Waste-to-energy has emerged as an option for localised composting of waste. But nauseating stench from these sites has made the option unattractive as residents’ protests have stalled the progress of such plants almost everywhere. A Pune firm, Xeon Waste Managers (XWM), has come up with ‘Energy Bin’, a custom-built plant which eliminates the stench and helps civic bodies tap methane and convert it into electricity.
Meant to serve bulk generators, the ‘energy bins’ have been customised for several civic bodies around the country. The biggest of such plants has been built for Kathmandu Metropolitan Corporation in Nepal where it takes around 5,000 kg of wet waste as the daily feed and produces 500 cubic metres of methane which is then converted into 700 to 800 units of electricity. The project was funded by the European Union.
The firm has so far installed around 50 units in various States. A typical unit consists of a stainless steel drum which takes the wet waste. It is mixed with wastewater and stirred for a few hours daily to be left for fermentation. The resulting slurry produces biogas which goes into balloons encased in metal boxes. The collected gas could either be used for filling cylinders under pressure or could be used for running of generators to produce electricity. The entire unit is firmly enclosed in a metal body leaving no scope for any noxious gases or stench to leak out.
According to Vishal Y. Khalde, Founder and CEO of XWM, Bhopal and Indore Municipal Corporations have installed these bins and they are already in operation.
The Indore Municipal Corporation has installed a unit at Star Chauraha in the city with an intake capacity of 2,000 kg (two tonnes) per day of waste, producing around 250 units of power a day.
For housing colonies
Khalde says bulk generators such as hotels, hostels, hospitals, canteens, Army messes, housing complexes, and railway stations could opt for these bins. Piramal Group’s housing complex in Hinjewadi, Pune, with 440 housing units has installed a plant which generates 90 units of power every day. It is used for lighting up common areas such as garden, driveways and basement.
Lokhandwala Group Housing Society in Andheri has opted for a 500 kg/per day intake energy bin at a cost of ₹ 48 lakh. According to M.M. Gore, sales executive, Jindal Steel Mills in Ballari, Thyssenkrupp’s plant manufacturing sugar mill machinery in Pune, Dibrugarh Railway Station, Volkswagen auto unit in Pune and TCS software units in Kochi and Nagpur are some of the clients who have opted for these bins. According to Gore, the feed could comprise food leftover, fruit and vegetable peel, trash from bakeries, fast food joints and confectioneries and waste from poultry, fish and meat markets.
Coconut shells are kept out of the purview as they take longer to decompose. The users must ensure that the feed does not carry any metals, plastic, glass, big bones, cigarettes and batteries, rubber or porcelain, and medicinal and chemical waste. The plant for housing complexes could also be in disaggregated form with drum being at one place, gas balloon at another location and control panels at a third location within the premises.
Gore says energy bins could be made for a minimum 100 kg intake per day to 5,000 kg capacity. A typical one-tonne capacity intake plant can reduce 3,000 tonnes of carbon dioxide from being emitted into the environment. Such a plant will consume 15 units of power for four hours of average stirring a day and can produce 120 to 150 cubic metres of biogas a day. It can easily be converted into 60 kg of LPG.
The sludge output would be around 100 kgs which can be sold off to farms as manure. In terms of area, it will be a 9 meter by 4 metre by 4 metre of space.
The bins are custom-built and supply could take 10 weeks post-order.