<P> The power generated by a power station is measured in multiples of the watt, typically megawatts (10 watts) or gigawatts (10 watts). Power stations vary greatly in capacity depending on the type of power plant and on historical, geographical and economic factors . The following examples offer a sense of the scale . </P> <P> Many of the largest operational onshore wind farms are located in the USA . As of 2011, the Roscoe Wind Farm is the second largest onshore wind farm in the world, producing 781.5 MW of power, followed by the Horse Hollow Wind Energy Center (735.5 MW). As of July 2013, the London Array in United Kingdom is the largest offshore wind farm in the world at 630 MW, followed by Thanet Offshore Wind Project in United Kingdom at 300 MW . </P> <P> As of 2015, the largest photovoltaic (PV) power plants in the world are led by Longyangxia Dam Solar Park in China, rated at 850 megawatts . </P> <P> Solar thermal power stations in the U.S. have the following output: </P>

Which process causes the production of most of the energy the fox uses to run