Plug in Prius - Most Environmentally Friendly Vehicle in Study

wow! that's tmi for my peanut size brain, but, if greenhouse gasses are your primary consideration for a new car, it's a very simple and helpful guide.

 

Thanks for posting. It has treasure trove of common sense and data not blinded by the love of EV.

 

I didn't see where it says what EV % it uses to evaluate the Prius Plug-in. This will make a big difference in energy consumption comparison to the Nissan Leaf and others, especially in states such as California that don't use much/any coal. My EV% is around 54% for the first 4000 miles. The Prius is already better considering vehicle manufacturing and fuel consumption.

On page 17 the table showing lbs c02e/mile (including vehicle manufacture) it shows the Plug-in at 0.81 and the Hybrid at 0.83 for 50,000 miles of driving. So I guess they make a very small assumption for EV% of the miles.

On page 27 it appears that the Prius Plug-in has a 7.6 kWh battery which is incorrect, its 4.4 kWh. The problem is the numbers in the right-hand column are misaligned one line up.

 

i think it was more about your commute distance, etc.

 

The kWh is actually shifted up one row up. 7.6 kWh is for the C-Max Energi.

 

They probably used the EPA/US DOT figures from fueleconomy.gov site. 29% for PiP, 48% for C-Max and Fusion Energi, 66% for Volt.

If your overall EV ratio is 54%, you are way ahead.

 

Emission from the battery manufacturing is a big chunk.

 

Thanks, that's a good catch. I am doing about 50/50.

 

Wow! Lots of data, but they are missing the trees in the forest but looking at the tiniest details of the leafs.

Top Ten reasons why this study is flawed

10. They are only considering CO2, and not inner city smog

9. They fail to see that promoting EVs and PHEVs in the short term helps the long term prospects of an electrified car industry. Failure to get the volume up, technology improved and widespread adoption (over decades) will mean more CO2 emissions overall. We can improve the grid as a separate goal.

8. Why no comparisons to the typical average car?

7. Short term thinking on VT. Doesn't virtually all their power come from a nuke plant that they are trying to shut down?

6. I suspect that they just use the steady state CO2 emissions from a gallon of gas. This minimizes the real world advantage of a PHEV that needs a warm up cycle that reduces mpg and thus increases CO2 in the first few miles. a PHEV (PIP, Volt, etc) eliminates these short trips and replaces with EV from a truly warmed up power plant, even if it is coal.

5. Do they consider at all the fact that most EV charging takes place at night? This tends to make power plants more efficient than they otherwise would be, in a throttled back state.

4. They only take into account 50K and 100K mile car lifetimes. This is not realistic given that the car batteries are designed to last 150K miles or more. Even if you are not in a CARB state, the same batteries "should" last beyond the 100K miles they assume and probably beyond 150K miles.

3. Do they consider the amount of CO2 expended in maintaining the cars? EVs should have less maintenance per mile.

2. Gas cars emit more and more pollutants as they age. Especially smog forming NOx, etc. This is a well-known fact as smog check requirements in many states allow a pass on older cars as they age. EVs will have no such degradation since all the CO2 and other emissions are at the power plant.

1. Battery cells can be replaced and refurbished, extending the life of EVs even beyond the 150K expected life

Mike

 

This report sheds many lights and will increase the awareness. It is no way "flawed".

They used 2010 and 2012 electricity emission to compare the progress the grid is cleaning up.

 

I didn't notice that, after all its on the 1st page.

However, they call a Chevy Volt a Plug-in and it goes 40 miles on a charge. If they used 50/50 for all plug-ins and the Prius gets better gas mileage after the battery is discharged there is probably another few percent (2%, maybe 4%) advantage for the Prius Plug-in.

 

The study says what I feel, it is hard to beat Prius Hybrid and PiP re: eco cost.

Since they used new 2012 data which was unexpectedly sharp down-turn for coal% in USA (will be interesting to see if 2012 trend conintues) the Prius hybrid is taken down a notch (still near top) but also now we have PiP. I have a personal concern about these sorts of studies, suspecting they may be missing the impact on CO2 of the EV's using air cond in summer and heater in winter ( I know many early adopters are conserving battery charge but general public would want to use those things).

 

Ya, we knew that already but this included manufacturing emission. PiP is cleaner than the Leaf even in one of the state with the cleanest grid, California. It was the other way around if we look only at the fuel from well to wheel.

 

I like the report, but I just noticed funny VA data in the report:

EPA Power Profiler shows 45% coal in Virgina (2009)(my zip), this report says we're down to 20% coal in 2012! I don't want to criticize my state, but we're not known for being too green, and I would not be aware of any steps taken to reduce coal use...I know many coal plants have nat gas turbines, so they have some hidden capability to shift fuels, but that seems huge shift.

 

A 24.8 MPG car shows on at least one graph, on Page 17 of the PDF. (Page 13 of the report)

I am assuming they are using combined EPA, so they do not bother to break out the Prius C, as it has the same EPA Combined number.

 

i noticed that in mass too, i assumed we're buying electricity from cleaner sources?

 

Yeah, that doesn't scale too well... the size of the battery will shift the typical percentage of usage between gas and electric, and with that pollutants also.

Treating all the plugins as having the same size battery disregards that (and any advantage/disadvantage the electric portion has, relative to the gas engine). Efficiency of each component alone isn't the only thing that affects the end result - the amount of contribution of each makes a difference as well.

Even if the ratio dealt with that, might've been better to keep electric/gas separate, or provide values at several ratios... I don't see it boiled down to a single number as being a good representation.

 

People will buy the plugin that fits their driving pattern/distance.

The ideal usage is half gas and half electric. Another way to put it is, use electricity when is does not exceed the greenhouse gas emission of the gas engine. For PiP that threshold seem to be 62 mph or below (city driving).

As the grid get cleaner, next gen PiP should become more biased toward electricity. But then, more efficient gas engine could sway the other way as well. It is about balancing and I think Toyota did a great job with PiP.