Environmental Engineering Reference
In-Depth Information
h ose methods and numbers were enormously controversial. 104 h is
was to be expected: modeling the dynamics of all the food and land use
around the world is not a straightforward task. But the basic bot om
line was simple: together with the controversy over rising fuel prices,
the new analysis meant new government support for corn-based etha-
nol was a nonstarter. New kinds of biofuels, including cellulosic ones,
though still controversial in some quarters, provide hope to those who
want to see a future where biofuels play a big role.
E lectric vehicles have a dif erent potential climate problem: their
emissions depend on the source of their electricity. “Electric cars,”
as one wag put it, “are really coal cars. 105 He was trying to point out
that if you plug your car into an electric grid that is being powered by
coal, you are still causing a lot of carbon dioxide emissions.
I decided to dig into the numbers behind the Focus Electric I'd
driven. h e car takes thirty-two kilowat -hours of electricity to travel a
hundred miles. 106 In Dearborn, Michigan, where I took the car out for a
drive, most of the electricity came from coal; producing a kilowat -hour
of electricity yielded about three quarters of a kilogram of carbon diox-
ide. 107 Put together, this meant I was generating twenty-four kilograms
of carbon dioxide for every hundred miles I drove. h at was slightly
more than the damage I would have done to the climate had I driven
a Prius fueled with normal gasoline. 108
Michigan, though, turned out to be one of the worst places in
the country to drive an electric car. In 2012, a team at the Union
of Concerned Scientists, an environmental advocacy group, worked
through the numbers for every state. 109 Nearly half of the country lived
in places where electric cars were bet er for the climate than even the
best hybrid vehicles, and another two out of i ve made their homes in
places where electrics were comparable to the best alternatives.
And the picture is improving as natural gas replaces coal and emis-
sions from the U.S. electricity system drops. Indeed, what mat ers to the
climate for the next decade or so isn't really how much carbon dioxide
emissions an electric car causes; there won't be enough of those cars
to make a big dif erence. What mat ers is the trend: Can electric cars
 
 
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