Our PTES is based on a high-pressure, positive-displacement, multi-cylinder ‘compressor-expander’ machine.
In the charging cycle, the system uses electricity to run the compressor, raising the pressure and temperature of an operating gas.
Thermal storage material is heated by the gas in a heat exchanger and the material can be stored in an insulated storage silo at atmospheric pressure.
The gas leaves the heat-exchanger and enters the expander where it drops in pressure and in temperature.
A second heat exchanger allows the cold gas from the expander to cool another flow of storage material. The very cold material then leaves the heat exchanger and is sent to a cold storage silo.
The gas then returns to the compressor and the cycle continues until the full storage depth has been met or the operator chooses to only partially charge the system.