Bioenergy and biogas

Bioenergy and Biogas
Roksana Aftab Ruhi
Department of Agriculture
Noakhali Science & Technology University
Noakhali,Chittagong.
Bangladesh

Bioenergy
 Bioenergy is one of the forms of renewable energy. Bioenergy from biomass, has been used for
thousands of years, ever since people started burning wood to cook food wood is still our largest
biomass resource for bioenergy.
 Bioenergy technology converts the chemical energy which is stored in a organic matter or its by
products into heat and electricity .
 The key bioenergy stocks are food and fodder crops, dedicated energy crops, forestry, waste and
agricultural residues.

Continued…
 Category of Bioenergy
Bioenergy resources maybe categorized into the following ways—
 Primary biofuels are wood,grasses, and other plant materials that are used directly.
 Secondery biofuels includes municipal solid wastes, pallets and construction debris,agricultural
residues,yard wastes.compost ad others.
 Refined biofuels include those manufactured from ethanol,biodiesel and hydrogens.

Biogas
Biogas is produced from anaerobic digestion and is considered a clean energy source for those who want an
alternative energy pathway.
Biogas typically refers to a mixture of different gases produced by the breakdown of organic matter in the
absence of oxygen. Biogas can be produced from raw materials such as agricultural waste, manure, municipal
waste, plant material, sewage, green waste or food waste.
*Types of Biogas Plant
1.Floating type
2.Fixed dome type
 Characteristics/Properties
1.Density – 1.219 kg/Nm3
2.Calorific Value-4500kcal/m3
3.Specific gravity-0.94
4.Explosion limit-higher=24% and lower=15%
5.Methane is the main constituent

Continued….
Composition of Biogas
The biogas composition depends on type and chemical composition of substrates, technology used and
operational parameters.
Compound Chemical
Formula
Percentage (%)
Methane CH4 50-70
Carbon dioxide CO2 30-49
Nitrogen N2,NH3 0-1
Hydrogen H2 0-5
Hydrogen Sulphide H2S 0.1-0.3
Water H2O Saturated

Continued….
 Substrates used for Biogas Production
Crop Residues- Animal Wastes
1. Residues of various plants 1. Dairy cow wastes
2. Sugarcane trash 2.Manure
3. Maize silage 3.Poultry litter
4. Rice husks, bran 4.Sheep and goat droppings
5. Tobacco wastes and seeds Urban Wastes
6. Water hyacinth 1.Municipal wastes
7. Tea wastes 2.House hold garbage
8. Cotton dusts 3.Knight soil

Continued….
 History of Biogas
 The first comprehensive study on various aspects of anaerobic fermentation was conducted, compiled and
published in early 30's, by Buswell. These studies included testing of various agricultural wastes in the
laboratory as well as in the field, with duration up to 800 days (Buswell and Hatfield, 1939).
 According to Mignotee (1952), the first attempt to build a plant to produce methane gas from manure by
biological decomposition appears to have been made in Bombay in 1900.
 This gas was discovered long time ago; some argue that Chinese knew about it 3000 years ago, while others
say that Assyrians used it to heat their baths .The first biogas production plant is thought to be built in India
in 1897 and served the function of sewage treatment as well (Harris, 2002).
 As the earliest form of biogas digester, the round-shaped water-pressure biogas plant was once popular
among farmers in China (He et al. 2013), and also welcomed by many developing countries with a name of
‘‘China-mode biogas’’ digester (Zeng et al.; 2007).

Continued….
 Since the 1980s, the development of biogas infrastructure had been included into the national long-term
development program by the central government of China (Jiang et al.; 2011).
 Agriculture-based biogas engineering projects have been promoted in China since late 1990s by local and
central governments, and the basic technology was introduced and ﬁxed.
 It has been reported that more than 4,000 farm scale biogas digesters were in operation in Germany;
followed by about 350 in Austria, 72 in Switzerland, 65 in the United Kingdom 35 in Denmark, and 12 in
Sweden (Raven and Gregersen, 2007; Wilkinson, 2011).The main substrate fractions, which are utilized
in these farm scale biogas plants are animal manure and energy crops.

Continued….
History of Biogas in Bangladesh
 In 1972, first biogas plant was set up in the university campus of Bangladesh Agricultural University (BAU) by Dr.
M A Karim.It was a floating type plant of 3m3 gas production capacity.
 In 1974,another biogas plant was constructed at Bangladesh Academy for Rural Development in Comilla.
 In 1976,Institute of Fuel Research and Development constructed family size biogas plant at BCSIR area at cost of
12000k.
 In 1980 another one plant was constructed at KBM college ,Dinajpur.
 In 1981 government established a department named Environment Pollution Contro Department through which they
started a programme at a cost of 34 lac..Under this project ,150 floating dome and 110 fixed dome plants were
installed in1984.
 In 1986,LGED constructed their first floating dome plant in Kurigram district and arranged seminer where 300
scientists,engineers,experts presents.

Continued….
 In 1992,two Chinese model fixed dome plant was constructed in Noakhali district under the support from
DANIDA,LGED,Grameen Bank by Mr.Abdul Gofran(Consultant,Grameen Shakti).
 In 1992, the Institute for Fuel Research and Development (IFRD), a research institute of Bangladesh Council
of Scientiﬁc and Industrial Research (BCSIR) and Dhaka City Corporation built a biogas plant of 85 m3 for
treatment of city garbage.
 In 2006,Grameen Shakti installed a generator of 2KW in Gazipur which run with Biogas.
 In Bangladesh IDCOL constructed about 50,000 biogas plants, BCSIR constructed 30,000 biogas plants,
Department of Youth constructed 18,000 biogas plants, but not a single by the M/o Power, Energy and
Mineral Resources. Government has set Master plan for collecting 10% energy from renewable. To achieve
the goal, SREDA needs 10% share of the national Energy Budget. Since maize based biogas can generate
6400000 tons of organic fertilizer annually, M/o Agriculture also should come up to support SREDA.

Continued….
 Different uses of Biogas
1. Direct combustion and Generation of electricity
2. One of the most useful decentralized sources of energy that can be used at industrial complexes to treat the
wastes generates.
3. Use of conventional biomass for cooking is time consuming but the use of biogas saves time, energy and cost.
4. Purification and export as compressed gas or in liquid form.
5. The main product of biogas production is slurry, a high quality fertilizer that is higher in nutrients than compost
or farmyard manure.
6. Biogas is the most suitable alternative source of energy that farmers in rural areas need to use to protect their
environment and increase crop production
7. It cuts down the cost of importing petroleum products such as kerosene for lighting and energy for cooking.

Continued….
 Advantages of Biogas:
1.The technology is cheaper and much simpler
2. Recovery of the product (methane) is spontaneous.
3. Dilute waste material (2-10% solids) can be used as substrate.
4. Organic pollutants are removed from the environment ,this helps clean up the environment.
5. Aseptic conditions are not needed for operation.
6. Any biodegradable matter can be used as substrate.
7. Biogas is suitable to generate electricity.
8. There is much reduced risk of explosion .
9. It also provided income generating opportunities.
10.It helps to clean the environment as well as improved the humen health.

Continued….
 Disadvantages of Biogas:
1. The product (biogas) value is rather low; this makes it an unattractive commercial activity.
2. The biogas yields are lower due to the dilute nature of substrates used.
3. The process is not very attractive economically (as compared to other biofuels) on a large industrial
scale

Bioenergy and biogas

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