The high turnover of carbon dioxide during bacterial oxidation of sulfides witnessed in cultures of Acidithiobacillus ferrooxidans, Leptospirillum ferroxidans, and even more efficient by Sulfolobus and other thermophile bacteria (e.g., Acidianus brierleyi), and the parallel rapid buildup of bacterial biomass suggests a coupling of these processes to solar energy in order to develop carbon dioxide cycling technologies for sustainable future applications. Synergistic effects can be expected with biometallurgical research and technology which also aims to further increase energy turnover reflected in higher leaching rates. The prospective technology has been investigated by growing bacteria on iron sulfide synthesized from iron sulfate using solar energy. A catalytic process was developed which allows sulfate to sulfide reduction at a carbon electrode at 120 °C. Photovoltaic energy is used to drive the electrochemical reaction and thermal heat for maintaining the operation temperature. H 2S is immediately converted in Fe 2+-containing solution to iron sulfide which is supplied to bacterial cultures for biological CO 2 fixation. It is estimated that solar-powered biohydrometallurgical processes for CO 2 fixation may reach efficiencies exceeding biological photosynthesis by one order of magnitude. In addition, they can be operated in infertile environments with very limited water. The bacterial biomass has a high quality and could be used for energy, materials, and even for food production. The perspectives and challenges for coupling biohydrometallurgical processes to regenerative energy utilization are discussed.