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From bin to bulb

Posted in Food waste
On 04 Apr 2018
By Jas Bagri

How waste can power your home and business.

Biffa helps customers of all shapes and sizes make the most of their waste. While some items like wooden pallets are reusable, and others like plastic bottles are recyclable, there will nearly always be some waste leftover.

The best thing to do with this waste? Turn it into renewable energy.

Biffa has an entire division dedicated to recovering renewable energy from waste. Our customers don’t need to do anything different – we take care of everything through our nationwide infrastructure.

Food waste to electricity

We process our customers’ inedible food waste in anaerobic digestion (AD) facilities. Biffa runs the largest AD facility in the country (in Staffordshire), and we have a team of experts working round the clock across all our sites to make sure we’re recovering the most energy possible from the available feedstock.

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.

 

We capture the gas and burn it 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.

Black bag waste to electricity

At Biffa’s flagship Mechanical & Biological Treatment facility in West Sussex, waste from residents’ black bags is sorted to remove anything recyclable, such as glass bottles and cans. This sorting process involves a complex mix of people and machinery to recover as much of the material as possible.

Food waste is also separated out, and this then enters the “biological” phase of the process, which is the same anaerobic digestion process described above. The food waste is blended before entering a tank where it is digested by special bacteria, producing methane gas and a digestate product used on farms.

The gas is burned and used to generate renewable energy, which is put on the National Grid and used to power homes and businesses.

Landfill gas to electricity

Biffa has a responsibility to carefully manage all its landfill sites for many years after they have closed. Waste in landfill sites can also release methane gas, and the best way for us to manage it is… you guessed it – convert it into electricity. Here’s how we do it:

First, we study the landfill site to understand the nature of the waste inside it (some historical landfill sites contain waste produced decades ago!) and then we dig pipes in to collect the gas. The gas travels up the pipes to an on-site mini power station. Here, we use bespoke technology 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.

Biffa’s landfill gas operations, alongside its AD facilities that turn food waste into electricity, help the UK keep its lights on without polluting the environment. The renewable energy we supply powers homes and businesses up and down the country, and is an important part of the energy mix that we all rely on.

So when you turn on your light bulb, it could well be powered by your rubbish!

About the author

image of jas bagri

Jas Bagri

Jas is part of Biffa’s digital team, writing a diverse range of content on a number on industry topics. Jas’s favourite subject to write about is recycling, so look out for her handy tips coming your way!