While the shortfalls of the U.S. electricity transmission grid are nothing new — from its aging infrastructure to its inefficiency to its lack of storage for variable energy sources like wind and solar -- exciting new technologies on the horizon are definitely something to talk about.
One of these is the Liquid Metal Battery project, headed by Dr. Donald Sadoway’s team at the Massachusetts Institute of Technology. Dr. Sadoway and his team have set out to advance the U.S. grid toward the modern era by creating a revolutionary energy storage device. Thanks to initial funding from ARPA-E in partnership with French energy corporation Total, as well as further investments in spin-out company Liquid Metal Battery Corporation by Total and Bill Gates, this technology helps prepare the grid for the storage and use of renewable energy. Even better — the Liquid Metal Battery also addresses many of the engineering and cost challenges that have prevented the development of an effective energy storage device to date.
True to its name, the Liquid Metal Battery is comprised of liquid metal electrodes of differing densities, which allows the liquids to separate and stratify without the need for any solid separator. With its all-liquid design, this battery is much more efficient than today's rechargeable batteries, which use 80-90% of the space to hold packaging and dead weight needed to separate the active materials of the batteries. Instead, the all-liquid battery uses more of the available space to hold the actual charge. Moreover, the all-liquid format allows for a scalable design to meet the needs of different communities where it will be deployed.
The benefits don’t end there. The research is focused on using low cost, earth abundant materials, which means the battery will achieve the low price point required for bulk energy storage applications.
So how does the battery work? In the initial design, each battery contains two different liquid metal electrodes and a molten salt electrolyte. Since metals and salts do not mix, these three liquids of different densities naturally separate into layers, eliminating the need for a solid separator. The liquid metal-salt reaction interfaces allow the system to operate at extreme current density, paving the way for a high energy capacity system. Dr. Sadoway’s team is also investigating a number of chemical components to determine their potential for improving efficiency and thus lower the battery’s cost to build and operate.
Although the Liquid Metal Battery certainly does not promise to solve all of the problems associated with the U.S. grid, success by Dr. Sadoway and his team will greatly speed America’s ability to upgrade its grid for the accommodation of renewable energy in a way that is both affordable and scalable, with targets for the cost of storage in the range of $100 per kilowatt-hour of capacity compared with $450/kWh of capacity for today’s rechargeable batteries.