Molten Salt, Sand, and Sweat: The Weird Batteries That Could Store Renewable Energy
From liquid air and molten salt to sand and human sweat, alternative battery technologies are being developed to store renewable energy without relying on scarce minerals like lithium and cobalt.
While lithium-ion batteries dominate energy storage, researchers and companies are exploring a range of unconventional materials. Unlike traditional batteries, many of these alternatives can be cycled indefinitely and recycled after a 20-year lifespan.
In the UAE desert, a massive project combining 5.2 GW of solar capacity with 19 GWh of battery storage is being built – the world's largest such system. In the UK, a former coal plant site in Trafford hosts the Carrington "cryobattery," which stores renewable energy as liquid air. The system cools air to -196°C, reducing its volume 700 times, then releases it to drive a turbine when energy is needed. The project, expected to be operational by year's end, will provide 300 MWh of storage and 50 MW output for six hours.
In Nevada, the Crescent Dunes plant has used molten salt technology for a decade: 10,000 mirrors heat potassium and sodium nitrate to 560°C, storing thermal energy for 10 hours after sunset. Denmark this year unveiled a 1 GWh molten salt battery that can store clean electricity for up to two weeks and produce high-temperature steam for industry.
Finland's small town of Pornainen uses a "sand battery" – 2,000 tonnes of crushed soapstone storing 100 MWh of heat. In summer, it covers nearly a month's heating demand; in winter, about a week. This unit is ten times larger than the 2022 prototype.
Meanwhile, Tokyo University of Science researchers have developed a wearable patch that generates electricity from human sweat. Using an enzymatic biofuel cell, it captures lactate from sweat to produce power for wearable devices without external charging.
