Atlas Copco provided the turboexpander solution for a pilot project delivered by solar-power experts RayGen.
(Photo credit RayGen)
Located in Carwarp, Victoria, southeast Australia, and covering an area of 30 hectares, a cutting-edge energy storage system that employs both solar photovoltaic and solar thermal energy to drive an Organic Rankine Cycle (ORC) has started to deliver renewable energy to the local grid. Atlas Copco provided the turboexpander solution for a pilot project delivered by solar-power experts RayGen.
(Diagram credit RayGen)
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.
Field of mirrors (Photo credit RayGen)
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.
Atlas Copco Turboexpander-generator (Photo credit RayGen)
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.
Sheep in the field (Photo credit RayGen)
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.
The adaptation of turboexpanders for use in solar-energy storage represents a promising development in the ongoing effort to meet the demands of a renewable-energy future, though full-scale production facilities will require technological advancements focusing on economies of scale and tapping into additional value streams.
For now, the pilot project at Carwarp is expected to save 10,000 tonnes of Co2 a year and provide renewable electricity for around 1,000 homes.
(Photo credit RayGen)
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