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Project Malta

Storing renewable energy in molten salt

In development
Engineer holding salt in her hands.

The challenge

Wind and solar power are abundant, clean, and increasingly inexpensive energy sources. However, they’re not always available when the demand for power is greatest.

If wind and solar farms are producing more energy than the electric grid needs, the energy goes to waste. In California, up to 30% of solar energy cannot be used when it’s produced. Worse, if electricity demand spikes during periods when the sun isn’t shining or the wind isn’t blowing, utilities will often fire up “peaker plants” to bring extra power online quickly. These are usually powered by fossil fuels and emit large amounts of CO2 relative to ordinary power plants.

Up to 30% of solar energy in California is wasted because it cannot be used when it’s produced.

Project Malta is building a grid-scale energy storage technology that stores electricity from renewable energy sources as heat inside large tanks of high temperature molten salt and as cold in large tanks of chilled liquid. The system can discharge electricity back to the grid when energy demand is high - effectively “time shifting” energy from when it’s produced to when it’s most needed.


The Process

The Project Malta team is built on the research conducted by Nobel Prize winning Stanford physics professor Dr. Robert Laughlin, who came up with a theoretical system that stores electricity as heat in high temperature molten salt and cold in a low temperature liquid similar to the antifreeze in cars. The energy stored in the system can be kept for days or even weeks, until it’s needed.

  1. Collects

    Renewable energy is gathered from wind or solar farms on the grid as electrical energy and sent to Malta’s energy storage system.

  2. Converts

    The electricity drives a heat pump, which converts electrical energy into thermal energy by creating a temperature difference.

  3. Stores

    The heat is then stored in molten salt, while the cold is stored in chilled liquid.

  4. Reconverts

    The temperature difference is converted back to electrical energy by a heat engine.

  5. Distributes

    Electricity is sent back to the grid when it is needed.


Building a real world and cost-efficient system

The Malta system has some important qualities that make it viable from both an environmental and cost perspective. The components are inexpensive because much of the system uses conventional technology – steel tanks, air and cooling liquids are all simple to procure. Salt is easily extracted from the earth and can store heat without degrading or emitting toxic byproducts. The salt tanks can also be re-charged many thousands of times, for possibly up to 40 years – at least three times longer than other current storage options.


The team is now working to bring Professor Laughlin’s system into the real world. They’ve now developed detailed engineering designs of each component that are nearly ready to be turned into real machinery – down to the exact angle of each blade in a turbine and the strength and thickness of the material used.

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Prototyping the next step in energy storage

The Project Malta team is looking to build a megawatt-scale prototype plant to prove the technology at commercial scale. They’re looking for partners with the expertise to build, operate and connect a prototype to the grid -- such as customers of grid-scale energy storage, energy system manufacturers, or energy system construction companies.