In this short article, I’ve estimated the amount of Carbon dioxide emissions from the maufacture of a standard aluminium bicycle frame weighing 1 kg. This is in an attempt to answer the question: “how far would I have to cycle [as opposed to driving a car] to offset the manufacture of my alloy bike frame?”
Alcan Aluminium states in one of their reports that:
14.9kW/hr per kg of aluminium produced.
6.8 tonnes of CO2 per tonne of Al.
1.8 tonnes of perfluorocarbons per tonne of Al.
= 6.8kg of CO2 per kg of Al.
~ 3786 litres of CO2 gas produced for a one-kilogram bicycle frame.
I have previously calculated that 1L of petrol produces 2.28kg of CO2, therefore 3L of petrol yields 6.8kg of CO2. A typical small car consumes 6L/100km. So you would only have to cycle 50km or so instead of driving a car, and you’ve already “offset” your frame.
So I would say that the humble bicycle is probably the only thing that I can think of that benefits the environment, if only because it’s more energy efficient than walking. I’ll save that calculation for another day…