We report a novel electro-reduction process that can convert CO2 to high-valued fuels with low electrolysis energy. In a designed electrolysis cell, a chemical regenerative catalyst, phosphomolybdic acid (PMo12), was used as an electron-coupled proton carrier, and glycerol, a by-product of biodiesel synthesis, was employed as a reducing agent to provide electrons to PMo12 under photo irradiation. Glycerol was firstly oxidized to value-added products of glyceric acid and acetic acid under the catalysis under PMo12, after an electrical potential was applied, the reduced PMo12 (H-PMo12(red)) releases electrons and was re-oxidized to PMo12 on the anode, while CO2 was reduced into valuable hydrocarbons by taking electrons on the cathode. The developed approach has multiple advantages over the conventional CO2 electrolysis, e.g. low electrolysis potential, and a noble metalfree anode due to the low overpotential of H-PMo12(red) oxidation on the anode. The electrolysis current densities of 0.23 and 0.29 Acm(-2) were achieved under 2.0 V of electrolysis voltage for the Cu and Ag cathode, respectively, which is 2-3 times of conventional electrolysis. The faradaic efficiency for CO2 reduction is 63.53% and 77.75% at 1.9 V, and the energy efficiency is 45.60% and 53.67% for the Cu and Ag electrode, respectively.