An electricity-generating system of the invention which includes the following: a carbonization apparatus for carbonizing a carbonization source to form a carbonized product; a heat recovery steam generator for producing first steam through heat exchange with the heat exhausted from the carbonization apparatus; a carbonized fuel steam generator which employs the carbonized product serving as a fuel; a mixing header for mixing the first steam and a second steam produced by the carbonized fuel steam generator, which steams are fed thereinto, to thereby discharge a steam mixture having a uniform pressure; an electricity-generating apparatus for generating electricity by means of the steam mixture discharged from the mixing header as an actuating source; and an electricity-storing apparatus for storing the electricity generated by the electricity-generating apparatus.