Life cycle assessment of an alkaline fuel cell CHP system

A life cycle assessment (LCA) of an alkaline fuel cell based domestic combined heat and power (CHP) system is presented. Literature on non-noble, monopolar cell design and stack construction was reviewed, and used to produce a life cycle inventory for the construction of a 1 kW stack. Inventories for the ancillary components of other commercial fuel cell products were consulted, and combined with information on the fuel processing requirements of alkaline cells to suggest a hypothetical balance of plant that would be required to produce AC electricity and domestic grade heat from natural gas and air.The emissions from manufacturing and disposing of this fuel cell CHP system were estimated to be equivalent to 510–1000 kg of CO2 and 1.0–2.0 kg of particulate matter. As with platinum based polymer electrolyte fuel cells (PEMFC), emissions of sulphur dioxide were the most significant impact, resulting in degraded human health in the regions where catalyst metals are mined. Improving the operating lifetime and reducing catalyst loadings were identified as the most effective routes to reducing this environmental impact, as they are with other fuel cell technologies.These impacts were compared to the results of existing LCAs for other fuel cell technologies. It was found that an alkaline fuel cell stack produces less environmental impact than an equivalent solid oxide or phosphoric acid (SOFC or PAFC) stack, while no conclusive comparison with PEMFC could be made. The inclusion of energy consumption during stack manufacture and data on the more exotic material inputs were highlighted as a problem in these studies.