Internal Combustion

All developed countries rely heavily on the internal combustion engine, the most common fuels being petrol ("gasoline") and diesel. These fuels are petrochemical in origin and so depend on a constant supply of oil.

There are, however, reasons why this is not sustainable:

· Oil is a non-renewable resource and will eventually run out
· Emissions from engines cause environmental and health problems - these include in particular carbon monoxide (CO), nitrogen oxides (NOx), sulphur dioxide (SO2), lead compounds (leaded petrol) and carbon dioxide (CO2)

Photo: Street scene
Greener Cars

Many developments over the last few decades have tried to address these issues. These tend to fall into several categories:

Change Examples Main advantages
Reducing the environmental impact of existing fuels Removing lead from petrol, low sulphur fuel, reduced benzene content, catalytic converters Reduced emissions of CO, NOx, SO2, benzene and lead
Using alternative petrochemical fuels or blends LPG, E85, methane Reduced emissions of CO, NOx, SO2 and lead Lower CO2 emissions
Developing fuels from renewable resources Bioethanol, Biodiesel No oil dependence, sustainable feedstockPotential for being carbon neutral
Developing alternative technologies Fuel cell vehicles (hydrogen), hybrid technology Reduced emissions, potential for use of renewable resources

Sulphur is routinely removed from oil and gas, and is now an important source of the element for the manufacture of sulphuric acid

More information on catalytic converters can be found on the Catalysis site

Diagram: Alternative fuels
Photo: Biofuels for sale in the US

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