The Waitrose supermarket in Rickmansworth has turned to an unusual source for its electricity supply - tomatoes sold in store.

Tomato plants, grown in greenhouses in Chichester and Stanstead are fed carbon dioxide, which, combined with the natural preocess of photosynthesis, generates heat to turn a turbine.

The power is then fed into teh national grid by Green Energy uk, supplier of 100% green electricity. All lights, tills and refridgeration units in the store, opened in November, are powered by the state-of-the-art process.

Bill Wright, Energy and Environment Manager at Waitrose, says: "It is essential to us that every aspect of our business meets our environmental standards. In addition to being an environmentally sound option, this surplus energy allows Waitrose to maintain our green commitments, and it helps the farms generate additional income - so everyone benefits."

All green energy uk's electricity comes entirely from green sources, including pig waste, vegetable oil, organic waste gasification, biomass, as well as wind and hydro power. Company founder and Chief Executive, Doug Stewart, said: "Electricity from growing tomatoes is extremely positive because it has multiple benefits and no waste - all the heat is used for warming the greenhouses, the CO2 is fed' to the plants and the electricity goes to consumers and businesses who want green power.

"It's great to work with Waitrose on a project like this because it makes a great deal of sense to use these resources. It's an excellent piece of joined-up-thinking"

In theory the UK has the resources to receive all of its electricity from green means, all we need do is harness this potential, and we are making great strides in that direction."