Long-duration thermal storage system based on silica sand

From pv magazine Global

Magaldi Green Energy, a unit of Italy-based dry bottom ash handling system provider Magaldi Power Spa, has developed a thermal storage system for long-duration storage based on a fluidised sand bed.

The Magaldi Green Thermal Energy Storage (MGTES) can be charged with renewable electricity or thermal energy such as waste heat generated by industrial thermal processes. Its discharge phase consists of the production of green thermal energy — steam or hot air — which can be used directly in industrial plants or for the generation of electricity using steam turbines. 

“Our storage technology can be used in the steam section of existing thermoelectric power plants based on the Rankine cycle or combined cycle gas turbines (CCGT) plants,” Letizia Magaldi, executive vice president at Magaldi Green Energy, told pv magazine.

The system consists of a blower, a fluidisation air blowing system, a fluidisation air suction system, an air filter and fan, an air pre-heater, and an integrated thermal energy storage module. Silica sands are the system’s storage media.

The fluidisation system is the core of the technology and is claimed to have high thermal diffusivity. The manufacturer ensures it is well insulated and that thermal losses are lower than 2% per day. The absence of convection and the insulation of the tank are said to limit the heat exchange with the outside of the casing, thus minimising energy losses. The system is discharged by reversing the integrated heat exchanger within the fluidised bed and the stored energy is released as superheated steam.

The system’s operating temperature can reach up to 1,000 degrees Celsius and its roundtrip efficiency is reportedly over 90% for heat production and between 35 and 45% for electricity generation.