Hydrogen

by Mike

What comes to mind when people think of the word hydrogen? The single electron element on the periodic table? The hydrogen bomb? Or even H20? Yet there is another use for this wondrous gas, fuel cell technology. Fuel cell technology is the combine hydrogen gas (or liquid) with oxygen to create water and energy. This is reverse electrolysis. Yet there are obstacles to make this a useful energy source such as accessibility, cost, and willpower from the public.

Hydrogen is the most abundant element in the universe. Our start, the sun, son consumes over 11 billion pounds every second. Yet hydrogen on earth, is very rare in its natural form, it is almost always paired with other elements. There are two solutions to this problem. First is to separate it from fossil fuels, which are already being mined, or separate it from water, which covers 2/3 of the world's surface. The obvious choice is water, it's simple, it yields clean air AND the fuel we need. The only problem is that much power from power plants and such would be needed to convert the water through electrolysis. Doing this would increase the fossil fuel consumption, due to the fact that most power plants are powered by non-renewable sources (i.e. Fossil fuels). Which defeats the purpose of using this expensive technology. There is always the option of extracting hydrogen from biomass, yet it I a costly and inefficient system as to yet.

There isn't ONE type of hydrogen fuel cell; there are many, and each have their downfall and their upside. Such as:

Phosphoric acid fuel cells (PACF)

Alkaline Fuel cells (AFC)

Molten Carbonate Fuel cells (MCFC)

Solid Oxide Fuel cells (SOFC)

Proton Exchange Fuel cell (PEFC)

And finally there is the PEMFCs, proton exchange membrane Fuel cell, it is a technology that was almost forgotten 10 years ago, but found itself in the spotlight after A Canadian company (Ballard systems) released documents showing it's effectiveness. The material and design of the membrane allows it to conduct and keep the reacting gasses from mixing and combusting, which would waste energy.

When the hydrogen passes in the PEMFC, it is stripped of its single electron. At the same time, in the air intake, there is oxygen being pressed against the platinum membrane, which separates it, creating 2O, instead of O2. The hydrogen continues as an H+ ion; it reaches a membrane covered with platinum particles, it is reunited with oxygen. Thus producing the only bi-product, H2O. The electron what had been stripped from the Hydrogen atom is collected and used as any other power. The chemical equation for this reaction is as follows:

2H2 ? 4H ? 4 electrons + 4H+

O2 ? 2O

Then,

4 electrons + 4H+ + 2O ? 2H2O + energy

This method of energy generation is particularly efficient, 50-80%! This compared to the bleak 10% of gasoline-powered automobiles. Although, there are problems with this system, there is a precise level of humidity needed to keep efficiency, even that the engine might not work if it becomes too saturated or too dry. This isn't a problem that should keep this fuel cell from being commercialized, yet will still need years to be perfected to the point where it can be used in vehicles, since they will be subject to very extreme surroundings.

Fuel cells are not only confined to use in vehicles, they are also an option as generators for homes. Household systems are very compact; a unit 1 m cube can provide enough power to heat and power a house with 209 m2 (Barlow, 1997). In the current combustion engine generators waste 80-90% of the energy input. This and the fact that they greatly pollute the environment make them a very un-economical choice for the short and long term. However Fuel cells can be used in their place. Fuel cells are clean, and produce at efficiencies 4-5 times greater than what is currently found on the market. A typical fuel cell is capable of creating a charge of .7 V DC, and with an estimated max of 1.23V DC (Barlow, 1997), The voltage can be increased when the cells are placed in a series. Increasing the possible outcome almost indefinitely.

This is a diagram of Electrolysis, the process in which water and oxygen and hydrogen are split. The concept of hydrogen fuel cells is the exact contrary in which the hydrogen is reunited with the oxygen and creates energy. Electrolysis is the cheapest and most abundant way to produce sufficient quantities of hydrogen to supply for mass consumerism.

References

David Booth, Home Power inc. 2001 http://www.homepower.com/files/Hp35p37.pdf

Russ Barlow, Home Power inc. 1997 http://www.homepower.com/files/homefuelcells.pdf

McAlister, Roy. 2002 http://www.clean-air.org/ahaknow.html