Electrochemical Energy Storage with a Supercritical CO2 Cycle
There are two primary methods for capturing and using sunlight today: direct conversion of sunlight to electricity using photovoltaic (PV) solar panels, or focusing sunlight onto a fluid that is used to drive a steam turbine in concentrated solar power (CSP) systems. Storing hot fluid in CSP systems is a less expensive way to generate electricity when the sun is not shining compared to storing electrical energy from PV in batteries. However, PV uses just part of the solar spectrum at high efficiency, while CSP systems use the entire solar spectrum but at low efficiency. Combining the best elements of these two technologies could provide a means to get the most out of the full solar spectrum, generating both electricity and storable heat (for later use) within the same system. Developing hybrid solar energy systems that perform both functions at the same time could provide electricity at cost comparable to traditional sources, whether the sun is shining or not.
Project Innovation + Advantages:
GE is designing and testing components of a turbine system driven by high-temperature, high-pressure carbon dioxide (CO2) to develop a more durable and efficient energy conversion system. Current solar energy system components break down at high temperatures, shortening the system’s cycle life. GE’s energy storage system stores heat from the sun in molten salt at moderate temperature and uses surplus electricity from the grid to create a phase change heat sink, which helps manage the temperature of the system. Initially, the CO2 remains at a low temperature and low pressure to enable more efficient energy storage. Then, the temperature and pressure of the CO2 is increased and expanded through a turbine to generate dispatchable electricity. The dramatic change in temperature and pressure is enabled by an innovative system design that prevents thermal losses across the turbine and increases its cycle life. This grid-scale energy storage system could be coupled to a hybrid solar converter to deliver solar electricity on demand.
If successful, GE’s gas turbine could enable efficient generation of dispatchable electricity from solar energy over a 25-year cycle life.
Developing new hybrid solar systems that generate both electricity and dispatchable heat at the same time could provide domestically-sourced power at costs comparable to traditional sources, whether or not the sun is shining.
Replacing energy systems powered by fossil fuels would provide an immediate decrease in greenhouse gas emissions, 40% of which come from electricity generation today.
Cost-effective, dispatchable solar energy alternatives would stabilize electricity rates for consumers as the penetration of renewable energy increases in the coming years.