This case study focuses on the possibility of heat use from the Bugey nuclear power plant (35km away from Lyon) to provide district heating or cooling for the Lyon region in France. It is based on a new heat transportation concept over long distances. The Lyon area involves about 1 300 000 inhabitants. The annual needs of the 108 900 dwellings connected to the heating networks are 867 000MWhyear1. The annual electricity production of this plant is 25 000GWhyear1. The average energy efficiency of the secondary loop of the plant is 33.6% and its exergy efficiency is 71.0%. Taking into account a possible transportation efficiency of 32%, the coverage of the Lyon area district heating needs is possible by replacing a pre-heater by a heat exchanger in two of the four reactors of the Bugey power plant. The new electric efficiency of the plant would be 32.5%. The global energy efficiency of the process, taking into account the heat provided at the user site, would be 33.5%, which means a decrease by only 0.1%. The exergy efficiency for the global process would decrease to 70.2%. This transportation could save a large amount of fossil fuels consumption and greenhouse gases emission that could be particularly harmful in densely populated areas. Copyrightr2008 John Wiley & Sons, Ltd.