Life Cycle Impact Assessment of a HT-PEM Fuel Cell Powered by Natural Gas Reforming

Abstract

This study uses life cycle assessment (LCA) to investigate the environmental impacts, including the cumulative energy demand (CED) and energy payback time (EPBT) of a 20 kWel HT-PEM power plant in Brazil. The power plant investigated is a pilot that uses High Temperature Proton Exchange Membrane (HT-PEM) fuel cell technology and natural gas (NG) reforming to produce energy for the commercial and residential sectors. The scope of the LCA study covered the production and distribution of natural gas in the state of São Paulo, including the phases of construction, installation and maintenance of NG reforming and HT-PEM systems, as well as the production of hydrogen and electricity over 40,000 hours of operation. The results indicated that the global warming potential (GWP) is the highest environmental impact of the system. The GWP resulted from the natural gas input into the system (77%). In the hydrogen production phase, 34% of emissions derived from fossil fuels were burnt in the heating process, while 44% originated from the consumption of NG in the reforming process itself. On the other side, both the reuse of hydrogen that has not been consumed in FC as fuel in the heating process and the recovery of waste heat generated in the system can lead to a reduction of up to 20% of the emissions generated in the use phase. In terms of cumulative energy demand, it points towards a reduction of up to 25% of the CED. Under these conditions the EPBT of the system is 10.96 years.