Bio-mass potential in Bangladesh
Partha Pradip Sarkar
Bangladesh is an agriculture based country where more than 65 per cent of the people live in rural areas. Recent study shows that 70 per cent of total energy consumption comes from biomass. Typically, agricultural residues vastly meet the household energy demands in rural and semi-urban areas. This is practiced mainly because of the fact that around 65 per cent of our economic activities are based on agriculture. The rain fed ecosystem on the other hand produces huge amounts of biomass resources e.g. agriculture residues(crop/tree residue, rice husk, , jute stick) , animal waste(cow dung, human excreta), wood/tree leaves, municipal waste, vegetation, sugarcane bagasse, water hyacinth, poultry droppings , garbage etc.
Bangladesh has good potential of harvesting bio-diesel/bio-fuel from cultivating Jatropha Curcas (JC). But JC cultivation is not yet taking place commercially. We have tremendous potential of utilising briquetting technology because of the availability of raw materials, like rice husk, wheat straw, saw- dust etc. Survey shows that about 3,538,400 million tons of rice husk, 17,760 million tons of saw-dust, 1,470,300 million tons of wheat straw, 2,607,000 million tons of bagasse and 22,900 million tons of rice straw can run more than 18,000 briquetting machines, although at present only about 1,000 machines are operating. Thus far it is reducing the emission of greenhouse gases.
Biomass resources Agricultural residues
Agricultural residues contribute significantly to the biomass sector of Bangladesh. Crop production generates considerable amounts of residue that can be used as energy source. Crop residues can be distinguished into field residue and process residue. Field residue is left in the field after harvesting, which is scattered over a wide area, and is generally used as fertiliser. Process residues are generated during crop processing, e.g. milling. They are available at a central location. Besides being an energy source, crop residues are used for several other purposes such as fodder and raw manufacturing material. Paddy straw, rice husks, maize, wheat, coconut, groundnut, mastered oil tree, beans, vegetables trees, jute, sugar cane etc. are the major agricultural residues.
Agriculture in Bangladesh has grown at 3.2 per cent annually from 1991-2005 and the dominant source of this growth has been the crop sub-sector growing at 2.3 per cent per annum. Total food grains production, according to Bangladesh Bureau of Statistics (BBS) in 1991/92 was 19.32 million metric tons, which has gradually increased to 29.77 million tons in 2007/08, 6.13 per cent higher than the previous year’s production.
Rice husk is a unique biomass fuel having good calorific value (heat value: about 14,000 KJ) per kg & is also ‘carbon-neutral’. Bangladesh is a major rice producing country. It produces on average about 40,000,000 MT of paddy and about 8,000,000 MT of husk per year (K Islam 2008). Bangladesh has over 100,000 rice mills all over the country which use both thermal energy (of steam produced by burning rice husk for parboiling of rice) & electric power (from grid) for entire operation of the mill (milling, boiler pumps, lighting etc.) Power generation through biomass gasification from rice husks could be a wonderful option in rice mills all over Bangladesh.
About 17.8 per cent of total area of the country has forest cover (BBS 1993). Broadly speaking, Bangladesh’s forests can be divided into four types: (1) mangrove forests in the coastal delta, (2) hill forests in the interior, (3) sal (shorea robusta) forests in smaller areas inland, 4) social forests. It is estimated that Bangladesh loses its forest lands by about 3.3 per cent every year (World Bank 1994) because of illegal wood logging for collecting firewood (tobacco curing, cooking) and making furniture. This rate of forest depletion is truly unsustainable. However, efficient use of forest residues could be a renewable source of energy in any given part of Bangladesh. Forest residue comprises of small branches, leaves, corn stove etc. These residues are organic by-products from different types of forestry and agricultural harvesting activities. Bangladesh has good potential of harvesting bio-energy from forest residues by setting up biomass gassifier in forest regions to produce power.
Presently, there are about 23.4 million cattle, 0.82 million buffaloes, 33.5 million goats, 1.11 million sheep, 138.2 million chickens and 13 million ducks (DLS 2000). It has been reported by the Bangladesh Bureau of Statistics (BBS 1999) that 52 per cent of male cattle, 62.3 per cent of female cattle and 60.9 per cent of cattle older than 3 years old are raised by small and medium-sized farms. The estimated biogas potential by using cow dung from cattle population in Bangladesh is about 29 per cent of the total cooking fuel demand (Bala & Hussain, 1989). So far animal dung based biomass energy production (biogas) and power generation may decentralise energy and power solutions in remote (off-grid) areas of Bangladesh.
Moreover, slaughter house waste based biogas plants may also be a potential solution for small scale power generation or household cooking fuel. Local government engineering department is already working in this new arena with the cooperation of German Technical Cooperation (GIZ).
There are about 1, 50,000 commercial poultry farms (broiler and layer farms) and nearly 130 parent stock farms in Bangladesh (ICDDRB, 2008) with a total of 42 million chickens, (Waste concern, 2005) producing around 3079 metric tons of poultry manure daily. Based on this large amount of poultry manure and litters (faeces with bedding materials), bio-gas and bio-gas based electricity can easily be produced by setting-up community size bio-gas plants. But this practice has been started only in a limited scale, although it has tremendous potential in rural/semi-urban areas.
Municipal and industrial solid wastes
At present, there are 522 urban centres in the country including 311 municipalities and 9 City Corporations (UMSU, LGED, 2011). Statistics shows that in 2004, a daily total of 16,382 tons of solid waste was being produced in urban centres (Source: ADBI and ADB, 2000) which have good commercial potential to transform into biogas and generate power as alternative power sources.
Bangladesh, having about 15 sugar mills, annually produces around 2,700,000 million tons of bagasse which is sufficient to produce power with minimum investment. In the north-western region, which is starved for energy, the sugar mills would be a great energy resource. This is also an advantage as all the 15 sugar-producing units were installed in the region.
Cultivation of Jatropha Curcas (JC) trees for bio-fuel production
The JC shrub has the ability to bear fruit for approximately 25 years, with each fruit containing an average of three seeds (Hussain, 2007). When the sheath and the shell of the seed are removed, the remaining kernel is the source of viscous oil. Using calculations from Dr Hussain’s study concerning JC’s compatibility in Bangladesh, oil yield per seed is between 25 per cent and 37 per cent. Considering that, 6 to 15 tons of seed are contained within one hectare of land, it means that approximately (taking an average of 30 per cent oil yield and 10 tons per hectare) 3000 litters of oil can be obtained per hectare of land (Hussain, 2007).
BAU is currently the primary national institution which has contributed to research concerning JC. Dr Daulat Hussain & Md Parvez Islam, setup the university’s Jatropha Plantation Group which has carried out extensive research concerning the shrub’s national potential. A study carried out by this team, named Proposal on Jatropha: model farm and business plantation farm for seed and oil production in Bangladesh, contains a detailed analysis of the cultivation and processing methods applicable to Bangladesh (Hussain, 2007). P Islam revealed that the potential for JC cultivation in Bangladesh was promising. The shrub showed similar growth patterns to that in neighbouring India and machinery was easily adaptable. He emphasised that the lack of government initiatives and foreign direct investment were two of the main setbacks.
In response to meeting the energy demand from sustainable sources, green energy technology implementation is essential. It will reduce the pace of deforestation, encourage animal husbandry, encourage poultry industry and diversify agricultural farming, new tree plantations and other farming. It will obviously generate income and create jobs for the rural poor, ensure food security, etc. All efforts will allow Bangladesh to have a healthier living standard with better livelihood. So far more biomass energy related intervention is highly desirable in Bangladesh.
The writer is project manager, Sustainable Rural Energy (SRE), Local Government Engineering Department (LGED)