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Rent v Own (a car for a work trip) Addendum: The Cost of Carbon

July 26, 2013

A love of over-analysis can be cruel since, if truly embraced, it never is complete.  Analysis begets analysis begets analysis ad infinitum.  So, building off a question from a friend, I realized there were two comparable metrics from my previous post on contrasting renting a car versus driving my own for an out of town work meeting:

  • Dollars – greenbacks, bucks, USD, the most popular false idol
  • Pollution – NOx, SOx, ppm, CO2, “carbon”… that stuff that is often produced by our actions that seriously messes with the planet (where we happen to live) and everything therein and thereon

The end result of my last post was that I had an added cost of $13, which I justified by valuing the more enjoyable 10 hour drive.  However, there’s another aspect to consider.  What if, perhaps, I spent that $13 to reduce the amount of pollution my trip caused.  As I mention, the rental car got 42.5 mpg compared to the 27 mpg that my car would have achieved.  Which means I burned 7.3 fewer gallons on the trip than I would have.

While there’s a mix of pollution from driving (methane, nitrous oxide, carbon monoxide, etc.), let’s stick to the biggest component and the most publicly recongnized: carbon dioxide (CO2).  A gallon of gas burned produces 8,887 g of CO2 (which is about 8.9 kg or 19.6 lbs).  So my rental avoided 143 lbs of CO2.  Which is on the order of what an adult human weighs, so you can go ahead and compare it to the last time you stepped on the scale.  If you want a different visual, a standard basketball holds about 0.25 cubic feet of air and a pound of CO2 fills approximately 8.1 cubic feet*.  So imagine, if you can, 4633 basketballs.  That’s the volume of CO2 I avoided.

But quantities of CO2 is a hard thing to wrap your head around since from there you need to take into account it’s impact on global heat retention and try to grasp what damage all those basketballs would have done.  But let’s not do that.  Let’s stick with the 143 lbs avoided for $13 and how this compares to other things going on to offset or reduce greenhouse gas (GHG) emissions.  Another way to put it, how cost effective was it to spend $13 to avoid 143 lbs of CO2.

There’s a pretty famous (at least in certain circles) study, with subsequent updates/revisions, that prices out the cost of GHG reductions in dollars for various methods.  Some seem pretty esoteric, like “reduced slash and burn agriculture conversion,” while others are very straightforward, such as “lighting – switch incandescent to LED (residential).”  In any case, here’s the results in one chart:

Source: McKinsey & Company Global GHG Abatement Cost Curve x2.1

Euros per metric ton of carbon dioxide equivalent (€ per tCO2e)… totally helpful.  This is what we get for letting Europe get ahead of us on dealing with the issue of anthropogenic (or human caused) climate change.  Well, $13 is approximately €9.8 and 143 lbs is about 0.065 tonnes.  Which puts me at about €150 per tCO2.  Sooooooooo, kinda of pricey.

As a carbon offset cost, it looks like again I’m not truly justified in the rental car.  But my conscience is a bit cleaner.  Also, I’m talking about thirteen bucks here.  I should probably just call this reasonable and move on.



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