A majority of the world’s power is generated by thermal sources such as coal, natural gas, nuclear energy, and concentrated solar energy. For almost a century, steam turbines have been the industry’s norm for turning such heating elements into power. Engineers have created a heat engine that is as effective as a steam generator but has no moving components. On average, steam turbines reliably convert around 35% of a heat supply into electricity, with approximately 60% marking the best efficiency of any heat engine to date. However, the equipment is dependent on temperature-sensitive moving components. In recent times, scientists have investigated solid-state alternatives, which are turbines with no moving components that may be able to function efficiently at higher temperatures. Engineers from MIT and the National Renewable Energy Laboratory (NREL) have created a heat engine with no moving components. This heat engine, a thermophotovoltaic (TPV) cell, transforms heat into electricity with a conversion efficiency of more than 40%.
Henry and his teammates aimed to collect higher-energy photons from a higher-temperature heat source in their novel TPV design, transforming energy more effectively. In comparison to prior TPV designs, the team’s novel cell uses advanced semiconductors and many connections, or material sheets. The effectiveness of the cell was evaluated by putting it over a heat flux sensor, which directly monitors the heat received by cell. They subjected the unit to a high-temperature bulb, focusing the light on it. They next altered the brightness, or heat, of the bulb and examined how the cell’s conversion efficiency fluctuated with temperature. The new TPV cell sustained performance of roughly 40% throughout a temperature range of 1,900 to 2,400 degrees Celsius. Henry explains that “we can achieve great efficiency across a wide temperature range, which is crucial for thermal batteries.”
In the tests, the cells were around a square centimeter in size. Henry envisages TPV cells scaling up to 10,000 square feet for a grid-scale thermal battery system. He points out that there is an infrastructure to support the production of large-scale solar modules, which could be converted to produce TPVs. “In terms of sustainable development, there’s obviously a significant net benefit here,” Henry adds. “The technique is secure and ecologically friendly throughout its life cycle, and it has the potential to significantly reduce carbon dioxide emissions from energy production.”