FUEL CELLS

Fuel cells can be thought of as solid state generators, but having two or three times the efficiency of all present electricity generators and also having no moving parts needing maintainence (an analogy is the solid state transistors which were developed into the computers we now use and all the intelligent electronic devices we all use so much). This shows how important fuel cells will be to the human race.

First concieved of 160 years ago the first working fuel cells were not developed until 1932 by Francis Bacon, but development was slow until 1959 when Francis Bacon + Co. built a five-kilowatt system and Harry Karl Ihrig built a twenty-horsepower fuel cell propelled tractor.   In the 1960's NASA decided that fuel cells were the best way of generating power (and water) in space.   At present an 11-megawatt unit is operating and hundreds of smaller units are operational powering buses and as stationary power generators.

Fuel cells when properly developed will produce power at very a high efficiency and due to this high efficiency they will consume small amounts of Carbonaceous fuel (though the type of fuel doesn't have to contain Carbon) and so produce relatively small amounts of Carbon dioxide, also they produce no Sulphur oxides because all Sulphur compounds must be removed before the fuel goes to the cells (Sulphur reacts adversely with the electrolytes and electrodes) and no Nitrogen oxides because Nitrogen will not pass through the electrolytes used (this will cut acid rain).
 
 

As long as they are supplied with a hydrogen containing fuel and and an oxygen atoms (possibly air) they will produce power.   Fuel cells work by producing either hydrogen or oxygen ions at one electrode which passes through an electrolyte (such as phosphoric acid, solid oxide or an appropriate polymer) to the other electrode to react with it's atoms of the other chemical producing power, water and in some varieties of cells a lot of heat raising efficiency to 80% of the latent heat of the fuel (other types of generation equipment used today are less than 35% efficient).   Each cell produces power at 1.23 volts and these are then stacked to produce power as required.
 

1) SOLID POLYMER (also known as PEM-Proton exchange membrane)

PEM cells are used in the mercedes-benz methanol powered concept car and is also used in many buses in Vancouver, Canada and Chicago, USA.
 

2) ALKALI

Useful machines with a track record in free competition against other types of power sources, unfortunatly this only in the niche market of spacecraft (spacecraft numbers will increase in future) because they produce water as well as having a high power density, possibly they would be of use in submarines and some are produced in Europe for vehicles. Some problems are the high Platinum loading of the electrodes (which makes them too costly), their low operating temperature means an external reformer is required and Carbon dioxide present in the air degrades the electrolyte and clogs up the electrodes though these are not insurmountable problems.
 

3) Phosphoric acid

Produced commercially at present and used in a variety of countries for stationary applications in environmentally-sensitive places where a government grant is available, possibly they would be useful for larger vehicles such as ships and trains. They have run for over 9000 hours (i.e. over 1 year) without maintenance, totally impossible with the commonly used types of generation units and they do provide some heat for cogeneration. Some problems are that some expensive Platinum is required as a catalyst at the electrodes, they need an external reformer to produce the hydrogen for fuel as the operating temperature is relatively low and and because of it's lower efficiency than both Molten carbonate and Solid oxide cells it will probably loose out in the end but they are available NOW.
 

4) Molten Carbonate

Very promising for stationary power applications mainly as multimegawatt installations. They can be run on either methane (eg. natural gas) or from coal gas (Hydrogen and Carbon monoxide) and they use Nickel as a catalyst (not the much more expensive Platinum), and because of their quite high operating temperature they do not need an external reformer. What happens is that the Oxygen and Carbon dioxide react with electrons at the cathode to form Carbonate ions which passes into the electrolyte (Carbonate based) while at the anode Carbonate ions react with Hydrogen or Carbon monoxide to produce Water + Carbon dioxide and free electrons. The major problem is that the Nickel electrodes operate in a very hot and corrosive but progress is quite advanced and pilot plants have been built to prove the concept.

This is very a very promising technology and in the future should take over from the presently common but very inefficient and polluting coal fired and nuclear power stations we now depend on.
 

5) Solid Oxide

Very promising for the very large market for medium power (kilowatts) devices, but this is an immature technology. The electrodes and eletcrolytes used are undergoing rapid development but usually the solid electrolyte is a Yttria coated Zirconia in which the Oxygen ions become mobile at 1000 degrees celsius and react with the fuel. Unfortunately at this early stage of development the materials used to construct the cells make the cells very expensive to produce, these are ceramics much like those used for the supermagnets under development.

These may be the least developed fuel cell type but their very high efficiency, the useful high grade heat they produce plus the large market they could reach (buses? trucks? trains, ships and stand alone gensets at least from 2-25 kilowatts in size) make them a very promising technology.
 
 

Fuels used just need to contain Hydrogen but most contain Carbon too, this fuel is reacted with Oxygen from air, some fuel cells will need to reform the fuel if it is Carbonaceous so that pure Hydrogen is used but some will reform the fuel automatically.

Some sources that spring to mind are:
 

• Methane - from drilling for natural gas, from decaying rubbish or sewage or gas hydrates

• Methanol/Ethanol - from hydrolysing natural gas or biomass

• Hydrogen - from electrically dissociating water molecules or from using solar cells which    dissociate water molecules

1) Methane

Gas hydrates are unknown to the general public but contain approximately twenty times as much gas as conventional deposits. Gas hydrate is gas held inert in ice both at the bottom of the deep oceans and at the base of Permafrost (Siberia, Canada, Antarctica, etc.). It may seem odd that there is ice at the bottom of the oceans but the water is only 1° Celcius and the great pressure causes fresh water to solidify, this ice covers very great areas of oceanfloor except the small and widely scattered hot vents.

Many landfills are already used to produce Methane for power generation (sewage could be used too).
 

2) Methanol/Ethanol

Hydrolysing Natural gas to convert the Methane to an alcohol as is done to make a feedstock for many chemical and physical processes now (making Methanol is a very common chemical process).

Biomass techniques are used to make drinking alcohol and alcohol for fuel (in some advanced countries such as Brazil). This would of course mean recycling the Carbon dioxide via the air and then plants and so would stabilize Carbon dioxide levels.
 

3) Hydrogen

This would come from either dissociating Water into it's component Hydrogen and Oxygen atoms using electrical energy or solar energy using the chlorophyll like chemicals used in some solar cells developed in the past.

What is a Fuel Cell very good till they push their product

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