MIT News April 13. 2022
Thermophotovoltaics (TPVs) can enable approaches to energy storage and conversion that use higher temperature heat sources than the turbines. However, despite predictions that TPV efficiencies can exceed 50% the demonstrated efficiencies are still only as high as 32%. A team of researchers in the US (MIT, National Renewable Energy Laboratory) has fabricated TPV cells with efficiencies of more than 40% and experimentally demonstrated the efficiency of high-bandgap tandem TPV cells. The TPV cells comprising III–V materials with bandgaps between 1.0 and 1.4 eV are optimized for emitter temperatures of 1,900–2,400 °C. The cells exploit the concept of band-edge spectral filtering to obtain high efficiency, using highly reflective back surface reflectors to reject unusable sub-bandgap radiation back to the emitter. A 1.4/1.2 eV device reached a maximum efficiency of (41.1 ± 1)% operating at a power density of 2.39 W cm–2 and an emitter temperature of 2,400 °C. A 1.2/1.0 eV device reached a maximum efficiency of (39.3 ± 1)% operating at a power density of 1.8 W cm–2 and an emitter temperature of 2,127 °C. These cells can be integrated into a TPV system for thermal energy grid storage to enable dispatchable renewable energy. The work creates a pathway for thermal energy grid storage to reach sufficiently high efficiency and sufficiently low cost to enable decarbonization of the electricity grid…read more. Open Access TECHNICAL ARTICLE
Tandem TPVs. Credit: Nature volume 604, pages287–291 (2022)Â