The world’s first bio plant, using enzymes to handle unsorted household waste without prior treatment, will be ready in early 2017 – and it’s in the UK.
Based in Northwich, Cheshire, it will be built and operated by Denmark’s DONG Energy using its own REnescience technology and is expected to have an annual capacity of 120,000 tonnes of waste from around 110,000 households. A full staff of 24 will handle up to 15 tonnes of household waste per hour.
So waste doesn’t have to be burnt, or trapped forever in landfill. Instead, it will receive a patented enzyme treatment in a bioreactor which breaks it down and turns the relevant parts into biogas.
Raw biogas is usually made up of around 60% methane and 29% CO2 (with trace elements of H2S) – not high enough quality to be used as fuel gas for machinery. But biogas can be cleaned and upgraded to natural gas levels, when it becomes bio methane. This raw biogas is then cleaned at the plant to produce green power, green gas and transport fuel via gas engines.
Meanwhile, recyclable elements like metal and plastic are then removed, cleaned and repurposed.
The technology has apparently been tested at a demonstration plant in Copenhagen since 2009, though this has not necessarily been with unsorted waste.
In theory, it’s a great idea, but not without problems. So much goes into household waste that it’s extremely difficult to sort it efficiently, and DONG is likely to encounter the same issues as everyone else in this regard. But if they can do it, it will help to take the onus off households, since waste won’t have to be sorted before it’s processed.
It’s also not yet clear exactly how much power the new plant will be able to produce but DONG suggests it could be something like 5MW of renewable electricity – considerably less than might be expected from a typical coal plant (closer to 600MW) but it will of course have a considerably reduced carbon footprint.
That may be reason enough to justify the plant’s existence, and hopefully the exercise will lead to further refinements to increase the efficiency of green fuels like biogas in future.