Inedible food waste can be processed in anaerobic digestion (AD) facilities to produce electricity which can be exported to the nation grid, powering local homes and businesses. In the UK, the largest AD facility is run by waste management company, Biffa in Staffordshire.
On arriving at an AD plant, the food waste first goes through a depackaging process to remove plastic bags and anything else that shouldn’t be there. It is then macerated (chopped up) and fed into a closed tank. Once inside, special bacteria eat the “soup”, producing methane gas and a nutrient-rich sludge.
Gas is then captured and burnt to heat water, releasing steam that turns a turbine and generates electricity. This power is sent directly to the National Grid, helping increase the country’s supply of renewable energy. The sludge is dried and supplied to farmers to plough back into the soil, closing the nutrient cycle.
Waste in landfill sites can also release methane gas, and the best way to manage it is… you guessed it – convert it into electricity. Here’s how it’s done:
First, a study the landfill site is done to understand the nature of the waste inside it (some historical landfill sites contain waste produced decades ago!) and then pipes are dug in to collect the gas. The gas travels up the pipes to an on-site mini power station. Here, a bespoke technology is used to clean the gas and make it ready for the engines. The cleaned gas is used as a fuel to power the engines and generate electricity, which is fed onto the Grid.
So when you turn on your light bulb, it could well be powered by your rubbish!