A novel variation on compressed air energy storage that should directly help replace a coal power plant by:

converting carbon dioxide gas into a compressed liquid form and then converting that liquid back into a gas, powering a turbine to generate electricity, according to the Department of Energy. The gas will be stored in what officials call an “energy dome.”

From a linked article discussing the proof of concept installation:

The company says its technology has an energy storage density 10-20 times higher than other compressed air energy storage (CAES) solutions and two-thirds that of liquid air energy storage (LAES). However, Energy Dome points out that its solution does not require the cryogenic temperatures of LAES which can increase system complexity and competitiveness, it claims.

The DoE adds:

Through the use of compressed CO2, the system aims to improve efficiency compared to similar systems, as it produces less heat during the compression cycle and can be stored as a liquid. Energy Dome’s modular system also offers flexibility that can support a more resilient power grid.

Compressed air energy storage currently tops out with round trip efficiencies of 67-71% in complex setups.

https://www.sciencedirect.com/science/article/pii/S2666202723002045# Search: “Compared to other adiabatic systems”

https://en.wikipedia.org/wiki/Compressed-air_energy_storage#

This seems kind of inefficient, but I love all these large-scale energy storage attempts. And these people are a hell of a lot smarter than I am.

Spent breakfast researching this:

• the plant would store 200 MWh
• given the 10-hour figure, one would assume it can feed up to 20 MW to the grid at any time
• they have already built a 4 MWh pilot plant in Italy
• the utility has also been building lithium-ion battery farms, so it stands to reason they see enough potential in this approach to continue pursuing it
• compressed CO2 storage has advantages over compressed air in that it can be stored indefinitely at ambient temperature and has a higher energy density in liquid form
• it has disadvantages in terms of plant safety

I would have expected Ohio to have pioneered anything involving energy domes, not Wisconsin