Leaf Powered by Fossil Fuels Gets Equivalent of 28 MPG?

[Stoaty]

http://energybulletin.net/stories/2011-08-29/mpg-electric-cars" onclick="window.open(this.href);return false;

I haven't studied the article closely, since my Leaf is powered by Green Power from LA DWP. However, I thought I read in the past that powering an EV with electricity produced from coal still released 30% less CO2 than a gasoline engine. Comments?

 

[palmermd]

well then its a good thing all the leafs are powered by electricity. ignore the fud.

 

[TomT]

Interesting... How does the green power know to go down the wires to only your house??? :lol:

I haven't studied the article closely, since my Leaf is powered by Green Power from LA DWP.

 

[surfingslovak]

I haven't studied the article closely...Comments?

The author overestimated the amount of energy needed to charge the Leaf by 15% (26 vs 30 kWh) and factored in charger inefficiency twice. Why? I believe that the EPA measured wall to wheels kWh usage, and their MPGe number already includes both charger and drive train inefficiency. Furthermore, the writer factors in transmission losses at 10%, although 6-8% are commonly used and fossil power plant efficiency of 35%, although natural gas stations commonly get at least 50% and new coal-fired plants get 60%.

http://www04.abb.com/global/seitp/seitp202.nsf/c71c66c1f02e6575c125711f004660e6/64cee3203250d1b7c12572c8003b2b48/$FILE/Energy+efficiency+in+the+power+grid.pdf" onclick="window.open(this.href);return false;

If you add that all together, the number quoted in the article is off by a factor of about 2. He also did not include the energy expended on gasoline refining.

 

[garsh]

At least he still points out that the fuel cost to the owner is still a lot less. Although his charging prices seem higher than what I've read elsewhere.

 

[Stoaty]

Thanks for the detailed analysis. I thought he was painting with a pretty broad brush that was not completely accurate.

The author overestimated the amount of energy needed to charge the Leaf by 15% (26 vs 30 kWh) and factored in charger inefficiency twice. Why? I believe that the EPA measured wall to wheels kWh usage, and their MPGe number already includes both charger and drive train inefficiency. Furthermore, the writer factors in transmission losses at 10%, although 6-8% are commonly used and fossil power plant efficiency of 35%, although natural gas stations commonly get at least 50% and new coal-fired plants get 60%.

http://www04.abb.com/global/seitp/seitp202.nsf/c71c66c1f02e6575c125711f004660e6/64cee3203250d1b7c12572c8003b2b48/$FILE/Energy+efficiency+in+the+power+grid.pdf" onclick="window.open(this.href);return false;

If you add that all together, the number quoted in the article is off by a factor of about 2. He also did not include the energy expended on gasoline refining.

 

[Stoaty]

Interesting... How does the green power know to go down the wires to only your house??? :lol:

There is a well-worn path made by millions of previous electrons, so it is pretty easy for them to follow. :lol:

 

[jkirkebo]

Theoretically, my generator (Honda EU65iS) at my cabin will use 3.2 gallons of fuel to fully charge the Leaf. If I get 90 miles of range, that is 90/3.2=28mpg. However, the generator will only be used for the beginning of my return trip from my cabin (175 miles each way), in addition to three slow charges and two QCs for the whole trip. So the total will be 350/3.2=109mpg.

I will of course test this in practice as soon as I get my Leaf (hopefully in a month).

 

[smkettner]

It is interesting that he will go back to the supply on the coal to produce electric and then assumes gasoline appears at the pump by some magic. :roll:

 

[SteveInSeattle]

Electric cars are less efficient if the issues related to electrical generation are factored in, but then the only fair comparison to gasoline cars must then include the energy involved in shipping and refining crude oil. Now the comparison tips way in favor of EV's. EV's will be more efficient when more alternative energy sources come on line for generation, gasoline will never get that much more efficient.

 

[surfingslovak]

Electric cars are less efficient if the issues related to electrical generation are factored in...

Steve, good point, but I would consider Tom Murphy's article to be the absolute wort-case scenario. In his calculation, he assumes that all of the electricity to power the Leaf came from a legacy coal-fired power plant, and he overestimates the losses every step of the way and still arrives at 28 mpg. Although not as good as a hybrid or a diesel, how is that worse than an average passenger car? I believe that the 2010 CAFE standard was 27.5 mpg and although the Bureau of Transportation Statistics does not list US fleet averages for recent years, new MY 2010 passenger cars are reportedly averaging 33.7 mpg. As you have noted, this worst-case scenario does not factor in the manufacturing and transport of gasoline. Although it neglects the same thing when it comes to coal and natural gas for power plants, I would expect EVs to be on par with conventional cars, if not slightly better.

 

[GeekEV]

...the only fair comparison to gasoline cars must then include the energy involved in shipping and refining crude oil.

+1
They *never* seem to factor in the energy usage to produce and distribute the gas when calculating the "emissions" of electric vs. gas, so, as you say, it's not a fair comparison. Cost comparisons, however, are fine as they do include the cost of production and distribution on both sides.

 

[palmermd]

...the only fair comparison to gasoline cars must then include the energy involved in shipping and refining crude oil.

+1
They *never* seem to factor in the energy usage to produce and distribute the gas when calculating the "emissions" of electric vs. gas, so, as you say, it's not a fair comparison. Cost comparisons, however, are fine as they do include the cost of production and distribution on both sides.

This is the most comprehensive list of links to references on energy to produce gas. By no means can we build a bulletproof argument with this data, but it does give ballpark figures....

http://evnut.com/gasoline_oil.htm" onclick="window.open(this.href);return false;

How much electricity does it take to make a gallon of gasoline? We don't know - but here's one stab at it. Ballpark figures only, and NOT a supportable conclusion. The most important message to take away is that it is not trivial! This part of gasoline is ignored by the folks who are concerned about the big impact on our electrical grid if we were to suddenly shift all transportation from gasoline to electricity.

To extract one gallon of gasoline (or equivalent distillate): 9.66 kWh (maybe not all in the form of electricity*)
To refine that gallon: 2.73 kWh additional energy (maybe not all in the form of electricity*)
Total: 12.39 kWh per gallon.

*Roughly one-third of the energy content of a gallon of gasoline produced from California wells is input from natural gas. Less than 2/3's is net energy (probably a lot less!).

So I can get 24 miles in my ICE on a gallon of gasoline, or I can get 41 miles (at 300wh/mile) in my RAV4EV just using the energy to refine that gallon. Alternatively - energy use (electricity and natural gas) state wide goes DOWN if a mile in a RAV4EV is substituted for a mile in an ICE!

Even if you cut the electric energy values taken to produce a gallon of gas in half, you could still travel 20 miles in an EV just in the electricity it takes to make the gallon of gas.

 

[GeekEV]

Even if you cut the electric energy values taken to produce a gallon of gas in half, you could still travel 20 miles in an EV just in the electricity it takes to make the gallon of gas.

And that's not even taking into account the gas burned by the tanker trucks hauling all that gas to the gas stations!

 

[youngr3]

According to the Sierra Club info there are a number of studies which says that an electric car yields 35-60% less carbon dioxide polution from electricity than the carbon dioxide polution from the oil of a conventional car with ICE. Reminds me of a variation of an old saying...numbers lie and liers use numbers. There are too many non-scientific trained people throwing around numbers that they do not understand just to make a point that they have been brain washed to believe. I continue to be surprised by how many nattering neybobs of negativity are still alive out there and how negative they can really be about electric cars. I think they have their heads in the sand about the significant impact of purchasing oil is on our negative trade balance and subsequent impact on our budget deficit.

 

[surfingslovak]

There are too many non-scientific trained people throwing around numbers that they do not understand just to make a point that they have been brain washed to believe.

Right, I thought the same thing until I realized that Tom Murphy, the author of the article, is an associate professor of physics at UCSD. According to his bio, he was an amateur astronomer in high school, physics major at Georgia Tech, and PhD student in physics at Caltech. That's why his write-up is even more disappointing.

Note how he dismissed or ignored relevant comments from his blog readers. Talk about head in the sand:

http://physics.ucsd.edu/do-the-math/2011/08/mpg-for-electric-cars/#comment-464" onclick="window.open(this.href);return false;

http://physics.ucsd.edu/do-the-math/2011/08/mpg-for-electric-cars/#comment-453" onclick="window.open(this.href);return false;

http://physics.ucsd.edu/do-the-math/2011/08/mpg-for-electric-cars/#comment-449" onclick="window.open(this.href);return false;

 

[Phoenix]

Theoretically, my generator (Honda EU65iS) at my cabin will use 3.2 gallons of fuel to fully charge the Leaf. If I get 90 miles of range, that is 90/3.2=28mpg. However, the generator will only be used for the beginning of my return trip from my cabin (175 miles each way), in addition to three slow charges and two QCs for the whole trip. So the total will be 350/3.2=109mpg.

I will of course test this in practice as soon as I get my Leaf (hopefully in a month).

What kind of hookup will you use to charge the Leaf from your generator?? Similar remote location and want to explore backup electric options.

 

[smkettner]

Even if you cut the electric energy values taken to produce a gallon of gas in half, you could still travel 20 miles in an EV just in the electricity it takes to make the gallon of gas.

And that's not even taking into account the gas burned by the tanker trucks hauling all that gas to the gas stations!

Or the amount of coal to make electric to refine the gasoline :lol:

 

[smkettner]

Then let's compare our cost to keep the world safe for coal vs oil.

Would we really be at war in the middle east if the US exported oil?

 

[klapauzius]

Another important point not mentioned in the blog is that usually there is an oversupply of electricity during nighttime, which would otherwise go to waste ( to some degree), but now can be used to charge your EV, because you cannot shut down the power plant simply because demand is low.
There is no such thing for gas.
While this does not affect the "efficiency", whatever this turns out to be, it has a real practical impact on emission and overall efficiency of our economy.