Sunday, April 10, 2005

"Garbage Power" Initiatives

There is a flurry of activity in renewables in India right now. While wind power is being touted as the likely leader, solar, bio-diesel and ethanol also have their own place under the sun. One area which has the potential to really alter the energy landscape on India, but escapes too much attention is biomass.

Organic waste can be decomposed to give off what is called bio-gas or gobar gas in India. This technology is green because the formation of the gas absorbs as much CO2 from the atmosphere, as it releases when burning. The killer part of the idea is that it can be used as a fuel in fossil fuel engines, with very little modification. On the other hand bio-degradable waste can also be converted into solid fuel.

Take the case of the Rajasthani motor mechanic who is successfully generating power from solid waste: "Rae Singh Daiya, has established a small garbage processing power plant, which can run tube wells, welding and cutting machines". From plants processing two tonnes of garbage a day, he wants to build plants that process seven tonnes a day. For this he has been promised finance by an organization called Navreet Energy Research and Information (NERI). NERI on its part has developed a compact gasifier, which could effectively use saw dust, dried dung powder, rise and mustard husk, leaves and many more agri-residues. The cost of power generated was about Rs 3/- per unit. In Indian villages though none of these agri-residues are truly "wastes" and find application in the traditional scheme of things. Still we could see significant traction there.

But what of the cities? "According to conservative estimates, in India at least 1000 MW of electricity can be generated from urban and municipal wastes and another 700 MW from industrial wastes."

Apparently Delhi is taking a lead in utilizing urban waste for power generation, where two projects to produce about 20 MW of power using 2500 tonnes of garbage are being finalized. 20 MW is enough for at least 4000 houses. If you look at the numbers it is pretty clear such plants are not feasible much beyond the limits specified here. 2500 tonnes is a lot of garbage to store, and unless you have reliable and dedicated supply, you will need a really huge storage area which will be both an urban eye-sore as well as possible a nose-store. Unless it is pretty well covered in which case the end-product would be even more expensive. Factoring in the garbage disposal capacity makes the plants a bit more viable though.

Though at the moment, the plants would only convert waste into solid pellets for burning (like coal), in future they will also have a bio-methanation plant (a highly advanced form of a bio-gas plant) and a sewage treatment plant. The bio-methanation plant would need a major overhaul of the garbage collection and classification mechanism to separate the bio-degradable stuff.

The Delhi plants are being treated as pilots, and once they get going, other cities would also be targeted. May the Force be with them.