Do Electric Vehicles Live Up To Their "Green" Reputation?

[dlich18]

Here is an article published today by the Berkeley Energy & Resources Collaborative regarding whether EVs are actually cleaner.

http://berc.berkeley.edu/blog/post/electric-cars-on-a-dirty-grid-clean-or-not

It reports on a new study by Climate Central which concludes that it depends on in which geographic area you are charging. In some areas, according to the study, EVs are not actually the most climate-friendly car choice. Fortunately, I am in California which is identified as one of the few states where EV's are actually cleaner.

"In 36 states, the hybrid electric Toyota Prius produces less greenhouse gas pollution than the all-electric Nissan Leaf, because when you plug in a Leaf to recharge, you are tapping into electricity generated largely by burning coal and natural gas in those states."

Coal is the largest contributor to the high carbon footprint of our electrical grid today. In states like Wyoming or Indiana, where 90 percent or more of the electricity comes from coal, driving a Leaf is responsible for much more greenhouse gas emissions per mile (about 0.9 pounds) than a Prius (about 0.5 pounds). The Leaf fares better in states that get a significant share of their electricity from natural gas, like Rhode Island or Nevada (about 0.6 pounds per mile), but typically still produces more emissions than a Prius. The Leaf does best in states that rely heavily on nuclear, like Connecticut (0.3 pounds), or on hydropower, like Idaho or Washington (0.1 pounds).

Here's a link to the full study:

http://www.climatecentral.org/news/climate-friendly-cars

 

[Alric]

The difference with EVs is that there are ways to decrease their carbon footprint even on "dirty" areas.

For example you can offset your charging electricity with renewables by paying a little extra to your power company. I buy this energy offset from my local electricity provider

http://db.tt/4CrA7sFW" onclick="window.open(this.href);return false;

The study is clear than in more than half the countries EVs are more beneficial even when compared to hybrids.

 

[kubel]

I currently drive a big V8 sedan. It's not very fuel efficient, and I don't lose any sleep over my carbon footprint. I'm probably in the minority here, but I didn't want a LEAF for its green qualities. I wanted it because I think electric drive is awesome. I'll let the utility companies worry about cleaning up their act. I hear the grid is getting cleaner every year. I also hear that electric cars typically charge at night, a time when there is otherwise wasted excess capacity. If coal is being burned regardless of whether there's an electric car plugged in, I might as well use the electricity that it produces. Why let it go to waste AND burn gas?

 

[planet4ever]

I'm no expert, but that study appears flawed to me. I find it impossible to believe that a LEAF could ever "be responsible for almost double the carbon-output per mile over a fuel-efficient hybrid like the Prius." Of course this applies only to states that generate nearly all of their electricity from coal, but is it really possible that burning coal in a large plant at a constant rate is half as efficient (in terms of GHG emissions) as burning gasoline in millions of small engines operated under wildly varying power conditions?

Two things I spotted:

A gallon of gasoline releases about 19 lbs of CO2 when burned, or about three times the weight of the gallon before it burns. To these CO2 emissions we must add the GHG emissions associated with extracting, transporting, and refining the crude oil used to make that gallon of gasoline. When these are included, the total lifecycle GHG emissions for using gasoline in a car come to 25.9 lbs of CO2-equivalent per gallon.

We have been led to believe that the amount of energy required (from all sources) just to refine a gallon of gasoline is equivalent to the electricity to drive 20 miles or more. How can the life cycle GHG of creating gasoline, much of it from oil transported halfway around the globe, be less than 40% of the GHG generated when it is burned?

To make our analysis tractable, we have chosen not to consider time-of-use variations in electricity emissions

In other words, they are assuming that a large fraction of EV charging will occur while the most inefficient peaking generation sources are in use.

Ray

 

[Smidge204]

We have been led to believe that the amount of energy required (from all sources) just to refine a gallon of gasoline is equivalent to the electricity to drive 20 miles or more. How can the life cycle GHG of creating gasoline, much of it from oil transported halfway around the globe, be less than 40% of the GHG generated when it is burned?

The "20 miles of driving" comes from the inference that it takes 7.5kWh of energy to make <i>and deliver</i> one gallon of gasoline. This is based on a DOE study stating the overall well-to-wheels efficiency for delivering gasoline is 83%. So 7.5kWh, if in the form of electricity, is ~20 miles of EV charging.

Note that the 7.5kWh is "energy" - not electricity, not fossil fuels, or anything specific. We have no way of knowing what the energy mix for that is. Be that as it may, the refining and delivering process produces ~27% more GHG than the gasoline itself - for only 17% of the total energy involved.
=Smidge=

 

[N1ghtrider]

The Union of Concerned Scientists notes that, whenever we talk about the great potential of electric vehicles (EVs) to reduce our oil use, rein in global warming emissions, and save consumers money at the pump, we always get the same question: how much will these vehicles really reduce emissions if they’re often plugged into electrical outlets that draw their power from dirty sources? Well now we know—a new UCS report finds that not only do EVs produce fewer emissions than average new compact gasoline powered cars, but nearly half of the U.S. population lives in a region where driving on electricity results in fewer emissions than even the best hybrids! Check out all the details and see how your region stacks up in UCS's State of Charge report.

http://www.ucsusa.org/publications/pulse/Pulse_may_2012.html" onclick="window.open(this.href);return false;

 

[llaumann]

Here is the direct link to the State of Charge report by the Union of Concerned Scientists-

http://www.ucsusa.org/clean_vehicle...issions-and-charging-costs-electric-cars.html

"Nationwide, EVs charged from the electricity grid produce lower global warming emissions than the average compact gasoline-powered vehicle (with a fuel economy of 27 miles per gallon)—even when the electricity is produced primarily from coal in regions with the “dirtiest” electricity grids."

"In regions with the “cleanest” electricity grids, EVs produce lower global warming emissions than even the most fuel-efficient hybrids."

"EVs charged entirely from renewable sources like wind and solar power produce virtually no global warming emissions."

There you have it. Thanks,

Lynn

 

[SteveInSeattle]

Leaf drivers who obtain their power from Seattle City Light are among the cleanest in the country-- 97% of City Light's power comes from hydroelectric, wind and (a little bit) of nuclear. Only 3% from carbon producing sources-- and those are natural gas, considered a pretty clean source. Most all of the West Coast is a clean sourced area and perfect for EV's. Maybe customers in 100% coal burning areas should weigh whether the Leaf meets their needs and expectations, but West Coast customers should be very pleased with the results they produce.