systems are described for the “ on - site ” production of substantial amounts of carbon dioxide and hydrogen . the systems include a stack of multiple electrochemical cells , which decompose organic carboxylated compounds into co 2 and h 2 without leaving any residue . from a bench - top small generator , producing about 1 lb of co 2 per day to a large - scale generator producing 1 ton of co 2 per day , the process is essentially identical . oxalic acid , either anhydrous or in its dihydrate form , is used to efficiently generate the gases . the energy required is less than 0 . 3 kilowatt - hours per lb of co 2 generated . individual cells operate at less than 1 . 2 volts at current densities in excess of 0 . 75 amps / cm 2 . co 2 production rates can be controlled either through voltage or current regulation . metering is not required since the current sets the gas production rate . these systems can competitively replace conventional compressed co 2 gas cylinders .