The UK's oldest green electricity supplier has just celebrated its tenth birthday. Ecotricity also claims to be the largest independent retailer of green power. The bulk of its business is merchant wind power: securing long term off-take contracts with large customers for output from dedicated on-site or off-site wind turbines. In addition, Ecotricity has some 10,000 domestic customers for its green power. Based in Stroud, Gloucestershire, Ecotricity says its success is underpinned by a "not for dividends" attitude to business. One hundred per cent of its profits are used to build new turbines it says. Last year it invested £7 million in wind energy projects. Ecotricity is endorsed by the World Wildlife Fund and the Soil Association. Ecotricity founder Dale Vince says the fundamental aim of the company is to change the way electricity is made in the UK. This is why it invests all its profits in building new sources of wind energy, he says. "Ten years ago we described ourselves as environmentalists doing business, not a business doing the environment. I can't think of a better way to put it today." Vince, awarded an OBE for services to the environment in 2004, has won personal praise from Prince Charles. In a letter sent during his honeymoon in April, the Prince lent his support, saying Ecotricity is a "fine company" and Vince is a "good chap," reported the Sunday Times newspaper.