Energy Dome’s technology enables storage of large quantities of renewable energy efficiently and cost effectively.

In June 2022 Energy Dome completed a 1.5-megawatt/4-megawatt-hour unit in Sardinia, the first commercial plant with this technology. They are also building a full-scale 20 MW/200MW plant expected to be operational in 2025 and another for major Italian utility A2A and a 1.5MW/4MWh facility in the US.

Energy Dome previously raised an $11 million Series A late 2021 from Novum, Barclays and Third Derivative, a climatetech accelerator launched by think tank RMI and New Energy Nexus.

Their proprietary technology uses CO2 to fight climate change. By means of a closed thermodynamic process, they use CO2 to store electricity cost effectively with round trip efficiencies and without emissions to the atmosphere.

Enabling high storage density at ambient temperature: CO2 is a great fluid to store energy cost effectively in a closed thermodynamic process as it is one of the few gases that can be condensed and stored as a liquid under pressure at ambient temperature. This allows for high density energy storage without the need to go at extreme cryogenic temperatures.

Their proprietary technology is based on a closed thermodynamic transformation that, by manipulating CO2 between its gaseous and liquid phase, enables efficient and cost-effective energy storage.

In charging mode, the CO2 is drawn from an atmospheric gasholder, the Dome, compressed and then stored under pressure at ambient temperature in a high density supercritical or liquid state. When energy needs to be released, the CO2 is evaporated and expanded into a turbine, and then returned back to the atmospheric gasholder, ready for the next charging cycle.

By storing in the liquid phase at ambient temperature, they significantly reduce the typical storage costs associated with CAES (Compressed Air Energy Storage) without having to deal with cryogenic temperatures associated with LAES (Liquid Air Energy Storage).

• CAES (Compressed Air Energy Storage) technology is a way of storing energy by compressing air and storing it under pressure. Air is not the perfect fluid to store energy because its energy density under pressure is very low. This means that to store energy cost effectively the only way is to use underground caverns which make this system site dependent and limits its competitiveness.

• LAES (Liquid Air Energy Storage) solves this issue by liquifying air and hence reaching very high energy densities. However, the high energy density of liquid air has the drawbacks associated with cryogenic temperatures, which makes the system complex and uncompetitive. By using CO2 instead of air, Energy Dome has the same benefits of LAES and CAES (high energy density and storing energy at ambient temperature respectively) but without their associated drawbacks relating to efficiency, cost and site dependency.

Energy Dome has developed standardized equipment «bricks» that can be combined together to build the CO2 Battery for different customer needs and applications.

Their proprietary technology uses CO2 to fight climate change. By means of a closed thermodynamic process, they use CO2 to store electricity cost effectively with round trip efficiencies and without emissions to the atmosphere.

CO2 is the perfect fluid to store energy cost effectively in a closed thermodynamic process as it is one of the few gases that can be condensed and stored as a liquid under pressure at ambient temperature. This allows for high density energy storage without the need to go at extreme cryogenic temperatures.

In charging mode, the CO2 is drawn from an atmospheric gasholder, the Dome, compressed and then stored under pressure at ambient temperature in a high density supercritical or liquid state. When energy needs to be released, the CO2 is evaporated and expanded into a turbine, and then returned back to the atmospheric gasholder, ready for the next charging cycle.

By storing in the liquid phase at ambient temperature, we significantly reduce the typical storage costs associated with CAES (Compressed Air Energy Storage) without having to deal with cryogenic temperatures associated with LAES (Liquid Air Energy Storage).

CO2 Batteries The CO2 Battery is a long duration and large scale energy storage system based on a thermodynamic process that efficiently stores energy by manipulating CO2 under different state conditions in a closed thermodynamic transformation. The CO2 Battery can operate in charging mode (absorbing power from the grid) and discharging mode (returning power to the grid).

When operating in charging mode the CO2 is withdrawn from an atmospheric gasholder, the Dome, and compressed into an inter-refrigerated compressor. The heat generated from the compression is stored into two Thermal Energy Storage Systems (TES).

The CO2 is then condensed and stored under pressure at ambient temperature in the CO2 liquid vessels. When the system is operating in discharging mode, the liquid CO2 is evaporated and heated by recovering heat from the TES. The CO2 stream then expands into a reheated turbine returning power to the grid and it is stored into the Dome at ambient temperature and pressure without any leakage to the atmosphere.

Energy Dome has developed standardized equipment «bricks» that can be combined together to build the CO2 Battery for different customer needs and applications. Charging power (Compression), discharging power (Expansion) and storage capacity can be configured independently within a range of standardized solutions in order to optimize the business plan of any specific project.

The system can also be adapted to provide Fast Response services with a special configuration of the compressor and expander. In this case the plant uses two separated electrical machines, a dedicated motor drives the compressor and the expander moves a dedicate generator. Both compressor and expander will spin synchronous to the grid whilst the compressor discharge feeds the compressed CO2 into the expander. In case there is a need for instant fast response power augmentation, the compresor’s switch breaker is opened after a signal from the grid and immediately net power augmentation to grid is measured. Vice versa, in case instant power absorption is required, the turbine can be tripped after signal and consequently instant power absorption from the grid can be measured.

CO2 ETCC: The Energy Transition Combined Cycle is a revolutionary way of combining power production and long duration, large scale energy storage. Combined cycles can now reach gas to power efficiency and at the same time operate with enhanced flexibility, being able to switch from absorbing and storing energy from the grid to full power production in a matter of seconds.

The CO2 ETCC is based on a closed thermodynamic transformation that uses CO2 as a working fluid to produce power and store energy in combination with a gas turbine. The process is based on similar principles to the CO2 Battery but with the main difference being that external heat from the exhaust of the gas turbine is added to the process by means of a boiler.

The CO2 ETCC can operate in four main working modes: Charging, Boost, Super Boost and Fast Response.

• In charging mode energy can be absorbed from the grid and stored for later use in the form of liquid CO2. This working condition is ideal for storing power during times when energy produced from the grid is available at low cost.
• In boost mode, the system works as a combined cycle, the Gas turbine is producing power and the exhaust heat from the gas turbine is recovered by means of a CO2 Brayton cycle which produces net power as a difference between the power produced by the CO2 Turbine and the CO2 compressor.
• In super boost mode, the compressor is shut off and pressurized CO2 is withdrawn from the storage vessels to be expanded into the CO2 turbine after being heated up in the boiler. In this configuration the gas turbine and the CO2 turbine produce power simultaneously exporting power to the grid with a combined cycle efficiency above 80%.
• The total power produced in super boost mode is more than double the installed capacity of the gas turbine. This configuration is great to benefit from high energy rates during daily peaks. Finally the system can be also adapted to work in fast response mode in order to start up the gas turbine in a matter of seconds without the need to operate the gas turbine in idle mode consuming gas just to keep it warm and ready to ramp-up.