A Life Cycle Assessment of the PC-25 Stationary Fuel Cell System: Providing a Guide for Environmental Improvement
The PC-25 is a stationary power system manufactured by UTC Power. It uses a 200 kW phosphoric acid fuel cell with a lifetime of 85,000 hrs and it has an internal natural gas steam reforming system. The PC-25 can operate in both grid-connected and grid-independent mode and it also provides the option of heat recovery. In case the PC-25 functions as a combined heat and power (CHP) system an efficiency of 80% is reached. Since 1991, more than 275 PC-25 power systems have been installed at various locations around the world.
UTC Power is currently redesigning the system and would value having a life cycle assessment (LCA) highlight opportunities for improvement when regarding its environmental performance. LCA can clarify which stages in the product life cycle and which elements of the product cause the most environmental pressure. Product development and improvement is therefore one of its direct applications.
The LCA results show that the PC-25 use phase, as compared to the manufacturing and end-of-life phase, has by far the biggest environmental impact. The input of natural gas in the steam reforming process and the emissions caused by this process are the main contributors to the use phase impact. Maximizing the hydrogen output of the steam reforming process and increasing the efficiency of the electrochemical reaction in the fuel cell stack are therefore the main opportunities to improve the environmental performance of the PC-25 system.
LCA results for a separate analysis of the PC-25 manufacturing phase show that the manufacturing of the fuel cell stack is responsible for almost half of the environmental impact of the manufacturing phase. The main cause is the high amount of energy used in the fuel cell stack manufacturing process. If one looks at the environmental impact per material in the PC-25 manufacturing phase, the biggest impacts are caused by platinum used in the fuel cell stack, copper used in the power conditioning and control devices, and stainless steel 304 used for manifold applications. In case of platinum especially it is beneficial to pursue a high recycling rate, since the environmental impact of recycled platinum is much smaller than that of raw platinum. The end-of-life phase has a small environmental impact compared to the use and manufacturing phase.
Besides an LCA of the current PC-25 system, this report also includes an analysis of two scenarios as opportunities for environmental improvement of the PC-25 system. One scenario analyzes the effect of using renewable hydrogen from wind energy instead of using hydrogen from natural gas steam reforming. The second scenario analyzes an alternative end-of-life treatment including reuse of PC-25 components and maximizing platinum recycling. The effect on the PC-25 environmental impact caused by component reuse occurs both in the end-of-life phase (less output to waste management) and the manufacturing phase (less input of materials and energy).
In case of the scenario with renewable hydrogen from wind energy the environmental impact is highly dependent on hydrogen transport from the wind turbine site to the PC-25 site. However, if a transport distance of 100 miles is assumed, a decrease in the total PC-25 life cycle environmental impact by a factor 7 is reached. The alternative end-of-life scenario analyzing reuse and maximized platinum recycling shows a 16% decrease in the aggregated environmental impact of the manufacturing and end-of-life phase. The use phase impact is not taken into account here because the alternative end-of-life scenario aims only at reducing the environmental impact of the manufacturing and end-of-life phase.