[chris (OP)]

I was contacted recently by someone who wanted to know at what age it's worth replacing a car on environmental grounds?

That is, how much carbon dioxide does it take to produce a car in the first place and hence how old and inefficient (i.e. bad for the environment) does it need to be before it's actually better for the environment to buy another one?

Can anyone provide any insights, and does anyone have any references for calculating embodied energy, CO2 and water?

Chris

[paul.fr]

in 2004, Ford had worldwide vehicle sales of 6,798,000. During 2004 they also produced 8.4 million metric tonnes of carbon dioxide from their factories. If my maths is correct that gives a figure of just over 12 metric tonnes of carbon dioxide to make each vehicle.

[chris (OP)]

Hang on a minute. 7 million cars, 8 million tonnes of CO2, where did you get 12 from? Have you got a decimal wrong somewhere?

Chris

[paul.fr]

oops, yes i forgot the decimal point.
eh erm, if my maths is correct...   1.2metric tonnes of carbon dioxide to make each vehicle.

[eric l]

Does that include the CO2 produced in making the steel (and other metals) used to make the cars ?

[Bored chemist]

I doubt it includes that or the CO2 made by the power station that ran the lights etc.

[paul.fr]

Does that include the CO2 produced in making the steel (and other metals) used to make the cars ?

No, just production and assembly.

[chris (OP)]

Mmm, that's what I meant by embodied carbon dioxide, and water and energy - you take into account all of these processes. I think the embodied energy in a car is pretty huge.

Chris

[paul.fr]

whilst not about the embodied energy in car manufacture this link http://www.canadianarchitect.com/asf/perspectives_sustainibility/measures_of_sustainablity/measures_of_sustainablity_embodied.htm
does provide details of the energy in building materials.

[chris (OP)]

Wow - look at the embodied energy in native aluminium!

[another_someone]

Aluminium has always been an expensive (in energy terms) material to produce.  By comparison, producing most plastics is quite cheap, so plastic cars (although they actually will contain more carbon within the body) will use less energy to produce (ofcourse, if you are deriving energy from nuclear power, or other non-carbon sources, then the carbon cost of aluminium might be far less than its commensurate energy cost might indicate - it all depends upon what assumptions you make about your sources of energy).

[paul.fr]

Yes, but once the aluminium is produced, is it not less hungy on energy and more economical to recycle?

[chris (OP)]

That's on the list too - about half way - have a look.

[paul.fr]

That's on the list too - about half way - have a look.

ah, so it is.