Schlumberger Energy Institute Solar | Page 6

03. Parabolic Trough l Good optical efficiency Storage possible l High water & and land use requirement l l Long rows of parabolic reflectors concentrate solar irradiance by an order of 70 to 100 times onto absorber tubes mounted along the reflectors’ focal line. l Superheated steam runs a turbine, which drives a generator to produce electricity. l Around 30% of the plants in operation are equipped with thermal storage, sometimes supplemented by a back-up fuel. Tracking aligned Mobile receivers enable an optimal arrangement between concentrator and receiver, regardless of the position of the sun. 04. Parabolic Dish l l l l l l l No water cooling & very limited land use Modular concept High solar-to-electricity efficiency Demonstration phase Storage limited to large dishes Costly Solar towers - aka central receiver systems - are made of a field of heliostats (i.e. devices the track the sun from a stationary point), surrounding a central receiver atop a built structure. l Heliostats can vary greatly in size. 6 | slb.com