Unprecedented Achievements: How Fourth Power Secured its $19M Series A Funding

Congrats, we did it! Solar and wind are now the cheapest sources of electricity in the U.S. Now we just have to sit back and let the market do the work, right?

Not so fast. It’s true that wind and solar are the cheapest when they’re providing electrons. But the wind doesn’t blow everywhere all the time, and the sun sets every day, so renewable project developers have to find ways to store that power.

The big winner has been lithium-ion batteries, which dominate the market, mostly because they’re manufactured at massive scale, driving the cost down. They’re modular and quick to respond to demand, making them a flexible addition to the grid.

But for all their strengths, lithium-ion batteries aren’t great at storing large amounts of power at low cost. In the last few years, researchers have raced to develop novel ways to beat them at the grid-scale game.

Asegun Henry has been working on one alternative for longer than that, though when he first started, he wasn’t trying to compete with lithium-ion batteries. He was trying to find a way to gather the sun’s energy and transport it in the form of heat at higher temperatures and efficiency than before.

“At that time, we were thinking about solar fuels,” the MIT professor told TechCrunch+, referring to the process of making liquid fuels from carbon dioxide and sunlight. “Then it kind of pivoted to liquid metal-based, concentrated solar power.” Liquid metal would allow a concentrated solar power plant to capture even more of the sun’s energy.

Concentrated solar power received a burst of attention in the early 2010s when a slew of them were built around the world. But after a few years, the cost of photovoltaic (PV) solar panels dropped dramatically. Concentrated solar rapidly fell from favor.

“PV really was winning,” Henry said. So instead of trying to beat them, he figured out a way to join them.