Hydrogen and Bio-Fuel Cars

Some unusual cars running on hydrogen and bio-fuels on exhibition in London

Reduce Carbon Dioxide Emissions !

Some advanced engineering and novel ideas were on display in London's Trafalgar Square in June 2007.

Featured were cars which can run on hydrogen, on bio-fuels, on electricity and some fuel cell cars. Most of these cars have very advanced technology to enable them to carry the energy needed to drive them and in the power units which convert the fuel to motion.

Bio-fuels have been in commercial use in some countries for many years. A more recent engineering development is the advent of the flex-fuel engine, as used in this example from Saab. The car can run on straight unleaded gasoline, or a blend of gasoline and ethanol (up to 85% ethanol). The engine management systems are designed to handle the variable characteristics of the fuel as the blend proportions of ethanol in gasoline change each time the fuel tank is refilled.

Hydrogen: the simplest of the elements, is a flammable gas. Burning hydrogen produces energy and only water as the result. If we can harness the energy for machines, such as cars, we have a very clean fuel indeed. Instead of carbon dioxide (greenhouse gas) being a main consequence of combustion, only water is produced.

But life isn't so simple, as hydrogen has to be produced and then it is not easy handle. 

Hydrogen is usually produced in large scale in some petrochemical plants (from oil and gas). It can also be made by passing an electric current through water. To store any useful quantity of hydrogen it must be compressed to a very high pressure, or liquified (at 250 degrees C below zero !)

In the BMW car shown opposite, liquid hydrogen is stored in a special fuel tank and, at the touch of a switch, the engine can change from operating on gasoline to hydrogen. very clean emissions are the result. Unfortunately, it is only possible to re-fuel with liquid hydrogen in a very few special locations, and, because hydrogen is a very low density material - even when liquified, the tank's capacity means the range this car has on hydrogen is very short. This is how hydrogen can be used in a converntional internal combustion engine.

 There is another optiopn for hydrogen - the FUEL CELL technology.

In a fuel cell hydrogen and oxygen are recombined to produce water and, instead of heat, the energy is released in the form of electricity. This is 'cool' technology. The driving motors are electric and thus themselves are non-polluting.  Once again, the source of hydrogen, the locations to refuel the car, and the ability to store enough hydrogen to drive any reasonable distance, are problems for the future. In this GM Fuel-Cell car compressed hydrogen is stored in the fuel tank. Compressed hydrogen is easier to manage than liquid, but still very low in density.