SEARCH Articles Figures Tables Application Areas and Relation to Polymer Electrolyte Fuel Cells Fuel, Oxidant, and Electrolytes Heat Balance in Fuel and Electrolytic Cells High-Temperature Applications of Solid Electrolytes Fuel Cells, Pumping, and Conversion Polymer Electrolyte and Direct Methanol Fuel Cells Proton Conducting Electrolytes and Their Application in Fuel Cells Total Efficiency of Fuel and Electrolytic Cells