The efficiency of a fuel cell is dependent on the amount of power drawn from it. Drawing more power means drawing more current, which increases the losses in the fuel cell. Most losses manifest themselves as a voltage drop in the cell, so the efficiency of a cell is almost proportional to its voltage. This book presents current research in the study of fuel cell efficiency, including modelling of a fuel cell DC/DC converter system; biopolar plates and PEM fuel cell efficiency; optimal design of fuel cell systems; increasing the system efficiency and reducing CO2 emissions by installing a molten carbonate fuel cell in a power plant and electrochemical techniques in an actual polymer electrolyte fuel cell stack.