In the extraction of metals from ores, the bound metallic cations may be oxidized before they are subsequently reduced to the final product. Alternatively, other ore constituents may be oxidized, liberating the metal into a soluble form. The free-energy release during ore oxidation is enormous, but in current technologies this energy is lost – either as heat or in the synthesis of microbial biomass. The biomass is the result of iron and sulfur oxidation reactions, which are catalyzed by naturally occurring chemolithoautotrophic bacteria that have evolved to live on and in sulfidic ores1-3. Metabolic engineering has the potential to use these organisms to convert some of this free energy into chemicals or fuels while still enabling production of a leachate, which is subsequently reduced to produce metal.
Project Innovation + Advantages:
The innovation lies in the exploitation of novel natural energy source: reduced metal deposits. The energy released during oxidation of these metals could be used to reduce CO2 into fuels and chemicals reducing petroleum usage.This proposed project fits within the Chemical-Chemical Area of Interest, as it involves the coupling of the oxidation of reduced minerals in the Earth’s crust to the production of reduced carbon chemicals for fuel utilization. This addresses both of Mission Areas of ARPA-E as the co-generation of fuels during copper bioleaching will potentially reduce the import of energy from foreign sources, reduce greenhouse gas emissions, improve energy efficiency in the mining industry, and ensure that the U.S. maintains a lead in the development of this disruptive new technology.