Why is generation of electricity from steam more efficient in a tower system?
New generations of turbines can convert supercritical steam to electricity at efficiencies of more than 50%. BrightSource’s tower systems take advantage of the most efficient steam turbine generators, and the company’s initial projects in California are rated at 540°C to 560°C and 140 to 160 bar with a net cycle efficiency of 40%. Future projects are planned to operate in the supercritical range of temperatures and pressures, with steam-to-electricity efficiency reaching 50%. Trough systems, on the other hand, cannot make use of the same advances in turbine technology to increase the efficiency of electricity generation because the synthetic oils used for heat collection are limited to temperatures of about 390°C. Based on currently available information, turbines serving parabolic trough systems are generally around 36% efficient.
