AutoEcoRating Blog, Prius more green than Leaf?

[planet4ever]

If you look at his car comparisons it's clear that all he did when looking at BEVs was to consider the pollution attributable to electrical generation. I won't even bother getting into why treating mass the same way for BEVs and ICEs makes little sense nor why CARB certification isn't a good proxy for emissions much less pollutions. What I will say is that IF he was going to consider the emissions and pollution attributable to refining, at a minimum he would have had to (1) use 36.4 kWh (the higher DOE number) as the energy content of gasoline since that's what you get when you treat gasoline like you do electrical generation and (2) account for refining as being, at most, 85% efficient. If you do that the Leaf gets 126 MPGe. But he uses the EPA number of 99 MPGe. Since this number most certainly does not account for the refining process it's safe to conclude that he is not considering refining in his comparisons and that his "apples to apples" comparison is in fact an "apples to potatoes" comparison.

If you consider that a rant you're entitled to your opinion.

That explanation is most definitively not a rant. Thank you for spelling it out. As I said before, "I find the results very suspicious. Show us how those numbers were derived and then we can decide if they are believable." You have now shown that, and his numbers are not believable.

 

[SanDust]

That explanation is most definitively not a rant. Thank you for spelling it out. As I said before, "I find the results very suspicious. Show us how those numbers were derived and then we can decide if they are believable." You have now shown that, and his numbers are not believable.

The more general problem inherent in comparing the Prius to the Leaf is that, while you can use averages if you want to compare the average EV with the average ICE vehicle, if you want to compare an individual EV with an particular ICE vehicle it's best to consider the particular grid the EV will use for charging.

You can do this for your own grid by going to this EPA website and typing in your zipcode. http://www.epa.gov/cleanenergy/energy-and-you/how-clean.html You'll get the pounds of CO2 per MWh. Just divide by 1000 to get pounds per kWh. Note that you'll get the national average as well as your local number. Also note that these numbers are from 2005 and the grid is getting cleaner. For example, if you look at San Francisco you'll see about .725/kWh but PG&E claims it is now down to .524. http://www.pge.com/about/environment/calculator/assumptions.shtml (This is why people say that EVs will get cleaner throughout their lives -- the grid will get cleaner).

Calculating the CO2 emissions produced by an ICE vehicle is straightforward and valid everywhere. The Argonne Labe GREET model finds that burning a gallon of gasoline creates 27.3 lbs of CO2. You can just plug in that number, meaning that a Prius going 100 miles will produce 54.6 lbs of CO2.

The Leaf uses 34 kWh from the wall to go 100 miles (range=73 miles). Since the EPA number gives the lbs of CO2 produced when delivering electricity to the wall, you can just multiply the lbs/kWh you got from the EPA website by 34.

While charging the Leaf from the average grid will produce less CO2 than the Prius, charging it from the grins in the markets where Nissan is selling Leafs should produce half or less. Hawaii would probably be the place where this result would not obtain since, unlike most of the states where the Leaf will be sold, HI uses oil to produce electricity.

 

[DarkStar]

You can do this for your own grid by going to this EPA website and typing in your zipcode. http://www.epa.gov/cleanenergy/energy-and-you/how-clean.html You'll get the pounds of CO2 per MWh. Just divide by 1000 to get pounds per kWh. Note that you'll get the national average as well as your local number. Also note that these numbers are from 2005 and the grid is getting cleaner. For example, if you look at San Francisco you'll see about .725/kWh but PG&E claims it is now down to .524. http://www.pge.com/about/environment/calculator/assumptions.shtml (This is why people say that EVs will get cleaner throughout their lives -- the grid will get cleaner).

Yep, that chart states 34% of my electricity comes from coal. Since I pay for 100% renewable energy, the actual total is 0%, but the chart doesn't tell me how to calculate that!

 

[garygid]

Yes, you might PAY for all green electrons (or M&Ms), but you actually get some "black" e-fuel as well.

 

[scottsim]

There are Prius' and there are converted PHEV Prius' like mine.

I have no regrets about sticking with my 12KWh (measured at recharge), converted PHEV Prius.

Scott
http://www.smilingdogsranch.com/priusblog

 

[evnow]

Yes, you might PAY for all green electrons (or M&Ms), but you actually get some "black" e-fuel as well.

You don't. Ofcourse you don't exactly get the green "electrons" - but the utility promises to buy that much green electricity.

Will renewable energy resources be delivered directly to my home or business?
The electricity generated from the renewable resources that you support is put into the Northwest power-supply grid along with electricity from all of our other resources. Much like water or natural gas, it isn't possible to differentiate the sources at the point of delivery. By choosing PSE's Green Power Program, you are supporting the environment and helping to increase the proportion of renewable energy that is available to the entire system.

http://www.pse.com/energyEnvironment/renewableenergy4/Pages/greenPowerProgramFAQ.aspx#q3

 

[garygid]

In CA each PU is required to buy an increasing percentage of its electricity from renewable sources, even if you do not volunteer to pay more for your e-fuel.

So, to satisfy you, they are (most likely) NOT buying MORE, but "yours" is just part of what they are already required to buy.

So, until there are LOTS of green-buyers, to make them by more than required, your extra $$ might just fund an extra executive-bonus program.

And, even if LOTS and LOTS of subscribers buy "green", who is going to catch the PU's bookkeeping "error"?

 

[evnow]

In CA each PU is required to buy an increasing percentage of its electricity from renewable sources, even if you do not volunteer to pay more for your e-fuel.

I have wondered about it. From what I've been told, they have to buy over the mandate.

Ofcourse, this is like buying organic food.

 

[bowthom]

Can you figure out where the difference in analysis comes from? TOYOTA :lol: