HT PEM Basics
The HTPEM (High Temperature Polymer Eloctrolyte Membrane) fuel cell system developed by Serenergy operates at 150-180 degrees C. This gives some key benefits and advantages over other types of fuel cell systems. Mainly CO tolerance (High fuel flexibility), ease of cooling and no need for humidification.
HTPEM fuel cells are highly tolerant to CO. CO is a known fuel cell poison and is a result of using reformed liquid fuels. The high CO content in gases from fuel reformers most often necessitates fuel clean up, which in turn then gives larger more complex and more costly systems.
Due to the elevated operation temperature of the HTPEM fuel cell, hydrogen with a higher CO concentration can be used without the same negative impact on performance, and without the same need for gas cleanup. This makes it possible to use hydrogen reformate originating from cheap, and easy to handle energy-carriers such as methanol, ethanol, diesel etc.
The HTPEM fuel cell can tolerate up to 3% (30,000ppm) CO and up to 20ppm of sulphur without permanent degradation. In comparison, LTPEM fuel cell normally can tolerate less than 30ppm CO and less than 1 ppm of Sulphur. This is a factor of 1,000 difference in CO tolerance. Because of the high operating temperature, a PrOx reactor after the reformer is normally not necessary. PrOx reactors are expensive, bulky and significantly lower the system efficiency. The result is that very simple, lightweight and inexpensive reformers can be used to produce hydrogen from a broad range of energy-carriers including the choices listed above.
As a result of not needing the humidifiers, air compressor and oversized radiator as in the LTPEM systems, the HTPEM system architecture seems very simple. The Serenergy fuel cell system uses less than 4% of fuel cell power output for balance of plant components -making this the system type with one of the lowest parasitic power consumption. We term it The Power of Simplicity. Partly due to the low parasitic losses we have achieved fuel cell system efficiencies of up to 57%. Most other fuel cell systems have an energy waste of approximately 10-20% of the fuel cell output, just to achieve operational status.