In the deserts of the United Arab Emirates, a massive clean energy project—spanning an area roughly the size of 12,600 football fields—is set to achieve a breakthrough: using solar power to supply energy equivalent to half a million homes throughout the night. The Gulf state has been steadily combining 5.2 gigawatts (GW) of solar capacity with 19 gigawatt-hours (GWh) of battery storage to create the world’s largest battery system.
Meanwhile, about 7,500 miles away at the US National Renewable Energy Laboratory in Colorado, researchers and engineers are developing some of the smallest batteries ever made. These are tiny compared to the grid-scale lithium-ion batteries used for storing renewable energy. They are designed to power electronic tags that will track young salmon and eels, which are about 3 inches (7.5 cm) long.
As traditional lithium-ion batteries push the limits of size and scale, other types of batteries could play a similarly vital role in harnessing low-carbon energy—without the need for critical minerals like lithium, cobalt, and nickel, which have raised concerns about environmental damage and harm to vulnerable communities.
Unlike lithium-ion batteries, which have a limited number of charge and discharge cycles, many of these alternative battery technologies can be used indefinitely and recycled after their 20-year service life ends. Developers are already turning to a wide range of materials to store renewable electricity when it’s available and use it to power everything from wearable tech to heating networks, factories, and even missiles.
Here are some of the most innovative energy storage technologies making headlines.
Liquid Air
Late last year, on the site of a former coal plant in Trafford, the former mayor of Greater Manchester marked the start of construction on a long-awaited energy storage project that could spark the “re-industrialisation” of the region. Andy Burnham said the development of the Trafford green cluster, which includes the Carrington “liquid air” cryobattery, could make “this decade the most exciting since the Victorian period for Greater Manchester.”
In simple terms, the Carrington project—developed by British startup Highview Power—aims to capture renewable energy when it’s abundant and store it as liquid air. In theory, a “cryobattery” can store energy for hours, days, or even weeks. The science is more complex: Carrington uses surplus renewable energy to cool air to -196°C, turning it into a liquid that takes up 1/700th of its original volume. It stays in this state until renewable energy becomes scarce and market prices rise. Then, the liquid is allowed to turn back into gas, rapidly expanding through a turbine to generate electricity without the emissions typical of gas-fired power plants.
The project has faced several delays, but once it starts operating—expected by the end of the year—it will provide 300 MWh of storage and deliver 50 MW of power for six hours. That’s enough clean, renewable energy to power nearly half a million homes.
Molten Salt
While energy is stored at sub-zero temperatures in Manchester, the opposite approach is used in the Nevada desert. There, 10,000 mirrors generate electricity for the Crescent Dunes project, which has spent the last 10 years using the sun’s power to heat a reservoir of potassium and sodium nitrate to 560°C. This temperature can be maintained for 10 hours after sunset, and the stored thermal energy is then converted into electricity by using the heat to drive a traditional spinning turbine.Molten salt storage is an effective way to store clean electricity as heat. These molten salt batteries serve as the main power source for most modern guided missiles and nuclear weapons. They work as “reserve batteries,” holding energy until the heat from a pyrotechnic charge—triggered when the weapon is launched—releases that stored energy.
In the 2020s, Denmark showed that molten salt storage could also help solve the challenge of decarbonizing heavy industry. The country, a leader in wind power, unveiled a large-scale molten salt battery project earlier this year with a capacity of 1 GWh. It can store clean electricity for up to two weeks by heating the salts to around 600°C. When needed, the hot salt is circulated through a generator that produces high-temperature steam, which can be used directly in industrial processes.
Sand
Just as renewable electricity can be stored by heating salt, clean energy can also be stored in sand.
In the small town of Pornainen in southern Finland, thousands of tonnes of sand help store energy used to heat schools, libraries, and town halls. This should allow the district to completely stop using oil in its local heating network and reduce its use of wood chips by about 60%.
The sand battery uses around 2,000 tonnes of crushed soapstone to store clean energy as heat, providing 1 MW of thermal power and a storage capacity of 100 MWh. In summer, the sand battery—about 13 meters tall and 15 meters wide—can cover nearly a month’s heat demand in Pornainen. In winter, it can cover close to a week. This is about ten times larger than an earlier version launched in the country in 2022, highlighting the potential for sand batteries to play a bigger role in cutting emissions across Finland.
Sweat Tech
In Japan, researchers at the Tokyo University of Science are exploring whether human sweat could be a viable energy source for powering wearable technology.
By treating the body as an energy source that can provide continuous power, the researchers hope to solve the problem of powering the sensors in wearable devices without relying on small batteries that make them bulky and require constant charging.
In response, they have developed a thin, wearable patch that generates electricity directly from human sweat. It uses an enzymatic biofuel cell to capture chemical compounds—especially lactate—released in sweat and convert them into power. When sweat comes into contact with the cell, enzymes embedded in the patch trigger a biochemical reaction that releases electrons.
This means electricity can be generated without any external power source, during everyday activities like walking, exercising, or running errands.
Frequently Asked Questions
Here is a list of FAQs about the unusual batteries that use molten salt and human sweat to store renewable energy written in a natural tone with clear simple answers
BeginnerLevel Questions
Q Wait are we really using human sweat to store energy
A Yes but not in the way you might think Researchers are developing a superthin flexible battery that uses the salt in human sweat as a chemical fuel When you sweat the battery generates a small amount of electricityenough to power tiny sensors or wearable devices
Q What is a molten salt battery
A Its a big industrial battery that uses salt heated until it becomes a liquid This liquid salt acts like a sponge storing heat or electricity Its mainly used to store energy from solar or wind power for later use
Q Why would we need batteries made from sweat or molten salt
A Regular batteries can be expensive hard to recycle or catch fire Sweat batteries are perfect for wearables because theyre safe and never need charging Molten salt batteries are great for the power grid because they can store huge amounts of energy cheaply and last for decades
Q How does a sweat battery actually work
A Your sweat contains salt A special enzyme in the battery reacts with the lactate to create a tiny electric current The more you sweat the more power it makes
Q Can a molten salt battery power my house
A Yes but not directly These batteries are usually built on a large scale for entire neighborhoods or solar farms They store heat and later turn it into electricity to power thousands of homes
Advanced Technical Questions
Q Whats the biggest advantage of molten salt batteries over lithiumion
A Cost and lifespan Molten salt uses cheap abundant materials They can last 2030 years without losing much capacity while lithium batteries start to fade after 510 years They also dont catch fire
Q How hot does the salt get in a molten salt battery
