Well-to-wheels analysis of energy use and greenhouse gas emissions of plug-in hybrid EVs

Impressive - that's an average of 140W 24/7 for 30 days.

My house (2 adults, 2 kids) average 400-500 kWh/month. I'm sure that the electric dryer is a big consumer. Need to do more air drying.

 

Yep. Hot water and clothes drying. So easy for many of us to use cheap/free solar.

 

As in, you tumble dry ALL your clothes?? It's not exactly sunny here in england but all my clothes just go on the washing line....

 

Line drying reminds me of baking sometimes. It is hard to get soft and fluffy.

 

I'm don't really care if skeptics pop up bad statistics continually argue that some programs worked that didn't or others don't work work but do.

As for green choice, if you look at the actual debates that purchased renewables you can get an honest picture. Some programs work, some don't, and some are just lies.

I also never said coal in texas had dropped in the past. I prefer looking at current statistics. If we look at 2006 instead of 2010 you can sucessfully argue that california has built and is building more wind than texas. A quick look at todays plans and loans shows that a great deal of wind is being built. Drees chart should show those honestly interested in the trends what is going on now.

As for the size of per capita electricity use, I would caution against quick judgement. Manufacturing and refining use a great deal of the energy, and it needs to be judged on productivity. Some big users just waste the energy, but others make perfect sense. One of the largest uses is in refining. As oil gets more sour (higher sulfer) and heavier (longer chain hydrocarbons) it takes more energy. Electric cars take a relatively small slice, if their use displaces heavy sour oil, electricity does not need to increase for the new refining processes.

 

Notice how the report conveniently excludes California from the main analysis and only mentions the lower g/mi GHG emissions in CD mode (up to 70%!) as an aside.

 

Just read Popular Mechanics March 2011 article "Tricky Sticker". It shows the Volt EPA mileage sticker showing 93 MPG equivalent in EV mode (37 in Gas Only mode). According to Popular Mechanics, EPA developed a simplified equivalent MPG calculation assuming "one (1) gallon of gas contains about 33.7 kwh". I guess the EPA is saying, in theory, if gasoline were converted at 100% efficiency to electric power it would be 33.7 kwh? But if so this is indeed a tricky (misleading) way to show EV equivalent MPG. According to PM, calculating well-to-wheels MPG is heavily debated -as we see here- and so EPA is instead going with some "back room" (dare I say politically correct) "calculations".

 

The EPA calc is not tricky and not back door; it is however widely misunderstood and misused even more.
Think of it as a socket-to-wheels or pump-to-wheels analysis. In the case of electricity the energy arrives from a wall plug socket to the car, while liquid energy comes from a petrol station.

The misuse stems from the fact that the source fuel is usually burned before socket in the case of electricity, but after the pump in the case of liquid petrol, so people that try to take the EPA numbers and conclude that electricity is more "efficient" or more "green" than liquid petrol do not understand what the numbers reflect.

Have you ever seen this picture ?

It shows an EV getting its electricity from a generator it tows behind that burns petrol. If this setup was measured by the EPA it would get a label of about 90 MPGe. Clearly nonsense, but it reflects the fact that the EPA ignores the energy cost outside of the car.

 

This is the most jargon/acronym laden analysis I've ever read. It's impossible to comprehend without a play guide. LOL. Wow, that's simply astonishing.

 

Sorry Dennis, I am not sure what comment of mine you are asking about.

 

Yep. Although that still ignores plant losses and transmission losses

If we start with 32% plant efficiency since that is the US average, the MPGe is 93*.32 = 30 mpg equivalent. The Volt is an energy pig, no two ways about it.

 

My earlier estimate (other thread) was about 20 MPGe if 100% coal (30% efficient).
Nat gas will be better efficiency. Thus I could possibly agree with 30-40 MPGe for EV if using a 50% coal/power plant blend. However, as Popular Mechanics points out (March 2011 issue), electrons are currently much cheaper than gasoline. On a fuel-up cost basis, if EPA's 93 MPG were cost equivalent basis, that might make sense.

 

No connection.

 

Sage- I do like the picture. Guess I should give EPA benefit of doubt as far as them not intending to mislead the public with their MPGe calc. But we probably need a new EPA MPGe basis if the current one is so widely misunderstood and abused.

If we said Miles per Pound fossil fuel burned, we'd be getting much closer to a comparative MPGe, neglecting nukes etc.

 

Whether the MPG(e) is useful or not depends what question it is meant to answer. Since the EPA has never clarified the question, I don't know the answer

I can *guess* that the EPA originally wanted consumers to waste less fuel in order to pollute less, and thought that providing information that rationalized pollution by consumption into money would affect behavior. Since all cars have the same pollution life cycle from ground until the end car, all they had to do was show car differences.

Now we are comparing EV to ICE, and the EPA forgot its mandate intent, but remembered that the implementation looked only at the car part of the life-cycle. Since pollution is proportional to energy consumed, they measured miles/energy -- but *only* energy consumed by the car.

Will one kwh of energy of electricity move a Volt about 3x further than one kwh of petrol ? Yes. Did it cost the same amount of energy and pollution to make that one kwh of energy in each of its forms ? Not even close, but EPA does not ask or answer that question for the car label.

I agree that they should.

 

I guess us Prius owners can understand that the EPA Volt MPGe number is almost the same number the Prius console shows (99 MPG) when we are coasting downhill on the battery. Similar to Toyota, EPA estimates about 60 MPG gasoline mileage for the Volt (average of 93 EV mode plus 37 gasoline mode for typical driver). The EPA 60 MPG number is probably a good estimate of gasoline consumption for the Volt, but it is more-or-less silent on how much electricity generation is also needed to go along with the gallon of gasoline.

 

Not at all. Lets try to compare apples to apples. Two tests would be required: one using petrol, and the other using electricity starting in the traction battery.

The petrol test is available using EPA numbers. Prius is 50 mpg, Volt is 37.
For electricity, EPA says the Volt travels 35 miles on 10.4 kwh removed from the battery, or 298 wh/mile. For the Prius all we can say for now is that people who test drove the Prius PHV were charging up the battery with about 3 kwh and traveling 14 EV miles, or 214 wh/mile.

Lets compare ratios, (and expect them to be similar.)

Petrol: 50/37 = 1.35
EV: 298/214 = 1.36

In terms of CAR ONLY energy efficiency, the Prius goes about 1/3 further on the same amount of the same form of energy. Incidentally, this lets us estimate the Prius PHV future EPA MPGe for CD mode as 1.36 the Volt result, or 1.36*93 = 126 MPGe.

You *know* that is going to cause some Volt fanatic angst