plug-in states and ghg

I've never claimed that so stop putting words in my mouth. We are disagreeing on the rate at which the grid is getting cleaner and the micro/macro emission views.

Sorry but this is off topic. This thread is about emission.

I think you are referring to PiP. As much as you want to downplay the significance of PiP, I have 41% of my miles in EV and 59% in HV. For people with commute like me, we are not going to buy Volt to lug the gas engine and the oversized battery around in return for less cargo volume and one less rear seat.

Per EPA (statistics), PiP should put 29% of the miles on EV while reducing the overall emission. That's pretty significant and effective.

 

But aren't you saying that those EV miles are higher emissions than the HV miles? If so, shouldn't you reduce your EV ratio?

 

Not with PiP. At 29 kWh/100mi consumption, the emission is lower. If you don't plug PiP in, it will get 222g/mi emission. If you plug it in, PiP is rated 210g/mi.

Note, lower g/mi is better. Lower ghg per mile.

 

So when the EV range drops below 12 miles during east coast winter or southwest summer, don't plug in?

 

EPA estimates are for all year round. 210 g/mi all year round average with statistic prediction of 29% EV miles.

C-MAX Enegi would cover 48% of miles in EV. Because it has 43 MPG gas engine, it is rated 240 g/mi.

Volt covers 66% EV and 37 MPG gas engine drags it down to 260 g/mi.

Gas engine efficiency is very important in plugin hybtid.

 

Only if you use gas. The less gas you use the less important the ICE efficiency is.

 

You are confusing me.

You seem to be saying that sometimes EV is less ghg than HV and sometimes it's not, but statistically it is lower over the course of an entire year?

Wouldn't it be even less if you didn't plug in when the full charge EV range is less than 12 miles (29 kWh/100mi)?

 

And with a large enough battery and/or quick charging, you might not use ANY gas.

Harder to do with a small battery and slow charger, hence the need for an efficient ICE in an undersized configuration.

I think usbseawolf is trying to explain that the ghg impact of a PiP vs a Prius is marginal, and perhaps negative in many instances depending on the source of the electricity. If I understand him, someone that is considering a Prius vs a PiP should NOT go the route of the PiP, except to save money on the purchase price if there are overstock deals to be had and to take advantage of the various tax credits.

To me this sounds like maybe any additional tax credits and incentives should not be extended to the PiP beyond those for the regular Prius.

 

The emission cross point between 50 MPG HV and EV is 34 kWh/100mi. That's when they both are rated around 222-230 g/mi.

If PiP is driven in such a way that you get only 8 miles per charge (roughly 340 Wh/mi), then it is better to drive it unplugged (just with gas, assuming you still get 50 MPG).

 

If you don't use gas, it is better to drop the gas engine and not lug it around right?

Even if you drive 100% of the miles in EV with the Volt, the emission will still be higher than a regular Prius. That's because Volt is rated 36 kWh/100mi. You need to beat the EPA figure and get down to 34 kWh/100mi in order to equal the 50 MPG emission (using national average electricity).

Apparently, the electricity consumption took a hit by lugging the gas powertrain around.

 

I'm currently at 32kWh/100mi. Is that good?

 

better than a 50 mpg Prius! according to usbseawolf.

 

Yup. If you drive the same way, you should do better with Leaf or PiP. How about your gas efficiency?

 

Some folks are more comfortable hauling around a gas engine just in case, some people want a 5th seat just in case they need to haul around thier mother-in-law.

 

The argument of considering local emissions patterns in deciding whether a plug-in is better than a Prius is fair enough, so long as the marginal effect is considered. I find funny the irony that AG wants to avoid average national grid numbers, but is happy to use average local grid numbers.

Once again, ideology trumps reason.

 

Yes EPA shows the average, but they don't misinterpret is meaning like you do. EPA lists it but does not recommend it be used to analyze which car produces less ghg.. that is you misusing the data. So we are free to point at you for doing bad things with EPA data.

Once again you are misusing EPA data.

The PiP is NOT EPA rated at 29kWh/100mi... its rated at (29kWh + 0.2)/100m, which is 95MPGe (or about 36kWh/100mile equivalent). So its EPA rating when operating in CD mode as PHEV is less efficient than the Volt (98MPGe). There is NO measurement of which I am aware that allows you to draw any other "EPA" related decision. If you had measured the volt efficiency on only the "easy" part of the EPA test you would get a different answer that is much less than 35kWh/100miles. In the New European Drive cycle it gets 52miles with 13kWh or about 25kWh/100miles.. You cannot just ignore the hard part of the test.


So in CD mode the PiP efficiency is about 36kWh/100 miles, so since you say, the break even point for ghg is 35, then the PiP should not be plugged in on average, and the PiP's ghg advantage over the Prius is not because of its PHEV but likely because it gets 49mpg highway vs 48mpg.

And as others have said, people don't buy from that source, they buy from whom they choose. They also have potentially very different driving ratios.

At any point in the "grid", either using electricity is more ghg efficient than a gas at 50mpg or its not. If local grid average is worse than 50mpg, like it is in my region, then any plugin, including the PiP, will produce more ghg than a Prius unless the owner buys renewable. As soon as they buy renewable, then more EV range will reduce their ghg by a greater level and the PHEV is better than a prius.

In places where its EV is less ghg intensive, then since when operating in CD mode the volt is more efficient, but on gas its less efficient, the difference in ghg is, is more a function of Driver EV/HV mix. The NHSTA projected default 66% EV for Volt and 29% for PiP is also a national level average.. so its also needs to be used cautiously.
Since the Volt has more EV range and better efficiency in CD mode, means it produces less ghg in regions.

The point of the thread was showing that, given where the PHEVs are being sold, its just plain wrong to consider the unweighted average. In a properly weighted average, the EV ghg of anything but the Karma is lower than a 50MPG hybrid, so the more EV the better.

 

Do you have any good sources for estimating local marginal impact? I am not aware of any such data, and tried hard to find it for Colorado. Marginal data, especially for only a few kWh, its very hard to estimate. E.g. if a coal plant is below its peak efficiency, increasing demand will improve efficiency per kWh, so do you attribute that to the added load or the base? How do you allocate the choices of the energy company, as I've posed before in CO we have companies idling wind because they don't want to take coal plants below minimum.. they often run those plant and just vent steam.. all while they ignore the wind they could buy from another vendor. What is the marginal impact then?

 

So I am hearing a confirmation of usbseawolf's assertion that someone that finds a Prius suitable for their needs should select a Prius rather than a PiP, unless the PiP costs less, but even then it shouldn't be automatically plugged into the grid.

These is not intuitive but "the devil is in the detail" as they say.