A long winding road climbs into a gathering dusk, coming to an abrupt dead end in front of a house. Here, a solitary flickering flame casts out a warm glow, illuminating the nearby ridge line of the Malvern Hills. Below the light sits a mysterious green contraption resembling a cross between a giant washing machine and a weather station. This is the UK’s first dog poo-powered street lamp, and it is generating light in more ways than one. The idea seems simple enough: dog walkers deposit the product of a hearty walk into a hatch and turn a handle. The contents are then broken down by microorganisms in the anaerobic digester, producing methane to fuel the light, and fertiliser. In India, the use of small household biodigesters to get gas for fuel from cow manure is common. One social enterprise is deploying the technology on a larger scale as part of a major initiative to end open defecation in the country by 2019. Sanitation and Health Rights in India (SHRI) turned to biodigestion as a way to keep public toilets clean – a major issue with existing communal facilities. At an initial cost of $30,000, SHRI builds blocks of 16 free-to-use toilets, half for men and half for women. The resulting sewage is broken down in a biodigester to produce methane, which powers a groundwater pump. The water is filtered, bottled and sold for half a rupee (half a pence) per litre, to pay for approximately half of the maintenance costs. Sandra Sassow, CEO and cofounder of SEaB, warns that some facilities that turn biomass, including excrement, into energy may not be as green as they appear, if, for example, they use fuel to transport waste a long way before it is turned into an energy source. Right now, waste is collected, trucked, moved and processed, often ending up in landfill at worst or having some energy extracted from it at best, says Sassow. “We want to disrupt that completely to incorporate decentralised, distributed, on-site appliances into farms and buildings around the world. A lot of things have been tried, but it’s a case of finding a technology that produces an energy benefit over the full life cycle, not just an apparent energy benefit.”
Guardian 1st Jan 2017 read more »