Malta has raised a $50 million Series B round to bring its super-long-duration energy storage to market, the company said Wednesday.

The startup spun out of Google parent company Alphabet's moonshot factory, X, in 2018. Many startups tackling energy storage breakthroughs have looked to batteries and other electrochemical devices. Malta turned instead to thermal energy: It uses grid power to compress air for storage in hot molten salts and cold antifreeze liquid. A heat engine later converts the energy back to electricity for consumption. This apparatus, in theory, allows for storing power economically on much longer timescales than is feasible with the lithium-ion batteries prevalent today.

The funding news came after an extreme winter storm blacked out the Texas grid for days on end, highlighting the value of power sources that can ride through multiday shortages of natural gas or renewable generation.

Swiss energy firm Proman led the Series B, joined by previous investors Alfa Laval and Bill Gates-backed Breakthrough Energy Ventures, which led Malta's $26 million Series A round in 2018. Dustin Moskovitz, co-founder of Facebook and Asana, also participated.

"The commercialization process is moving along nicely," VP of Commercialization Ty Jagerson said in a Tuesday interview. "Anyone looking at 4 hours [of energy storage] is starting to look 8 to 10. The market is transitioning rapidly."

Malta has already submitted bids for storage solicitations, he added, and plans to have its first commercial project online in 2024 or 2025. That timeline is driven in part by the scale of the enterprise. Malta's core plant design would charge at a rate of 185 megawatts and will be able to discharge at 100 megawatts for up to 10 hours. This industrial facility would be designed to operate for 30 years.

The gap between power in and power out reflects heat losses in the conversion process, but over the last few years, the company identified a commercial use for that inefficiency: industrial heat. Decarbonization of industry will drive numerous uses for carbon-free, 100-degree-Celsius heat on demand. It's no accident that investor Alfa Laval is a leading supplier of heat exchange technology.

Repurposing proven tech for long-duration storage

In the first cleantech investment bubble a decade ago, venture capitalists (including Gates) bet on startups that proposed novel hardware and spent serious cash building factories for their exotic devices. Those bets largely failed.

These days, a more fashionable tack is to assemble proven technologies with mature supply chains and put them to new use.

“Malta’s innovative application of well-established technologies and materials could accelerate the rollout of long-duration storage to support the transition to fully dispatchable renewable energy,” Moskovitz, a founding member of Breakthrough Energy Ventures, said in a prepared statement.  

Another challenge is convincing customers that a young technology company can stand behind its technology, or even get it installed. That's where strategic partners like Alfa Laval and Proman come in. The latter firm handles development and project management. If Proman becomes convinced of Malta's effectiveness, it could lend credibility to the novel technology.

Breakthrough Energy Ventures has placed other bets on rival long-duration energy storage technologies, such as Form Energy. That Cambridge-based startup similarly tackles storage for days on end but does so with a stealthy "aqueous air" electrochemical design. 

These companies anticipate a market that does not yet exist. Utilities are still getting comfortable with lithium-ion batteries capable of storing 4 hours' worth of electricity, enough to store solar production for use in the evening, for instance. Long-duration storage entrepreneurs anticipate a future state when rapid uptake of wind and solar creates surpluses that could be cheaply stored and called upon when the sun and wind stop producing. 

Commercial deployments are coming into view. Form Energy closed a deal with Minnesota utility Great River Energy to install a 1-megawatt/150-megawatt-hour pilot project in 2023. Highview Power, which stores electricity via liquefied air, is constructing a commercial-scale plant near Manchester, U.K. That company closed a $70 million growth capital round earlier this year.

Malta, like Form, has begun working with utilities to model how its long-duration storage might perform in their systems since the technology does not exist in legacy grid-planning systems. Jagerson said the emerging long-duration storage ecosystem stands to benefit from having multiple capable contenders emerge.

"Utilities want to see that there's a viable sector out there," Jagerson said. "We hope that there's a robust cadre of other long-duration storage companies like us that survive and thrive."

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