Fuel Cell Comparison

Various fuel cell types and their operating characteristics.

Each type of fuel cell has different characteristics making it suitable for specific applications. PEM Fuel Cells have a wide range of applications.

Below is an overview showing various fuel cell types and their typical operating characteristics.

	PEM water- cooled	PEM air cooled	DMFC	AFC	HT PEM	PAFC	MCFC	SOFC
Typical output range	1 - 100 kW	mW - 1 kW	mW - 1 kW	1 - 5 kW	100W - 10kW	25 kW - 125 kW	50 kW - 125kW	mW - 125 kW
State of development	Pr	Pr	Pr	Pr	D	Pr	Pr	D
Scalability	E	Li	Li	P	U	Li	P	P
Turndown dynamics	E	Mo	Mo	P	Mo	Mo	P	P
Power density	E	Mo	P	P	Mo	P	P	Mo
Quality of heat	L	N	L	L	M	M	H	H
Variety of fuels	P	P	P	P	Mo	Mo	Mo	G
Sensitivity to contaminants	H	H	H	H	M	M	L	L
Start-up time	F	F	F	F	M	M	S	S
Robustness	E	E	Mo	Mo	U	E	P	P
Lifetime	G	Mo	Mo	Mo	U	E	G	P
Pr=Proven; D=Development; E=Excellent; Li=Limited; P=Poor; U=Unknown; Mo=Moderate; L=Low; N=Nil; M=Medium; H=High; G=Good; F=Fast; S=Slow

Comparison of low and high temperature fuel cells

Different types of fuel cells operate at different temperatures. While PEMFC and AFC are generally called low temperature fuel cells and MCFC and SOFC being called high temperature fuel cells, the PAFC falls in between and can be called an intermediate temperature fuel cell. The same holds for PEMFCs using phosphoric acid doped electrolytes. Low temperature fuel cells do not require the cooling and thermal shielding necessary for high temperature fuel cells. For mobile applications, the PEMFC is the obvious choice. AFC, once thought to be the optimal solution for road transportation, is losing ground. Even NASA is considering changing over from AFC to PEMFC.

For stationary applications, both low and high temperature fuel cells seem to qualify. In practice, specific conditions lead to a preference for the one or the other.

Low temperature fuel cells, especially PEM fuel cells, can be characterized by their rapid start-up, freeze capability, high robustness towards temperature cycles, pressure variations, and redox cycles. Thanks to many automotive oriented R&D programs focusing on aggressive cost reductions, cost levels of PEMFC systems have become competitive in many stationary applications, such as backup and remote power, and power generation using hydrogen that is available on-site from existing processes.

High temperature fuel cells, such as SOFCs and MCFCs, are able to operate on fuels containing large fractions of carbon monoxide, and can thus be operated either with an external or internal reformer without extensive gas cleaning. In applications where load following dynamics and start-up times are not critical, and where other fuels than hydrogen are preferred, these high temperature fuel cells are often selected. The critical point for high temperature fuel cells will be whether they can meet the cost and lifetime criteria simultaneously.

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