Converting Waste Agricultural Biomass
into Useful Energy
Surya Prakash Chandak
Senior Programme Officer
International Environmental Technology Centre
Division of Technology, Industry, and Economics
United Nations Environment Programme
(UNEP DTIE IETC)
HP: www.unep.org, www.unep.fr, www.unep.or.jp
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International Environmental Technology Centre
UNEP
What is biomass
Broad term generally refers to any plant or
animal matter.
Waste Biomass – Main Categories
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Waste agricultural biomass
Forestry residues
Wood
Animal residues
Organic waste from cities and
dwellings
International Environmental Technology Centre
UNEP
Why convert waste agricultural biomass
into energy/materials ?
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Reduced carbon emission
a) Due to obviating use of fossil fuels
b) Due to avoidance of open burning and rotting
(methane emission)
Enhanced energy security
Enhanced access to energy particularly in rural
areas
Reduced problem of management, treatment and
disposal
Additional revenue for farmers
Job creation
International Environmental Technology Centre
UNEP
Global availability of waste agricultural
biomass
(in EJ/year)
Region
Maize
Straw
Wheat
Straw
Rice
Straw
Bagasse
TOTAL
Africa
0.48
0.25
0.20
0.54
1.47
US &
Canada
2.95
1.93
0.13
0.19
5.20
Latin
America
0.71
0.38
0.29
3.58
4.94
Asia
1.74
3.65
8.96
3.19
17.54
Europe
0.61
2.39
0.04
0.00
3.04
Oceania
0.23
2.26
0.06
0.22
2.77
TOTAL
6.72
10.86
9.68
7.72
31.98 (765
million tons oil
1 Exa joule = 1018 Joules : 1 KiloJoule = 0.239 Kcals:
1 EJ = 24 million tons oil (approx.)
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International Environmental Technology Centre
UNEP
Geographic distribution of availability of
waste agricultural biomass
(in percent of total)
Region
Maize* Wheat**
Rice
Cotton
Sugar#
Total
China
8
6
15
3
2
33
India
3
3
8
1
3
18
All Asia
13
13
39
5
6
77
Brazil
2
0
1
1
4
8
All South
America
5
1
1
1
5
13
Africa
5
1
1
1
1
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TOTAL of Asia,
S. America and
Africa
23
15
41
7
12
100
*including millet and sorghum
**including barley
#including minor agro industry
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International Environmental Technology Centre
UNEP
Technologies for converting waste
agricultural biomass into energy
Waste Agricultural Biomass to Energy – Technology Options
Basic Process
Type of
Technology
Fermentation
Examples of types of waste handled
Biochemical
(aerobic)
Fermentation
Sugar/starch containing wastes like waste palm
trees
Thermochemical
Pyrolysis
Crop residues such as wheat straw, rice straw,
rice husk, coconut shell
Thermochemical
Gasification
Crop residues such as wheat straw, rice straw,
rice husk, coconut shell
Thermochemical
Direct
Combustion
Crop residues such as wheat straw, rice straw,
rice husk, coconut shell
Physical
Processing
Briquetting
Waste saw dust, waste wood chips
Biochemical
(anaerobic)
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Fruit and vegetable market waste, waste from
fruit/vegetable processing industries
International Environmental Technology Centre
UNEP
Interesting features of converting waste
agricultural biomass into energy
• Availability of energy source at the place which is energystarved and conventional energy (electricity and fossil fuels)
systems are difficult to reach there
• Abundant availability -- a large amount is currently wasted by
either burning open or by allowing it to rot in the field
• Little or no pollution; generally no emissions of toxic gases
like sulfur oxides and nitrogen oxides
• Provides a clean fuel for both domestic and commercial use –
current patterns of using WAB directly in households usually
gives rise to emission of smoke and gases which are very
harmful to human health
• Can provide and alternative source of income to farmers
• Can spur rural economic development due to enhanced
energy availability thus generating jobs
• Climate neutral
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International Environmental Technology Centre
UNEP
Constraints in converting waste agricultural
biomass into energy
• Dispersed availability spread over wide areas hence
challenges of collection
• Usually voluminous material hence high transportation cost
per unit weight – compacting prior to transportation may be
required
• Lower calorific value as compared to fossil fuels particularly
oil and gas
• Some WAB has high moisture content (e.g. fruit and
vegetable waste)
• Some WAB is easily putrescible (e.g. fruit and vegetable
waste)
• Seasonal availability and variations
•Matching of demand and supply of energy – energy load in
rural areas varies widely over the day
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International Environmental Technology Centre
UNEP
Features for considerations when converting
waste agricultural biomass into energy
• Systems required for collection and compacting
• Considerations for future costs of WAB although it may be
available free at present
• Considerations for alternatives if WAB is being used for some
other purposes presently e.g. as domestic fuel, animal feed,
mulching for soil etc.
• Cost of transportation in case of large size WAB2E systems
• Disposal of ash particularly for WAB like rice husk
• Flexibility in WAB2E systems to use different WAB
• Storage of WAB to meet the needs during lean seasons
• WAB2E systems to have high turn down ratios and/or
systems to store energy
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International Environmental Technology Centre
UNEP
What needs to be done for converting
waste agricultural biomass into energy
• Assessment of WAB quantities generated and quantity
available for conversion into energy – careful consideration of
seasonal variations
• Characterization of WAB
• Study of possible systems for collection, compaction and
transportation
• Assessment of present cost structure and projections into
future, including cost of transportation
• Assessment of present energy demand (type and amount)
and projections into future
• Assessment of funds availability
• Assessment and selection of WAB2E technology
• Development of a management system for sustainable
operations
• Supportive policy framework
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International Environmental Technology Centre
UNEP
What this project on converting waste
agricultural biomass into energy aims at
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Building capacity on various aspects of WAB2E:
assessment of quantification and characterization,
assessment of prevailing management systems,
assessment and selection of technologies
Provide hands-on experience by working at a
selected site
Demonstration of an appropriate technology which
can be further replicated
Getting together technology suppliers and
entrepreneurs to facilitate commercial uptake of
WAB2E systems
Support to government on framing conducive
policies
International Environmental Technology Centre
UNEP
THANK YOU
For further information:
http://www.unep.org
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International Environmental Technology Centre
UNEP