Storage of renewable energy in fuels and chemicals through electrochemical reforming of bio-alcohols

Hydrogen production using primary renewable energy sources, such as wind, solar, tidal, etc. is an ideal way to deal with intermittent supply and demand. Electrolytic water splitting is limited by the thermodynamic barrier of water oxidation. Useful levels of hydrogen production can only be obtained with an electrical energy consumption exceeding 45 kWh kg-1 H2. Electrochemical reforming overcomes such thermodynamic limitations by replacing oxygen evolution with the facile oxidation of an alternative substrate. Energy savings of 50% can be obtained using alcohols such as ethanol, ethylene glycol and glycerol. Electrochemical reforming can be used to exploit the partial oxidation of various alcohols to valuable intermediates of industrial interest. In this way, the production of hydrogen is combined with the bio-refinery concept for the combined production of fine chemicals. This short review describes the current status and provides a summary of the steps required to bring the technology to useful application.