MAIL: EVs, Carbon & Rainwater

Electric Vehicle Plug
"You quote the CO2 per year emissions from various EVs. These figures seem to offer little advantage over a typical Japanese four-cylinder ICE car."
Electric Vehicle Plug

I wish to make several points. First, in the plug-in vehicles Q&A in HP151 (“Plug-In Vehicles”), you quote the CO2 per year emissions from various EVs. These figures seem to offer little advantage over a typical Japanese four-cylinder ICE car. For example:

  • The U.S. national average for EV emissions is 8,035 pounds of CO2 per year.
  • My Honda Accord emits 0.71 pounds of CO2 per mile.
  • Say I drive 12,427 miles per year: That’s 8,823.5 pounds of CO2 per year, about the same emissions as the U.S. national average for an EV.

This result makes me wonder what the U.S. national average is for the distance an EV is driven annually? It seems from these results any lowering of emitted CO2 would be negligible by switching from a four-cylinder gasoline car to an EV.

Second, while I enjoy reading about all of the new and novel products discussed in your magazine, I also see a very polarized view of the current climate predicament we have placed ourselves in. Due to the requirement we adhere to—a maximum average global surface temperature warming of 2°C—the range of pathways for our future emissions are limited, resulting in a global carbon budget. These emission pathways have been modeled. This can be taken a step further whereby it is recognized that all 7 billion of us on this planet have an equal right to the remaining carbon emissions in our remaining global carbon budget.

Such constraints are explained in AVOID: Avoiding Dangerous Climate Change ( and Solving the Climate Dilemma: The Budget Approach ( They certainly paint a different picture than that presented by your magazine. I do not think it unreasonable to state that your magazine presents a future where we can have our cake and eat it too—using technology to maintain our current lifestyles. This would have been possible with this technology a decade or two ago, but not now. In light of the remaining emission pathways even in exclusion of equal rights to per capita emissions, any dependence on technology as a solution to climate change is delusional. That is a pity, because I do enjoy your magazine.

And finally, I agree with your New Zealand reader in the letter about rainwater. We’ve lived off of rainwater collected from our roof for seven years without any first- flush diverter or sterilization rubbish—that gear is all a con. Our rainwater is crystal-clear and is the best-tasting water I’ve ever had. We’ve got 70,000 U.S. gallons in storage, just collected from our roof, and nothing more than mesh filters are used on the gutter down-pipes. Lovely.

Shane White • South Australia

While we don’t know the average EV miles driven per vehicle per year (there are too few data points), we do know that the national average commute is 40 miles—most EVs can get there and back for such commutes.

It’s important to remember that averages are just that. If your grid is full of electrons from very dirty coal, then CO2 emissions reductions from not burning gasoline may be negligible. If your grid is much cleaner, so will the effective emissions from driving an EV. If you use PV-generated electricity to fuel your EV, your CO2 emissions, for all practical purposes, are zero.

If an EV is charged at night, when coal plants are nonetheless polluting but producing little electricity because of lower demand, your effective CO2 emissions from driving are far less because you didn’t burn any gasoline on board and you used kilowatt-hours that otherwise wouldn’t be used, but pollute just the same.

—Andy Kerr

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