Leftover cooking oils and grease washed down the sink mix with solids in the sewers and form giant lumps of floating waste, threatening to clog cities’ drainage. Safe to assume, the bigger the city, the larger the threat. Clogged sewers are not just an inconvenience but are also one leak away from being a full-scale public health hazard. Against such a backdrop, mining these ‘fatbergs’ to generate biodiesel is a double bonanza. A UK company, Argent Energy, is now mining London sewers and converting the untreated fats, oils and greases (FOG) into usable fuel. The fatbergs are brought to the conversion, and the masses are heated to separate the oils and fats from the solid waste. The extracted oil is then treated with a few chemicals to yield an industry-standard biodiesel that can be used for a string of purposes. Roughly a quarter to two-fifths of a fatberg is converted into biodiesel.
Fatberg fuel is far more environmentally friendly than, say, a crop-based biodiesel like the one from palm oil—palm farming has caused destruction of rainforests in South East Asian nations. Thus, the carbon footprint of some crop-based biodiesel is considered by many to be even worse than that of fossil diesel. As per a report in The Independent, Argent is extracting 30 tonnes of fatbergs from just one wastewater facility every week. That is enough to derive fuel to power 6,000-7,000 trucks and buses in the UK. Europe’s first FOG-fuelled power plant, based in London, uses urban waste for 50% of its generation. Edible oil consumption in India has grown from nearly 15 million tonnes in 2008-09 to over 23 million tonnes in 2014-15. Given the waste oil being generated, tapping the opportunity would do both India’s waste management and climate change efforts a world of good.