Invest in Green Funds "Green funds" are mutual funds which invest in environmentally friendly companies, such that are involved in clean energy (wind, solar, biomass); or in progressive companies which use environmental technology to reduce greenhouse gases in industries such as oil, gas, coal and mining. U.S. mutual funds with green leanings total $2-trillion, according to Jantzi, which account for about 10 per cent of total investments in that country.