The advent of fuel cells for the generation of electricity for portable, small and large-scale stationary and automotive purposes portends radical changes in electricity supply over coming decades. The five main types of fuel cell technology are reviewed (alkaline fuel cell (AFC), solid polymer fuel cell (SPFC), phosphoric acid fuel cell (PAFC), molten-carbonate fuel cell (MCFC), and solid-oxide fuel cell (SOFC)) along with their characteristics and electrochemical reactions plus those of a more recent nonhydrogen based regenerative fuel cell for large-scale power delivery.