Monday, September 13, 2010


The legendary septic tank which ushered in the toilet revolution in India is all set to make its debut in a western country and the purpose is not night soil disposal but generation of power at the farm level using local crops. Gobar gas system which became a standard feature in many rural farms basically generate methane gas for self consumption and these are mostly small scale operations insufficient to generate power. The process in absence of Oxygen uses a mixed culture of microorganisms uses many organic matters which include waste paper, grass and other farm wastes, left over food, sewage, animal waste etc. Though the primary intention is to dispose off the waste, it also serves to reduce emission of landfill gases to the atmospheres considered to be responsible for global warming and generates a biogas mixture containing mostly Methane (50-75%), CO2 (25-50%), and small quantities of Nitrogen, Hydrogen, Hydrogen Sulfide and Hydrogen. While small scale generators mostly use the gas for house hold cooking, medium scale units can yield power by burning just like fossil fuels. A typical anaerobic digester using municipal waste can generate about700 to 1300 kWH per ton of refuse. That anaerobic digestion approach is seriously being considered in the UK for generating power and production subsidization by the government there may be a good news for the eventual viability of the technology.

First up, energy firm Farmgen broke ground on the first in a wave of anaerobic digestion plants, designed to provide farmers with an additional revenue stream from "energy farming". The £2.5m project at Carr Farm in Warton, Preston will be the first AD plant built under Farmgen's proposed £30m UK-wide investment programme. Local crops will be used to create biogas that will generate 1MW of electricity, which will then be exported to the national grid. Farmgen said that it also plans to build a second £2.5m plant in Silloth, Cumbria later this year and is preparing planning applications for sites in Lancashire and Staffordshire. The coalition government has earmarked the accelerated roll out of AD plants as a key part of its renewable energy strategy and last month launched a consultation designed to assess how new policies could help increase support for the emerging sector. Under the existing feed-in tariff scheme, farmers or businesses installing AD systems generating up to 500 kilowatt hours (kWh) a year are eligible for payments of 11.5p per kWh, while those installing larger systems producing 500kWh to 5MW receive 9p per kWh. Industry insiders have warned that the rates are not currently high enough to drive the widespread roll out of AD plants and have been calling on the government to increase in the incentive. In related news, airport operator BAA announced yesterday that it has signed a deal with food management firm Vertal that will see travellers food and drink waste turned into fertiliser for use on local farms. The company said that food waste from Heathrow's daily 180,000 passengers will be collected separately and sent to Vertal's recycling facility in South London where it will be composted within 72 hours. It added that it hoped the initiative would save carbon emissions equivalent to around half a million air miles. Vertal founder and managing director Leon Mekitarian said he hoped the deal would encourage other firms with large amounts of food waste to invest in composting technology to reduce their carbon footprint.

United Nations Development Program (UNDP) of the UNO recognizes anaerobic digestion approach as one of the most useful decentralized sources of energy supply at low capital cost compared to that required for large power plants. In India this technology has remained more or less at the house hold and community level for which government extends economic incentives.But it has the potential to be a viable route to the energy grid in the country if proper policy initiatives are forthcoming from GOI. The enormous Municipal wastes generated all over the urban townships, collected and sent to landfills must be harnessed to produce energy through the anaerobic digestion system. Same is true with organic wastes emanating from industrial processing centers. Probably providing reasonable prices to the privately generated energy may trigger higher interest amongst the entrepreneurs to set up such facilities.


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