\(H_2\)-mediated electrosynthesis uses solar electricity to drive water splitting and proton reduction to \(H_2\), which is then consumed by a \(H_2\) oxidizing microbe to power carbon fixation and the synthesis of energy storage molecules like butanol, isobutanol, and \(C_3\) and \(C_5\) alcohols (Figure 1B).
Micro-organisms that use hydrogenase to oxidize \(H_2\) including S. ovata and Ralstonia eutropha reduce NAD into NADH with \(H_2\), so NADH is the primary reducing agent in these organisms (REF- Petersen 2011, Beinart 2014, BUZ 2015). These organisms have been commonly found around hydrothermal vents and at atmospheric pressure, and have existed for long periods of time prior to availability of \(O_2\) (REF- Li H, 2013- Adesina 2016, Appel 2013,Lemon 1999).