Page 46 - Introduction to Transfer Phenomena in PEM Fuel Cells

– low emissions (particularly, in terms of CO, NOx, CnHm and
particulates, but depend on the fuel used and the type of application);
– they are of modular construction; Introduction to Hydrogen Technology 35
– various operating temperatures: this allows the use of heat by coupling
with a turbine or for applications ranging from hot water to steam;
– no rotating parts.

Whereas the issues to overcome are:
– the cost: downfall of fuel cells, the price is much higher ensuring
competitiveness. The key points are the catalyst (platinum), membranes,
bipolar plates, periphery, etc.;

– weight and volume: especially if you want to integrate it into a vehicle;
– the lifetime: they must last more than 40,000 hours in stationary
applications;
– thermal integration: from heat recovery to heat evacuation according to
the fuel cell and the application.

1.3. The proton-exchange membrane fuel cell

Among the various types of fuel cells currently developed, the so-called
“solid polymer” sector has been adopted by almost all automobile
stakeholders in the world. Generally known as PEMFC, it is also of interest
to manufacturers for stationary (hundreds of kW), portable (up to 100 W)
and transportable (around 100 kW) applications. This technology is gaining
attention for three main reasons: its relatively low operating temperature
(< 100°C) allows for simplified technology to ensure a quick startup and
easy evacuation of heat produced at room temperature, which is essential for
automotive applications; it is also insensitive to the presence of CO 2 in the
air, unlike the alkaline type; and finally, its all-solid technology can therefore
allow significantly superior lifetimes to liquid electrolyte fuel cells, as well
as a simpler industrialization. This makes it possible to envisage a future cost
that is compatible with the targeted market, especially since it offers a
significantly greater compactness than other types. This type of fuel cell
provides a high power density and a lower weight, a reasonable cost and a
low volume. A PEM fuel cell consists of a negatively charged electrode
(anode), a positively charged electrode (cathode) and an electrolyte (the