Potential global warming impact of 1 kW polymer electrolyte membrane fuel cell system for residential buildings on operation phase
Rakhyun Kim, Cheonghoon Baek, Eun Young Kim, Youngsun Jeong, Suhyun Cho
Abstract
This study established global warming potential(GWP) emission factors through a life cycle assessment on the operation phases of two different 1 kW polymer electrolyte membrane fuel cell (PEMFC) systems for residential buildings (NG-PEMFC, fed with hydrogen from natural gas reforming; WE-PEMFC, fed with hydrogen from photovoltaics-powered water electrolyzer). Their effectiveness was also compared with conventional power grid systems in Korea, specifically in the area of greenhouse gas emissions. The operation phases of the NG-PEMFC and the WE-PEMFC were divided into burner, reformer, and stack, and into water electrolysis and stack, respectively. The functional unit of each fuel cell system was defined as 1 kWh of electricity production. In the case of NG-PEMFC, the GWP was 3.72E-01 kg-CO2eq/kWh, the embodied carbon emissions due to using city gas during the life cycle process was about 20.87 %, the carbon emission ratio according to the reformer's combustion burner was 6.07 %, and the direct carbon emission ratio of the air emissions from the reformer was 73.06 %, indicating that the carbon emission from the reformer contributed over 80 % of the total GWP. As for the WE-PEMFC, the GWP was 1.76E-01 kg-CO2eq/kWh, and the embodied carbon emissions from photovoltaic power generation during the life cycle process contributed over 99 % of the total GWP.