Zero-Emission Geothermal Power Generation: Experimental Study on Carbonate Mineralization through CO2-Andesitic Pyroclastic Rock Interaction at Oku-Aizu Geothermal Plant

Abstract

In order to achieve advancement in zero-emission geothermal power generation for fixing the CO 2 in the geothermal fluids to the carbonate minerals after binary power generation and reinjection of the fluid into the reservoir, batch-type experiments and geochemical simulations of CO 2-andesitic pyroclastic rock interaction (tuff from Oku-Aizu geothermal area) were performed at 150 °C with and without CO 2 gas for 15 days. Despite the low Ca content (0.9% wt.%) in the rock, the Ca 2+ concentrations in the solutions that were reacted with CO 2 were observed to initially increase rapidly and then decreased after two days. In contrast, the Ca 2+ concentrations in the solutions reacted with Ar gas remained almost constant. The solutions reacted with CO 2 gas became oversaturated with respect to the carbonate minerals according to saturation degree with respect to calcite. These findings along with the other previously available data demonstrated that Ca 2+ in calcite and glass in the rocks