It is claimed to be the first investment fund dedicated entirely to renewable energy, and will only support projects proved to be environmentally and socially sound. Money will be invested in small wind farms or other renewable energy sources and, it is hoped, will earn dividends for shareholders.
Subscribers are automatically entering an illiquid market. But while a guaranteed exit is unobtainable, the "matched bargain" market run by the fund manager - matching buyers with sellers -will provide an opportunity to get out.
The fund charges an initial 2.5 per cent, half the normal charge for a unit trust, and an annual charge of 1 per cent.
With a minimum investment of £300, the Wind Fund has attracted subscriptions from a wide cross-section of the public. Now its initial offer period will be extended.
Glen Saunders, a fund director, said the response showed that "the public are willing to support an investment where they can make a direct contribution to the environment."
The driving force behind the idea is the Dutch Triodosbank NV, which has linked up with a British counterpart, Mercury Provident. The bank has already pioneered a successful wind fund in the Netherlands.
Last December, Charles Wardle, Parliamentary Under-Secretary of State for Industry and Energy, welcomed the Wind Fund's decision to open an investment fund.
Additional governmental support has come through the Non Fossil Fuel Obligation process.