Solar and wind energy aren’t spreading slowly because big oil is plotting against them, no matter what conspiracy theorists say. A far more mundane factor is at play — batteries.

Power is needed even when the sun isn’t shining and winds die down. Like on most typical nights. How does one store renewable energy, like oil companies do with tanks of oil?

Investors are backing a variety of technologies that address this problem. While lithium-ion batteries, the current dominant technology used to store energy created by renewables, is effective on a small scale they are prohibitively expensive for larger-scale projects. For instance, building enough lithium-powered storage to bring California to 100% renewable power would cost a staggering $2.5 trillion.

Researchers are seeking other substances that can store power more cheaply and for longer periods.

“There are substantial challenges.” Nathanael Greene, a senior renewable energy policy analyst at the Natural Resources Defense Council, told Karma. “We need to find ways to not only store electricity from noon until 6 p.m. tonight, but also from say, Monday till Friday, and eventually store power in July for use in December.”

One company that may have the answer is Form Energy Inc. The MIT spinoff founded in 2017 is developing a sulfur-based battery that can store renewable energy for long periods at a fraction of today’s cost. Its technology aims to guarantee cheap power delivery for weeks and months. 

Form Energy raised $40 million in a Series B financing round led by Eni Next LLC, the venture capital vehicle of Italian oil giant Eni S.p.A. Other backers include Bill Gates-backed Breakthrough Energy Ventures, venture capital firm Prelude Ventures, Macquarie Capital and MIT offshoot The Engine. Saudi Aramco, one of the world’s largest companies, joined the $9 million Series A round, but not Series B. The funds will be used to develop engineering prototypes and a megawatt-scale commercial pilot of the energy storage system.

“The arrival of cost-effective long-duration storage is not nearly as far off as many would believe,” Mateo Jaramillo, CEO, and co-founder of Form Energy, said in a statement. “We are laser-focused on quickly developing the product to meet an urgent market need and enable a future that is 100% renewable, affordable and reliable.”

Other Projects

Breakthrough Energy Ventures, where Gates is joined by the likes of Michael Bloomberg, Jack Ma and Hasso Plattner, backs companies that can promote growth without adding to global warming. It is supporting several other energy-storage startups. Quidnet Energy uses pumped hydro electricity to provide cost-effective, grid-scale power storage. Malta Inc has developed an electro-thermal energy storage system that collects and stores energy for long durations. 

Shell GameChanger, the energy giant’s incubator program, is backing Antora and e-Zin, two companies developing energy storage technology. Antora will use a low-cost thermal battery for grid-scale energy storage then converts it back to electricity with a thermophotovoltaic heat engine. Another option is offered by e-Zn, which stores electricity in zinc material. The metal can be flexibly and inexpensively contained for large scale storage of energy.

Renewable energy storage investments from venture capital and private equity have doubled so far this year to $95.2 million worldwide, compared to the same period last year, according to Pitchbook. Still, investments have declined in the wider energy storage industry: in the U.S., so far this year, investments have slipped to $371.2 million from $539.1 million over the same period in 2018, Pitchbook data show.

New energy-storage technology will be needed if California, Washington, Oregon, Hawaii, New Mexico, Idaho and Nevada are going to meet their mandates to become 100% carbon-free by 2045. States with the most renewable energy still depend on natural-gas peaker plants when demand increases during periods when skies are still or the sun is down. Peaker plants are so-called because they serve peak-demand areas. 

Lithium-ion batteries, even with their limitations, may continue to dominate the energy storage sphere. More will soon be pouring from new factories in China, the U.S. and elsewhere. This should further drive down prices, which have already plunged 85% since 2010, according to Bloomberg. Further developments will be needed to bolster the batteries’ lifespan and deal with their environmental impact.

“I’m excited about energy storage,” Greene said. “There’s a lot of innovation happening, and I’m sure we will have the technology when we need it.”