Briefs: double-effect trigeneration for energy savings in French space centre

The Centre Spatial de Toulouse, which is part of the French Centre National d'Etudes Spatiales is now equipped with a large-scale trigeneration plant. The Centre comprises 60 buildings and employs 2500 employees and until 2002 also had a huge power bill. The site has major cooling requirements because of its powerful computers and purchased a trigeneration plant in 2001. Natural gas powers the heat engines generating electricity. Heat is then recovered on the cooling circuit for water heating, then further heat recovery from the exhaust fumes feeds cooling system providing water at 6°C. The "double effect" consists in a dual heat exchange an absorption cooling system level, providing high-performance cooling. The energy initially consumed is upgraded to up to 80%. The plant will avoid consuming 70 000 MWh of energy and emitting 19 000 tonnes CO2e over a 12-year period. Its initial cost was 3.85 M € but will save 668 000 € annually and thanks to subsidies from ADEME and regional authorities, the return on investment will be achieved within a five-year period.