Italian Company Wants To Use CO2 To Store Renewable Power
In the quest to find a better way to store power for the grid, an Italian startup is turning to an unlikely source: Carbon dioxide.
Photo Insert: The demonstration facility where Energy Dome recently started trials has a capacity of 4 megawatt-hours, enough to power the average US home for about four and a half months.
The company, called Energy Dome, has built a test facility to put the greenhouse gas to work in energy storage, Casey Crownhart recently reported for the MIT Technology Review.
Energy Dome thinks carbon dioxide could have a role to play in energy generation and storage. The company says its demonstration plant in Sardinia, Italy, where it has designed and begun trials, will soon be able to safely and cheaply store energy using carbon dioxide sourced from commercial vendors.
Compressing gases to store energy isn’t new: For decades, a few facilities around the world have been pumping air into huge underground caverns under pressure and then using it to generate electricity in a natural gas power plant. But Energy Dome turned to carbon dioxide because of its physics.
Carbon dioxide, when squeezed to high enough pressures, turns into a liquid, which air doesn’t do unless cooled down to ultra-low temperatures. The liquid carbon dioxide can fit into smaller steel tanks close to where renewable energy is generated and used.
In Energy Dome’s designs, a flexible membrane holds the carbon dioxide in a huge dome at low pressure. When excess electricity is available, the gas goes through a compressor to reach high pressure.
This process also generates heat, which is stored too. Then, when energy is needed, the stored heat is used to warm up the carbon dioxide, which decompresses and turns a turbine, generating electricity.
Energy Dome’s CEO, Claudio Spadacini, says its first full-scale plants should cost just under $200 per kilowatt-hour (kWh), compared with about $300 per kWh for a lithium-ion energy storage system today.
Spadacini says that the costs could drop further, to about $100 per kWh, if the company is able to scale up to a few dozen large facilities.
The concept of compressed carbon dioxide storage is “really promising,” says Edward Barbour, an energy systems researcher at Loughborough University in the UK. However, he expects the company to face some significant engineering challenges, like keeping the heat exchangers working for the decades-long lifetime of the plant.
The demonstration facility where Energy Dome recently started trials has a capacity of 4 megawatt-hours, enough to power the average US home for about four and a half months.