EarthEn’s CO2 Battery Stores Renewable Energy for Four to 100 Hours, Enabling a Cleaner Grid

As renewable energy sources have matured and become more affordable, a challenge remains in dramatically increasing the amount of clean power on the electric grid: long-duration energy storage. 

Certain key renewables—including solar and wind power—are intermittent, meaning that it’s critical to store power from these sources to ensure reliable electricity, even on cloudy or windless days. 

EarthEn is solving this challenge with an efficient, cost-effective CO2 battery that can store energy for four to 100 hours of discharge, both enabling a cleaner grid and utilizing carbon captured from the atmosphere. 

With a background in chemical engineering and oil and gas research, EarthEn’s CEO and Co-founder Manas Pathak recognized a pressing need for innovation in this area: “It was obvious to me that the clean energy transition is happening, and the only nut uncracked in the transition from fossil fuels to solar and wind is energy storage,” he says.

The startup’s main solution, EarthEn Pods, is a thermo-mechanical energy-storage system—meaning that it leverages temperature and pressure differential in CO2 to charge and discharge its system. The system uses supercritical CO2 (sCO2), which is carbon dioxide in a state that has high density, especially at high pressures, allowing for compact storage and efficient utilization of space. Furthermore, sCO2’s low viscosity, high heat capacity, and non-toxic nature allow EarthEn to create a compact, small-footprint system. EarthEn’s technology utilizes 27 metric tons of CO2 per megawatt hour.

Pathak explains that EarthEn Pods can store energy for four to 100 hours, meaning they provide customers who may want to start with shorter-duration storage a “future-proof” system, should they decide to increase their storage down the line. They also have a lifespan of 30 years—significantly longer than that of lithium-ion batteries—and aren’t prone to battery fires or explosions.

EarthEn’s second product, EarthEn Edge, utilizes artificial intelligence to tell the startup’s customers the best times to charge and discharge the CO2 battery to save on costs.

EarthEn’s target customers include utilities, solar and wind developers, micro-grid operators, EV-charger owners, and commercial and industrial entities. Eventually, EarthEn could evolve its offerings beyond energy storage, including innovations in nuclear power due to its sCO2 power-cycle innovations, Pathak says—emphasizing the startup’s mission to provide universal access to clean and reliable electricity.

EarthEn received support from the Department of Energy in 2023, has concluded a successful lab demonstration, and is now working on pilot projects with two customers, alongside cost-reduction R&D. The company will begin raising its first funding round this February, Pathak says—interested investors can reach out here.

The startup became a member of Greentown Houston in 2023, which Pathak says has been beneficial for the EarthEn team.

“Greentown Labs is the center of the bubbling cleantech ecosystem in Houston,” Pathak says. “[Its programming] allows us to network with our peers, investors, and partners in the energy ecosystem, which expedites everything we do.”