The Potential of Biomass Conversion in Meeting the Energy Needs

44 The Potential of Biomass Conversion in Meeting the Energy Needs of the Rural Populations of Developing Countries — An Overview V. MUBAYI and J. LEE Downloaded by UNIV OF PITTSBURGH on November 22, 2015 | http://pubs.acs.org Publication Date: August 29, 1980 | doi: 10.1021/bk-1980-0130.ch044

Brookhaven National Laboratory, Upton, NY 11973 R. CHATTERJEE Institute for Energy Research, State University of New York, Stony Brook, NY 11794

Biomass, in the form of firewood, dried crop residues and animal dung, is the fuel most extensively utilized in the rural areas of most developing countries. What was true of the United States over a hundred years ago, when wood accounted for over 90% of energy consumption, s t i l l holds good for many developing nations, particularly in their rural settlements. Current utilization of these resources generally takes place outside of a market economy (hence the term "noncommercial" usually applied to these resources) and in varying amounts for both energy and nonenergy uses. Crop residues, for example, are used as fuel, building material and as animal feed. Dung is used both as fuel and fertilizer. Practically all of the biomass use that takes place at present is in the form of direct combustion at very low efficiencies to supply heat for essential human needs such as food preparation. The mechanical power needs of agricultural production are largely met through the metabolic energy input of draft animals and human labor. Constraints on land and the population it can support make the raising of agricultural productivity essential if food production is to expand in step with population growth. Furthermore, the provision of basic human needs and amenities to improve the "physical quality of life" is an important social goal of almost all of the developing countries. Energy is universally recognized as essential for development. Greater amounts of energy capable of being utilized more efficiently and productively are particularly needed in rural areas of LDCs in order to raise agricultural productivity, provide off-farm employment, essential amenities such as lighting and to improve the physical quality of life. Hence, in addition to low temperature heat necessary for subsistence, mechanical energy is required for agricultural tasks (e.g., pumping water for irrigation), transportation, and small industry, chemical feedstocks whose manufacture requires energy are needed as fertilizer and electricity is needed for lighting. 0-8412-O565-5/80/47-130-617$05.O0/0 © 1980 American Chemical Society In Thermal Conversion of Solid Wastes and Biomass; Jones, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.

Downloaded by UNIV OF PITTSBURGH on November 22, 2015 | http://pubs.acs.org Publication Date: August 29, 1980 | doi: 10.1021/bk-1980-0130.ch044

618

THERMAL

CONVERSION OF SOLID WASTES AND Β TOM ASS

H i s t o r i c a l l y , i n those r u r a l areas where modernization has occurred, petroleum products have provided the necessary energy inputs required f o r a v a r i e t y of a c t i v i t i e s . Kerosene i s a widely used i l l u m i n a n t , d i e s e l o i l f o r powering i r r i g a t i o n pumps and other farm equipment, g a s o l i n e f o r t r a n s p o r t a t i o n and f e r t i l i z e r s are o f t e n manufactured from naphtha. However, the world o i l s i t u a t i o n now makes the "petroleum route" to development an i n c r e a s i n g l y d i f f i c u l t one f o r many developing countries to undertake. Biomass conversion technologies, which can convert already a v a i l a b l e biomass into a v a r i e t y of s o l i d , l i q u i d , and gaseous f u e l s , capable of being u t i l i z e d more e f f i c i e n t l y and productive l y , w i l l be e s s e n t i a l i f the future subsistence and developmental energy needs of r u r a l areas i n developing countries are to be met. This paper represents a very p r e l i m i n a r y attempt at assess ing the c o n t r i b u t i o n biomass conversion could make i n the context of the r u r a l areas of s i x developing c o u n t r i e s : India, Indonesia, Peru, Sudan, Tanzania, and T h a i l a n d . The choice of countries was d i c t a t e d p a r t l y by the a v a i l a b l i t y of data on resources and con sumption and p a r t l y by the f a c t that these countries t y p i f y the r u r a l energy s i t u a t i o n i n a l a r g e number of developing countries l o c a t e d i n South and South-East A s i a , A f r i c a , and South America. This overview assesses the p o t e n t i a l resources of biomass a v a i l a b l e i n the s i x countries s e l e c t e d . With a few exceptions (such as Peru's f o r e s t resources) these resources are already being c o l l e c t e d and used, a l b e i t i n e f f i c i e n t l y . We focus on r u r a l energy end-uses i n each of the c o u n t r i e s , i n c l u d i n g a d i s c u s s i o n of the current energy consumption patterns and t h e i r magnitudes. Current consumption i s projected i n t o the f u t u r e , to the year 2000, with emphasis placed on c o n c e p t u a l i z i n g both subsistence needs (e.g., cooking) and developmental needs ( i n c r e a s i n g produc t i v i t y and l i v i n g standards). The method adopted i n our approach i s that i n the context of r u r a l development an assessment of new technologies has to be anchored w i t h i n the perspective of future energy requirements to s a t i s f y both the b a s i c subsistence needs of growing populations as w e l l as t h e i r developmental needs. The technologies s e l e c t e d f o r a n a l y s i s are: anaerobic d i g e s t i o n of wet biomass to produce methane and p y r o l y s i s of dry b i o mass to produce c h a r c o a l , l i q u i d f u e l s , and low-Btu gases. Pre l i m i n a r y estimates are made of the amounts of f u e l s that could be produced i n each of the s e l e c t e d countries by a combination of these technologies. We f i n d that i n f i v e of the s i x c o u n t r i e s , with the exception of India, implementation of these technologies could p o t e n t i a l l y meet the future energy needs of t h e i r r u r a l populations f o r both subsistence and development. Current Sources of Biomass Supply The p r i n c i p a l sources of biomass used f o r energy purposes are wood, gathered from f o r e s t s , orchards and farms, a g r i c u l t u r a l crop residues and animal wastes. Human wastes can a l s o be p o t e n t i a l l y

In Thermal Conversion of Solid Wastes and Biomass; Jones, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.


44.

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Biomass Conversion to Meet Energy Needs

619

considered as an energy resource f o r biomass conversion technolo gies such as anaerobic d i g e s t i o n i f appropriate c o l l e c t i o n prac t i c e s are employed (as, f o r example, i n many Chinese v i l l a g e s ) . We exclude from our purview organic matter which could be poten t i a l l y grown i n "energy p l a n t a t i o n s " i n a g r i c u l t u r e , s i l v i c u l t u r e , or aquaculture. This i s not to suggest that such p l a n t a t i o n s are not p o t e n t i a l l y important sources of biomass energy i n developing c o u n t r i e s . However, an e v a l u a t i o n of t h e i r c o n t r i b u t i o n would r e quire an a n a l y s i s of a l t e r n a t i v e land-use patterns which are spe c i f i c to each country and f a l l s outside the scope of our a s s e s s ment. Table I provides estimates of the biomass produced annually i n each of the s i x c o u n t r i e s . However, t h i s biomass i s not a l l a v a i l a b l e f o r energy conversion. There are numerous u n c e r t a i n t i e s i n v o l v e d i n attempting to estimate the amounts of biomass that could be used as an energy source such as the f r a c t i o n of wood, crop r e s i d u e s , and animal wastes that can be c o l l e c t e d and the a l t e r n a t i v e non-energy uses that e x i s t f o r the amounts that are cur rently collected. Crop r e s i d u e s , f o r example, are commonly u t i l i z e d f o r animal feed and sometimes as b u i l d i n g m a t e r i a l s , animal dung i s u t i l i z e d as a f e r t i l i z e r , and so f o r t h . We have neverthe l e s s attempted p r e l i m i n a r y estimates of the biomass a v a i l a b l e f o r energy conversion i n the s i x countries based i n part on data pro vided i n other studies and i n part on reasonable assumptions made i n these s t u d i e s . However crude, f o r the purposes of an o v e r a l l assessment of the impact of biomass conversion technology on r u r a l energy needs, these estimates are b e l i e v e d to be r e a l i s t i c approxi mations of the amounts of biomass that could be made a v a i l a b l e f o r energy conversion. Assuming an average energy content of 14 b i l l i o n j o u l e s / d r y ton f o r crop r e s i d u e s , 15 b i l l i o n j o u l e s / d r y ton for animal wastes and 16 b i l l i o n j o u l e s / d r y ton f o r fuelwood, the t o t a l p o t e n t i a l f o r energy from biomass can then be c a l c u l a t e d based on these estimates (Table I I ) . In order to assess the s i g n i f i c a n c e of these estimated energy p o t e n t i a l s , we have compiled the best a v a i l a b l e data on the cur rent r u r a l biomass consumption f o r energy i n the s i x c o u n t r i e s (Table I I I ) . I t appears that f o r Sudan the biomass energy poten t i a l , estimated a t 650 χ 1 0 ^ j o u l e s , i s about ten times i t s cur rent biomass consumption. For Peru, the p o t e n t i a l i s estimated at 1341 χ 1 0 ^ j o u l e s , which i s enough to supply a l l i t s r u r a l b i o mass energy needs 7.5 times. The p o t e n t i a l f o r other countries i s about twice the r u r a l consumption f o r Indonesia, Thailand, and Tanzania, and 1.5 times f o r I n d i a . To f u l l y u t i l i z e t h i s poten t i a l , however, r e q u i r e s an understanding of a disaggregated pat t e r n of r u r a l energy needs and the biomass conversion technologies that can transform t h i s p o t e n t i a l into usable f u e l s .


620

THERMAL CONVERSION OF SOLID WASTES AND BIOMASS

Estimated

10

6

10

Ton Human Waste

3

Animal^ Manure


Crop Residues

Potential

15

S o u r c e s o f Biomass i n R u r a l (per annum)

Ton

Joulgg

Tanzania

Indonesia 1Ô Ι Ο Ton Joulei 5

Joulci

1

Areas

10*To

5

Ton

Ton ... Joulag

Joulis

Ton

1 5

Joules

0.2

3.0

1.0

15.0

3.2

48.0

14.3

214.5

0.5

7.3

0.4

6.0

6.9

103.5

12.8

192.0

10.0

150.0

L98.0

2970.0

24.0

360.0

20.6

209.0

6.0

84.0

37.0

520.0

52.0

728.0

160.0

2240.0

9.3

130.0

2.1

29.4

Fuelwood^

510.0

8160.0

198.0

3168.0

720.0

11520.0

300.0

4800.0

132.0

2112.0

152.0

2432.0

Total

523.1

8350.5

248.8

3895.0

785.2

12446.0

632.3

10224.5

165.2

2609.3

175.1

2776.4

b

c

d

Based Based Based Based

on on on on

UN s t a t i s t i c s (1,2) and 33 Kg ( d r y w e i g h t ) o f waste p r o d u c t i o n p e r p e r s o n p e r y e a r . l i v e s t o c k p o p u l a t i o n (1) and manure p r o d u c t i o n r a t e o f m a j o r l i v e s t o c k s 13,4.). p r o d u c t i o n o f m a j o r c r o p s p r o d u c t i o n (I) and t h e i r r e s p e c t i v e r e s i d u e c o e f f i c i e n t s (5,6). a c t u a l f o r e s t r y a r e a (6-11) and p e r u n i t a r e a i n c r e m e n t o f wood by t y p e o f f o r e s t (12).

Estimated A v a i l a b i l i t y

Peru 5

10* Ton

1 5

10 Joules

Thailand 1Ô ÏÔ Ton Joules 5

1 5

o f Biomass f o r E n e r g y C o n v e r s i o n ( p e r annum) Indonesia lô

Human Waste

0.1

1.5

0.5

7.5

Animal^ Manure

5.2

77.6

9.6

144.0

2.7

38.0

76.5

1224.0

29.7

475.0

84.5

1341.1

56.5

860.5

c

16.7

10" Ton

io -

Sudan

10 Ton

A

Joules

Areas

To«15 Joules

1

7.2

107.3

0.3

4.4

0.2

3.0

148.5

2227.5

18.0

270.0

15.5

231.8

24.0

560.0

4.2

58.5

1.0

13.2

119.0

1900.0

19.8

316.8

22.8

365.0

298.7

4794.8

42.3

649.7

39.5

613.0

24.0

7.5

112.5

23.4

328.0

234.0

108.0

1728.0

140.5

2192.5

Âssuming 50% c o l l e c t i b i l i t y . Assuming 75% o v e r a l l c o l l e c t i b i l i t y . Assuming 50% o v e r a l l c o l l e c t i b i l i t y . I t i s f u r t h e r assumed t h a t 50% o f t h e c o l l e c t e d c r o p r e s i d u e s i s used f o r a n i m a l f e e d i n I n d i a , 10% i n T a n z a n i a (5) and t h e r e m a i n i n g c o u n t r i e s . Assuming 15% u s e o f t h e e s t i m a t e d t o t a l a n n u a l i n c r e m e n t o f wood ( t h e p e r c e n t a g e may be an o v e r e s t i m a t e f o r P e r u and I n d o n e s i a due t o t h e l o c a t i o n o f f o r e s t r e s o u r c e s ) . F o r I n d i a , t h e a v a i l a b i l i t y has been assumed t o e q u a l c u r r e n t consumption. d

Estimated

Consumption o f Biomass a s an Energy Source (10 Joules)

i n Rural

Areas

15

Peru

Thailand

Indonesia

0

India

d

Sudan

6

Tanzania

f

Human Waste Animal Manure Crop Residue

5

1 0 * 1 0 Ton Joules

Joules

1.6

Crop Residues

f

5

Ton

i n Rural

8.7

54.4

200.0

472.0

2.4

138.0

440.0

800.0

1900.0

60.0

320.0

Sources: U.S. Dept. o f E n e r g y (6). U.S. Agency f o r I n t e r n a t i o n a l Development (13), assuming a l l c r o p r e s i d u e s a r e consumed i n r u r a l a r e a . °Mubayi e t . a l . ( 1 4 ) . Mubayi e t . a l . (15) . A b a y a z i d OU) . Per c a p i t a c o n s u m p t i o n o f fuelwood i n r u r a l a r e a from R e v e l l e (16). E s t i m a t e d 1975 r u r a l p o p u l a t i o n from UN (2). 3

e


44.

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621


Rural Energy Supply-Demand P a t t e r n Table IV shows the estimated energy use by type and end use f o r the s i x countries studiedIt appears that the energy share of cooking and heating, which i s p r i m a r i l y by wood, ranges from a high of 98.5% (Tanzania) to a low of 86.4% ( I n d i a ) . Lighting (mainly supplied by kerosene) accounts f o r about 3% or less of the t o t a l r u r a l energy consumption. Although the d i r e c t f u e l use i n a g r i c u l t u r e ( i r r i g a t i o n , s o i l p r e p a r a t i o n and harvesting) i s pro p o r t i o n a t e l y small (from 0.3% i n Tanzania to 9.7% i n Sudan), the t o t a l energy requirements of t h i s sector are i n general much greater i f draft animal power were to be included. This i s per haps more true i n the case of r u r a l t r a n s p o r t a t i o n which p r i m a r i l y depends on animal draft power. In order to assess the p o t e n t i a l increase of f u e l demand due to mechanization of a g r i c u l t u r e and t r a n s p o r t a t i o n , we have estimated the amount of u s e f u l work con t r i b u t e d by d r a f t animals i n the s i x LDCs based on the number and i n t e n s i t y of u t i l i z a t i o n of these animals i n each of these coun t r i e s (5,11,16). The estimates show that t o t a l animal energy demand v a r i e s widely, from a n e g l i g i b l e amount i n Tanzania to about 94 χ 1 0 joules i n India. Cottage i n d u s t r i e s which include a c t i v i t i e s such as brick-making, p o t t e r y and metal works mainly use energy to provide process heat and t h e i r energy share appears g e n e r a l l y small except i n India (9.3%). 1 5

Technology

Overview

Biomass conversion technologies can be c l a s s i f i e d into three main types: Anaerobic d i g e s t i o n , p y r o l y s i s and a l c o h o l fermenta tion. In anaerobic d i g e s t i o n , organic m a t e r i a l s are broken down by microorganisms i n the absence of oxygen to produce methane. Although t h i s process has been used i n urban waste d i s p o s a l f o r many decades, i t s u t i l i z a t i o n f o r producing energy at the v i l l a g e or i n d i v i d u a l household l e v e l i s s t i l l r e l a t i v e l y new. China and India are two countries where the technology has, perhaps, been most e x t e n s i v e l y implemented i n r u r a l areas (4,21,22). Animal wastes are the most widely used input m a t e r i a l s i n the d i g e s t o r s c u r r e n t l y operating although crop residues or a mixture of crop residues and animal wastes can also be u t i l i z e d . One great advan tage of anaerobic d i g e s t i o n i s that the l e f t - o v e r s l u r r y a f t e r the d i g e s t i o n process g e n e r a l l y preserves the n u t r i e n t values of the input feed and can be used as a good organic f e r t i l i z e r . P y r o l y s i s i s an i r r e v e r s i b l e chemical change through heating i n an oxygen-free or low-oxygen atmosphere. Depending on the sys tem c o n d i t i o n s and input m a t e r i a l , the p y r o l y s i s of biomass y i e l d s a mixture of s o l i d , l i q u i d and gaseous f u e l s . Although p y r o l y t i c conversion of wood into charcoal by means of simple earth-covered k i l n s has been widely used f o r many centuries i n the r u r a l areas of many LDCs the process i s very i n e f f i c i e n t and does not permit the recovery of the l i q u i d and gaseous energy by-products. How-


THERMAL

622

CONVERSION OF SOLID WASTES AND BIOMASS

TABLE IV

Peru (1977) FUELWOOD

CROP RESIDUES

ANIMAL WASTES

COMMERCIAL FUEL

SUBTOTAL

X OF TOTAL


RESIDENTIAL Cooking/Heating

138.0

24.0

Lighting AGRICULTURE

6.3

168.3

90.8

5.6

5.6

3.0

9.5

9.5

5.7

1.0

1.0

0.5

1.0

1.0

0.5

23.4

185.4

Irrigation Soil Preparation,etc. COTTAGE INDUSTRY TRANSPORTATION TOTAL

138.0

Estimated Animal work in agriculture and transportation: Source: (6).

7 χ 10 15 Joules

Thailand (1978) FUELWOOD

CROP RESIDUES

ANIMAL WASTES

COMMERCIAL FUEL

SUBTOTAL

% OF TOTAL


440.0

446.7

86.5

13.4

13.4

2.6

46.5

46.5

9.0

1.7

8.0

1.5

1.7

1.7

0.4

63.3

516.3

100.0

6.7

Lighting AGRICULTURE Irrigation Soil Preparation,etc. 6.3

COTTAGE INDUSTRY TRANSPORTATION TOTAL

440.0

13.0

Estimated Animal work in agriculture and transportation: Sources: (1) and (19).

15 8 χ 10 Joules


44.

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623


ET AL.

TABLE IV (cont.) Tanzania (1977) FUELWOOD

CROP RESIDUES

ANIMAL WASTES

COMMERCIAL FUEL

SUBTOTAL

X OF TOTAL


RESIDENTIAL* Cooking/Heating

320.0

320.0

Lighting

4.0

AGRICULTURE

4.0

1.2 0.3

1.0


320.0

—

—

5.0

Estimated Animal work in agriculture and transportation: Sources: (15) and (20) .

325.0

100.0

Negligible

India (1972) FUELWOOD

CROP RESIDUES

ANIMAL WASTES

COMMERCIAL FUEL

SUBTOTAL

X OF TOTAL

RESIDENTIAL Cooking/Heating Lighting

1700.0

460.0

760.0

50.0

292.0

86.4

—

—

—

74.0

74.0

2.2

--

—

--

55.0

55.0

1.6

—

—

--

13.0

13.0

0.4

200.0

12.0

100.0

4.0

316.0

9.3

AGRICULTURE Irrigation Soil Preparation,etc. COTTAGE INDUSTRY TRANSPORTATION TOTAL

— 1900.0

~

—

472.0

860.0


2.0

2.0

0.1

198.0

3380.0

100.0

94 χ 10

Joules


624

THERMAL CONVERSION OF SOLID WASTES AND BIOMASS

TABLE IV (cent,) Indonesia (1972)


FUELWOOD

CROP RESIDUES

ANIMAL WASTES

COMMERCIAL FUEL

SUBTOTAL

X OF TOTAL


800.0

1000.0

Lighting AGRICULTURE

96.4

30.0

30.0

2.8

4.0

4.0

0.4

1.6

1.6

0.2

1.7

1.7

0.2

37.3

1035.7

100.0


800.0

200.0


67 χ 1015 Joules Λ

Sudan (1974) FUELWOOD

CROP RESIDUES

250.0

2.4

ANIMAL WASTES

COMMERCIAL FUEL

SUBTOTAL

X OF TOTAL

RESIDENTIAL Cooking/Heating Lighting

252.4

96.0

3.0

3.0

1.1

3.0

3.0

1.1

4.0

4.0

1.5

0.2

0.2

0.1

0.4

0.4

0.2

9.6

263.0

100.0

AGRICULTURE Irrigation Soil Preparation,etc. COTTAGE INDUSTRY TRANSPORTATION TOTAL

250.0

2.4

Estimated Animal work in agriculture and transportation: Sources: (10) and (18).

1.0 χ 10

15

Joules



44.

MUBAYI

ET AL.


625

ever, a number of promising pyrolytic processes have been developed to produce charcoal and other high grade f u e l s : (a) continuous low-temperature p y r o l y s i s of wood and crop residues with various r e t o r t designs (22), (b) small scale g a s i f i c a t i o n of wood and crop residues (24,25), ( c ) medium to l a r g e scale d i s t i l l a t i o n of wood to produce methanol (25,26)* A l c o h o l fermentation i s a m i c r o b i o l o g i c a l process to produce ethanol from a v a r i e t y of sugar containing m a t e r i a l s . Various c e l l u l o s i c forms of biomass which can be converted to glucose sugar through enzymatic or a c i d h y d r o l y s i s are also being tested as substrates i n t h i s process i n many on-going research p r o j e c t s (27). Because of geographical, economical and other c o n s t r a i n t s on producing the fermentable sugar needed i n t h i s process on a l a r g e s c a l e , B r a z i l i s the only country, at present, which has developed a s u b s t a n t i a l program to produce ethanol f o r energy use. Table V l i s t s eight processes that appear as the most l i k e l y candidates f o r processing organic m a t e r i a l s into f u e l s . I t should be noted that the table i s intended f o r d e s c r i p t i v e purposes only and not f o r comparison of these processes. In a d d i t i o n , the determination of the maintenance requirements were h i g h l y q u a l i t a t i v e and the energy costs of each process were not n e c e s s a r i l y derived on the same basis or d e f i n i t i o n s . In the assessment that f o l l o w s , we have excluded a l c o h o l fermentation because i n i t s present status of development, i t requires grown organic m a t e r i a l s such as sugarcane as s u b s t r a t e s . In planning a future biomass conversion development s t r a t e g y , however, the s e l e c t i o n of technologies f o r a country are much more complicated and the f o l l o w i n g c r i t e r i a should be taken i n t o c o n s i d e r a t i o n : (a) sustainability of substrate (b) maintenance and technology requirements (c) c a p i t a l costs (d) a d a p t a b i l i t y to a v a r i e t y of d i f f e r e n t environments (e) a b i l i t y to supply the e x i s t i n g and p r o j e c t e d p a t t e r n of end use needs ( f ) a c c e p t a b i l i t y i n the c u l t u r a l and s o c i a l s t r u c t u r e . Supply-Demand I n t e g r a t i o n Based on the current end-use patterns discussed e a r l i e r , we have generated a scenario f o r the year 2000 to examine the f u t u r e r u r a l energy demands and the p o t e n t i a l of biomass conversion to meet these demands. It was assumed that energy f o r subsistence would grow at the same average growth rate of 2.5% as projected f o r the r u r a l population i n the s i x L D C s . Direct f u e l use f o r development has been projected to grow at 5% annually. In a d d i t i o n , i t was also assumed that 20% of the animal d r a f t energy used i n a g r i c u l t u r e and t r a n s p o r t a t i o n would be replaced by mechanization. The aggregate r u r a l energy growth implied by these assumptions are r e l a t i v e l y on the high side when compared with other LDC energy p r o j e c t i o n s (32). On the supply end, we have held the biomass a v a i l a b i l i t y at the current l e v e l to provide a "lower bound" of the future biomass energy p o t e n t i a l . The f u t u r e



Wood Crop r e s i d u e s

Wood

Sugarcane

Crop r e s i d u e s

Wood

Charcoal, pyrolytic o i l

Methanol

Ethanol

Ethanol

SNG

Research stage Development stage

Gasification

Available

Batch fermentation

Batch fermentation

High

Med ium

High

High

Available

Pyrolysis/ distillation

Low

Low

High

developed

developed

Available

Well

Well

Pyrolysis

Carbonization by k i l n s

Anaerobic digestion

Country dependent

High

Country dependent

Country dependent

High

Country dependent

High

Sustainability of S u b s t r a t e

C

b

d

e

6-8

6

30-5$

18-20

8-10

1-3

2-6

2-4~

Estimated Energy Cost ($/lCrJ)

6

^Based on a 75 m^/day community s i z e p l a n t . Does not i n c l u d e c o l l e c t i o n c o s t of wastes (28)• Lower l i m i t based on r e t a i l p r i c e of c h a r c o a l (1977) i n T h a i l a n d (29) and upper l i m i t based on r e t a i l p r i c e of c h a r c o a l (1977) i n Ghana (23). Lower l i m i t based on p r o d u c t i o n cost of a p y r o l y t i c c o n v e r t e r w i t h one ton/day c a p a c i t y (7_) . Ûpper l i m i t based on p r o d u c t i o n cost of a designed c o n v e r t e r w i t h s i x ton/day c a p a c i t y i n Ghana ( 2 3 ) . Based on the economic f e a s i b i l i t y of a p l a n t of 100,000 gallon/day c a p a c i t y a t a f e e d s t o c k c o s t of $19/ton dry wood (13). ^ C a l c u l a t e d s e l l i n g p r i c e based on a f e e d s t o c k c o s t of $13.6/ton i n B r a z i l (30). Based on the economic f e a s i b i l i t y of a p l a n t of 75,800 gallon/day c a p a c i t y a t a f e e d s t o c k c o s t of $15/ton dry wood (13). ^Based on the economic f e a s i b i l i t y of a p l a n t of 6.4 χ 10 SCF/day c a p a c i t y a t a f e e d s t o c k c o s t of $19/ton dry wood (13).

Wood

Charcoal

Substrate

Crop r e s i d u e s Animal wastes

Energy Product

Methane

Maintenance Requirement

Technologies

Status of Technology

Biomass C o n v e r s i o n

TABLE V



44.

MUBAYI

E T AL.


627

supply of biomass i n these countries could be higher because of f a c t o r s such as increased a g r i c u l t u r a l production. This scenario can therefore be judged as a conservative one i n assessing the p o t e n t i a l of biomass conversion. In matching the projected energy demands by end use and the various f u e l s that can be produced through the few biomass convers i o n technologies s e l e c t e d f o r t h i s study, we have converted the projected biomass energy needed f o r d i r e c t combustion (predominantly cooking at 10%-20% e f f i c i e n c y ) i n t o the energy equivalent of converted f u e l forms which can be u t i l i z e d at a much higher end-use e f f i c i e n c y (30% to 50%). In t h i s study we have used a conversion f a c t o r of 0.4 to estimate f u e l requirements i n 2000. This conversion i s important because greater end use e f f i c i e n c y requires l e s s energy input to generate a f i x e d amount of u s e f u l energy. Figure 1 i s a general network diagram which i n d i c a t e s energy flows from resources a v a i l a b l e i n r u r a l areas of LDCs through current and projected conversion technologies to the d i s aggregated end uses. This network, which i s a subsystem of the Less Developed Countries Energy System Network Simulator (LDC-ESNS) developed at Brookhaven N a t i o n a l Laboratory (33), can be u t i l i z e d to make q u a n t i t a t i v e assessments of the impacts of new technologies. Table VI shows the amounts of energy that can be produced by the technologies we have s e l e c t e d matched against the end-use demand f o r energy i n the s i x countries f o r the year 2000. Energy f o r subsistence denotes almost e n t i r e l y the domestic household demand f o r cooking and l i g h t i n g . Energy f o r development focusses on the energy needs of a g r i c u l t u r a l production, r u r a l i n d u s t r i e s , t r a n s p o r t a t i o n and improving l i v i n g standards of the r u r a l populat i o n ( 17,32). A very rough attempt has been made to d i v i d e the developmental energy needs into the need f o r heat energy and the need f o r motive power, which we assume w i l l have to be met almost completely by l i q u i d f u e l s , and s t a t i o n a r y mechanical power, which can be met by gaseous f u e l s as w e l l (e.g., biogas) or by conversion to e l e c t r i c i t y . This d i v i s i o n , however, i s subject to a large number of u n c e r t a i n t i e s . It i s provided here as a purely normative estimate to serve as a q u a n t i t a t i v e benchmark against which the impacts of biomass conversion technologies can be evaluated. From t h i s p r e l i m i n a r y a n a l y s i s we see that biomass conversion technologies have the p o t e n t i a l to meet the projected r u r a l energy demands i n both the subsistence and developmental categories i n f i v e out of the s i x c o u n t r i e s . Only i n the case of India does there appear to be a r e l a t i v e s h o r t f a l l and much of that i s i n the category of l i q u i d f u e l s . This shortage r e f l e c t s the fact that the technology we have chosen, methanol from wood, requires an input which i s i n r e l a t i v e l y short supply i n I n d i a .


THERMAL

C O N V E R S I O N O F SOLID W A S T E S

AND


628

BIOMASS

1 to

5C ^>

Si v.

2



230

Tanzania

230

200

2530

960

330

130

a

1

1

505

7

15

3

1

1

400

7

15

3

Developmental, Energy (Heat) Demand Supply

4

27

370

90

150

40

4

>100

>100

86

— 27

>100

99

>100

Supply/Demand (%)

90

145

40

Developmental (Mech. Energy Power) Demand Supply

Joules)

215

240

-1070

500

- 10

1040

In

form of Methanol.

Assuming 50% e f f i c i e n c y f o r p y r o l y s i s / d i s t i l l a t i o n of wood.

În terms of energy content of biomass wastes.

C

În forms of charcoal, p y r o l y t i c o i l , and pyrogas. Assuming 75% e f f i c i e n c y f o r g a s i f i c a t i o n u n i t s of feedstock produce 5.8 u n i t s of gas and 1.7 u n i t s of charcoal).

(

Biomass 'd Surplus

(10 energy

I n forms of charcoal, biogas, and p y r o l y t i c o i l . Assuming 55% conversion e f f i c i e n c y f o r anaerobic d i g e s t i o n and 66% f o r p y r o l y s i s of crop residues and fuelwood (15 energy u n i t s of feedstock produce 6 units of charcoal and 4 u n i t s of p y r o l y t i c o i l ) .

a

200

Sudan

960

Indonesia

2530

330

Thailand

India

130

Peru

Country

Subsistent Energy Demand Supply

(10

Projected Rural Energy Demand (2000) and Supply of Bioconverted Fuels

TABLE VI


630

THERMAL CONVERSION

OF SOLID WASTES AND

BIOMASS


Conclusion We have shown, that from an o v e r a l l t e c h n o l o g i c a l and r e source standpoint, biomass technologies do appear to o f f e r a s i g n i f i c a n t p o s s i b l i t y f o r meeting the future energy needs of the r u r a l areas of a number of developing c o u n t r i e s . In p a r t i c u l a r , biomass conversion technologies can p o t e n t i a l l y provide the kind of high-grade energy, e s p e c i a l l y l i q u i d f u e l s , necessary f o r f u r ther development and which can serve as an a l t e r n a t i v e f o r scarce petroleum f u e l s . Biomass resources are, i n many cases, l o c a l l y a v a i l a b l e and renewable, i f proper resource management, e s p e c i a l l y of f o r e s t s , i s p r a c t i c e d . (An exception to t h i s f o r the countries studied i n t h i s paper are the f o r e s t resources of Indonesia and Peru which are remote from the main areas of r u r a l settlement.) From a system point of view, since r u r a l energy demand a r i s e s from a large number of dispersed and poorly connected uses, the a v a i l a b i l i t y of l o c a l resources which can be transformed into u s e f u l energy products on a d e c e n t r a l i z e d l e v e l i s a d e f i n i t e b e n e f i t . It avoids the n e c e s s i t y of i n v e s t i n g i n an elaborate c e n t r a l i z e d energy d i s t r i b u t i o n system which i s s u s c e p t i b l e to a number of problems, as i s i l l u s t r a t e d , f o r example, by the experience of r u r a l e l e c t r i f i c a t i o n programs i n many developing countries. However, the d i f f i c u l t i e s of implementation of biomass t e c h n o l o g i e s i n the r u r a l context should not be underestimated. Current biomass use p r a c t i c e s have evolved through many m i l l e n i a of s o c i a l and c u l t u r a l adaptation and new ways of dealing with the same resource w i l have to overcome a number of i n s t i t u t i o n a l , c u l t u r a l , and s o c i a l b a r r i e r s . For example, a community s i z e anaerob i c d i g e s t e r operating on the animal waste inputs from p r i v a t e l y owned c a t t l e or other animals presupposes a c e r t a i n degree of cooperative arrangements among the owners f o r e f f e c t i v e management of a c o l l e c t i o n scheme. Wood that was formerly gathered p r i v a t e l y and used i n i n d i v i d u a l households but now has to be turned over to a processing plant f o r manufacture of higher-grade f u e l s requires new i n s t i t u t i o n a l set-ups to ensure that b e n e f i t s are properly distributed. Furthermore, even f o r technologies that are r e l a t i v e l y simple, a c e r t a i n number of t e c h n i c a l s k i l l s are necessary f o r adequate maintenance and o p e r a t i o n . Such s k i l l s are not usua l l y a v a i l a b l e i n most r u r a l areas and t r a i n i n g and education programs w i l l be needed. Also important i s the fact that r u r a l areas are not a closed system by themselves. Given previous development patterns i t i s l i k e l y that high-grade f u e l s would be siphoned to b e t t e r - o f f urban areas l e a v i n g the r u r a l areas short of energy as before. The B r a z i l i a n ethanol program whose output l a r g e l y goes to f u e l urban automobiles i s an i l l u s t r a t i o n of t h i s problem. Most importantly, implementing a biomass conversion program w i l l require s u b s t a n t i a l inputs of c a p i t a l i n r u r a l areas. The low energy consumption and correspondingly low standard of l i v i n g of most r u r a l inhabitants r e f l e c t s t h e i r low l e v e l s of income and the economics of biomass conversion has to take t h i s fact into



44.

MUBAYI ET AL.

Biomass Conversion to Meet Energy Needs 631

account. Unlike the situation in developed countries, the collec tion costs of the basic raw material will be low, but the capital constraints will be high. In this overview, we have not tried to analyze the potential implementation of biomass conversion tech nologies in terms of a market penetration model. We feel that such an approach would make little sense in analyzing resources and consumption patterns that, broadly speaking, currently occur outside of a market economy. A normative approach that analyzes the energy needs of development and the resources available to supply those needs, appears to us more feasible at present in assessing the impact of conversion technologies. However, a great deal of further analysis aimed at reducing the uncertainties in making quantitative judgements of technology impacts is necessary to better define the potential of biomass conversion in developing countries.

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4. 5. 6. 7.

8. 9. 10.

Dept. of Economic and Social Affairs, "1976 Statistical Year book," United Nations, New York, 1977. Dept. of Economic and Social Affairs, "Trends and Prospects in Urban and Rural Population, 1950-2000," United Nations, New York, 1975. Mubayi V.; Kahn, P.; Keane, J, "Some Considerations on the Use of Village-Scale Biogas Plants in Developing Countries," (Internal Report), Brookhaven National Laboratory, Upton, New York, 1976. Barnett, Α.; Pyle, L.; Subramanian, S. "Biogas Technology in the Third World: A Multidisciplinary Review," International Development Research Center, Ottawa, Canada, 1978. Makhijani, Α.; Poole, Α., "Energy and Agriculture in the Third World," Ballinger Publishing Company, Cambridge, Mass., 1975. "Joint Peru/United States Report on Peru/United States Coop erative Energy Assessment, Volumes I and V," U.S. Dept. of Energy, Washington, D.C., 1979. Henderson, J.; Barth, H.; Heimann, J.; Moeller, P.; Shinn, R., Soriano, F.; Weaver, J.; White, Ε., "Area Handbook for Thailand," U.S. Government Printing Office, Washington, D.C., 1970. Vreeland, N.; Just, P.; Martindale, K.; Moeller, P.; Shinn, R.; "Area Handbook for Indonesia," U.S. Government Printing Office, Washington, D.C., 1974. Fuel Policy Committee, "Report of the Fuel Policy Committee,: Government of India, New Delhi, India, 1974. Abayazid, O., "Prospects of Fuel and Energy in the Sudan," University of Khartoum, Sudan, 1975.


632 11. 12. 13. 14.


15. 16. 17. 18. 19. 20. 21. 22. 23.

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THERMAL CONVERSION OF SOLID WASTES AND BIOMASS Herrick, Α.; Harrison, S.; John, H.; MacKnight, S.; Skapa Β., "Area Handbook for Tanzania," U.S. Government Printing Office, Washington, D.C., 1968. Earl, D., "Forest Energy and Forest Development," Clarendon Press, Oxford, 1975. Agency for International Development, "Thailand-Renewable Non-Commercial Energy" (Draft), USAID/Thailand, 1979. Mubayi, V.; Lee, J., "A Preliminary Analysis of Energy Supply and Consumption in Indonesia," Brookhaven National Labora tory, Upton, N.Y., 1977. Mubayi, V., "Background Information for the Assessment of Energy Technologies for Developing Countries," Brookhaven National Laboratory, Upton, N.Y., 1976. Revelle, R., "Requirements for Energy in Rural Areas," AAAS Selected Symposium 6, Westview Press, Boulder, Colorado, 1978. Reddy, Α.; Prasad, Κ., "Technological Alternatives and the Indian Energy Crisis," Economic and Political Weekly, 1977. Food and Agriculture Organization, "1977 Yearbook of Forest Products," United Nations, Rome, 1979. Lee, J.; Mitchell, G.; Mubayi, V., "A Preliminary Analysis of Energy Supply and Consumption in Thailand," Brookhaven National Laboratory, Upton, N.Y., 1978. "Workshop on Solar Energy for the Villages of Tanzania," Tan zania National Scientific Council and USNAS, Dar Es Salaam, 1977. Food and Agriculture Organization, "China: Recycling of Organic Wastes in Agriculture," United Nations, Rome, 1977. Parikh, J.; Parikh, Κ., "Mobilization and Impacts of Biogas Technologies," Energy, 1977, Volume 2. Chiang, T.; Tatom, J.; Graft-Johnson, J.; Powell, J., Pyro lytic Conversion of Agricultural and Forestry Wastes in Ghana,: Georgia Institute of Technology, Atlanta, Georgia, 1976. "Symposium Papers: Clean Fuels from Biomass, Sewage, Urban Refuse, Agricultural Wastes," Institute of Gas Technology, Chicago, Illinois, 1976. "A Conference in Capturing the Sun Through Bioconversion: Proceedings," Washington Center for Metropolitan Studies, Washington, D.C., 1976. Jones, J.; Barkhorder P.; Bomberger, D.; Clark, C.; Dicken son, R.; Fong, W.; Johnk, C.; Kohan, S.; Phillips, R.; Sem ran, K.; Terter, Ν., "A Comparative Economic Analysis of Alcohol Fuels Production Options," SRI International, Menlo Park, California, 1979. "3rd Annual Biomass Energy Systems Conference Abstracts," Biomass Energy Systems Conference, 1979. Ghate, P., "Biogas: A Pilot Project to Investigate a Decen tralised Energy System," State Planning Institute, U.P., Lucknow.


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MUBAYI ET AL.

633 Biomass Conversion to Meet Energy Needs

"Energy Situation in Thailand-1977" National Energy Adminis tration, Bangkok, Thailand, 1978. Yang, V.; Trindade, S., "The Brasilian Fuel Alcohol Program," Centro de Tecnologia, Promon, Brazil, 1979. Schooley, F.; Dickenson, R.; Kohn, S.; Jones, J.; Meagher, P.; Ernest, K.; Crooks, G.; Miller, K.; Fong, W., "Mission Analysis - Market Penetration Modeling," SRI International, Menlo Park, Calif., 1979. Palmedo, P.; Nathans, R.; Beardsworth, E.; Hale, S. Jr., "Energy Needs, Uses and Resources in Developing Countries," Brookhaven National Laboratory, Upton, N.Y., 1978. Reisman, Α.; Malone, R., "Less Developed Countries Energy Network Simulation LDC-ESNS: A Brief Description," Brook haven National Laboratory, Upton, Ν.Y., 1978.

RECEIVED November 16,

1979.


The Potential of Biomass Conversion in Meeting the Energy Needs

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