Energy Dome, a long-term energy storage technology startup based in Italy, said recently that the company has completed its series B financing, and its energy storage technology is a long-term energy storage system based on carbon dioxide.

Energy Dome has announced the completion of a €40 million ($44.15 million) financing round. The round was led by Eni Next, the venture capital arm of Italian oil company Eni, with participation from the venture capital arm of Italian private bank Intesa Sanpaolo. The company has a mix of existing and new investors, including Barclays Sustainable Impact Investments, the Japanese Energy Fund and Us-Based Elemental Xcelerator.

Energy Dome has developed a "CO2 Battery" energy storage system that works by first compressing carbon dioxide gas while storing the heat generated by the adiabatic compression process, and then liquefying the carbon dioxide. When the stored energy is released, the liquefied carbon dioxide is affected by the stored heat and then expands into a gas that drives a turbine to generate electricity in a closed-loop process.

The company has already operated a megawatt-scale commercial demonstration project and claims that the round-trip efficiency of the charging and discharging of the technology is around 75 percent. While this is less efficient than the round-trip efficiency of lithium-ion battery storage systems, which are typically higher than 95 percent, Energy Dome claims it's a cheaper way to store energy and last longer.

In a recent interview with industry media, Ben Potter, vice president of strategy, corporate development and investor relations at Energy Dome, said that the investment cost of this technology is half that of lithium-ion battery storage systems, and 10 hours is the optimal duration for CO2 batteries.

Potter noted that Claudio Spadaccini, founder and CEO of the company, came up with the idea to develop this energy storage technology and developed it by combining the skills and experience of engineers and entrepreneurs in different industries.

One result of this is that the Energy storage technology can be assembled using off-the-shelf components that Energy Dome obtains from existing original equipment manufacturers, without the need to procure complete sets or highly customized components.

"It means the supply chain is so scalable that we don't have to build a production plant to get to market, we just order from the customer and then from the supplier in succession," Potter said.

Potter says the cost of such energy storage systems still has a lot of room to fall. Currently, the company is selling its first CO2 battery energy storage system with a scale of 20MW/200MWh at a price of 220 euros /kWh. However, if 30 to 50 of the same energy storage systems are produced, their capital expenditure will drop by 44%.

Potter said the latest round of investment in Energy Dome brings its total investment to 54 million euros since the company was founded in 2020. In January, the company also received a €17.5 million ($18.5 million) grant and equity financing from the European Innovation Council, which was established by the European Commission.

Its Series B funding will be used to further commercialize the technology and help Energy Dome expand into key markets, with the company identifying the United States as a focus.

The Americas, Europe and Asia markets are said to have 9GWh market opportunities for CO2 battery energy storage systems, while the company will build and deploy the first two 20MW/200MWh CO2 battery energy storage systems and become operational by the end of 2024.

While the company does see a huge potential market opportunity and, like other Long term storage (LDES) suppliers, sees the global push towards decarbonisation as an inevitable driver, there are still some challenges to overcome.

These challenges do not lie in the technical domain, but in the market, policy and regulation, as few energy markets around the world have assessed the capacity value of such long-term storage systems.