Presently most of the Biogas plants installed traditionally are either defunct or working unsatisfactorily and inefficiently. The studies reveal following reasons for the above status: 1.The The Digester loadings such as cattle dung and water are not thoroughly mixed which results into either non-generation of gas or lesser quantity gas production. 2.Due to the quality and pressure of the gas produced is being insufficient, it cannot be transported to far of houses with required pressure.
The above constraints and defects were rectified and corrected by Gram Vikas Trust. The mixture of cattle dung and water are stirred in required proportion uniformly and thoroughly by a mixing mechanism with proper air circulation. This results into maximum generation of the gas and utilization of the plant capacity. As such, with the help of pressure regulating tank and mechanism, the gas can be distributed to individual households with uniform pressure as is done in case of CNG in major cities.
Recently, Gram Vikas Trust, introduced GOBAR BANK concept and has manufactured, installed and commissioned 2 Gobargas Plants in Bhintbudrak village in Uchhal Taluka, Dist. Surat. The plants are of 85 M3 capacity each totaling to 170 M3 of biogas generation per day. The gas is further purified and distributed satisfactorily to 121 houses through pipeline. The design of the plant emphasizes the use of minimum motive power as compared to plant total power output. Apart from the above application, the purified biogas with maximum content of Methane can be used to generate electricity through gas generators and also can be bottled and used to run the vehicles. The gas purification systems are developed by Gram Vikas Trust.
(1) Loading Platform The Gobar Bank members bring the dung everyday to the community biogas plant which is weighed and accounted for in their pass books.
(2) Slurry Preparation The cattle dung taken from dung loading platform area is delivered to feed preparation tank section. The fed dung is mixed with water for maintaining ratio of 1:1 for fresh cattle dung and 1:1.25 for stale (hard) cattle dung. The mixture is then mechanically mixed to have homogeneous slurry.
(3) Anaerobic Digestion Anaerobic digestion tank (biogas digester) creates an anaerobic condition to generate methane gas by methanogenic bacteria. The digester employed here is mostly KVIC model with floating dome & water jacket. The water jacket helps in curbing the methane leakage and wastage.
(4) Common Collecting Tank An intermediate gas storage before Pressure regulating tank for distribution to concerned beneficiaries.
(5) Pressure Regulating Tank Gas is compressed by blower and fed to the pressure regulating tank where gas is upgraded due to the passage of pressure
ENVIRONMENTAL NUISANCE – SMOKE FROM WOOD BURNING EARLIER
An happy villager with her biogas connection and equipment NOW
The Slurry being transported to composting pits.
The The slurry generated by these biogas plants are being converted into Vermi- Compost for Organic Farming. This This Compost is very good fertilizer for the agriculture having rich nutrient values.
Entrepreneurship Models on Biogas for Rural Areas Large Scale/ Community level Biogas Enterprises for Cooking needs- Pipeline supply and Rural Sanitation and bio manure production I. Size of Biogas Plant- 85 m 3 /day No. of families Beneficiaries—50 Cow dung required—2 Tons/day- Rs 250/Ton A complex of 20 community toilets Gas utilization—Cooking If for Cooking – 2 hrs. morning & 2 hrs. evening(1.5 m3/family per day) Pipeline length—up to 1km. distance Pipe quality—HDPE, pressurize system—0.3 kg./cm2(Rs. 2.5 lacs cost) Gas charge—150/month-family
II. Raw material—Cow dung+ Toilet (community-20 toilets costs 1.5lacs) III. Slurry Management—Biogas digested slurry Four options- 1. Liquid slurry 2. Recycle water (upto 40 to 50% only) 3. Dry slurry 4. Semi dry 750 kg semi dry slurry @ Rs 2/- per kg costs Rs 1500/day Local consumption of slurry is advised Quality of slurry should be maintained
Cost estimates Non- recurring cost—Rs. 8,20,000 ($ 20,500) Recurring/ Variable cost—Rs. 2,12,000 ($ 5300) Manpower-- Rs.96,000 ($ 2400) Depreciation—Rs.80,000 ($ 2000) Sum of recurring cost- 3,88,000 ($ 9700) Revenue generation- 5,90,000-3,88,000= Rs.2,02,000 (& 5050) Note- In addition to this Carbon credit benefit to the tune of Rs.71,000/yr. ($ 1775) will also be available.
2. Large Scale/ Community level Biogas Enterprises for Electricity Generation and supply for domestic consumption, water supply and community consumption and Rural sanitation 15 KVA Power Generating System from - 85 m 3 /day Biogas Plant No. of families Beneficiaries—50 No. of Animals—200 Cow dung required—2 Tons/day- Rs 250/Ton Gas utilization— Electricity Domestic connection—2CFL, 1 Fan= 100 Wt.*50=5000Wt. Water supply connection—4000 Wt. Community Hall—2 CFL, 2 Fan & 1 TV.= 500 Wt.
Cost A.Non recurring Plant Cost – Rs 4,50,000 Electricity distribution cost – Rs 2,00,000/- Genset Cost – 15 kW – Rs 1,00,000 Genset Room Cost – Rs 1,00,000 Sum - Rs 8,50,000 B. Recurring Manpower ( mechanic – 5000, helper – 3000) – Rs 90,000 Raw Material – 1,62,000 Miscellaneous – 50,000 Depreciation – 85,000 Sum = 3,87,000
Cost estimates A. Non recurring Sum =8,50,000 ($ 21,250) B. Recurring Sum=3,87,000 ($ 9675) Income— Electricity supply 130 unit @ Rs.6 per unit *365 = Rs.2,84,700/yr. ($ 7117) Slurry—Rs.1500/day= Rs.5,00,000/yr. ($ 12,500) CDM benefits – Rs.71,000/yr. ($ 1775) Sum= Rs.7,84,000 ($ 19,600) Surplus— Rs. 7,84,000-3,87,000= Rs. 3,97,000 ($ 9925)
Cylindering of methane available from biogas plant for tractors and rural vehicles and production of bio manure Feasibility analysis for a community biogas plant of 300 M 3 per day capacity with biogas enrichment and bottling plant has been shown below. Dung requirement - For 300 cum. Biogas Plant = 6000 Kgs. Assuming cost of Dung = 0.20 Rs/kg. Cost of Dung for Biogas plant = 1200 Rs. per day. CAPITAL COST – 1.Bio Gas Plant (Digester)Provided by Buyer (@Rs. 3000/- per cubic meter capacity, for 300 cubic meter capacity Rs. 900000/-) 2.Cost of Scrubbing unitRs. 6,00,000.00 3.Cost of CompressorRs. 6,00,000.00 4.C.N.G. cylindersRs. 2,00,000.00 5.Storage tank Rs. 1,00,000.00 6.Installation Exp.Rs. 2,00,000.00 TotalRs. 17,00,000.00
OPERATION COST - A.Fixed operational cost- 1.Interest on capital @ 10% per annum= 0.1x 14,00,000 = Rs. 1,40,000 per annum 2.Depreciation @ 5% per annum = 0.05x 42,50,000= Rs.70,000 per annum. Total cost = 2,10,000 per annum B.Annual Running (Operational) Cost: - 1.Dung cost 1200x350 = Rs. 4,20,000 P.A. 2.Labors Cost (1 skilled and 2 unskilled labors) 300x 350 = Rs. 1,05,000 P.A. 3.Electricity cost (10 kWh x12 hr) 360x350 @3/- unit = Rs. 1,26,000 P.A. 4.Repair and Maintenance@ 2% capital cost on 14,00000 = Rs. 28,000 P.A. Total cost = 6,79,000 per annum Sum of Fixed Operation cost and annual running cost: =6,79,000+2,10,000 = 8,89,000.00
Cylindering of methane available from biogas plant for tractors and rural vehicles and production of bio manure Biogas plant of 300 M 3 per day capacity with enrichment and bottling CAPITAL COST – Rs. 28,00,000.00 ($ 70,000) OPERATION COST – A.Fixed operational cost-3,00,000 per annum ($ 7500) B.Annual Running (Operational) Cost: -12,00,000 per annum Total cost of Operation = Rs. 15,00,000 /- ($ 37,500) Income:- income generate by selling CBG and slurry = Rs. 22,00,000/- ($ 55,000) Profit = Rs. 7,00,000/- ($ 17,500) Payback Period = 4 years