Malta Inc. Announces Key Milestone for Pumped-Heat Energy Storage System Deployment

DOE Pilot Plant Commissioned by Southwest Research Institute Models Malta’s Long-Duration Energy Storage Technology

Aug. 30, 2022 (SAN ANTONIO) – Malta Inc., a leading long-duration energy storage solution provider, announced today that Southwest Research Institute (SwRI) has completed assembly and commissioning of the first-of-a-kind pumped heat (or thermal) energy storage (PHES) demonstration facility based on the utility-scale thermal energy storage system created by Malta as part of a project supported by a $2.6 million ARPA-E award from the U.S. Department of Energy.

Long-duration, large-scale storage capabilities, like PHES, can help balance energy volatility and reliability issues caused by high market penetration of variable renewable energy resources such as solar and wind energy and create solutions to fulfill worldwide carbon reduction goals.

Breakthrough Energy Storage

PHES is a breakthrough for long-duration energy storage (LDES), repurposing conventional, commercially proven power plant equipment and processes to provide cost-effective, large-scale energy storage. While the SwRI pilot is laboratory-scale, a full-size Malta PHES system will be able to store more than 100 megawatts (MW) of power for eight hours to eight days or longer (800 to 19,200+ MWh). The pilot will next be tested to demonstrate operation, verify system control strategies, and validate data.

"SwRI is a leader in advanced power systems and has pursued extensive PHES research. With the potential for high system performance and its ability to be built anywhere, PHES is an extraordinarily promising energy storage technology,” said Tim Allison, R&D Director of the Machinery Department at SwRI.

By efficiently storing electricity for long durations, Malta’s system can enable increased penetration of renewable energy from intermittent sources, maintain grid reliability, and accelerate the decarbonization of the energy sector.

“SwRI has been a terrific collaborator in deploying this scaled, pilot version of the Malta system,” said Malta CEO Ramya Swaminathan. “We look forward to leveraging this project to help further streamline this existing technology as Malta deploys commercial, similarly-integrated PHES systems in Europe and North America.”

Time-Tested Technology

The Malta PHES energy storage system is built upon well-established principles in thermodynamics and uses conventional components that have been present in power plants for hundreds of years. Electricity from the grid is used to heat molten salt and cool a chilled liquid. In these forms, energy can be efficiently stored for long durations. When the energy is needed, the system operates as a heat engine to discharge the stored energy, using the stored heat and cold together to generate electricity on demand. This form of storage offers a low-cost solution to supplement or replace the use of fossil fuel “peaker” plants in matching intermittent energy supplies with customer demand.


About Malta Inc.

Based in Cambridge Massachusetts, Malta, Inc. has developed a Pumped Heat Energy Storage (PHES) system to provide long-duration, large-scale, cost-effective, and safe energy storage. Malta’s system stores electricity as thermal energy and then re-generates the electricity on demand for 200 hours or longer, meeting daily and weekly needs. Malta’s PHES system also generates clean heat for industrial and district heating applications. Visit:

Media Contact
Steven C. Sullivan