PROBLEM TO BE SOLVED: To provide a method and system for solid polymer power generation, which, without requiring the maintaining of high temperatures or the introduction of energy from the outside, can convert carbon dioxide into beneficial hydrocarbon compounds while generating energy, can control the amount generated and ratio by type of hydrocarbon compounds and the like, increase the use efficiency of a generated product, and can simplify even equipment for separation and recovery.SOLUTION: Carbon dioxide is supplied to the cathode 111 side of a power generation part 110 having a membrane electrode assembly 113, and hydrogen is supplied to the anode 112 side thereof. The power generation voltage of the power generation part 110 is controlled to alter the amount and ratio by type of hydrocarbon compounds generated per unit time.
