The Malta project is being developed under Alphabet's X division, the same research lab responsible for Google's driverless car and Glass optical head-mounted display. The new project is aimed at "time shifting" renewable energy to make it available on demand - when needed- by capturing and storing it during times when more energy is being produced than the grid needs, and which would otherwise be wasted.
Malta is based on the idea of storing electricity as both heat, in massive tanks of molten salt, and as cold, in a low-temperature antifreeze-like liquid - an idea originally proposed by Nobel prize-winning Stanford physics professor Robert Laughlin . It works by initially taking in energy (as electricity) and turning it into streams of hot and cold air - the former is used to heat up the salt, while the latter cools the antifreeze.
When energy is needed from the system, the process is reversed and the resulting turbulence from the recombined hot and cold air is used to power a turbine that produces the required electricity. The energy stored in salt, say the researchers, could remain kept there for days or even weeks until it's needed.
The system is claimed to offer several benefits compared to other mass storage solutions. It uses inexpensive components (including steel tanks, air, and the cooling liquid, as well as the salt itself); it can be situated in a variety of locations; it is longer lasting than other current storage solutions like lithium batteries and can be easily expanded with the addition of more tanks of salt and liquid.
The Malta team is looking next to test commercial viability and interested in finding industry partners. They say the next step is to build a megawatt-scale prototype plant - one large enough to prove the technology at commercial scale.