Bath is well known for its fascination with coffee but the caffeine craving could help the city to become self-sufficient in mushrooms.
He trained as an exploration geologist and has worked with Julian House but now Hugh Prentice, 56, is spending his days collecting 40 kilograms of used coffee beans from cafes around the city.
It is estimated that Bath produces 200 kilograms of used coffee beans every day.
Mr Prentice, who is a trustee of Transition Bath, is taking the coffee beans to underground vaults at Green Park Station and using them to grow oyster mushrooms.
"The idea has been a long time gestating.
"It started with the retirement of the mushroom seller at the farmers' market, and discovering that coffee grounds are used elsewhere in the world as a source of nutrients for growing mushrooms and that there was spare space under Green Park Station in which to grow mushrooms."
Mr Prentice launched Fungi Fruits at the end of last year to trial whether or not he could, by mixing the coffee beans with special spawn, grow mushrooms under the city.
He is now turning to crowdfunding website, buzzbnk.org, to raise the final £11,000 needed to expand the operation. By the end of the year he hopes to be collecting 100 kilograms of coffee beans every day.
The appeal has already attracted £5,000 in funding pledges. Investors are being promised three per cent interest or four per cent interest if paid in mushrooms. The offer closes on March 31.
Mr Prentice said he hopes to have the first crop of mushrooms on sale at the Bath's Farmers' Market by the end of April.
A display about Fungi Fruits will be at the city's farmers' market on Saturday.
For more information, visit www.fungifruits.org. To pledge funding, visit www.buzzbnk.org/fungifruits.
