Researchers have discovered a new thermophotovoltaic element (TPV) that converts heat into electricity with an efficiency of more than 40%, which is almost in line with the characteristics of traditional steam turbine power plants.
Such cells can potentially be used in “thermal batteries” that work in networks that reliably generate energy without moving parts. Until now, TPV cells reached an efficiency of only 32% because they operated at lower temperatures.
The project from the Massachusetts Institute of Technology and the National Renewable Energy Laboratory (NREL) uses energy from hot heat sources in the range from 1900°C to 2400°C. Measuring efficiency with a heat flow sensor, the team found that power depends on temperature. That’s how they’ve reached an efficiency of 40%.
Steam turbines can provide the same efficiency, but they are much more complex and work only at lower temperatures.
“One of the advantages of solid-state energy converters are that they can operate at higher temperatures with lower maintenance costs because they have no moving parts,” MIT Professor Asegun Henry told MIT News.
“They just sit there and reliably generate electricity.” In the long run, in a grid thermal battery, the system will absorb excess energy from renewable sources such as the sun and store it in the well-insulated hot graphite jars. If necessary, TPV elements will be able to convert this heat into electricity and send it to the power system.
“Thermophotovoltaic cells were the last key step toward demonstrating that thermal batteries are a viable concept,” Asegun Henry said. “This is an absolutely critical step on the path to proliferate renewable energy and get to a fully decarbonized grid.”