A representation of Malta’s grid-scale energy storage technology (Source: X)
Excerpt:
Alphabet Inc.’s secretive X skunk works has another idea that could save the world. This one, code named Malta, involves vats of salt and antifreeze.
The research lab, which hatched Google’s driverless car almost a decade ago, is developing a system for storing renewable energy that would otherwise be wasted. It can be located almost anywhere, has the potential to last longer than lithium-ion batteries and compete on price with new hydroelectric plants and other existing clean energy storage methods, according to X executives and researchers.
The previously undisclosed initiative is part of a handful of energy projects at X, which has a mixed record with audacious “moonshots” like Google Glass and drone delivery. Venture capitalists, and increasingly governments, have cut funding and support for technology and businesses built around alternatives to fossil fuels. X’s clean-energy projects have yet to become hits like its driverless cars, but the lab isn’t giving up.
Malta is not yet an official X project, but it has been “de-risked” enough that the team is now looking for partners to build, operate and connect a commercial-sized prototype to the grid, Felten said. That means Alphabet may team up or compete with industrial powerhouses like Siemens AG, ABB Ltd. and General Electric Co.
X is stepping into a market that could see about $40 billion in investment by 2024, according Bloomberg New Energy Finance. Roughly 790 megawatts of energy were stored last year and overall capacity is expected to hit 45 gigawatts in seven years, BNEF estimates. Existing electrical grids struggle with renewable energy, a vexing problem that’s driving demand for new storage methods. Solar panels and wind farms churn out energy around midday and at night when demand lulls. This forces utilities to discard it in favor of more predictable oil and coal plants and more controllable natural gas “peaker” plants.
How does it work? (See the representation above.)
Two tanks are filled with salt, and two are filled with antifreeze or a hydrocarbon liquid. The system takes in energy in the form of electricity and turns it into separate streams of hot and cold air. The hot air heats up the salt, while the cold air cools the antifreeze, a bit like a refrigerator. The jet engine part: Flip a switch and the process reverses. Hot and cold air rush toward each other, creating powerful gusts that spin a turbine and spit out electricity when the grid needs it. Salt maintains its temperature well, so the system can store energy for many hours, and even days, depending on how much you insulate the tanks.
Here’s a diagram from X, maybe explaining it better:
