If you are looking for a green investment with attractive returns, and are prepared to take a risk with your money, a corporate retail bond offered by a renewable energy company is promising to pay 7.5% annually for the next four years.

Wind Prospect Group, which has been operating for more than 15 years, has launched the bonds with the aim of raising £10m, which it will use to build a wind farm in Staffordshire. The minimum investment is £500.

Wind Prospect says its ReBonds are likely to appeal to investors looking for an opportunity to invest in green energy projects while supporting a UK-based, employee-owned business.

The bonds pay a fixed-rate return of 7.5% over a four-year initial investment period, with a slightly higher rate for larger investments. The offer is open until 20 July or it is fully subscribed.

Much of the money raised will be used to fund the first commercial wind turbines to be built in the West Midlands, on land owned by South Staffordshire College.

Crucially, the company says there is already planning consent for the two-turbine project, with construction due to start this summer. However, this is an investment for people who are happy to accept some risk.

Corporate bonds are essentially a loan to the company, where the money invested by the bondholders is repaid at maturity. If the firm went bust you could lose some or all of your cash. However, the return is better than those offered by deposit accounts.

The invitation document states: "It will not be possible to sell or realise ReBonds … [they] are an unsecured debt of the company, and there is no certainty or guarantee that [it] will be able to repay them." For more information go to rebonds.equiniti.com.

Meanwhile, Gossypium, a Fairtrade and organic cotton retailer, has launched a share offer which aims to raise at least £250,000. The money will be used to increase its range of products and franchise shops.

The shares will be issued by parent company Vericott, which is 90% owned by Gossypium founders Abi and Thomas Petit, and 10% owned by an Indian farmers' co-operative. The company aims to pay an annual dividend "that at least matches banks' savings rates", and shareholders also get 25% off Gossypium products.

The minimum outlay for private investors is £500. Investors can register their interest on the company's website.

• British Gas has launched a green tariff open to any customer which is designed to raise money to help communities generate renewable energy and improve energy efficiency.

Customers signing up to the energyshare tariff will also get the electricity they use matched with electricity from 100% British renewable sources at the same price as the British Gas standard tariff, a spokesman says.

For every year a customer remains on the tariff the company will pay £10 into a fund which will raise money for local community energy projects. The tariff is a part of energyshare, a renewable energy "community" founded by the River Cottage food empire and British Gas.