Alphabet’s secretive research lab X is developing a new way to store renewable energy that otherwise might be wasted — by using salt and antifreeze, reports Bloomberg. Researchers are developing a system that can be located anywhere, has the potential to last longer than lithium-ion batteries, and competes on price with new hydroelectric plants and other energy storage methods.
"If the moonshot factory gives up on a big, important problem like climate change, then maybe it will never get solved," Obi Felten, a director at X told Bloomberg. "If we do start solving it, there are trillions and trillions of dollars in market opportunity." The project is codenamed “Malta,” but it isn’t an official X project yet, so it doesn’t currently enjoy the benefits of a full-blown undertaking like Project Loon.
The Malta team is currently working on an early test prototype in Silicon Valley. In renderings cited by Bloomberg, the system features four cylindrical tanks connected via pipes to a heat pump. Two are filled with salt, while the other two are filled with antifreeze or hydrocarbon liquid. The system takes in energy in the form of electricity, creating two streams of air: hot air that heats up the salt, and cold air that cools the antifreeze. A switch is then flipped which reverses the process: the hot and cold air “rush toward each other” which creates gusts powerful enough to spin a turbine to produce electricity when needed. Depending on how the tanks are insulated, the system can store energy for many hours or days. Thermal salt-based storage has the potential to be several times cheaper than lithium-ion batteries and other existing grid-scale storage technologies, Raj Apte, Malta's head engineer, told Bloomberg.
Scientists have previously proven this system as a plausible technique in storing energy. Malta’s contribution has been to lower the operating temperature of the system so that materials like expensive ceramics and steels won’t be needed. A working system can vary in size from a “large garage” to a “full-scale traditional power plant.”
Existing electrical grids struggle with renewable energy, a factor seen when the entire state of South Australia suffered a blackout earlier this year, prompting Elon Musk to pledge to build the world’s largest lithium-ion battery there. This year alone, around 790 megawatts of energy will be stored globally, with overall capacity to hit 45 gigawatts by 2024, according to Bloomberg New Energy Finance, which estimates the lucrative market could see $40 billion in investments by that time.