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Jul 28, 2011

Small scale Biomethanation (Biogas) in India

**References in this post need to be updated**


Anaerobic digestion (AD) of kitchen waste to produce biogas and liquid slurry on a small scale has been very successful in India, especially South India, where the region’s temperate weather conditions favor the process yearlong.  Many households have such biogas units installed. Total number of units installed in cities is unknown as there are too many companies offering them and the units being installed in both urban and rural areas, while the numbers are not necessarily recorded. In order to have a closer look at this technology, I identified a private company called Biotech with its office in Thiruvananthapuram, Kerala as a case study for small scale biogas. This company alone installed twenty thousand (20,000) units of small scale biogas in Thiruvanathapuram and Kochi, combined. Biotech can be considered a more successful company in this area, which might help gauging number of units installed by others. These units divert about 40 tons of waste from landfills, which is 3.5% of the organic waste generated in both cities together. It also implies avoidance of 2.6% of collection and transportation costs and resulting GHG emissions.


A small scale (2 kg per day) Biogas unit at Biotech's office in Thiruvananthapuram

**References in this post need to be updated**

Capacity and Cost

Each unit can handle kitchen waste from a household with 3 – 5 members and can generate one cubic meter of biogas every day. Biogas mainly constitutes methane and carbon dioxide and the unit can be connected directly to a cooking stove. Per capita organic waste generation in Thiruvananthapuram and Kochi is 0.17 kg/day and 0.38 kg/day respectively. A single household in Thiruvananthapuram and Kochi produce 0.51 – 0.85 kg/day and 1.14 – 1.9 kg/day respectively (depending on the number of persons in the house). Thus, the capacity of these biogas units is enough for households in these two cities and each unit occupies only 1.25 sq.m of space. They cost $ 470 (INR 21,000) per unit and almost half of this cost is subsidized in different ways. The remaining cost of the digester is paid back in approximately 3 years in the form of savings on cooking fuel. 

The technology was successfully scaled-up by the company to handle 300 kg of organic wastes every day. Space required per kg of waste treated increases with the scale due to increase in the number of single-units used and piping involved. More than 235 institutional units were installed at different hotels and canteens, hospitals, schools, markets and slaughter houses. These institutions use a generator to convert the biogas into electricity which in turn is generally used for street lighting. 1 cu.m of gas can produce 1.5 KW of electricity.

**References in this post need to be updated**

Comparison

This decentralized technology is the most environmentally friendly technology to recover energy from organic wastes. It can be successfully deployed in South India where the temperatures favor the process yearlong. Biotech company is researching ways to introduce this into other regions of India which are colder. However looking at the public investment and integrated waste management perspective, it takes many such single units to address organic waste from a single community and the technology would be able to address only 51% of the waste stream in Thiruvanathapuram or Kochi. Also, the public investment into the technology is comparatively much higher (Table 1) and the units produce organic slurry which needs to be properly utilized. Table 1 is a comparison between small scale biogas and WTE incineration as waste to energy solutions to the MSWM crisis in Chennai. The values used in these calculations are generation of 6,464 TPD of MSW (in year 2005), organic waste percentage of 41% and calorific value of 10.9 MJ/kg.

Table: Comparison of small scale biogas and WTE incineration as options for MSWM for Chennai (cost in $)


Small Scale Biogas
WTE Incineration
Comparison
Capital cost*
623 million
241 million

Operational +transportation cost* (20 yrs)
Negligible
243 million

Total expenses to society

623 million
Note: Present Value
484 million
Note: Future Value
0.77
Landfilling avoided (%)
41%
90%
2.1
Electric energy produced (MWh/day/ton)
0.75
0.76
Total energy produced in 20 yrs (MWh)
26 million
64 million
2.5
Pollution from transportation avoided
41%
0
41
*Costs calculated for the society as a whole

The difference in total costs is because of the difference in scale of the technologies compared and the difference in total energy produced is because the feed for small scale biogas is only organic waste whereas feed for WTE includes rest of the MSW fraction too which are an extra 40 - 50% and have higher calorific value. Despite these differences, small scale anaerobic digestion would (is more likely) be the most sustainable way to treat source separated organic wastes considering the avoidance of emissions from transportation. Since anaerobic digestion works only for source separated organics as is the case with small scale biogas plants, it is not at all an option for mixed solid wastes. As source separation is not practiced in India, it is difficult to collect separated organic wastes on a large scale. That also explains why large scale biomethanation which could have been an option otherwise is not a part of this report.

9 comments:

  1. Seems good but have you guys visited Pune Biogas plants? the model is superb and i have heard and personally visited 4 biogas plants based on different technologies in pune and all are absolutely good.
    People can be contacted for Biogas Installations in Pune are:
    1)Srinivas Kasulla & Sumedh Bapat - 9004689601 & 9881090693
    2)Sanjay Nandre - 9890044785
    3) Sameer Rege - 9373339159

    These are the people who have done good work in pune rest there are few more biogas plants but are not at all attractive and working but i personally visited their biogas plants and all were working - i have visited their biogas plants without informing them and took their contacts from Pune Municipal Council and for past 2 years each plant has taken more than 2500 tons of waste each plant which was really a big amount of waste to be reduced on earth...hatz off to srinivas kasulla, sumedh bapat, sanjay nandre and sameer rege they all are reall ecosavers

    ReplyDelete
  2. No, I could not visit Pune. I chose Biotech company for biomethanation case study, so for biomethanation, my destination was Kerala. Also, this research is towards my thesis and I'm towards the end of this research. I'll however mention about the company and that might help someone interested, to have a closer look

    ReplyDelete
    Replies
    1. I am presently staying at Bangalore, can I have a close look at this plant somewhere
      in Bangalore.Moreover please mention about the company.

      Delete
  3. Do visit or have a look at the compact biogas plant designed by Sumedh Bapat and Srinivas Kasulla which has been installed for JSW, mumbai.

    ReplyDelete
  4. WHAT WILL BE THE UNIT PRIZE OF BIOGAS AFTER UPGRADATION?

    ReplyDelete
  5. In bio gas plant manufacturers, Biogas Plant is mainly used for biologically breaking down organic matter, in the absence of oxygen.

    ReplyDelete
  6. Hello

    Please revert if anyone is interest for construction of Anaerobic Digester for our Combined Heat and Power Project in Westbengal.

    Regards
    Parveen Sajjad
    email: parveen.sajjad@enfragy.com



    ReplyDelete

Glossary

CH4 Methane
CO2
Carbon Dioxide
GOI
Government of India
INR Indian Rupee
JnNURM Jawaharlal Nehru National Urban Renewal Mission
LFG Landfill Gas
MBT
Mechanical Biological Treatment
MSW Municipal Solid Waste
NEERI National Environmental Engineering Research Institute
RDF
Refuse Derived Fuel
SLF Sanitary Landfill
SWM Solid Waste Management
USD United States Dollar
WPs Waste Pickers
WTE Waste-to-Energy
WTERT Waste-to-Energy Research and Technology Council