Thermodynamic engineers at The National Centre for aerospace, energy and transportation research (DLR) in Colonge, Germany have suggested replacing coal power plants with giant ‘carnot batteries’ to store energy from renewable generators.
The carnot batteries are an alternative form of energy storage to conventional metal-acid batteries, which are expensive to build and maintain on large scales.
Carnot batteries work by storing energy as heat. Excess electricity from renewables generated at peak times is used to heat salt to 500°C, at which point it becomes molten. The liquid salt retains heat energy well and when production from renewables falls, due to lack of sunlight or wind, the molten salt can be used to heat water and drive steam turbines to generate electricity.
The DLR claims that retrofitting former coal plants with giant carnot batteries could “be the key technology for storing large quantities of energy in a carbon-neutral energy system of the future”.
DLR executive board chair Pascale Ehrenfreund said the technology could help progress the energy transition.
“The Energy Transition is one of the most pressing challenges faced by society. With the development of storage as part of its energy research, DLR is working on solutions to one of the key issues in this field,” she said. “Efficient storage can ensure a reliable energy supply with an ever-increasing share of renewable energies. Furthermore, large heat storage units can also help to reduce carbon dioxide emissions from coal-fired power plants worldwide by converting them into power plants with heat storage.”
Engineers at the DLR, along with the University of Stuttgart and the Karlsruhe Institute of Technology have been developing carnot battery technology since 2014 and are set to conclude an 18-month project into the technology this summer.
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