Page 40 - Introduction to Transfer Phenomena in PEM Fuel Cells

Introduction to Hydrogen Technology 29
1.2.1.7.2. Advantages and disadvantages
The migration of methanol from the anode to the cathode through the
membrane results in poisoning of the catalyst on the oxygen side. To solve
this problem, it will be necessary to design membranes less permeable to
methanol than those currently used.
In addition, the low oxidation temperature of methanol requires a large
amount of catalyst compared to the PEMFC cell. However, it has the
advantage of using a liquid fuel and requires no reformer.

Another disadvantage of these batteries is the toxicity of methanol, which
is why some companies are exploring another way, that is, the direct ethanol
fuel cell (DEFC), in which methanol is replaced by ethanol. Currently,
DMFC batteries are more efficient than DEFCs.
1.2.1.7.3. Aging

Chemical or mechanical aging may occur in DMFC batteries and the
main causes are:

– degradation under the effect of temperature;
– loss of catalytic activity (poisoning of the catalyst, agglomeration of the
particles, etc.);
– heterogeneity of the materials used;

– insufficiently controlled humidity.
1.2.1.8. Reversible fuel cell (RFC)

The RFC is a closed-loop system that can provide electricity, heat and
water. Hydrogen is provided by the electrolysis of water using renewable
energy such as solar, wind and geothermal.

This battery is used by NASA in the Helios project, a drone equipped
with a fuel cell and solar panels: the solar panels allow the drone to fly by
day and store hydrogen so that the fuel cell can operate during the night.