On Fuelling Fuel Cells

Most fuel cells use hydrogen as fuel because of its high reactivity for the electrochemical reaction in the anode and the water release from oxidation, which is harmless to the environment. Thus, vehicles that employ PEMFCs (Proton-exchange Membrane Fuel Cells) may be classified as zero-emission. However, hydrogen is not readily available in most places and it has be generated before fuel cells can be used.

One common way of producing hydrogen is through the electrolysis of water, which is the reverse process of a fuel cell. Even though the method may seem perverse, it is in fact a very convenient way of providing hydrogen for mobile fuel cells.

Another method of providing fuel is through biological processes that can break down fossil or bio-fuel. Some of these methods are based on enzymes, bacteria or light.

In other cases, hydrogen is produced in large central plants, or by electrolysers and is stored for use in fuel cells. There is already something of an infrastructure for producing, storing, and supplying hydrogen, as it is widely used in the chemical industry, in petroleum refining and in ammonia
manufacture, for example. There are those who see hydrogen being widely used in this
way as an energy vector (a method of storing and transporting energy) in the future,
when we rely less on fossil fuels and more on renewable sources of energy. However, for
certain applications of fuel cells this may be a suitable way of providing fuel even now.
This is especially so in the case of small, portable, low-power fuel cell systems. In these
circumstances the special and difficult problems involved with transporting and storing
hydrogen come to the fore.

The problem behind storing hydrogen is very complex since some ways of doing it differ a lot among themselves. Despite of that, two groups in such context can be distinguished: in one, hydrogen is simply stored as is and in the other, the hydrogen is produced in large chemical plants and is then used to produce hydrogen-rich chemicals or man-made fuels.

Compounds of 'hydrogen-carrier' can be created to release their hydrogen a lot easier than fossil fuels and can be employed in mobile systems.

Reference:

LARMINIE, James; DICKS, Andrew. Fuel Cell Systems Explained. 2. ed. West Sussex, England: Wiley & Sons Ltd., 2003. 418 p.

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