Battery Startup Eschews Costly Metals for Thermodynamic Storage

Carbon dioxide is the greenhouse gas most responsible for our rapidly warming planet. But it also has useful properties that help to store electricity from renewable energy sources when it’s converted from gas to liquid.

Italian startup Energy Dome is harnessing those attributes through a system that can store power generated from wind and solar when it’s plentiful and dispatch electricity as demand rises. If successful, the energy storage company’s technology could play a crucial role in the rapidly expanding market for long-duration, utility-scale storage systems — a sector comprised of more than 40 startups that collectively raised more than $1 billion last year, according to clean energy research group BloombergNEF.

Energy Dome’s battery charges by drawing CO₂ gas from a sealed dome through a compressor and condensing it into a liquid, which is then stored under pressure at ambient temperature in vessels. Heat generated during the compression process is captured and stored. To discharge, the system evaporates the liquid CO₂ with the recovered heat, then pushes the gas through a turbine to generate power and back into the dome. There are no emissions from the closed-loop system.

We recently spoke with Energy Dome founder Claudio Spadacini about how his battery system works and global storage opportunities. The interview has been edited for length and clarity.

Can you describe the basics of how your CO2 battery works? This is a new process that has never been done before, although it’s based on the principle of storing energy with pressure and heat, which is used in biogas plants. To charge the battery, we take CO₂ at near atmospheric temperature and pressure and we compress it. The heat that is generated during compression is stored. When we exchange the thermal energy with the atmosphere, the CO₂ gas becomes liquid.

To generate and dispatch electricity, the liquid CO₂ is heated up and converted back into a gas that powers a turbine, which generates power. The CO₂ gas is always contained and the entire system is sealed.

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We don’t use any exotic materials. The technology uses steel, CO₂ and water. So there is no dependency on rare earth materials like cobalt, or lithium. This makes our technology geopolitically independent. It can be produced everywhere and it can be used everywhere. This is a very important.

What are the optimal conditions for the Energy Dome battery to operate as it should?Our sweet spot is the long duration market, in which power is typically stored or dispatched over a period of between four and 24 hours. This market is potentially very big and aims to store solar energy captured during daylight hours to use after sunset.Being able to switch to green energy from the period when it is mostly produced to the period when demand is high, that is the big market we are chasing and this is what grids need for deeper penetration of solar and wind.What is the status of your first demonstration project?We are commissioning our first commercial demonstration facility right now in Ottana, Sardinia. This is an island that has a lot of renewable sources, including solar and wind and a very weak connection to the continent. It’s phasing out two coal-fired power plants so there is very high demand for green energy. Hopefully we’ll be fully tested in a few weeks and we’ll demonstrate that the technology works. As soon as [the battery] is successfully tested, the technology will ready be for commercial deployment.Have companies or governments expressed interest in your technology?We have had a lot of requests to come and see our plant. There is big demand for long-duration energy storage technologies because lithium is simply too expensive and has too short a lifespan. We have had interest from large companies and utilities in Europe, the Middle East and North America.