While the price for lithium-ion batteries has dropped significantly in recent years, the technology is still a tad too expensive to be the best solution for the long-term storage of renewable energy, most of which is weather-dependent. As such, innovators are looking beyond lithium-based batteries to find viable energy storage alternatives that could help accelerate our green energy transition.

One of the most interesting emerging energy storage solutions comes from a Bay Area startup called Noon Energy. The company is developing an ultra-low-cost rechargeable battery that would be powered by CO2 that has been split into carbon and oxygen using excess renewable energy.

What differentiates Noon Energy from other battery companies is that instead of using pricier materials such as cobalt and lithium, the startup aims to radically lower long-term storage costs by creating a simpler technology that uses carbon and oxygen.

“To enable a 100 percent solar and wind scenario, several-hour capacity [storage on the electric grid] doesn’t cut it,” says Chris Graves, founder of Noon Energy. “you need quite long storage capacities in the 100-plus hour storage-capacity range, and this will give you the full on-demand electricity that normally would have some fossil fuels. That’s what we’re going for.”

Currently, Noon Energy’s batteries only make economic sense in large-scale applications, but they hold the potential to revolutionize both the electric grid as well as long-distance transportation, such as cargo ships.

“The potential energy density could enable long-range shipping and trucking,” says Amy Duffuor, a principal at Prime Impact Fund, a climate tech fund that recently secured a $3 million investment for the startup. “And for us, in the climate tech space, that is literally one of the hardest knots to crack in the energy transition.”