Green Guru: Do Electric Cars Really Reduce Pollution?

Green Guru: Do Electric Cars Really Reduce Pollution?

The emissions of an electric car from production to the charging station. 

By Susan Cosier
Published: September-October 2011

Do electric cars really reduce pollution in the long run?

Patricia Carey, Bellvue, CO


Cars fueled by an electric charge produce fewer emissions than their gas-guzzling cousins, even when taking into account that plug-ins draw energy from power plants. Most electricity in the United States comes from natural gas, nuclear energy, and coal--the latter being the most polluting source. Still, says Stan Hadley, a senior researcher in the Energy and Transportation Science Division at Oak Ridge National Laboratory, even if the juice in your outlet comes from a coal-fired power plant, "plug-in hybrids, for most all situations, would be cleaner than conventional cars."

Studies show that in some cases, certain plug-in electric vehicles that pull electricity from gas-fired plants produce up to 60 percent fewer emissions than a conventional car with an internal combustion engine.

Another consideration is that it's easier to reduce pollution from a few thousand smokestacks than from a million tailpipes. In light of the EPA clamping down on air pollution violations, utilities are taking steps to move away from coal. For instance, one of the nation's largest coal-burning utilities, the Tennessee Valley Authority, has announced that it will shutter 18 boilers and retrofit other plants to decrease emissions. To replace the electric capacity, it's considering renewable energy, natural gas, nuclear power, and energy efficiency. To find out which fuel your utility uses, go to and type in your zip code.

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Susan Cosier

Susan Cosier is former senior editor at Audubon magazine. Follow her on Twitter @susancosier.

Type: Author | From: Audubon Magazine


Bill needs to get his facts straight.

The 43 pounds of CO2 do not only come from the gallon of gas which weighs ~8 pounds. The only thing that comes from the gas is the carbon (C). The oxygen from the surrounding air provides the 2 oxygen atoms for the CO2, which are themselves much heavier than the carbon.
Nevertheless, this still does not account for the 43 lbs of CO2. By my calculations, 43 lbs of CO2 -> 11 lbs of pure carbon. The actual estimate for pounds of CO2 released per gallon is more like 2 pounds.

@reality..... So what you are

@reality..... So what you are claiming is that a gallon of gas that weighs approx 8lbs pruduces 43lbs of CO2? Where did the extra 35lbs of weight come from? If we are to take your numbers of 75/25%, that would make the 75% a total of 6lbs which now brings the magical weight factor to 37lbs of CO2... Can you account for the extra weight created by burning 8lbs of liquid fuel? I'm all for dropping our pollution levels as much as possible, but rediculous claims with rediculous figures such as yours causes the average person to question the entire green movement. Instead of making up figures and lying to the public, the green movement needs to come clean itself before it can expect the public at large to take it seriously.

You're right, mostly.

The 43 pounds of CO2 do not only come from the gallon of gas which weighs ~8 pounds. The only thing that comes from the gas is the carbon (C). The oxygen from the surrounding air provides the 2 oxygen atoms for the CO2, which are themselves much heavier than the carbon.
Nevertheless, this still does not account for the 43 lbs of CO2. By my calculations, 43 lbs of CO2 -> 11 lbs of pure carbon. THe actual estimate for pounds of CO2 released per gallon is more like 2 pounds.

one sided data

Power plants and the distribution system are horribly inefficient....All you are doing is shifting the polution to another location. Take a look at the pounds of CO2 produced when you produce a kwh with a coal power plant and don't forget to add the coal transportation, electric and petroleum energy used to produce the coal and the horrible environmental destruction caused by mining. Fly over the Appalachians and other areas of the US and look what coal production has done.

Switching to a

Switching to a battery-powered vehicle will yield measurable savings in a motorist’s energy bills, according to a new study, while also reducing global warming emissions.
But the report by the Union of Concerned Scientists, or UCS, finds that the advantages vary widely depending upon where you live. In the best regions, savings on energy can add up to more than $1,000 annually – with battery cars cleaner than anything else on the road. But even in the worst regions, those heavily dependent upon coal to generate electricity, the UCS report says battery vehicles retain a significant advantage over traditional automotive powertrain technology.
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“No matter where you live in the United States, electric vehicles are good choice for reducing global warming emissions and saving moneyon fueling up,” said Don Anair, the report’s author and senior engineer for UCS’s Clean Vehicles Program.
The organization bills the new study as a first-of-its-kind, and unlike some more limited reports, it tracked total energy use on a wells-to-wheels basis. In other words, it measures everything from the energy actually used to pump and then refine oil to the energy used to run an internal combustion engine. For electric vehicles, the study also considered such things as the energy used and pollution created while mining coal.
Chevy Sees No Impact on Volt Sales from Battery Lab Explosion
But the advantage, reports the UCS, is clearly in favor of pure battery-electric vehicles, or BEVs, as well as plug-in hybrids.
The study shows that 45% of Americans live in what are categorized as “Best” regions, where battery vehicles result in reduced energy costs and lower greenhouse gas emissions than even the best hybrids or internal combustion-powered automobiles – those now getting at least 50 miles per gallon.
In fact, in California and New York State, a hybrid or conventional gas vehicle would need to yield at least 80 mpg to keep up with the likes of a Nissan Leaf or Chevrolet Volt (the latter operating two-thirds of the time on battery power).
About 37% of Americans live in “Better” regions, according to the new study, where a battery car still is likely to meet or exceed the emissions performance of a 40 mpg hybrid. And in “Good” regions, like Midwest states heavily dependent upon coal power, battery car emissions are equal to the best non-hybrids, such as a Ford Fiesta or Chevrolet Cruze, Anair said.
States in the “Best” category are located primarily along the East and West Coasts and include: California, Nevada, Oregon, Idaho and Arizona, New York, Massachusetts and Virginia;
“Better” states include Texas, New Mexico, Florida, Ohio, Indiana, Kentucky and Tennessee;
“Good” states are largely concentrated in the Midwest and Plains states and include Michigan, Illinois, Wisconsin, Colorado, Kansas and Minnesota.
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“No matter where you live,” he added, “electric vehicles save you on fuel costs.” With the Chevy Volt, for example, the annual savings are likely to range between $580 and $890 annually. The fully electric Nissan Leaf should bump that to anywhere from $770 to $1220 annually, according to the UCS.
Your Best – and Worst – High-Mileage Car Deals
The UCS study acknowledged significant differences in the nationwide electric grid that need be addressed, said Anair, but he added that with such efforts already underway, “The good news is that as the nation’s electric grids get cleaner, consumers who buy an EV today can expect to see their car’s emissions go down over the lifetime of the vehicle.”
Consumers have a fair degree of control over how much they save on energy by choosing rate plans – as well as when they actually charge up their vehicles, noted the UCS. Many utilities now have or are planning to offer interruptible or time-sensitive rates. And early adopters appear to be taking advantage of these. The study found the majority of current electric vehicle owners charge up overnight.
That not only means lower-cost power but also reduces the strain on the electric grid as there is less overall demand. This could permit a significant increase in the number of electric vehicles on the road without forcing the addition of more generators, the UCS report suggested.
BMW Stretches the 3-Series
Whether that will continue to be the case is far from clear. Some industry analysts warn that as more battery cars get on the road – and as the number of public charging stations increases – it will become more common for vehicles to power up during daytime. This could be especially true with the addition of high-speed “Level III” charging systems that could permit a vehicle like the Leaf to get an 80% recharge in as little as 15 to 20 minutes.
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That, experts are betting, will enhance the appeal of battery technology beyond the relatively marginal audience now turning to the technology. So far, plug-ins and battery-electric vehicles are capturing barely a tenth of a percent of overall U.S. new vehicle sales.
But Anair said the UCS is betting that demand will also increase as new models roll out, giving consumers greater choice. Before the end of this year, a wide variety of makers will enter the market, including Toyota, with its RAV4-EV and Plius Plug-in; Ford with its C-Max plug-in and Focus Electric, and Honda, with its first battery-electric vehicle since the early 1990s, a version of the subcompact Fit.

Electricity is 77% cleaner even with dirty generation!

First off gas is a dirty fuel. Refining one gallon produces 24 pounds of CO2 and burning it produces another 19 pounds of CO2 that’s a total of 43 pounds of CO2 for every gallon of gas consumed.
Secondly the internal combustion engine is incredibly inefficient. Roughly 75% of the energy found in one gallon of gasoline is wasted meaning that only 25% of the energy (or less) is used to move the vehicle . Electric engines are by comparison very efficient (upwards of 90% efficient).
If you put 16 gallons of fuel into your Prius you’ve put 384 pounds of CO2 into the environment before you leave the gas station
Once the Prius driver has burned all of their fuel they will have released 688 pounds of CO2 into the environment (versus the an EV at 158 pounds – given the worst case scenario for the electricity)
Driving an electric vehicle results in a 77% reduction of emissions compared to conventional vehicles. (even in the worst case scenario of coal fired electricity)

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