A group of researchers from the University of Denmark has developed a new idea to convert thermal power plants into renewable energy sources using Carnot batteries.What is a Carnot battery?
Carnot batteries are batteries that can store and use electricity as heat energy using methods such as water, molten salt or rock. They can also work with methods such as liquid liquid, thermal cycling or adsorption techniques. Therefore, it can help balance the grid by storing excess energy from solar and wind energy.
Researchers say thermal power plants are the perfect place to place Carnot batteries because of the steam turbines, boilers and heat exchangers found in the plants. They also state that using conventional generators with Carnot batteries instead of inverters can balance the grid.
The researchers focused on a specific type of Carnot battery that uses a large tank of rocks as the storage medium and air as the heat carrier. They applied the concept they developed to an old 300-megawatt coal power plant in Chile that produces 160 bar pressure and 565-degree steam.
They designed a rock-bed storage system with a capacity of 1.37 GWh and a temperature of 730 degrees. They placed the heaters, valves, and pipes at the top of the tank for easy loading and maintenance. They also minimized heat and pressure losses in the system.
The system is designed to provide energy at night while charging with solar panels during the day. Electric heater to rock bed tank; They connected the steam generator to the turbine and condenser of the coal power plant.
How is the performance of the system?
Analyzing the system performance, the team observed that 443 GWh of net energy was produced per year for 4 hours of storage, 797 GWh for 8 hours, and 1150 GWh for 12 hours. They also found that the system became cheaper and more efficient as capacity increased. The researchers noted that the system is competitive with conventional power plants and other alternatives that use molten salt for storage.
Stating that the system can be further optimized, the researchers stated that the method they developed could help transform coal power plants and reduce carbon emissions.
Assuming natural gas prices remain low, the researchers noted that Carnot batteries would be a competitive solution if the levelized cost of storage (LCOS) was lower than 66 euro/MWh.
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