Renewable energy sources might be able to reduce energy costs, but storing energy remains a serious challenge.
Better batteries could solve the energy mismatch with solar panels, for example. They produce energy in the day but slow down at night when demands are the highest.
Most batteries currently rely on chemical reactions. While modern batteries keep our smartphones, computers and other devices running, they come with limitations. Chemical batteries can lose their charge rather quickly, even when they're not being actively used. They can also catch fire or even explode. Moreover, chemical batteries are expensive to produce, use relatively rare materials, and gradually lose capacity.
Molten sand batteries may be able to store energy for months at a time with minimal loss. They can use common and easy-to-find sands, don't require dangerous chemicals, and don't generate dangerous emissions. They can also be reused for several years.
How do molten sand batteries work? Quite simply, sand is heated to very high temperatures (in excess of 1,000 degrees Fahrenheit), thus storing thermal energy.
Still, while molten sand batteries offer promise, they're far from a panacea. Crucially, the sand batteries take electricity and convert it into heat. If you happen to need to heat your home or otherwise use heat in another process, sand batteries are very efficient. However, if you want to convert that heat back into electricity, you'll need to produce steam to run turbines, which results in a lot of energy loss.
Regardless, the first commercial molten sand batteries have been rolled out in Finland and elsewhere. Researchers are also exploring various other battery technologies, such as aluminum-sulfur batteries. For now, lithium-ion batteries will likely remain the mainstay, but future battery technologies could make renewable energy sources easier to use.