Mobile Proton-Exchange Membrane Fuel Cell Powered by Diesel Fuel: System Simulation and Life Cycle Analysis

Abstract

Diesel engine generators used at construction sites generate noise, vibration, and large amounts of pollutant emissions. With the strengthening of emission standards for construction equipment, technologies must be developed to meet new requirements. We proposed and analyzed a mobile proton-exchange membrane fuel cell diesel-powered system to address these issues. The proposed system consisted of an autothermal reformer, a proton-exchange membrane fuel cell, and a balance of plant components. Previous studies on the system have not explored the optimal design and operating condition of the system and have not shown whether the proposed system is superior to the system using the hydrogen-fueled proton-exchange membrane fuel cell system in the life-cycle greenhouse gas emissions point of view. In this study, we clarified system operation characteristics, determined the operational design point, and evaluated system performance and life-cycle greenhouse gas emissions. The system was analyzed by constructing a zero-dimensional simulation model. Several control parameters were varied in parametric studies to determine the operational design point (steam-to-carbon ratio of 2, oxygen-to-carbon ratio of 0.5, fuel utilization factor of 0.85, and heat exchanger effectiveness of 0.85). Considering system performance, the determined design point achieved a 32.3% efficiency. Additionally, we assessed the life-cycle greenhouse gas emissions of the system and compared them with those of an alternative system, which is a hydrogen-fueled proton exchange membrane fuel cell system. It was confirmed that in the United States of America, the proposed system emits 1010.2 g-CO2-eq/kWh of greenhouse gas at a 300 km fuel transportation distance, which is similar to a hydrogen-fueled proton-exchange membrane fuel cell system (1001.1 g-CO2-eq/kWh). The proposed system emits less greenhouse gas emissions than the hydrogen-fueled proton-exchange membrane fuel cell system if the distance from the hydrogen production site to the construction site is more than 318 km. Therefore, for a construction site far from a hydrogen production plant, the proposed diesel-fueled proton-exchange membrane fuel cell system is preferable from both the greenhouse gas emissions and convenience perspectives.