by Ed Towns

Created on: November 16, 2010   Last Updated: November 17, 2010

Hydrogen-fueled electric cars emit no pollutants. The cars use compressed hydrogen mixed with oxygen to create electricity to power their motors and the only by-product is water.

Now a zero-emissions vehicle, which can be compared to the comfort and performance of the current polluting internal combustion engine vehicles that we have become so fond of, may sound too good to be true. 

There must be a cost to the environment of producing the gas needed for the hydrogen-fueled cars to operate - or is there? 

Currently, the most common way of producing hydrogen is steam reforming from natural gas, a limited renewable energy source. There is an environmental cost of extracting hydrogen in this way with a medium to small amount of CO2 released during production. However, running an electric car fueled by hydrogen generated from natural gas can result in a 60 per cent reduction in emissions compared to a conventional car.

Other ways to produce hydrogen include:

*Gasification and reforming. Energy used in this method comes from oil or coal, a non-renewable energy source with a large amount of CO2 released during production.

*Burning. The energy for this comes via electricity from coal-fired power stations, again a non-renewable energy source with a high amount of CO2 released during production.

*Water electrolysis - 1. The energy comes via electricity from nuclear power stations, a non-renewable source with no CO2 released during production but with high long-term costs and potential safety risks.

*Water electrolysis - 2. This method uses electricity from solar, wind or hydro, renewable energy sources with no CO2 released.

Certain production methods are better suited in different areas of the world but, nevertheless, experts say it possible to achieve a stable supply of hydrogen from renewable energy sources.

For example, the water electrolysis method, where electricity is used to extract hydrogen from water, can produce hydrogen from completely renewable energy sources when solar, wind or hydro-electric power is used. 

A sustainable approach is a real possibility, with the ideal scenario being the use of renewable energy to extract hydrogen from water via electrolysis. 

The water created as a by-product of the operation of an electric car’s on-board fuel cell, where the hydrogen is mixed with oxygen to produce electricity, would return to the rivers and oceans before once again being converted into hydrogen via electrolysis. 

Another argument against the fact that a hydrogen-fueled car can be completely emissions free is that the energy required during the compression process of hydrogen is derived from non-renewable sources.

At present, the hydrogen is turned into compressed gas form so more can be fitted into the fuel tank on a car. However, developments are improving the fuel efficiency of cars and, therefore, less hydrogen is being used, meaning less compressing is required thus saving energy.

In addition, high-capacity hydrogen tanks are using a newly-developed absorption material which increases the amount of hydrogen the tank can store. This means the need to compress is reduced, again saving energy.

So it can be seen that emission-free driving is not quite here yet but progress is being made.

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