Malta
Storing renewable energy in molten salt
Malta is a long-duration energy storage company that builds grid-scale energy storage solutions to convert variable renewable energy into on-demand, around-the-clock, reliable power. While incubating at the moonshot factory, the team developed a new approach to long-duration energy storage—using high-temperature molten salt to store heat, and a low-temperature liquid to store cold for days, or even weeks until needed. After prototyping its technology at X, Malta became an independent company and works with partners globally.
Next-Generation Energy Storage
Renewable energy is abundant, clean, and increasingly inexpensive—but it’s not always available when demand is highest. Excess wind and solar farms often goes to waste — in California alone, up to 30% of solar energy can’t be used when it’s produced. Electricity demands often spike when the sun isn’t shining or when the wind isn’t blowing, forcing utilities to fire up “peaker plants,” emit high levels of CO₂ relative to ordinary power plants.
The Malta team was inspired to tackle this challenge after coming across research from a Nobel Prize-winning physics professor, who came up with a theoretical system to store electricity as heat in high temperature molten salt and cold in a low-temperature liquid. Using common, cost-effective materials like molten salt, steel, anti-freeze, and air—they designed a system that can store energy and release it on demand, even days or weeks later.
An early model of the Malta system
Electro-Thermal Storage
Renewable energy is gathered from wind or solar farms on the grid as electrical energy and sent to Malta’s energy storage system.
The electricity drives a heat pump, which converts electrical energy into thermal energy by creating a temperature difference.
The heat is then stored in molten salt, while the cold is stored in chilled liquid.
The temperature difference is converted back to electrical energy by a heat engine.
Electricity is sent back to the grid when it is needed.
Salt of the Earth, Storage for the Future
The Malta system stands out for its cost effectiveness and environmental advantages. It relies on readily-available, low-cost materials like steel tanks, air, cooling liquids, and salt—a substance that is easily extracted from earth and capable of storing heat with minimal degradation or toxic byproducts. Unlike other storage solutions, Malta’s salt tanks can be recharged thousands of times and have a potential lifespan of up to 40 years, at least three times longer than many existing options. The system can store energy for days or even weeks, ensuring power is available when it’s needed.
The Project Malta team
Malta Today
While at X, the team incubated its electro-thermal storage technology and developed detailed engineering designs for each component. They also worked with utilities, grid and power experts to ensure that Malta could meet the energy needs of the future grid.
Now, as an independent company based in Cambridge, Massachusetts, Malta Inc. is now working with partners around the world to develop storage solutions that will collect and store large quantities of energy to dispatch quickly as electricity on demand.
