At FareShare Cymru we try to minimise our waste as much as possible, but we inevitably have some food that we cannot use. For example, occasionally, we receive donations with too short a life to redistribute, or we get the odd bit of fruit and veg that has gone moldy, so we ensure we dispose of it responsibly. That’s why we send it to Bryn Power’s anaerobic digestion plant in Hengoed where they turn food waste and agricultural waste into renewable energy via the clever process of anaerobic digestion. Recently, we visited Bryn Power to learn all about this process. 

At Bryn Power, they receive a mix of residential and commercial food waste from Caerphilly council’s doorstep collections, food factories and food catering facilities all over South Wales. They also use agricultural waste from their dairy farm, including crops not eaten by cattle and cattle slurry.  

The 3000-ton anaerobic digester at Bryn Power is ‘fed’ the food and agricultural waste to produce around 1 megawatt of renewable electricity each day. Half of the electricity powers the whole site, including the dairy farm, whilst the other half is put into the national grid. Jennifer, from Bryn Power, explained that their digester performs at 200% of what it’s supposed to, meaning it is one hard-working digester! They’re also planning to expand with a second anaerobic digester so that they can give more to the national grid. The process is extremely efficient and is a great ‘baseline electricity’ for the grid, meaning it stays at the same level 24/7. For this reason, anaerobic digestion trumps other renewable energy sources like wind and solar power which are constantly changing.  

How does it work?

Initially, they mix the food waste and cattle slurry and blend them into a liquid and filter out any contaminants. They pump the liquid into holding tanks and feed it to the anaerobic digester every hour. Microbes in the digester feed on the liquid which allows them to grow and reproduce. As they do so, they produce methane biogas which is then used to turn the generators to produce electricity. The leftover product from the process, called digestate, is a natural fertiliser that Bryn Power uses on their own farmland and gives to neighbouring farms. Once the cattle have fed on the land and produced more slurry, the cyclical process starts again. 

Using food waste to produce renewable energy is a real no-brainer. Not only does it help reduce waste, but it also provides a reliable source of green energy that contributes to a more sustainable future. By tapping into a renewable resource that will continually be available, we can reduce our reliance on non-renewable energy sources, lower carbon emissions and ultimately put food waste to good use.