Scientists at ETH Zurich are developing a reciprocating piston engine which converts solar irradiation into electrical power. A concentrated solar beam is redirected between the engine’s cylinders and absorbed in an efficient porous receiver in the cylinder heads. Due to the moving beam, thermal load on the components is reduced compared to stationary solar receivers.
The concentrating solar power (CSP) technology has the potential to reach very high solar-to-electricity efficiencies. In particular, it can take advantage of the very high top temperatures (>2000°C) that can be reached with current solar concentration systems within a solar-thermal power cycle.
The researchers say the technology should be very cost effective: with similar investment costs to solar Brayton/Rankine-based systems, it is expected CSP can reach significantly higher solar-to-electricity efficiencies. The engine is suitable for decentralised medium-scale power plants as well as centralised large-scale plants in regions with high solar density and low cloud coverage.
Typical electrical power output of one engine unit is in the range of 0.1-1 MW. In order to further increase the thermal efficiency it can be combined with a bottoming steam power cycle.
Based on the very high solar-to-electricity efficiency CSP is expected to become competitive with fossil fuel-based electricity in the near future.