Design, performance, and field operation of twisting heliostats for highest concentration and temperature

Concentrated sunlight has the potential for manufacturing syngas and cement, and also for direct air capture of CO2. Small scale demonstrations have been made, mostly in Europe and Japan, of concentrating sunlight to reach the required reaction temperatures, as high as 1,500℃. However, for commercial viability, these high temperatures must be reachable in summer and winter, through the day, not just for high DNI and small angles of incidence. To address these requirements, Angel’s team has developed a new kind of heliostat to achieve the maximum possible concentration set by thermodynamics. It does this by having the reflector shape twist automatically to eliminate the astigmatic aberration that prevents fixed-shape heliostats from imaging the solar disc. We show different configurations of heliostat field and secondary reflector that allow high reaction temperatures to be maintained, even at 500 DNI and solar elevation of 26 degrees.