[timthelion]

Things the author failed to include in the study:

1) Road land use, a bike lane is narrower than a car lane.

2) The energy invested in building the car. Aluminium parts, which cars are made of, have very significant energy investments.

3) CO2 emissions of asphalt used to pave the roads that cars drive on.

4) CO2 emissions of the cars tires vs the bikes tires

5) Calorie consumption of the person driving/riding in the car!!!!!!!

6) Parking land use.

7) Land use associated with mining the materials used to build a car vs bike.

8) Land use of pollution barriers to protect residential areas from car intensive ones.

9) CO2 emissions associated with heavy raised roadways made of concrete and steel, such as highway overpasses.

Basically, this analysis is laughably absurd and is an insult to the Harvard name.

[timthelion]

That's not to say that this kind of analysis is always useless. I have a whole bunch of old junk in the attic, and I feel it would be a pitty to throw it out, but if I were to spend hours sorting through all it and finding uses for the things, the callories burned would probably outweigh any benefits from reusing the items which probably aren't needed by anyone anyways. So my instinctive reaction to "not throw things out" might actually be bad for the environment when taken to the extreme.

I'm just saying that this analysis in particular is simplistic, wrong, and harmful.

[maxerickson]

The recent Ford F-150s with aluminum bodies were huge news. The frame is still steel.

Personal vehicles are mostly made of steel.

[timthelion]

And steel actually produces even more CO2 to cast. Carbon steel, melting point 1500C vs aluminium, just 600C. http://www.engineeringtoolbox.com/melting-temperature-metals...

[maxerickson]

The specific heat is also important, not just temperature.

You also have to look at refining (it takes a huge amount of energy to produce raw aluminum) and recycling (steel is really, really recyclable).

[timthelion]

Well they both take more energy to cast than my average bowl of mashed potatoes and peas that's for sure!