Tuesday, 5 August 2008

Car? Bike? CO2 part 2

I love my car. I looooove my car. Even when it's raining and the roof is leaking and the cooling system is rusting from the inside out. Love love love.

How much does it love the environment? It's not all that bad... compared to an SUV.

This is part two of a fourish-part post on my CO2 usage. Let me know if you're bored yet and I'll stop.

The only question I really need to answer here is: how many kg CO2 per kilometre? I don't use my car all that much and I can easily keep track of how many km I do on any given day. I already know how many km per litre I get (just over 11.5) and I don't drive enough for it to be worth changing cars to get better efficiency.

That breaks down into:
1. How many kg CO2 / km for unleaded 91 octane fuel, on average?
2. Does it differ by car, in any way?
3. Does it differ by fuel provider, in any way?

And then: how many km do I do on an average day, and how many kg CO2 does that translate to?

To question 1

The NRMA says every litre produces 2.3kg of CO2

The Canadians say 2.4kg. And they've made a handy dandy calculator - cut out and make! It's papercraft for greenie geeks.

The US EPA, via Yahoo Answers, say every litre produces 2.343kg...

That's a much better consensus than the tree question earlier. And that last article also tells me something of the answer to questions 2 and 3. Check out, by the way, the final answer to that question. Love it.

To question 2
Per the Yahoo Answer quoted above, only a very efficient engine would produce the whole 2.343 kg of CO2. Less efficient engines produce more CO (carbon monoxide, not a greenhouse gas although it's pretty nasty to humans) and so on. Can I find out for my car what its efficiency is? I'm good about getting it serviced but it is eleven years old.

For now let's assume it's really efficient and it's putting out all 2.343 of those kilograms.

The internets say to make sure the air filter's clean and the spark plugs are working right. Sounds like a job for Super Roverland!

To question 3
Again per the Yahoo Answer, part of the efficiency is down to the additives. Local received wisdom says some petrol companies (Shell, Caltex) always buy the top grade of petrol from the refinery, and some (Gull, I'm looking at you) buy whatever's available. I'd love to run some statistical tests to check this out but I don't use anywhere near enough petrol - I'd be waiting a year for meaningful results. Any of you like to volunteer to keep records of your petrol purchases and mileage for a while?

Last question. How many km / day do I do. This is where I get to be insufferably smug: since 3 June (the day I came home) I've done 500km, one tank of gas. That works out to (clicks over to Excel... type type type ... clicks back) 9.1 km / day. Thus, an average of 1.84 kg CO2 per day from driving.

And bikes? Well, if I was going to bike to work, I'd be very happy to hear about BikeCentral, a new enterprise opened up just near Britomart, which has bike storage, lockers and showers, repairs and coffee. Shame I already life in the CBD...

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