Thermophotovoltaic Conversion. From Principles to Applications

Thermophotovoltaic conversion enables electricity to be generated from thermal energy radiated by a hot body heated to very high temperatures, typically in excess of 1,000°C. It is part of an effort to make the most of industrial waste heat deposits and to offer low-carbon electricity production solutions, based on renewable energy sources but without the constraint of intermittency, which is possible thanks to the storage of energy in thermal form at very high temperatures. The fundamental principles governing thermophotovoltaic conversion are similar to those of solar photovoltaic conversion. However, it is necessary to optimize radiative exchanges between the hot body and the photovoltaic cell. This requires spectral selectivity, and means that efficiency and electrical output cannot be maximized simultaneously. The science and engineering of radiative transfer, photovoltaic conversion and heat management must therefore be brought to bear on the judicious design of converter components. Pair efficiencies in excess of 40% have been achieved under laboratory conditions. Academic research and entrepreneurs are focusing on the development of thermophotovoltaic batteries and advanced concepts to overcome certain obstacles.