Life Cycle Assessment, LCA To understand the environmental impact of any activity (in this case the construction and use of a motor car) we can use LCA in which the resources needed to mine, refine, deliver and fabricate the components of the car are identified and quantified. This cradle section will also include issues such as deforestation, and heavy metal runoff where a mine is exposed. Next comes the part where the environmental impacts of using the car are assessed: the fuel consumed, the carbon dioxide and other gases emitted, and the visual, economic and ecological damage. Finally, in the grave section, the final disposal of the car is considered. European legislation requires car manufacturers to construct cars in such a way that the majority of the components can be recycled, and to do this the manufacturer has to ensure that metals, glass, batteries, plastics, rubber etc can all be easily identifies and separated.

In use the average car emits about four tonnes of carbon dioxide each year. This is because the internal combustion engine operates by combining oxygen with carbon in a reaction which gives lots of heat and releases about 3 times the mass of petrol in the form of carbon dioxide.

Example If you covered 10,000 miles in a year at an average fuel consumption of 30mpg then you would have used 10000/30 gallons i.e. 333 gallons Naturally being a modern outfit we have to work in metric units and since a gallon is 4.5 litres you used 333 x 4.5 ie 1500 litres of petrol If the density of petrol is 0.85kg/l then you used 333 x 4.5 x 0.85 ie 1275 kg of petrol Converting this to carbon dioxide, by multiplying by a factor of three, gives 333 x 4.5 x 0.85 x 3 kg of carbon dioxide. That is about 4000 kg or 4 tonnes !

Another way of looking at this is that each car produces about four times its own mass in carbon dioxide each year. In the UK we each are responsible for about 17 tonnes of CO2 released into the atmosphere each year. This figure is based upon computing the total emissions from all spheres of life such as domestic buildings, vehicles, industry and commerce and sharing the CO2 out amongst everyone.

Task 3 Work out how much petrol you personally used last year from your mileage, consumption figures and density of fuel, how much Carbon dioxide is this?

In America the average amount of CO2 per person per year is much higher at around 25, whereas in many developing countries the figures may only be 2-5 tonnes CO2 per person per year.