It was almost exactly one year ago that X, Alphabet’s secretive “moonshot” development division, released the details of its energy storage concept code named Project Malta. Led by Nobel Prize–winning Stanford physics professor Robert Laughlin, the technology is said to offer vast cost and functionality improvements on lithium ion batteries and pumped hydroelectric for grid-scale energy storage. If the concept proves successful it could offer the means to power our energy system with 100% renewable generation.

Less than a year on from the Bloomberg article that first announced the X project, rumours are circulating that Project Malta is ready to be spun off. Reports suggest that discussions may be advanced for a transaction involving Breakthrough Energy Ventures (BEV), the $1 billion investment fund led by Bill Gates and other well known millionaires including Jeff Bezos, Jack Ma, Mukesh Ambani, and Richard Branson.

BEV have declared their mission to support technologies capable of cutting global carbon emissions by at least 500 million metric tons annually. They have assembled a team of experts to assess which methods offered the most promise for tackling greenhouse-gas emissions, and in 2018 they announced the first two startups that will receive investment, as discussed in our article last month. If reports are to be believed, then Project Malta could be next on the list of potentially groundbreaking energy storage concepts to gain the billionaire’s backing.

The proposed system, as stated in Laughlin 2016 paper, is “a thermal heat-pump grid storage technology is described based on closed-cycle brayton engine transfers of heat from a cryogenic storage fluid to molten solar salt.” In other words, power generated from renewable sources can be used to heat vats of molten salt and cool vats of an antifreeze liquid. Stored energy can then be released using the difference in temperature between the substances.

Laughlin makes the case that his storage technology has the right engineering compromises to prevail when the need for storage eventually becomes acute. He claims that his “brayton battery” applies acceptable metrics of safety, while offering an energy storage solution at low cost and high efficiency. He suggests that the round-trip efficiency would be competitive with that of pumped hydroelectric storage, currently the most efficient large-scale storage but limited by geography, cost and localized environmental concerns.

“Instead of pumping water uphill from a low reservoir to a higher one to store energy, as occurs in pumped hydroelectricity, one pumps heat from a cold body to a hot one by means of a heat engine. In either case the process is reversible, so that energy banked can be withdrawn later to satisfy demand,” Laughlin writes in his seminal paper on the technology.

After mapping out the overall system and proving the math, X took on the project and created a small team to take the next step. They designed the individual components and brought them together with the aim of evaluating whether the technology would work in the real world and, crucially, at a competitive price point. After more than 2 years building CAD drawings, running extensive computer simulations, and 3D printing prototype parts, they found it feasible due to the following characteristics:

• Inexpensive components. Although the turbines and heat exchangers need custom engineering, much of the system uses conventional technology – steel tanks, air and cooling liquids are all simple to procure. Salt is easily extracted from the earth and can be used over and over again to store heat without degrading or emitting toxic byproducts.
• Flexible siting. This system isn’t dependent on particular weather or specific locations. It can be close to the renewable energy source, or near where there’s high demand on the electric grid.
• Long-lasting and easy to expand. The salt tanks can be charged and re-charged many thousands of times, for possibly up to 40 years – three or more times longer than other current storage options. To add more storage capability, you just add more tanks of salt and tanks of cold liquid, which keeps system costs low.

“The next step is to build a megawatt-scale prototype plant which would be large enough to prove the technology at commercial scale. We are looking for partners with the expertise to build, operate and connect a prototype to the grid. Also, we are interested in talking to customers of grid-scale energy storage, energy system manufacturers, and energy system construction companies,” X’s project page states.

Which brings us back to the unofficial news of a spin off from Alphabet involving Bill Gates’ BEV. In the abstract of a talk at Stanford scheduled for late May 2018, Laughlin noted that a “key patent” for the molten-salt technology was issued in early April, and added that, “spin-off activity associated with Bill Gates’s Breakthrough Energy Ventures is presently underway.” However, this abstract and the associated page was removed after an inquiry by MIT’s Technology Review.

Another conspicuous link is that Phil Larochelle, now investment principal at BEV, once worked with Laughlin on an earlier thermal storage venture and co-holds several patents relevant to the Project Malta technology. These links are enough to conclude that a discussion is happening, or has happened, between Alphabet’s X and BEV on Project Malta but whether this will turn into a deal is yet to be seen. Nevertheless, such a spin-off and the potential for an accelerated development of this technology is quietly spreading excitement around the clean energy community.