LGED has been created mainly to provide technical support to the local government institutions. This organization can play an important role in disseminating appropriate technology all over the country as it has setup at Thana level.  LGED constructed it's first Biogas plant in 1986 in Kurigram and organized a seminar on Biogas technology there. By now LGED constructed 300 of Biogas plants in different districts of Bangladesh, of which 106 are on night soil, 15 on garbage, 3 on poultry droppings, 2 on water hyacinth and the rests on cow dung.  Initially LGED constructed 15 floating dome type plants.  Due to corrosion and leakage on steel domes, these plants did not work for long  time. In June 1992, LGED constructed two fixed dome type Chinese model plants in Noakhali. These plants are working without any problem.  After close monitoring of success of these two plants, LGED started wide application of this.  Subsequently, based on local condition and practical situation, LGED developed its own model.

First Biogas plant based on night soil was constructed by LGED in Faridpur orphanage.  Before construction of this plant, load there was an apprehension about its acceptability.  But after completion of the plant there was no social and cultural barrier.  This plant could drew attention of all concerned. Small bore sewerage system, in conjunction with Biogas plant installed by LGED in Bauniabad slum in Dhaka proved to be cheaper and better solution for sewage disposal.  Solid waste and water hyacinth based Biogas digesters of LGED also created great interest among the users.  LGED has so far trained 70 professional engineers on Biogas technology, 4 of whom received higher training in China.  To provide technical support to the beneficiaries, gradually all the engineers of LGED will be trained on Biogas technology.

 Some Examples :

• Biogas plants in  orphanage/other institution : LGED has constructed 61 Biogas plants in different educational institutes,  orphanages, hospitals, school/college hostels for solving the sanitation problems and getting biogas as an alternative energy source.  One of these important plants is in Faridpur orphanage.  There are 250 students and staff in Faridpur orphanage.  For their night  soil disposal they needed to construct a septic tank for 250 users with Tk. 60,000.LGED in mid 1992 constructed a Biogas plant with Tk. 16,000 which served the purpose of septic tank as well as a source of gas and fertilizer.  This has reduced the investment by Tk. 34,000 and the mission has been saving Tk. 25,000 against fuel cost per year.

• Bauniabad small bore sewer system  : The project is an innovation of environment friendly energy source and sanitation system and described in some detail elsewhere.

• Ganaktuli Sweeper colony, Dhaka :  There are five buildings for sweepers and 40 families reside in each building.  The latrines of the buildings were not connected with any septic tank or sewerage system.  Previously, night soil was passing through surface drain creating health hazard.  To connect the latrines of building No-I to the nearby sewer line Tk. 60,000 and to construct a septic tank for 221 users of the building Tk. 50,000 were necessary.  Instead, LGED constructed a Biogas plant for Tk. 20,000 in 1993 which is working till today without any problem giving sufficient gas to meet fuel need of 3 families.  There was some maintenance for leakage and Tk. 300 was spent. Observing the performance of the plant, residents of other 4 buildings created pressure on the city corporation to construct similar plant in those buildings. By now Biogas plants have been constructed in all the remaining 4 buildings.

• 'Ecological Village' Amgram/Uttar Hogla in Madaripur  : LGED took up 'Ecovillage' project on experimental basis as pilot programme with the objectives to make the villagers aware about environment and technology, create clear, healthy and acceptable environment in the villages and inspire the people around the villages to accept such project. There are 662 people in the village in 123 families.  Besides other socio economic activities, the following facilities were also provided: There was no latrine in the village and 95 latrines were constructed. .As an alternative source of energy 15 Biogas plants were installed, three persons were trained in the construction of Biogas plant. The Biogas plants are providing energy input to the villagers.

Biogas plant installation under LGED

Potentials of Biogas in Bangladesh :

Cattle dung available from 22 million cows and buffaloes is nearly 220 million kg. One kg. Of dung can produce 0.037 cum of Biogas. i. e. available cattle dung can produce 2.97XIO⁹  cum of gas which is equivalent to 1.52X10⁶ tons of kerosene or 3.04X10⁶ tons of coal. Besides, a substantial amount of Bio-gas can be produced from human and animal excreta, garbage and water hyacinth.  If all the household can be brought under Biogas technology, it is possible to get 1.03X 10⁹ cum of gas from the filth of human being only. A conversion of 5% of different raw materials should produce an estimated 2X10⁸ cum/day of Biogas.

At present Bangladesh meet 46.15% of its energy need by agricultural residue, 10.5 % by fule wood and 33% bt tree residue. Biogas will reduce energy deficit 15 %.  

Types of Biogas Digester :

There are three types of basic designs of biogas plants tried in Bangladesh :

(i)    floating cover digester, (ii) fixed cover digester, and (iii) plastic cover digester. 

(i) Floating cover digester : It works on the principle of constant pressure, changing volume. The disgester, cylindrical well, commonly made from brick and cement, is covered with a floating steel cylinder with an open bottom (Fig. A). As the cylinder has a contant weight, it moves up when gas production is higher than consumption and comes down under the reverse conditions. 

(ii) Fixed cover digester : It works according to the principle, constant volume, changing pressure. When the rate of gas production is higher than that of gas consumption pressure inside the digester rises and expels some digester contents into the outlat compartment. When the consumption is higher than production, pressure inside the digester falls and the expelled materials in the outlet compartment run back to the disgester

(iii) Plastic Cover digester :     A long cylindrical polythene/PVC bag, half-buried longitudinally in the ground, is fed with fresh cow-dung slurry at one end and discharged at the other. With the formation of gas, the bag swells like a balloon and the gas is led out to the point of use through a pipe by putting pressure on the balloon form outside

In early 80’s, the floating type design  was used for biogas plant. But due to corrosion of the steel dome, the gas leakage problem happened and it could not be removed. Later on BCSIR tried with fixed done type design and it has been successful in all biogas plants. The plastic bag type design is not used in Bangladesh It is used in China. In this project, the fixed dome type design has been proposed.

Gas Generation Rate :

Daily input in the digester is 221xO.5 kg. =110.05 kg.  Assuming water content to be 83% the quantity of suspended solid will be 18,71 kg.  For optimum gas generation, the percentage of suspended solid should be 8%.  To attain this percentage, water and night soil mixing proportion should be 1:1.  But in practice the users generally use more then 3 liters of water for the cleansing purpose, as a result the percentage of solid reduced to 2.5. This causes drastic reduction in gas production.  This problem is no more acute where there is no water supply reduction in gas production.  This problem is no more acute where there is no water supply system.  To improve this situation, we have decided to add kitchen waste with night soil.

Uses of Biogas Residues : 

• Improved organic fertilizer

• For Mass room cultivation

• Aquaculture

•  Purl Cultivation

• Poultry, fish foods

• Seeds fermentation

Advantages of Biogas Technology :

 (a) Produces pollution free bio fuel

 (b) Improved organic fertilizer

Bio product of biogas plant is improved organic fertilizer. This fertilizer contains organic component like  Nitrogen, Phosphorus, Potassium & Micro Nutrients

(c) Nutrition's comparison between Compost fertilizer and biogas residues. (Production in percentage): 

(d) Nutrition's comparison of   between Chemical  fertilizer and biogas residues from Biogas plant. (Production in percentage) :

Affordability :

Biogas is a proven technology, There is no risk of failure if proper design and supervision can be ensured.  Most of the commercial banks are now convinced and took decision to provide loan for the construction of Biogas plants.  Most of the urban poor can not afford gas connection as it costs Tk  200 to Tk. 400 per month.  Instead they can install Biogas plants with. bank loan and repay the loan out of their fuel savings 'domestic' size Biogas plant of 100 cft capacity cost Tk. 15,000 to Tk. 18,000 and can meet the cooking energy need for a five- member family.

Impact on health and environment ;

Large scale bio energy development in Bangladesh could bring significant environmental benefits. Sustainable bioenergy development could:

• Reduce higher level of deforestation

• Reduce net greenhouse gas emissions

• Improve air quality and reduce acid deposition

• Improve soil quality and reduce erosion

• Reduce land filling by adding value to residues

• Reduce agricultural chemical runoff

• Improve sanitation condition

• Improve habitat for native wildlife and improve biodiversity.

• Outlining sustainable land use and improved air quality.

• Improved habitat for wildlife and reduced use of fertilizers and insecticides compared with lands used for row crops,  protection of riparian areas, and erosion protection for sensitive land areas.

• Reduction of Greenhouse Gases from biomass power takes place because the carbon dioxide released during combustion is absorbed by the plants as they grow.

Biomass could play a role in reducing C0₂ emissions in both of these sectors.  As the slurry remains in the digester for 30-40 days in anaerobic condition, the effluent becomes pathogen free and the output is smell-free combustible gas and organic fertilizer improving the environment and preventing diseases. At present Bangladesh meet 46.15% of its energy need by agricultural residue, 10.5% by cow dung, 12.9% by fuel wood and 33% by tree residue.  This means that to meet our energy need we are depriving, ourselves from organic fertilizer and creating environmental imbalance by deforestation.  One pragmatic estimate puts that the use of Biogas will reduce energy deficit  by 15%.