How will the Chevrolet Volt be better than a Toyota Prius plug-in hybrid?

In my last post (about national average), I presumed your math was right, just questioned your assumptions. Looking back I realized I cannot see how you did your computation and that your numbers seemed way off.

There are 2.08 lbs of CO2 per kWh for coal generation so
1837 *2.08 = 3820.

There are 20 lbs of CO2 per gallon of gasoline
so 3820/20 = 191 is the carbon equivalent of the coal.


So not only were the assumptions questionable, the basic math was wrong.

Even estimating using your assumptions fo 50% coal, your estimated "fossil fuel" equivalent was way too low.

A nice discussion of the "MPG" equivalent of the volt, for different california Power companies, is given at
Electric Car Mileage for Chevy Volt from Equivalent Carbon Dioxide Pollution
At the national grid average.. its about 60mpg (not surprising that is the EPA's MPGe overall estimate.)

 

For who? That implies they cost the same.
.

 

Right except I have Chicago at 70% coal...so we are giving national averages above.

 

You are quoting a very low CO2 yield, I will let you know if I agree with it after some checking.

 

2.08 sounds about right to me, although it does not include the 10% used by the central power plant itself, the ~ 7% transmission losses, and the ~15 -20% charging losses.

A reasonable estimate of power-plant-to-battery is therefore
2.08/(.9*.93*.83) = 3 pounds CO2 for a kwh in the battery from coal.

It takes about 15 kwh of battery energy to travel 50 miles in the Volt, or 15*3 = 45 pounds of CO2 if all the electricity is from coal. If the power-plant had half the carbon intensity, the Volt would about equal the Prius.

While the grid is ~ 50% coal nationally (actually I think 45% is closer), the other ~ 50% is mostly other fossil fuels. They have to be included in the CO2 comparo.

 

Here we go again focusing only on the vehicle efficiency and ignoring the fuel production (FP).

Prius PHV's 95 MPGe includes gas, which has much higher FP efficiency than electricity. The only comparable figure is well to wheel efficiency. In doing so, it reveals Volt is less efficient.

That's not all. Volt will spend more than a third of it's life tied to a plug.

 

It assumed Volt uses 25 kWh/100mile. The official EPA figure is 36 kWh/100mile. There is 40% optimism. 60 MPG x 0.6 = 36 MPG.

 

I used 36 in my previous calc just because I have a 2011 that doesn't show it. You can feel free to use 23.1 below instead in my calcs <grin> but that makes them look much better ... just to warn you.

This guy with a 2012 that does show kWh used sees 23.1 kWh / 100 miles.

 

So redoing my calcs with the 23.1 kWh and using my real midnight kWh cost of about $0.06 instead instead of my avg of $0.09 here is my years cost. Yes, that price includes taxes and fees.

OLD:
(10208 EV miles) / 100 miles = 102.08
(102.08) * (36 kWh) = 3674 kWh
(3674 kWh) * ($0.09/kWh) = $330 for 12 months of electricity using EPA numbers in calc.

NEW:
(10208 EV miles) / 100 miles = 102.08
(102.08) * (23.1 kWh) = 2358 kWh
(2358 kWh) * ($0.06/kWh) = $142 for 12 months of electricity using 2012 users numbers in calc.

 

There is no need to cherry pick. The link drinnovation provided used EPA 50 MPG for Prius so we should stick with the EPA figure for the Volt to remain comparable.

 

Feel free to use 23.1 kWh from the real world example or 25 kWh. I was just pointing to my example which you then used to run your own numbers to do CO2 chest pumping.

I like reducing my gas usage and the Volt does it amazingly well.

I like the CO2 aspect as well and love that various states and countries (Canada for example) have cleaner and cleaner ways of producing electricity. After my yearly obligation to ComEd and my hourly rate plan I plan on looking at some of the other "cleaner" options but overall I'm satisfied with my early adopter status leading the way for others who may be cleaner and cleaner.

Quote from a Canadian Volt owner:

 

OK I understand a little better. I have been using as a ballpark number, when you burn coal electric generatation is about 1 kWhr per pound of coal. This represents ~34% heat recovery which is reasonable (some plants ~30% some plants >30%).

My MPG "fossil fuel equivalent" is pounds (lbs) coal burned vs. pounds (lbs) gasoline burned.

Also I have been neglecting nat gas for example if its elec 50% coal, then I divide coal by 2.

When you start talking CO2 per se then coal is 70-75% carbon vs. 84-85% for gasoline. Coal has sulfur, ash, oxygen etc. Therefore coal is a little less CO2 yield per pound vs. oil, but then you have the other waste products.

 

I got 70.1 mpg in my Lexus going to work today. Feel free to use that.

 

My point was it was a real world 2012 example and they have not changed the efficiency between the 2011 and 2012s so I expect it to be comparable to my 2011 in reasonable weather.

 

From Wikipedia

Quite a bit higher than I wrote earlier, yet Volt is already a pollution contraption using my underestimates and an "average" grid.

 

Meaning what ?

Compare EPA to EPA, or some other apples to apples test. The anecdotes from you and your friend are very interesting I am sure (to somebody), but useless in estimating fleet pollution per unit, or in comparison to a Prius.

 

Wikipedia sometimes is not reliable. 30% is fine number for the coal fleet we have now, but new coal plants are certainly much better than that. I found it funny that an oxyfuel combustion coal plant (which has extremely extremely low emissions) actually has a higher efficiency than the current average of coal generators. However given there is no carbon price there is absolutely no reason to entice a utility to build such a coal plant.

 

Dennis, I'm surprised to see you still write

Fixed fees are paid on the first kwh

 

Wikipedia in this case has excellent source. The data are fine.

When the new-fangled plants are up and running in enough quantities to change the carbon density of electricity from coal I'll be happy to recalculate. One thing is for sure though: EVs bought today will be in the dumpster before that happy day arrives.

I 100% agree with your point that carbon taxation is the way out of our mess.

 

Don't get me wrong. I think it is great and do wish there are more like him/her.

I was using national average (which includes renewable), if you call that chest pumping. My point was, it was an extreme example. Another example is a Volt owner (2011-01715) in West Virginia where 98% of the electricity is from coal.