The disclosure provides a process that converts CO2 to higher alcohols (e.g. isobutanol) using electricity as the energy source. This process stores electricity (e.g. from solar energy, nuclear energy, and the like) in liquid fuels that can be used as high octane number gasoline substitutes. Instead of deriving reducing power from photosynthesis, this process derives reducing power from electrically generated mediators, either H2 or formate. H2 can be derived from electrolysis of water. Formate can be generated by electrochemical reduction of CO2. After delivering the reducing power in the cell, formate becomes CO2 and recycles back. Therefore, the biological CO2 fixation process can occur in the dark.