secondly water is used for volume control of chemical and radiological liquid wastes produced during normal operation nuclear power plants currently being built have a thermal efficiency of about while modern coalfired power plants achieve almost and combined cycle gas turbine ccgt plants reach thermal efficiency higher thermal efficiency means not only a reduced cooling requirement but also more electricity for a given amount of fuel as an example according to a french government study siting an epr near a river reduces the electricity output by with respect to a location near the sea siting the planned new hirkish nuclear project on its black sea rather than on its mediterranean coast would allow for a gain in electrical output since average water temperatures in the black sea are about c lower