How to make your own cooking gas from food waste

Brian Stokes and his family have a unique Irish breakfast experience. They can fry their eggs on gas they produce, at home, from nothing but food waste and water. As the rest of us navigate the newly fraught fossil fuel world, Brian and his family in Cobh, Co Cork, are more fuel-secure. They have been making their own biogas for 14 months.

The biodigester that lives in their greenhouse pipes the gas to a small burner in their kitchen. The system is simple. A 10-litre bucket under the sink collects all food waste. “It likes what you eat, so it doesn’t like tea leaves because we don’t eat tea leaves,” Stokes explains. There is a “no tea bag” rule. Everything else goes in: peelings, leftovers, cooking fat, meat and cooked food.

The set-up cost for the Home Biogas (homebiogas.com) was about €600. It looks like a large black rubber bladder (picture an un-fun bouncy castle) which is inflated and part-filled with water. The food is tipped into a pipe. It produces gas for cooking and liquid fertiliser for the garden. Sometimes they need to add some manure to adjust the pH levels, but otherwise that's it. No brown bin charges, free gas and garden fertiliser from something that would otherwise have to be carted away. The looped circular nature of the system is what the family loves. "I can't believe I can fry my breakfast off the gas from my food waste," Stokes says.

Food waste

We have a rubbish system for treating rubbish. Biogas digesters could be installed in restaurants, cafes and catering facilities, keeping food waste onsite to produce a fuel and fertiliser to grow food more locally.

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Much of the estimated one million tonnes of food Ireland wastes annually shouldn’t go to waste. Supermarkets need to do more to engineer out the vast amounts of waste they create.

Social enterprise FoodCloud makes a Trojan effort to get that surplus food into the kitchens of people who need it. Anything they can’t find a home for ends up in Nurney, Co Kildare.

This is an industrial version of what's happening in a greenhouse in Cobh. Green Generation turns food and agricultural waste into biogas at scale. It uses the gas to produce renewable electricity to power its operations, and refines it further to produce biomethane which fuels its heavy goods vehicles. The rest of the biomethane is injected into the gas grid.

We could have biogas operations collecting slurry from farms and using it to produce renewable gas and sterile digestate for fossil-fuel-free fertiliser. Large farms could install their own biomethane operations.

Fuel security is under our nose. Scaling it up has never been a more urgent priority: to cut fossil fuel emissions and defund a war criminal.

Catherine Cleary is co-founder of Pocket Forests