Comparison of a Multi-Megawatt High Temperature Fuel Cell System With Reciprocating Engines and Aero-Derivative Gas Turbines

Abstract

High temperature fuel cells can be successfully integrated in a simple cycle or in a combined cycle configuration and achieve lower heating value (LHV) efficiencies greater than gas turbines and reciprocating engines. A simple cycle fuel cell system reaches 50 to 51% LHV efficiencies. A fuel cell system integrated with gas and steam turbines in a hybrid system could lead to LHV efficiencies of 70% to 72%. An aero-derivative gas turbine that is the most efficient simple cycle gas turbine achieves 40% to 46% thermal efficiency and a new generation reciprocating engine 39% to 42%. Upon integration in a combined cycle configuration with steam injection, aero-derivative gas turbines potentially reach LHV efficiencies of 55% to 58%. The purpose of the present paper is to compare initially the performance of a stand alone fuel cell with a stand alone gas turbine and a stand alone reciprocating engine. Then the fuel cell is integrated in a hybrid system and it is compared with a gas turbine combined cycle plant. The system sizes explored are 5MW in the stand alone case, and 20MW, 30MW, 60MW, 100MW and 200MW in the hybrid / combined cycle case. The performance of the hybrid system was reviewed under different ambient temperatures (0° F–90° F) and site elevations (0 ft–3000 ft). High temperature fuel cells are more efficient and have lower emissions than gas turbines and reciprocating engines. However fuel cells cannot be used for peak power generation due to long start-up time or load following applications.