Malta Inc — the molten-salt energy-storage company spun off from Google at the end of 2018 — currently lags behind its competitors in the growing world of Baldies (build-anywhere long-duration intermittent energy storage).
But with a group of investors that reads like a Who’s Who of the world’s most famous billionaires — including Jeff Bezos, Bill Gates, Mark Zuckerberg, Richard Branson, Jack Ma and Michael Bloomberg — it has more than a fair chance of being able to change the world.
“The hope is to create low-cost, long-duration energy storage as a means of effecting, stabilising and injecting resiliency and reliability into grids all over the world… [something] that would really be the underpinning of the ability to transform electricity markets, and thereby enable an energy transition,” Malta chief executive Ramya Swaminathan tells Recharge. “And that's really a global market. It's a global problem.”
Huge amounts of low-cost long-duration energy storage will be needed if the world's electricity system is to run mainly on intermittent renewable energy — to provide stored carbon-free power when the wind isn't blowing and the sun isn’t shining.
One of Malta’s key investors, Breakthrough Energy Ventures — which is largely funded by philanthropic billionaires — was literally set up to change the world for the better (see below). And the $1bn fund seems to believe that Malta — which was initially a secret project at the Google X R&D organisation (now known simply as "X") — will solve the problem of intermittency and enable 24-hour wind and solar energy, thus eliminating the need for fossil-fuel power plants.
Yet at least three competitors are further ahead in terms of development — Highview Power, Siemens Gamesa and Stiesdal A/S (see pages xx-xx).
“We’re actually still in the design phase,” Swaminathan tells Recharge. “We are in the process of selecting a site to do a 10MW pilot demonstration project.
“We’re hoping to start construction [on the pilot] in the next one to two years; finish construction within 18-24 months thereafter and we do expect to be moving to commercialisation right after that.”
So Malta is not expecting its molten-salt thermal-storage technology to become commercially available for another two-and-a-half to four years.
And unlike its competitors, Swaminathan was not able to give any indication of the expected levelised cost of storage (or energy) for a future project.
“We’re certainly designing our development process to make the cost of the Malta system competitive,” says Swaminathan. “And so what I can say is that, you know, our targets involve being at or below where we see the competitors in the future.
“Our goal is to… make Malta a dominant solution from not only a flexibility-of-purposing standpoint, but also a cost standpoint.”
How the system works
The Malta system combines a range of well-known technologies in an innovative way.
It takes electricity from the grid to drive a heat pump that creates streams of hot and cold air, which are directed to tanks of molten salt (heated to 565°C) and anti-freeze (cooled to minus 65C). This thermal energy can be stored for days or weeks due to effective insulation.
Then, when required, the above charging process is effectively reversed using a heat engine — basically a compressor and a turbine — which drives a generator to produce electricity.
This discharge process is similar to the way a jet engine works. Jet engines draw in cold air, compress it in a compressor, then the jet fuel is combusted to heat the air, and the hot air is expanded through the turbine, sending it spinning at high speeds. Malta uses the hot molten salt to provide the heat to the air in its process (instead of jet fuel), while the cold anti-freeze liquid cools the air that is normally rejected to the atmosphere by a jet engine.
The round-trip efficiency — ie, the proportion of the inputted energy that is outputted by the system — would be in “about the 60% range”, with improved efficiencies for larger systems, Malta's technical lead, Adrienne Little, tells Recharge. This round-trip efficiency is similar to Highview’s, but higher than Siemens Gamesa’s (45-50%).
Heat losses during storage are negligible. Molten salt — which has been used as a storage medium in concentrating solar plants for years — would only lose about 1°C of its heat per day of storage in Malta's system, Little explains. And a small amount of electricity is required to run a heat-tracing system — heat-generating wires wrapped around pipes to prevent the salt freezing (ie, returning to a solid) in a valve or a corner of a pipe.
“One of the advantages of the Malta system have is that there is not a lot of R&D. We're not really demonstrating any physics or any chemistry,” says Swaminathan. “It's really a matter of putting a system [together] where each of the subcomponents or the subsystems are well known, well understood and known to work.
“So the challenge really lies in system integration, not in the development of any one of the subsystems.”
Little says that Malta has a less complex system than its competitors, and requires less heat — explaining that temperatures above 565°C cause problems for steel and therefore require more expensive materials (Siemens Gamesa’s hot rocks reach 750°C, and Stiesdal’s 600°C). The Malta system also uses fewer heat exchanges and pressurised tanks than Highview’s system, she adds.
“I think there's a lot of competitive technologies out there and it's difficult to say at this point, given the level of development of all these different ideas, which one is going to be the best,” says Little.
How the Malta system can be used
The Malta system can be scaled to pretty much any size, both in terms of power output (measured in MW) and storage capacity (measured in MWh).
“You could go up to the hundreds of megawatts, potentially, with this type of technology,” says Little. But she explains that the company will initially focus on two formats, a smaller system of around 10MW and a larger set-up in the 100MW range.
A 100MW system would be able to sell large amounts of power on wholesale energy markets or provide round-the-clock power from large intermittent renewables projects. A 10MW facility could similarly supply firmed power from smaller wind and solar farms, or provide back-up to island grids, data centres, microgrids or military bases, or reduce the need for expensive network upgrades by reducing congestion at grid bottlenecks.
“There are many different places where it could be used and really it comes down to what the given customer needs,” says Swaminathan.
Placing the system at a wind or solar farm would be sensible “if there's value to the customer in firming their renewable power before it goes on the grid”, she adds.
The company is already speaking to potential customers interested in many of these use-case scenarios, including with corporate purchasers of renewable energy, Swaminathan tells Recharge.
“We've had a number of conversations across a wide range of customer uses and all of that is really important to us from a product-development standpoint,” she adds.
Swaminathan could not say when she thinks Malta Inc might become profitable, meaning it will need financial backing for many years to come. But access to cash would appear to be the least of Malta’s worries.
When it left the womb of Google's X in December and became an independent company, it announced that it had raised $26m in venture capital — from Breakthrough Energy Ventures, Hong-Kong based Concord New Energy Group, and Swedish company Alfa Laval, the world’s leading heat-exchanger manufacturer.
Any technology start-up seeking investment could probably not find a better investor than Breakthrough Energy. The fund’s cash comes largely from billionaires who want to do good with their money — and the likes of Bezos, Gates and Zuckerberg are not to going to run out of money any time soon.
The likes of Bezos, Gates and Zuckerberg are not to going to run out of money any time soon
“The goal of Breakthrough Energy is to make sure that everyone on the planet can enjoy a good standard of living, including basic electricity, healthy food, comfortable buildings, and convenient transportation, without contributing to climate change,” the organisation says on its website, adding that the fund was created to “build the new, cutting-edge companies that will deliver on that promise”.
Google, or Alphabet as the parent company is now known, also retains a sizeable stake in the company.
“We believe very much in our products and our development path, and so do our investors, so we are very fortunate to have that kind of support,” says Swaminathan. “At the same time, I would not take it for granted.”
Technology companies like Malta, which require large amounts of capital for years before an investor would see any returns are “by their nature difficult to raise capital [for], and access to capital is a major issue.
“[It’s] a relatively tough proposition for investors.”
The wealthy investors in Breakthrough Energy Ventures, and therefore Malta, also include billionaire entrepreneur and investor Vinod Khosla, Facebook co-founder Dustin Moskovitz, and Ray Dalio, the founder of the world's largest hedge fund, Bridgewater Associates.
“This was from back in the X days,” says technical lead Adrienne Little. “They always give code names to projects that had absolutely nothing to do with the technologies, so people can't guess. ‘Malta’ is completely random, although sometimes they liked to joke around and say it sounds like ‘molten’ or it's not so far from ‘salta’.