System Studies of Fuel Cell Power Plants

Abstract: This thesis concerns system studies of power plants wheredifferent types of fuel cells accomplish most of the energyconversion.Ever since William Grove observed the fuel cell effect inthe late 1830s fuel cells have been the subject or more or lessintense research and development. Especially in the USA theseactivities intensified during the second part of the 1950s,resulting in the development of the fuel cells used in theApollo-program. Swedish fuel cell activities started in themid-1960s, when ASEA (now ABB) ran a fuel cell projectdeveloping fuel cells to power submarines.When the then project manager, Olle Lindström, wasappointed professor of Chemical Technology at KTH, the fuelcell activities at KTH were initiated, these activities havesince then been pursued at varying levels of intensity.The fuel cell development experienced a recession during thelatter part of the 1970s and early 1980s, only to bere-vitalised during the 1990s as the full potential of theadvantages of environmental benefits and efficiency wereidentified.System studies and process simulation utilising differentcomputer software programs may be used to study the behaviourand characteristics of fuel cells and their supportsystems.Paper I describes the characteristics of a naturalgas-fuelled fuel cell power plant using alkaline fuel cells,both regarding efficiency and economics.In paper II, a benchmark study of three different types ofsimulation software is presented. Theintention was to clarifyhow the selection of software might influence the resultsobtained, and some of the associated possible pitfalls.Paper III presents a study of a fuel cell power plant wherethe primary source of energy is biomass (wood chips), which viahigh-pressure gasification and subsequent gas cleaning is madeavailable for conversion into electricity and heat by moltencarbonate fuel cells.The last paper, paper IV, presents a s system study of ahigh-temperature fuel cell system, where the primary fuel iscoal, which through gasification is converted into a gaseousform. This study was a vital part of an EU-project studying thetechnical and economical feasibility of such systems.Keywords: fuel cells, fuel cell systems, system studies,process simulation, system analysis, alkaline fuel cells,high-temperature fuel cells.