A report by engineering consultant Parsons Brinckerhoff has stated that Isentropic’s pumped heat electricity storage (PHES) would cost less than 30% of the capital cost of comparable heat pump storages systems.
The report’s example estimated the cost for a plant with six hours of storage to be $618/kW, giving a per hour storage cost of $103/kWh.
UK-based Isentropic developed a 100MW electrical heat pump system, which comprises a reversible gas cycle machine, working as an engine and heat pump. It incorporates heat exchange directly to a storage medium within the gas circuit of the heat engine, regenerating most of the electricity from the temperature difference. The process results in an electricity-in to electricity-out between 72 to 80%, according to the company.
“Pumped Hydro is the current market leader for low-cost energy storage. It is much cheaper than batteries, even factoring in future price reductions. This report shows Isentropic Ltds technique to be 30% of the cost of Pumped Hydro, making it a potential game changer,” claimed James Macnaghten, CEO of Isentropic.
The system can also be built from equipment developed from mass produced components, added Macnaghten.
The Energy Technologies Institute funded Isentropic with £14m ($22m) in 2012.