STEP: Efficient Carbon Capture and Solar Thermal Electrochemical Production of ammonia, fuels, cement, carbon nanotubes, metals and bleach

Abstract: STEP (Solar Thermal Electrochemical Production) is an alternative solar energy conversion process. New and original, unpublished STEP results are compared with other STEP results. The STEP process uses semiconductors, solar energy and electrochemistry to generate a wide range of useful chemicals, rather than electricity, as the product. Using both subgap (to generate heat) and super bandgap (to generate electrons) insolation, STEP is more efficient than either photovoltaic or photoelectochemical solar energy conversion. STEP theory is derived and experimentally verified for the electrosynthesis of energetic molecules at high solar energy efficiency. In STEP the efficient formation of metals, fuels, chlorine, and carbon capture is driven by solar thermal heated electrolyses occuring at voltage below that of the room temperature energy stored in the products. As one example, CO2 is reduced to either fuels, or storable carbon, at solar efficiency over 50% due to a synergy of efficient solar thermal absorption and electrochemical conversion at high temperature and reactant concentration. CO2 is efficiently transformed to carbon nanotubes (C2CNT) with or without solar energy. New results on CO2-free STEP ammonia, iron and cement production are delineated. Water is efficiently split to H2 by molten electrolysis. A pathway is provided for the STEP decrease of atmospheric CO2 levels to pre-industial levels in 10 years.