Turboexpander solution delivers cutting-edge solar energy storage

The need for innovative energy-storage solutions is becoming increasingly important due to the challenges of intermittency presented by renewable sources. Turboexpanders are traditionally used in renewable energy applications, such as in an ORC within binary geothermal power plants, and they are now being adapted to novel solar-energy storage applications in a similar configuration. In this new context, turboexpanders used in an ORC retain a central role in ensuring system efficiency and reliability.

The power plant works by a series of mirrors on the ground focusing sunlight across to a receiver tower with solar cells. On the one hand, the cells convert the rays into electricity, as in a traditional solar farm. That electricity is subsequently used in two ways: firstly, to supply the electricity grid in the usual way; secondly, to chill a body of water to near freezing.

On the other hand, because the cells are highly concentrated, they generate a lot of heat, which is used to heat a body of water to near boiling point. With this temperature difference in the two bodies of water, via an ORC and turboexpander, the storage system supplies electricity to the grid on demand.

The RayGen Power Plant Carwarp (RPPC) started supplying the grid with renewable electricity in mid 2022 and the storage and became fully operational in the second quarter of 2023. It adds 4 MW of solar and 2.8 MW/50MWh (17 hours) of storage to the grid. The energy storage system supplies power during peak energy demand periods when the availability of other renewable sources, such as wind and solar, is limited.