A technological analysis of PEM and SOFC fuel cell systems for residential CHP applications
Special Symposium - Energy
Invited Session on Energy Issues (S-2)
Keywords: fuel cell, pem, sofc, chp
Fuel cell systems are gaining considerable attention for the production of electricity at high efficiency from a range of different fuel sources. A significant potential application of fuel cell systems is to produce electricity for residential applications in a decentralised manner. In these applications it is also possible to utilise some of the waste heat from the fuel cell system for space heating, increasing the overall energy conversion efficiency.
In this paper, two different fuel cell technologies are considered for application in small, or micro combined heat and power (CHP) systems. Firstly, the polymer electrolyte fuel cell (PEFC), which operates at approximately 70-80 degrees Celcius, and requires high purity hydrogen as the anode feed. The second fuel cell technology is the solid oxide fuel cell (SOFC), which operates at much higher temperatures, around 800 degrees Celcius and may utilise hydrogen or partially reformed natural gas as the anode feed.
There is currently limited distribution infrastructure for hydrogen, especially in residential areas, however there is a well established natural gas distribution network in much of the western world. This study will examine the use of natural gas as the CHP system fuel, which means for the PEFC option a reformer and purification system is necessary, while for the SOFC system a pre-reformer is utilised.
An important aspect of CHP performance is the dynamic response to changes in demand, for example the changes in heating demand throughout daily and seasonal periods, and so for this project dynamic models of both major fuel cell systems, along with the balance of plant, have been developed and implemented using MATLAB-Simulink. This allows for detailed simulation of the transient behaviour of the systems, at both short time scales (such as for changes is system voltage in response to a change in the external load), and longer time scales (such as the change in stack temperature). An analysis of the suitability of the different systems has been carried out, focussing principally on the technological differences between the two systems.
Presented Tuesday 18, 16:30 to 17:00, in session Invited Session on Energy Issues (S-2).
