Economic potential for thermophotovoltaic electric power generation in the steel industry

A steel mill extrudes steel billets at temperatures above 1400 °C continuously 24 hours a day. The steel billets then go to cooling beds where they slowly cool down to below 1100 °C. JX Crystals Inc makes Gallium Antimonide (GaSb) thermophotovoltaic (TPV) cells that can generate over 1 W/cm
²
when exposed to infrared radiant energy from glowing steel at temperatures above 1100 °C. There is a great opportunity to integrate GaSb TPV receivers into steel mill operations to generate electricity economically utilizing this now wasted radiant energy. In a recent visit to a steel mill in China producing 10 million Metric-Tons (MT) of steel a year, the operators o, the mill told us that they have 2000 m
²
of glowing steel in process continuously. At 1 W per cm
²
, this equates to the potential to produce 20 MW o, electricity for that steel mill. In 2012, the world steel production was 1,548 million MT. So, the world wide potential for TPV electricity production could be 3.1 GW. At what cost will TPV be affordable? This application has two advantages over solar PV. The first is the high power density, a factor of 100 over solar PV modules, translating to a potential cost advantage. The second distinct advantage over solar PV is the 24 hours of operation since the sun is only available on average for 8 hours per day. One can estimate the potential value of a TPV plant ,rom the potential annual revenues. Assuming electricity at 8 cents per kWh, 1 kW of TPV electric power capacity will produce 8765x0.08 = $700 dollars per year. This implies a 3 year payback at $2.1 per W. Cost is a function of volume but should come down to below $1.5 per W at volumes above 1 MW.