Projected thermodynamic efficiencies of fusion power plants

Estimated thermal efficiencies of proposed fusion power plant concepts are compared to the efficiencies of nonfusion power plants. Present trends in electrical power generation are also discussed. The fusion reactor system designs will have about the same thermal efficiencies as present day power plants using steam if these designs require the collection of thermal energy at the blanket and the transfer of that energy to a heat exchanger or boiler using the current technology. Two general methods should be pursued for increasing the thermal efficiencies of fusion power plants and thereby reducing the amount of waste heat. Methods should be developed for increasing the temperatures of the reactor coolants since the maximum attainable thermal efficiency of systems using coolants can be increased only by increasing the coolant temperatures. Second, advanced power recovery systems such as potassium topping turbines, MHD, and direct conversion should be developed since such systems avoid the limits on steam systems due to excessive operating pressures at high temperatures. Direct conversion is particularly attractive because it avoids the theoretical Carnot limit on thermal efficiency when heat is converted to electrical energy