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A new solar furnace system using a stationary elliptic dish and heliostats is proposed. Since the elliptic dish has two focuses (an upper focus and a lower focus) for elliptic geometry, this system has three advantages. The first is enable to fix a solar reactor on the ground, the second to expand the heliostat field largely, and the third to concentrate the direct solar radiation in a small area around the lower focus. The horizontal deviation from the lower focus of the direct solar radiation was estimated within ±1.2m for the heliostat field of 100m and the tower-reflector height of 70m. The system using the elliptic dish and heliostats is available as high-concentration system due to large scale of solar energy.

Multi-step water splitting with Mn-ferrite(MnFe2O4)/sodium carbonate(Na2CO3) system accompanying endothermic reaction was investigated for converting solar energy into chemical energy. This water splitting is caused by the oxidation-reduction of manganese ion in the Mn-ferrite. Multi-water splitting with MnFe2O4/Na2CO3 system was consisted of three steps. The first step was hydrogen generation at 1073K. The second step was oxygen release at 1273K. The third step was Na2CO3 reproduction at 873K. The mechanism of multi-water splitting has been considered by XRD, chemical analysis of colorimetry and back titration. The temperature range 873 to 1273K is quite lower than those studied on the solar furnace reaction (O2 releasing step) in two-step water splitting (1500-2300K). This lower temperature range would permit further progress in converting the direct solar energy into chemical energy.