"CO2 battery". Italians offer energy storage systems based on the liquefaction of carbon dioxide. Cheaper than hydrogen, lithium, ...

The Italian startup Energy Dome has developed an energy storage device that it calls “CO battery.₂“A battery that uses the phase transformation of carbon dioxide into liquid and gas. The warehouse is used for long-term energy storage, is very efficient and extremely cheap, costing less than $ 100 per MWh.

Phase change of carbon dioxide instead of lithium, hydrogen, air, gravity

Energy Dome claims that it does not require special solutions, publicly available elements are enough. The current estimated cost of storing 1 MWh of energy is less than $100 (equivalent to PLN 380), but the startup estimates it will drop to $50-60/MWh in the next few years. For comparison: with lithium-ion batteries it is 132-245 dollars / MWh, with liquefied air - about 100 dollars / MWh for a warehouse capable of receiving a power of 100 MW (source).

It is expected that the warehouse efficiency using phase transitions of carbon dioxide will be 75-80 percent.therefore outperforms any other long-term energy storage technology on the market. This applies not only to hydrogen, but also to air, gravity storage or compressed or condensed air storage.

In the Energy Dome, carbon dioxide is subjected to a pressure of 70 bar (7 MPa), which turns it into a liquid heated to 300 degrees Celsius. The thermal energy of this phase transformation is stored in “bricks” of quartzite and steel shot, while liquid CO₂ enters tanks made of steel and carbon fiber. Each cubic meter of gas will store 66,7 kWh..

When energy recovery (“discharge”) is required, the liquid heats up and expands, converting carbon dioxide into a gas. Expansion energy drives a turbine, resulting in energy generation. The carbon dioxide itself passes under a special flexible dome, which will store it until the next use.

Energy Dome intends to build a prototype energy storage unit with a capacity of 4 MWh and a capacity of 2,5 MW in 2022. The next will be a large commercial product with a capacity of 200 MWh and a capacity of up to 25 MW. According to the founder of the startup, carbon dioxide is better than air because it can be turned into liquid at 30 degrees Celsius. With air, it is necessary to drop to -150 degrees Celsius, which increases the energy consumption during the process.

Of course, such a "CO2 battery" is not suitable for use in automobiles. – but it can be used to store excess energy produced from renewable sources, solar farms or wind turbines.

Worth reading: New carbon dioxide battery will make wind and solar dispatching "at an unprecedented low cost"

Introductory photo: visualization, wind farm and Energy Dome with a characteristic visible (c) Energy Dome

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