Ontario Power Generation Inc. (OPG) is a Crown corporation wholly owned by the Government of Ontario. OPG is responsible for approximately half of the electricity generation in the Province of Ontario, Canada. Sources of electricity include nuclear, hydroelectric, wind, gas and biomass. Although Ontario has an open electricity market, the provincial government, as OPG's sole shareholder, regulates the price the company receives for its electricity to be less than the market average, in an attempt to stabilize prices. Since 1 April 2008, the company's rates have been regulated by the Ontario Energy Board.