A British company believes sewage could provide the solution to the UK’s salad supply shortages as a huge rise in wholesale gas prises has impacted growers.
Oasthouse Ventures has huge greenhouses in Bury St Edmunds and Norwich which extract heat from the sewage at local treatment works, transferring it to heat pumps at their sites.
This provides the majority of the heat needed to grow peppers, tomatoes and cucumbers.
The move comes as the National Farmers’ Union warns Britain is facing its lowest year for salad production since records began.
Growers who rely on gas to heat their greenhouses have been hit by a 156% rise in wholesale gas prices since 2019.
The is partly why the country experienced shortages of some fruit and vegetables in supermarkets at the beginning of this year, which means the UK continues to be hugely reliant on imports for salad and fresh produce.
Ed Moorhouse, business development manager at Oasthouse Ventures, says their method of extracting heat from sewage provides greater stability than relying on gas.
He said: “Our greenhouses are not subject to geopolitics and global fluctuations in the hydrocarbon market that have shut many greenhouses in the UK and abroad, one of the key reasons we had shortages this spring.
“We’re also largely immune from the effects of climate change. When you decouple your day-to-day operation from gas prices and grow fresh produce in a country with ample rain and good levels of sunshine, you largely deliver food security and provide assurances of supply to supermarkets.”
But the running of these greenhouses is expensive and the equipment is costly.
Initially they benefited from the government’s Renewable Heat Incentive scheme, which has now finished.
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Schroders Greencoat, the investor behind Oasthouse Ventures’ sites, presented a plan to the government in 2022 for 40 possible new sites but they haven’t yet been given support despite the ongoing issues with food production and security of supply in the UK.
Some sectors are on the government’s Energy and Trade Intensive Industries (ETII) scheme, which provides a tax relief on energy bills.
But companies which grow crops in greenhouses are not eligible for this financial support.
Minette Batters, president of the National Farmers’ Union, said: “It’s been a complete anomaly that the Royal Botanical Gardens, as important as they are, have been able to access the government ETII scheme and yet people growing the country’s food haven’t been able to access it.
“It just seems absolutely bizarre. It would have gone a long way to preventing the situation of shortages from Morocco and Spain affecting our market, we would have been able to produce a lot more here.”
A government spokesperson said: “We have helped businesses over the winter with nearly £6bn of support, enabling some to only pay around half of predicted wholesale energy costs.”