ucsEums>0u cs>s1xssum ususEsuse asnm
0H swsszo wsumaoessuuou
0H0: use msnas> m0 swdsm
ucssums>nu

0s>s1xssum

 

 

 

.A.e.ee660 e muses

100

most important physical factor was the LP gas burner efficiency
followed by the efficiencies for the bomb calorimeter adjustment,
drying and gasification. Again, the rate of nitrogen retention by
the soil was the least important factor.

When considering the influence of these physical factors, note
that the bomb calorimeter adjustment efficiency and the LP gas burner
efficiency are not subject to great change. The drying efficiency
could approach 100 percent if the bed of grain were very deep with
very low air flow rates. However, an 80 percent drying efficiency
would be near the maximum for farm drying systems. Likewise, the
upper limit for gasification efficiency is approximately 80 percent.
Note also that the direction of change associated with an increase
in the physical factor was always the same for cobs and stover but
not for grain.

It is somewhat more difficult to compare the remaining factors
because the units and/or functions are completely different. For
example, wet grain moisture content and interest rate are both
measured in percent and are important parameters but have little else
in common. An increase in the moisture content of the grain ampli-
fied the break-even investment costs; that is, the break-even invest-
ment for cobs and stovers increases while there is a decrease in the
break-even value for using grain as a fuel source. An increase in
interest rates tends to have the opposite effect with break-even
investment converging toward a zero value for grain, cobs and stover.
This is equivalent to saying that the opportunity costs for invest—

ment limits what can be spent for gasification equipment when using

101

cobs or stover. In the case of grain which initially has a negative
break-even value, the convergence means that it's easier to subsi-
dize a bad investment with other funds when interest rates are high.

Factors of moderate importance considering the probable range
of values are the life of the gasification equipment and the annual
charge for operation and maintenance. The price of nitrogen is of
little importance as is the cost of harvesting grain. However, the
cost of harvesting cobs and stover are very important considerations
as are the market values of the biomass components.

The high market value for grain is primarily responsible for
the negative break-even investment. If cob and stover had similar
market value in terms of erosion control, future productivity of the
soil, cattle feed, other energy uses, etc., their break-even market
values could also become negative.

Much of the economics of using biomass as a fuel source lies
with the real increase in the price of the price of the primary fuel
substitute LP gas, as compared to the other price of other factors.
Even under today's prices, cobs and stover have a positive break-even
investment. As can be seen from Table 4 and Figures 26-34, it would
not take great changes in the real price of LP gas for grain to also

have a positive break-even investment cost.

CHAPTER VIII

SUMMARY AND CONCLUSIONS

In this study, it has been shown that there is sufficient energy
in the form of grain, cobs and stover so that the gasification pro-
cess may be used to dry corn over the range of moisture contents typi—
cal of harvest. Certain physical and economic parameters were deter-
mined to be essential in computing the economic feasibility of gasi-
fication. When using representative values for these factors, it was
found that as much as 38.90 and 23.50 per U.S. No. 2 bushel dried
could be invested in gasification equipment when using cobs and stover,
respectively, as sources of energy for 10 points of moisture removal.
However, grain itself could be used as a fuel source only if it were
subsidized by the equivalent of 37.60 per bushel dired. Therefore, it
would be extremely doubtful that grain would ever be economically com-
petitive with cobs or stover as a source of fuel for grain drying.

The economic feasibility of using cabs and stover would be
enhanced under the following conditions:

1. Increases in the efficiency of the gasification process.

2. Increases in the economic life of the gasification

equipment.
3. Employment of high temperature drying methods that

typically have lower drying efficiencies.

102

103

4. Increases in the quantity of moisture to be removed

from the grain.

5. Reductions in the interest rate.

6. Reductions in the annual charge for operation and

maintenance.

7. Reductions in harvesting costs.

8. Limited market value of cobs and stover.

9. Low prices of nitrogen.

10. Real increases in the price of LP gas.
The altering of these factors can have significant additive effects
on the break-even investment cost. For example, if the base condi-
tions given in Table 3 were altered to reflect the conditions shown
in Table 5, the break-even investment would be $1.59, $2.63 and
$2.42 for grain, cobs and stover, respectively. This would represent
a change in the base values of break-even investment of approximately
$1.97, $2.00 and $2.18, respectively, for grain, cobs and stover.

It would appear that the use of cobs is the best gasification
alternative. Cobs are presently passed through the combine and could
be most easily gathered with existing grain harvesting machinery.
This could be accomplished by either blending the cobs and the grain
and separating them later, or by collecting the cobs as they exit
the combine. It would also be possible to use ear corn harvesters
and stationary shellers. In addition, cobs are more flowable than
stover and thus offer advantages in terms of materials handling.
Likewise, nitrogen removal is less with cobs than with stover, and
stover is more effective in erosion control. The net effect of

these advantages is that the break-even investment cost will probably

104

Table 5. Modification to the base condition values given in

 

 

Table 3.
No. Input Description New Value
1. Initial grain moisture, percent 30.50
8. Percent efficiency of drying process 40.00
9. Percent efficiency of gasification process 80.00

16. Change in LP gas price, percent increase

from previous year 15.00
19. Annual interest rate, percent 12.00
20. Economic life of gasification equipment, years 15.00

22. Harvest-transport cost for cobs in field,
dollars per ton of wet material 2.50

23. Harvest—transport cost for stover in field,
dollars per ton of wet material 5.00

24. Market value of grain at 15.5 percent moisture
dollars per bushel 2.00

 

Computed break-even investment costs using the above values,
¢ per dry bushel (U.S. No.2):

Grain 158.58
Cobs 262.73

Stover 241.95

 

105

be greater when using cobs than with stover. The costs of gasification
equipment may also be influenced by the type of biomass used as fuel,
thus altering the relative economics concerning the choice of biomass.
In conclusion, the break-even investment cost for gasification
equipment is positive under existing technology and prices when using
either cobs or stover as a fuel source for drying. This indicates
that cobs or stover can compete with LP gas under present economic
conditions so long as investment in gasification equipment does not
exceed the break-even values. Cobs appear to be a more economical
source of fuel than stover, and grain is not presently an economical

energy substitute for LP gas.

APPENDIX

APPENDIX

BIOMASS COMPUTER PROGRAM LISTING, DATA AND SAMPLE OUTPUT

*Pus
L0EHER.L9O.JCSOO1R02.
PHvflWlO
FTN.UPT=2
LE?
*.1H
PROGRAM BIOMASS (INPUT. OUTPUT. TAPEs-INPUT1TAPEé-DUTPUT)
DIMENSION COSTLP(2O)1XLPGSSA<20)1RG(20)1RC<20)1RS(2O)1AG(6)1AC(6)1
2fS;01.RATIO(6 6)1GPV (20)1OPVC(20110PVS(20)
IR=5
1w=e
NR1TE<IW1SOO)L
500 F0RMAT(2X."§§§0&§§§§§ AT STEP ",12,'§§§s§§§§§**")
l FORMAT(F5. O)
READ IN PHYSI AL PARAMETERS

C
GINC -GRAIN MOISTURE CONTENT1PERCENT1INITI
GFMC -GRAIN MOISTURE CONTENT1PERCENT1FINAL
GECORN—GROSS ENERGY AVAILABLE1BTU/LB.1GRAIN
GECOBS-GROSS ENERGY AVAILABLE1BTU/LB 1COBS
GEETOV-GROSS ENERGY AVAILABLE1BTU/LB.1STOVER
BOMBPC-PERCENT ADJUSTMENT FOR BOMB CALORIMETER

READ(IR11)GIMC1GFMC1GECORN1GECOBS1GESTOV1BOMBPC

THFFF -EFFICIENCY OF LP GAS BURNERS1PERCENT

DEFF -EFFICIENCY OF DRYING PROCESS1PERCEN NT

GEFF -EFFICIENCY OF GASIFICATION PROCESS1PERCEN NT
PCNG —NITROGEN CONTENT IN GRAIN1 PERCEN OF DRY HT.

AL

PCNC -NITROGEN CONTENT IN C0881 PERCENT OF DRY HT
PCNS -N1TROGEN CONTENT IN STOVER1 PERCENT OF DRY NT.
HVAP —HEAT OF VAPROIZATION

READ<IR11)THEFF1DEFF1GEFF1PCNG1PCNC1PCNS1HVAP
READ IN ECONOMIC PARAMETERS

PLPBAS- PRICE OF LP GAS1C/GAL. THIS YE

PPYRLP- PROJECTED INCREASE IN LP GAS1CONSTANT CHANGE PER YEAR1 C/GAL.
PCYRLP-PROJECTED INCREASE IN LP GAS1PERCENT INCREASE FROM PREVIOUS YR.
PNPLB -PRICE OF NITROGEN1 CENTS PER POUND

READ(IR1I)PLPBAS1PPYRLP1PCYRLP1PNPLB

AUPKEP- -ANNUAL UPKEEP FOR GASIFICATION UNIT1PERCENT

AINTPC-ANNUAL INTEREST RATE1 PERCENT

YEARS -ECONOMIC LIFE OF GASIFICATION UNITY1YEARS

HCPBUG-HARVESTING AND TRANSPORTATION COSTS FOR GRAIN1C/HARVESTED DU.
HCPTNC-HARVESTING AND TRANSPORTATION COSTS FOR COBS1$IHARVESTED TON
HCPTNS-HARVESTING AND TRANSPORTATION COSTS FOR STOVER13/HARVESTED TON

READ(IR11)AUPKEP1AINTPC1YEARS1XCPBUG1HCPTNC1HCPTNS

VMRKG -MARKET VALUE OF GRAIN AT 15.5 PERCENT MC1OIBU.

VMHKC -MARKET VALUE OF COBS AT EXISTING FIELD MOISTURE1$ITON

VMRKS ~MARKET VALUE OF STOVER AT EXISTING FIELD MOISTURE1O/TON

RRN -PERCENT OF NITROGEN RETAINED BY SOIL OF BIOMASS
READ(IR11)VMRKG1VMRKC1VMRKS1RRN

C33$$$$$$$$$$$$$S$$$80’COSCCSCCSCSO’CCCOCOCCSCCCCCCCCCCCCOOCSCCOCSS$8.38
C$$$$$33$g338$:3332:8:SSCSCCCCOCOSCCGCC$083.83.$$$$$$$$$$$$O$$$$$$$$8388
NR1TE<IN1803)LOOP1OIMC1/PCYRLP1PPYRLPoPLPDAS
803 FORMAT172("$")/72("
XT271' 'LOOP NO. "1I3/
XT271' 'GIMC ="1F6. 2//
IT271"PCYRLP="1F6.2//
1T271"PPYRLP'“1F6. 2//
1T271LPBAS="1F6.2/l
X72("$")/72("$")/ )
CCOOOOSOOOO8.3.3.3308OCOCOCOCOOCOCOC.33CCCQCOCOCCCCQOCOCCOOCCOCCOOOCOOCO

106

0 00000 00000000 0000000 000000000 00000000

107

C$$$$$$$$$30088COCOSO3‘$333.800‘COCCCCCCCCOCOCIOCCCCOCOCCOCOOCOOOOOOOOQO
C

0000

R TE’IN150)
5O FORMAT(72("*")/72("*")//T271"DATA INPUT"//72(“*“)/1X1“ITEM"1
1T271"DESCRIPTION“l72("*“)/)

NRITE(IN151)GIMC1GFMC1GECORN1GECOBS1GESTOV1BOMBPC1THEFF
51 FORMAT(

ISX1"I INITIAL GRAIN MOISTURE1PERCENT": T641F9.S/
13X1"2 BASE AND DESIRED FINAL GRAIN MOISTURE1PERCENT"1T641F9.3/
13X1"3 GROSS ENERGY IN GRAIN1 BTU/ DRY YLB. T641F9.3//
13x1"4 GROSS ENERGY IN COBS1 BTU/DRY LB. ": T641F9.O/
IOX1"5 GROSS ENERGY IN STOVER1BTU/DRY LD."1 T641F9.3/
63X-"6 PERCENT ADJUSTMENT FOR BOMB CALORIMETER"1 T641F9.3//
g?x1“7 PERCENT EFFICIENCY OF L.P. GAS BURNER"1 T641F9.3
NRITE(IH1527DEFF1GEFF1PCNG1PCNC1PCNS1HVAPoPLPBAS

ad FORMAT(
83X1 "8 PERCENT EFFICIENCY OF DRYING PROCESS"1T641F9.3/
93x. "9 PERCENT EFFICIENCY OF GASIFICATION PROCESS"1T641F9J3//
X2X1"IO NITROGEN CONTENT IN GRAIN1PERCEN TOF DRY NT. 1 T641F9.O/
12X1"11 NITROGEN CONTENT IN COBS1 PERCEN TOF DRY HT " 1 T641F9.3/
22X1"12 NITROGEN CONTENT IN STOVER1 PERCENT OF DRY NT."1T641F9.3//
32x1"13 HEAT OF VAPROIZATION OF HATER1BTU PER LB. T641F9.O/
§§1-"14 PRICE OF L.P.GAS IN YEAR NO.IoC/GAL."1 T641F9.O
NRITE(IN153)PPYRLP1PCYRLP1PNPLD1AUPKEP1AINTPC1YEARSoXCPDUG

53 FORMAT(
52x1”15 CONSTANT CHANGE PER YEAR IN L P. GA S PRICEoC/GAL"1T641F9.3//
$gé1g}6 CHANGE IN L.P. GAS PRICE1PERCENT FROM PREVIOUS YEAR"1T641
72X1”I7 PRICE OF NITROGEN1C/LD."1T“A1F9.3/
82X1"IO PERCENT/YR FOR MAINTENANCE OF GASIFICATION EOUIPMENT"/
82X1" BASED ON PURCHASE PRICE“ T641F9.3//
92x1"19 ANNUAL INTEREST RATE1PERCENT“ T641F9.3/
X2X1"20 ECONOMIC LIFE OF GASIFICATION. E0UIPMENT1YEARS"1 T641F9.3/
§§é1ggg HARVEST'TRANSPORT COST FOR GRAIN1C/DU AT 56LB/BU"1T641
NRITE(IN1547HCPTNC1HCPTNS1VMRKG1VMRKC1VMRKS1RRN

{I "1 FOP MAT (
22X1”22 HARVEST’TRANSPORT COST FOR COOS IN FIELD:’/TON"1 T641F9.3/
§gé1573 HARVEST‘TRANSPORT COST FOR STOVER IN FIELD1O/TON"1T641
42X1"24 MARKET VALUE OF GRAIN AT 15. 5 PERCENT MC1S/DU. "1 T641F9. S/I
52X1"25 MARKET VALUE OF COBS IN FIELD1GINET TON" T641F9. 3/
62X1"26 MARKET VALUE OF STOVER IN FIELD1G/NET TON '1 T641F9. S/
62x1"27 RETENTION RATE OF BIOMASS NITROGEN DY SOIL:PC"1 T641F9. O//
772("*")//)

DETERMINE THE PERCENTAGE OF GRAIN1COBS AND STOVER PRESENT ON A DRY

THEN CALCULATE THE RELATIVE DRY HEIGHTS OF EACH COMPONENT

PCGDB=70.4 - 0.0*GIMC

PCCDB=12.4 - 0.035*GIMC

53308317. 0 + O. 84*GIMC

F=YNB*(IOO O-GIMC)/(704O O-OO. OPGIMC)

DRYNTG=YNB*(IO0.0-GIMC)/IO0.0
DRYHTC=FiPCCDB
DRYHTSBFiPCSDB

BASIS

108

C
C ADJUST THE GROSS ENERGY AVAILABLE BY THE BOMB CALDRIMETSR FACTOR
C
AECDRN=BDMBPC1GECDPNx1oo.o
AECDBS=BOMBPC*GECOBS/100.0
AESTDV=BOMBPC*GESTOV/100.0
C
C ES1ABLISH THE MOISTURE CONTENTS OF THE CDBS AND STOVER
C
CMC= 0*GIMC
1F<G1MC LT 25 0)CMC=-25 o+3.o1GxMC
1F<G1MC LT 12.5)CMC=G1MC
C SMC=2 0*GIMC
C ES1ABLIST THE RELATIVE NET NEIGHTS FDR GRAIN1COBS AND STDVER
c
HETHTG=DRYHTG/( 1. O-GIHC/IOO 0)
NETNTC=DRYN1C/(1.o-CMC/1oo.o>
c NSTNTScDPYNTS/(1 o-SMC/1oo 01
C DETERMINE THE ENERGY AVAILABLE FOR DRYING AFTER THE BOMB CALDPIMETSB
C AND MOISTURE CONTENT ADJUSTMENTS ARE MADE PER POUND NET NT.
C
SAGNTG=(1. o- -G1MC/1oo. 011AEC0PN -(G1MC/1oo O)*HVAP
EAGNTC=(1. o— CMC /1oo. 011AEC0BS -(CMC l100. 011HVAP
EAGNTS=<1 o- SMC /1oo o>1AESToV -(SMC /1oo O)*HVAP
C DeweRMINS THE AVAILABLE ENERGY FOR DRYING CONSIDERING THE EFFICIENCY
E OF THE GASIFICATION PROCESS1PER PDUND NET NT.
EAANTGSEAONTO§GEFFIIOO.O
EAANTC=EAGNTC1GEFF/100.o
C EAAHTS=EAGHTS§GEFFIIO0.0
c DETERMINE THE AVAILABLE ENERGY FOR DRYING CONSIDERING THE EFFICIENCY 0F
8 THE DRYING PROCESS. PER POUND NET NT.
SANNTG=SAANTG1DEFF/1oo.o
EANHTC=EAANTC§DEFFIIO0.0
C EANHTS=EAANTS§DEFFI100.0
C DETERMINE THE TOTAL ENERGY AVAILABLE FOR DRYIN01NET1C0NSIDERING THE
E RELATIVE PROPORTIONS 0F NET MATERIAL
TGE=SANN1G1NSTNTG
TCS=EANNTC1NSTNTC
c TSE=EANNTS§NETHTS
C AT THIS POINT1DETERMINE THE ENERGY REQUIREMENTS FOR DRYIN NG
C CAICULATE THE AMOUNT OF NATSR TO BE REMOVED FPDME ONE LB. 0F NET GRAIN
E THFN CDMPUTE THE DRYING ENERGY NEEDED ON A 100 PERCENT EFF. BASIS.
C*INININI'*‘HIHININ!*fii’fil’l’i‘l’i’fififil’fi‘lfifiifi‘l’fl’fi‘lINI‘I‘ININI'IHI'Q‘I.’§§**I§§§§*§§**§§§§§GI‘IQO
C NOTE THAT THE NATSR REMOVED IS FOR ONE UNIT 0F GRAIN NITH FINAL
c MOISTURE CONTENT OF GFMC IF THIS 18 U. S. No 2 GFMC NILL BE
C EGUAL 10 15 s PERCENT. THUS ALL REFERENCES TO A DRY BUSHEL REFER
c TO A BASE MOISTURE CONTENT OF GFMC.
C‘I‘l‘l****§**§{MINI**§§§§§**§I~I§§§{*‘I*9}{*1}«II».{CHIOlfiii’fiiifi{*‘I‘I’Q‘I'I’Q‘IO‘I‘I’QII‘IM'

GRAINP=1.0
NATERP=GRAINP§(GIHC-GFMC)/(100. O-GIHC)
ENERGP=NATERPNHVAP

CONVERT TO A 56 POUND BU.
ENERGB=56.0*ENERGP

C
C
C DETERMINE THE QUANTITY OFL .P. GAS NEEDED1GAL. PER POUND OF DRY GRAIN.
C CONVERT TO A 55 POUND BUSHEL
EPGLPG= 9200 00. O
OLPGF‘P= ENERGPilOOOO. O/(EPOLPGiTHEFFfiDEFF)
OLPGBU= GLPGPPfiSb O

000 0000 O 0000

0000

00 000

00000

000

109

COMPUTE THE COST FOR LP GAS FOR EACH YEAR OF THE GASIFIERS LIFEuAND
THE POTENTIAL SAVINGS

IYEAR=YEARS
COSTLP(1)=PLPBAS
XLPGSA(1)=QLPGBU*COSTLP(1)

DO 2 182.1YEAR
COSTLP(I)=COSTLP(I-1)§(1,0+PCYRLP/IO0.0) +PPYRLP
XLPGSA(I)=COSTLP(I)*QLPGBU

2 CONTINUE

COMPUTE THE QUANTITY OF HET BIOMASS NEEDED FOR DRYING A 56 LB.DRY BU.
QUANTITIES IN POUNDS

QHTGDOENERGB/EANHTG
QHTCD=ENERGB/EANUTC
QNTSDBENERGB/EANNTS

COMPUTE THE QUANTITY OF DRY BIOMASS NEEDED FOR DRYING A 56 LB. DRY BU.
QUANTITIES IN POUNDS

QDRYGD=QHTGD*(1 O-GIMC/IOO O)

QDRYCD=QUTCD*(1.0-CMC /100 O)

QDRYSDBQHTSD*(1.O-SMC /100.0)

COMPUTE THE QUANTITY AND VALUE OF NITROGEN REMOVED FROM THE FIELD.
POUNDS OF N PER BU OF GRAIN DRIED: AND C/BU OF GRAIN DRIED

PNREMG=QDRYGD*PCNG/IOO O *RRN/IOO O
PNREMC=ODRYCD*PCNC/IOO O iRRN/IO0.0
PNREMS=QDRYSDiPCNS/IO0.0 lRRN/IO0.0

VNREMG=PNREMG*PNPLB
VNREMCIPNREMC§PNPLB
VNREMSBPNREMS*PNPLB

CONVERT THE COST PER 2000 LB NET TON FOR HARVESTING AND TRANSPORTING
TO A COST PER 56 POUND DRY BU. IN CENTS.

HCPBUG=XCPBUG*QNTGD/56 O

HCPBUCSHCPTNC§QNTCDl2OOO.0*100.O

HCPBUS-HCPTNS*QUTSD/2000 O*100.0
CONVERTg TgEcMARKET VALUE OF GRAIN.COBS AND STOVER TO A FIELD BU BASIS

VMRKNG=7(IOO. O-GIMC)/(100. O-BMC))§VMRKGGIOO. OGQHTGD/56. O
VMRKSB=VMRKS¥QNTSDl2000 O {100 O
VMRKCB=VMRKC*QNTCD/ZOOO O 9100. 0

AT THIS POINT.ALL THE COSTS ARE OR HAVE BEEN COMPUTED. THEREFORE COMPUTE
THE YEARLY SAVINGS VIA GASIFICATION AND CONVERT TOA QUANTITY THA
MAY BE SPENT FOR GASIFICATION EQUIPMENT.

TGPVG=0.0
TGPVC=0.0
TGPVSBO.O
IY=IYEAR

DD 3 131: IV
PVTERM=(1.0+AINTPC/IO0.0)**I
COMPUTE ANNUAL SAVINGS:R.FOR GRAINICDBS AND STOVER
)SXLPGSA(I)-HCPBUG-AMAXI(VNREMG.VMRKNG)

RG(I
RC(I)8XLPGSA(I)-HCPBUC-AMAX1(VNREMC.VMRKCB)
RS(I)-XLPGSA(I)-HCPBUS-AMAX1(VNREMS.VMRKSB)

GOO 000 0 0000

0000

110

CONVERT THE GROSS ANNUAL SAVINGS TO A PRESENT VALUE BY YEAR AND IN TOTAL
GPVG(I)=RG(I)/PVTERM
TGPVG=TGPVG + GPVG(I)

GPVCtI)=RC(I)/PVTERM
TGPVC=TGPVC + GPVC(I)

GPVS(I)8RS(I)/PVTERM
TGPVS=TGPVS + GPVS(I)
3 CONTINUE

CONSTANT PERCENTAGE OF THE PURCHASE PRICE NILL BE ASSIGNED FOR
AINTENANCE AND UPKEEP EACH YEA R.
OMPUTE THE PNF

AI=AINTPCl1OO O

XPNF=((1.0+AI)**IY-I.O)/(A

PNF=1.0 + XPNFiAUPKEP/IOO.
PNF FOR UPKEEP ALONE
PNFUPK=PNFiAUPKEP/IO0.0

COMPUTE THE AMT. THAT MAY BE SPENT ON MACHINERY CONSIDERING UPKEEP
PURMG=TGPVGlPNF
PURMC=TGPVClPNF
PURMS=TGPVS/PNF

COMPUTE THE ANNUAL COST FOR MAINTENANCE AND UPKEEP
UPKEPG=PURMG*AUPKEP/100 O

UPKEPC=PURMC*AUPKEP/IO0.0
UPKEPS=PURMSiAUPKEP/IO0.0

A
M
C

5*(1.0+AI)**IY)

CHECK TO SEE IF THIS IS A NEGATIVE PRESENT VALUE.

IF(PURMG.LT.O.O)PURMG8PURMG + XPNFiUPKEPG
IF(PURMC.LT.0.0)PURMC=PURMC + XPNFfiUPKEPC
IF(PURMS.LT.0.0)PURMS=PURMS + XPNF*UPKEPS

DETERMINE THE PERCENT OF AVAILABLE DRY AND NET MATERIAL REQUIRED.
PCAVDG=GDRYGD/DRYNTG*100.0 /56.
PCAVDC=QDRYCD/DRYNTC*100.0 l56.
PCAVDS=QDRYSD/DRYNTS'IO0.0 l56.
PCAVNG=QNTGDlNETNTG*IO0.0 l56.
PCAVNC=GNTCDlNETNTCGIOO.O l56.
PCAVNS=QNTSD/NETNTS*100.0 l56.

NRITE(IN.70)NATERP.ENERGP.ENERGB.EPQLPG.QLPGPP.QLPGBU.XPNF.
XPNF.PNFUPK

000000

70 FORMAT(

13X. '1 POUNDS OF NATER PER POUND NET GRAIN“; T64.F9.3/
23X.“2 THEORETICAL BTU/LB OF NET GRAIN" T64.F9.3/
33X."3 THEORETICAL BTU/BU OF NET GRAIN". T64;F9.3/ /
43X."4 ENERGY CONTENT OF LP GAS.BTU/GAL.": T64.F9.3/
53X.“5 LP GAS NEEDED.GAL/LB NET GRAIN": T64.F9.3/
63X."6 LP GAS NEEDED.GAL/BU NET GRAIN": T64oF9.3//
73X.”7 PRESENT NORTH FACTOR". T64.F9.3/
83X.”8 PRESENT NORTH FACTOR.ADJUSTED": T640F9. 3/
93X."9 REPAIR AND OPERATION MODIFIER": T64uF9. 3!)

NRITE(IN.55)
55 FORMAT(72( "i" )/72( "i“ ) /

égi§of%§g:0: RELATIVE GROSS ADJUSTED AVERAGE RELATIVE ENERGY"/
gI}3."AVAIL. NEIGHTS ENERGY ENERGY MOISTURE HEIGHTS AVAILABLE
g¥3?."PERCENT IN FIELD AVAILABLE AVAIL. CONTENT IN FIELD MC ADJUS
g};3:( ':BRY/) DRY LB. (BTU/DLB)(BTU/DLB) PERCENT NET LB. (BTU/NLB)“

6000

111

NRITEtIN.5 )PCGDB DRYNTG.GECORNoAECORN.GIMC.NETNTG.EAGNTG
56 FORMAT<3X."GRAIN". T1L 7F9 3)

NRITE(1N.5 )PCCDB.DRYNTC. GECOBS.AECOBS.CMC NETNTC. EAGNTC
57 FORMAT(3X."COBS".T1.7F9 3)

NRITE(IN.58)PCSDB. DRYNTS.GESTOV.AESTOV.SMC NETNTS.EAGNTS
58 FORMAT<3X."STOVER". T11. 7F9 3//72("§“)//

RITE(IN.59)

59 FORMAT(72("*")/72("§")/

13X."ITEMS”.

II}§;"ENERGZ)" NET RELATIVE QUANTITY QUANTITY QUANTITY VALUE OF

2311-”AVAILABLE ENERGY ADJ.ENER. FOR FOR NITROGEN NITROGE
:4 "

gI 1 “GAS P.ADJ AVAIL. AVAIL. DRYING DRYING REMOVED REMOVED
Ejél. "(BTU/NLB)(BTU/HLB)(TOT. DTU)(HET LB) (DRY LD) (LB.) (C)"/
) fi("i"

NRITE‘IN.56)EAANTG.EANNTG.TGE.QNTGD.QDRYGD.PNREMG.VNREMG
NRITE(IN.57)EAANTC.EANNTC.TCE.QNTCD.QDRYCDoPNREMcoVNREMC
NRITE(IN.58)EAANTS.EANNTS.TSE.QNTSD.QDRYSD:PNREMS.VNREMS

NRITE(IN.6
60 EORMAT (72.("*")/72(“*")/

13 "1TEMS
1T11."GATHERING FIELD PERCENT PERCENT"/
22x.'(1S-17) TRANSPORT MARKET OF TOTAL “OF TOTAL“/
3T13."COST VALUE AVAIL. AVAIL
4T11."(C/DR BU)(C/DR.BU) (DRY) (NET)“/72(“§")/)
NFITE(IN.6 61)HCPBUG.VMRKNG.PCAVDG. PCAVNG.HCPBUC.VMRKCB.
XPCAVDC.PCA AVNC. HCPBUS.VMRKSB. PCAVDS.PCAVNS
FORMAT(3X. "GRAIN". T11 4F9. 3/

6]
23X."COBS”.T11.4F9. 3/
33X.”STOVER". T11. 4F9. 3/[72(“*")//)

NRITE(IN.62)
Z’ FORMAT(72(”*“1/72("*")//T29."ECONOMIC SUMMARY *"l/72(“§")/

11x “ITEM YR GROSS COLLECT- COST OF MARKET GROSS ANNUAL
NET AMT "/

2:12 "LP GAS ION COST NITROGEN VALUE. SAVINGS. COST OF AVAIL.FO
'/

5T12."SAVINGS”.TSO.”REMOVED BIOMASS BIOMASS EQUIPMENT PURCHASE"!

6;;§("(C<?U) (C/BU) (C/BU) (C/BU) (C/BU) (C/BU) (C/BU)"
I 11*"

DO 10 I=I.IY
NRITE(IN.63)I.XLPGSA(I).HCPBUGoVNREMG.VMRKNG.RG(I).UPKEPG.PURMG
63 FORMAT(IX."GRAIN ".I2.7F9.3)

NRITE<IN. 64)XLPQSA(I). HCPBUC. VNREMC. VMRKCB:RC(I).UPKEPC PURMC
64 FORMAT(IX."COBS “.2X.7F9 .3)

NRITE(IN.65)XLPGSA(I).HCPBUS.VNREMS.VMRKSB.RS(I).UPKEPS.PURMS
65 FORMAT(1X."STOVER "o2X.7F9.3)

NRITE(IN.67)COSTLP(I)
67 FORMAT(1X."LPGAS.C/G“.F9.3/)
IF(I.EQ.IY)NRITE(IN.66)GFMC

66 FORMAT(1X.“* ALL VALUES BASED ON A BU. AT “.F5.2." PERCENT MOISTUR
XE CONTENT"/72("*"))

112

10 CONTINUE
AG(I)=DRYNT G
AG(2)=DRYNTG§GECORN
AG(3)=TG E
AG(4)=HCPBUG + VNREMG - VMRKNG
AG(5)=TGPVG/YEARS
C AG(6)IPURM C
AC(1)=DRYNTC
AC(2)=DRYNTC*GECOBS
AC(3)'TCE
AC(4)-HCPBUC + VNREMC + VMRKCB
AC(5)-TGPVC/ YEARS
C AC(6)-PURM C
AS(1)- S
AS(2)=DRYNTS*GESTOV
AS(3)8
AS(4)=HCPBUS + VNREMS + VMRKSB
AS(5)=TGPVS/YEARS
C AS(6)-PURMS
C
C DO 101 J-I 6
RATIO(1.J)8AG(J)/AC(J)
RATIO(2.J)=AG(J)/AS(J)
RATIO(3.J)¢AC(J)/AS(J)
RATIO(4.J)=AC(J)/AG(J)
RATIO(5.J)=AS(J)/AG(J)
C RATIO(6.J)’AS(J)/AC(J)
101 CON NTINUE

NRITE(IN.6B)
68 FORMAT(72("*")/72("§")/3X."RATIOS".

2T20. "RELATIVE GROSS NET“.T49."TOTAL AVERAGE AVAIL.“/

3T20."DRY NTb IN ENERGY ENERGY GROSS ROS OR"

373?." )FIELD AVAIL. AVAIL. COSTS SAVINGS PURCHASE“/
"*0.

NRITE(IN.69)((RATIO(I.J).J-1.6)o1.1.6)

69 FORMAT(3X.“GRAIN/COBS". T20.6F9.3/
23X ."GRAIN ISTOVER" T20.6F9.3/
33X."COBS/STOVER ".T20.6F9.3/
33X."COBS/GRAIN “.T20.6F9.3/
53X.”STOVER/GRAIN“.T20.6F9.3/
$3;2:STOY§5;COBSH .T20.6F9. 3/

"*ll
C$$$$$$$$$$$$$§$$SSSGSSSSGSSSSGCGSCCCGSSSCQGGSSOGSCGSGCGSSGSGGGGSSSQGGGC
Cfggg$gafi¥§;ag$$t$S$$$$$$$$$3$$$$$$$$$$$$$$$$$$$$$$G$$3$3333$33SCGSSGGCG
C$$$$$$$$$$$$$$$$$$$$$$$$$$$QGGGSCGCCCO$$$$$$$$$3$$$33$$$$$$$$$$$$$$S$$C
C$$$$$§¥33$GSGGGSGGSCSGGSSSSCSSGCGGGCGGGGGGGQCGCCSGGGGGCGSGBCSCGGGS3‘333

END

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t TF7J> TILML bTU/Lr OF BET GRAI' 228.777
3 T~"-LTILLL ETD/vb 0F BET GRAIN 12611.511
‘9 ’.’-5 Y LE'TENT 0F LE GASQETUIDAL. 92030.000
5 Lr b-“ NE;ULDOGbL/LE LET GRAIN .00H
6 LE 04? L;EUED.GAL/BU BET GRAIN .435
7 9"“.3; T .‘DTF‘. FACTOR 6.911
c Fn.SL T .EFTh PACTOR. ADJUSTED 1.272
9 «3951- AFT UPERATION “ODIFIER .051

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ITLYS LKL’GY NET RELATIVE DUA'TITY QUANTITY DUfiNTITY VALUL CF
(8'14) bVAILAbLE ENERGY ADJ.EHER. FOP F0 NITROGEN NITROGEN
(AS.P.ADJ AVAIL. AVAIL. DRYING DRYING REMOVED REOUVCD
(FTU/HLB)(ETU’ULEIITDT.§TUIIBET LE) (DRY LB) 3LL.) CCI
‘.'...i'ttfit' 39".‘..‘.’.’.‘.".O’."ODOOOD‘O‘t‘DD‘D‘O.‘D'.."'.'.O..'..‘
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COLE 17:4.68“ 717.07“ 314.812 17.966 6.9Eh .025 .502
STOVE“ 1557.36“ £22.9R6 1028.551 20.565 8.021 .074 1.070

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IT‘“S CATHERINL FIELD PERCENT PERCENT
(15-17) Thé’ SguFT MAFKET OF TOTAL OF TOTAL

VALUE AVAIL. AVAIL.
(C/z..EL'1(C/['R.EU1 (DRY, (LET)
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CL'“; (.233 0.050 2.671 72.571
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LPGASOC/ 1-4.°51

66‘1“ 10 76.5““ 3."?9 1.161 19.163 53.35? 6.3“? 159.555
C085 76.5““ 2.273 .502 0.000 73.80" 10.500 262.72L
STOVER 76.5““ 5.192 1.476 0.000 69.927 .675 241.999
LPG‘SoC/l 175.?9»

GRAIN 11 E?.U?f 3.3(O 1.161 10.163 65.830 6.363 158.5“?
C065 96.026 2.233 .502 0.CUC 65.291 10.5"q 2t?.729
S7OVLR 66.026 .1 1.976 0.00C 91.909 9. 79 241.949
LPGLSOCI‘ 202.27*

GRKIN 12 101.230 3.029 1.161 19.163 79.038 .34 158.5t3
COES 101.235 2.233 .502 0.000 96.495 10.5%: 962.72;
STUVER 1C1.'¢3§ 5.192 1.“76 0.000 (24.613 c.67‘ 2401.949
LPGASQC/C 232.62;

GRAIN 13 116.414 3.02“ 1.161 19.163 04.222 6.343 159.553
0086 116.61“ 2.255 .502 0.0LU 113.67O 10.509 262.720
STUVEP 116.“1“ 5.1“2 1..76 0.000 105.797 9.678 261.999
LPGASQC/L 267.513

5R£1N 16 133.877 3.9“c 1.161 1°.163 111.695 6.343 158.593
CUBS 133.877 2.233 .502 0.000 131.142 1C.5U° 262.72q
STOViR 7 135.677 5.142 1.976 0.90C 127.25c °.b76 241.9%.
LPGASoC/o 3u7.63“

SRIIk 5 163.959 3.029 1.161 19.163 151.766 6.343 158.563
0056 153.951: 2.?35 .50? 0.000 151.223 10.50? 262.72%;
STOVEF 155.95? 5.142 1.476 6.000 147.3“1 9.676 241.999
LPGASOC/b 353.705

fi ALL VALUFS EASLL ON A fit. tT 15.50 PEPCEHT PPISTUPE CONTENT

.c............................t.........................................
.t...........a............t.......................t.....................
.9......................................................................

RATIOS RELATIVE 69055 N17 TOTAL ‘VLFABE AVAlL.
DFY 57.1% EVEQGY CNLRGY 59055 69055 FOP

FIELD tVAlL. AV‘IL. COSTS Stv1~$z PUHCfiASE
.‘f.."."t"'.’."."..."'.".'.."’f..'.‘,"'*....""'.'f’,'*.'..*'f
GRAIN/C0135 “.059 5.096 6.236 ’5o‘i7f .60“ .604
GRAIN/STJVz‘ 1.979 1.509 1.909 “3.263 .655 .655
CUES/STOVE* .266 .296 .306 .613 1.0“6 1.066
CCl‘S/GCAV- .2“6 .196 .160 ’.1‘5 1.61:7 1.657
STOVLRI:FLI .927 .663 .52“ ‘.442 1.5(6 1.526
STLvVER/CQF: 3.761 3.376 3.267 2.623 .°L1 .921

'.'...Qiit'fil8".tittliifiiififitfftitft9...!‘6'0......003099.....‘09969609

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BIBLIOGRAPHY

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