A hybrid solid-oxide fuel cell -- rankine cycle to supply shipboard electrical power

To reduce the harmful effects of airborne pollutants, regulations limiting allowable airborne emissions from ships are becoming increasingly more stringent. In some sea ports, regulations are being enacted that restrict or, in some cases, prohibit the operation of diesel-driven generators on visiting ships. The use of a fuel cell to produce the electrical power required by a ship while in port represents a potential alternative to the operation of diesel-driven generators or the use of shore power. In addition, the fuel cell could also be used while the ship is underway to reduce the load on the vessel's diesel-driven generators.;This dissertation includes a history of maritime fuel-cell usage and a review of regulations limiting shipboard airborne emissions. In addition, the results of a feasibility study conducted to evaluate the use of fuel cells as a source of shipboard electrical power are presented. Included as part of this study is the description and analysis of a novel integrated hybrid system in which the waste heat from a solid-oxide fuel cell (SOFC) is used to generate steam in a heat recovery steam generator (HRSG) that also receives heat from the ship's propulsion-diesel-engine exhaust during periods when the vessel is underway. The steam produced would then be supplied to a steam-turbine-driven generator. This system was analyzed based on the production of steam at either a single pressure or at two pressures. Furthermore, variations with and without the addition of a gas-turbine-driven generator were evaluated.;As part of this work, a parametric study was performed using computational fluid dynamics (CFD) to optimize the configuration and determine the performance characteristics of the SOFC used in the hybrid cycle. CFD was also used to develop a method to extrapolate the results of the analysis of a single fuel cell in order to predict the performance of a stack containing multiple fuel cells.;The results show that an SOFC -- hybrid cycle has the potential to be a source of shipboard electrical power that produces fewer harmful emissions and operates with a higher efficiency than the diesel-driven generators often used on ships today.;The opinions expressed herein are those of the author and do not necessarily reflect those of the United States Department of Transportation, the Maritime Administration, or the U.S. Government.