Leaf C02 versus Prius C02

Right... and when any car maker in the past 100 years has mentioned emissions it has only been the tailpipe emissions discussed... without the word "tailpipe." Upstream emissions have been ignored for gasoline cars forever. And for the most part, they still are today. If the best thing for Leaf sales is to advertise how dirty electricity is made, then shouldn't we expect Prius advertisements to show oil being extracted from tar sands? It has to stop somewhere. Fact of the matter is that gasoline cars require gasoline. EVs do NOT require dirty energy. Talking about averages in a snapshot in time doesn't give us any sort of clear picture about the comparison of driving gasoline cars vs EVs as we move foward with ever dirtier gasoline and ever cleaner eletricity.

I read the word equivalent (in ggE) as meaning equivalent in energy, and absolutely nothing more. It is a measure of efficiency. It is NOT a measure of pollution. There is no way to accurately compare the upstream emissions of an EV with a gasoline car. The DOE has tried. I don't think it is relevant. Certainly isn't relevant in my case. And the sands are shifting for both energies at an ever accelerating pace.

 

I love how they spend a lot of time breaking out the various liquid fuel varieties and then get lazy and say "EV" using the average energy mix. That's not terribly useful as the carbon intensity of energy in different parts of the country can vary quite a bit. Right now, a massive part of emissions for petrol cars is being ignored. I love how "gasoline" is treated as if it's all the same. The end product is, but what if you start with tar sands? Or imported oil that is then refined and distributed? Each has a different emissions number attached to it that isn't reflected in those numbers... unless they just took the average... The only really useful and tangible number is tailpipe emissions. Everything else is a distortion or one kind or another.

 

They don't give separate summer and winter mileage ratings for gas cars. Why would they for EVs? The problem (for both gas and EV) is that "summer" and "winter" are not standardized. Summer in TX is a lot hotter than summer in Spokane, and winter in N.D. is much colder than winter in Spokane. Who's summer, and who's winter are you going to use?

I'll agree that they ought to have given separate city and highway range. But I think they've done pretty well, considering what they were up against.

 

The MPG hit in EVs in cold weather is going to be greater than ICE because the EV does not have waste heat to send into the cabin. Heating energy will be an additional load on the battery.

This is another example of the problem of trying to shoehorn an EV into an ICE equivalent.

 

Yet, as already mentioned, winter in Texas will have a very different affect than winter in Minnesota.
EPA numbers always have variability with any type of vehicle. I would suggest the problem is more one of consumer education than the EPA numbers.

 

Those can become wide swinging varibles too. The ICE can grill block, and/or use a block heater, a hotter thermostat etc. The EV can pre-warm when it's plugged in too.

 

I was thinking more along the lines as the EPA trying to make a consumer friendly label. Just as the EPA drive-cycle now includes AC use since it is prevalent amongst US drivers and leads to significant energy use, it makes sense to me to include heater use for the same reason in EVs.

I think the EPA should also take into account the range considerations an EV buyer will want to know. E.g., I want to use an EV for up to 35 miles between charges in all seasons where I live. I want a 10% buffer, and expect deep winter to take up to 50% more energy. This makes me a consumer for a 'standard' EPA labeled 60 mile range EV. I'll hazard a guess that even amongst serious consumers for EV these days, many do not have a solid idea how much battery capacity buffer to buy. The EPA could help in that regard.

 

My Prius, in North Dakota, got HALF the mpg that it got in summer, due in part to my short commute.

My Zap Xebra in Spokane takes only about a 10 to 20 percent hit in winter from using the heater. Admittedly, I don't wear shorts in the car in winter, and I use the heat sparingly.

It's just common sense that A/C and heater use are going to take some energy away from range, but trying to quantify that is impossible because it's going to range from nearly nothing to probably around 25%. Do you want the EPA to have a separate label for every state and for every month?

It's also going to depend on how wasteful you are about energy in general. Do you set your A/C to 68 degrees in summer, and your heat to 78 degrees in winter? Or do you wear shorts in hot weather and sweaters in cold weather and use just the energy you need? All these variables make what you're asking impossible.

I turn the heat up in a gas car in winter, because that heat is free. I use heat sparingly in the Xebra. So my real-life range is not impacted as much as would be implied if the EPA assumed people would use the same amount of heat regardless of vehicle.

My Prius in winter in N.D. was miserable. On my short commute it NEVER got warm. I froze my patooties off. The Leaf will have the ability to heat the cabin from grid power before setting out. How about pointing that out in the EPA label?

No, the label gives the information that it can give, under the circumstances. There are bigger things to gripe about than an EPA label that fails to give the range under every possible combination of weather and terrain and driving style.

 

Daniel makes some great points, as usual. Should the EPA mention that a Prius won't get anything near 50 mpg if it is driven on a two mile commute every day?

But to the point of HVAC use in an EV... the concept of a consumer not having a solid grasp of range considerations is obvious to me every day. There are people who think that playing the radio will reduce range. They worry about using the wipers and the headlights. The only way you'll notice range reduction when using accessories in the car is when you use the HVAC. BUT... and this comment is aimed at the idea of having the EPA "help" us... very few (if any) non-EV drivers understand how simple it is to maintain range even with the AC or heat on full blast. You drive one or two mph slower. Presto - your range is restored. Armed with that knowledge, your range anxiety evaporates. So... can the EPA help us with useful knowledge as well as "you may not have as much buffer as you want" knowledge?

 

I do not find persuasive arguments that boil down to something akin to "if the EPA does not mention *every* possible scenario, it should not mention any of them." Driving in cold weather is not uncommon, and its energy drain in an EV is not the same as an ICE car. People buy EV precisely because they are not ICE; I think trying to be informative is a good idea. I cannot help but think sometimes that the strident opposition to information stems from a worry that information is criticism.

People yap about "range anxiety." I concern myself with "capacity anxiety," as in capacity I bought and carry around day after day for no good reason.

 

Two reasons. First is that the ICE based HWY MPG number usually represents close to the absolute maximum performance (rarely achieved), whereas the City MPG represents something achievable. On an EV, I really would like some "standardized" range value that reflects less than ideal conditions. It will never be possible to come up with one test scenario that reflects all possible conditions, but a sensible "Cold Northeast Winter" EV range would provide a real world value to work from.

Second reason. With a EV, the range can be the critical selling value, not necessarily efficiency. When selling vehicles, it's better to provide a value that can be achieved by most of the buyers rather than just provide a number that can only be achieved by very few buyers. No good will come from over-promising the range of a new EV. The lower range value might also include the range reduction due to battery capacity at the End of the Warranty Period.

 

"If I buy a Leaf but fail to make it clear to my electric company I do not support coal, I will get the pollution I demanded."

"If I buy a Leaf but fail to make electricity myself, I will get the pollution I demanded."

"If I buy a Leaf but fail to change electric policy, I will get the pollution I demanded."

None of these is the fault of the Leaf.

 

And yet, the Prius states a city mpg higher than the highway mpg, and I've never achieved the EPA city mpg. But DaveinOlyWA regularly exceeds the EPA city rating.

Other than making the city and highway tests reflect actual city and highway conditions, I would not expect the EPA to do other than what it does.

And note they always say "YMMV"! And we all understand that means your driving style, speed, use of heat and A/C, etc. Here in Spokane, I never really need A/C, though I use it in the Prius on the hottest days; and if I'm driving the Xebra in winter I adjust accordingly how far I know I can go.

People say "Why should I have to learn math? I'm never going to need it." Then they complain because they don't know how to subtract 20% from the range of an EV because they cannot be bothered to wear an extra sweater in winter, or because they've chosen to live in a climate they cannot cope with without A/C. We're becoming lazy, soft, and stupid.

 

I rather doubt you make a habit of seeing 'kid's movies', Daniel, but you should see Wall E. The portrayal of 'what we've become' is both apt and funny.

 

Darrel said

Can you show me the calc ?

Wikipedia says that AC cooling uses 3 - 4 kw. If baseline travel averages 30 mph and a mile consumes about 300 wh, then AC increases battery load from ~ 10 to 13-14 kw. I guess this is something of a maximum, since I don't see anywhere near that kind of fuel economy drop in my Prius when I use AC. More in the range of 3 - 5%, but I benefit from a dry climate.

 

I'm in agreement. I guess we just disagree on what *should* be mentioned in the limited space available... and why all (well, most) of the massive negatives of gasoline cars should be left off the list. Or how about this: If the EPA mentions every negative scenario of EVs, it should maybe list the negatives for the gas cars too?

Nor is driving short distances that don't deliver the "promised" gas mileage in gasoline cars. Shouldn't we warn gas drivers about that? Or is it because they have so much range to waste that it doesn't matter how crappy the gas mileage really is in some common real-world scenarios? That's likely it.

Nope. Tons of energy is thrown away constantly as "waste heat" in a gas car. A tiny bit can be recaptured to heat the cabin when desired, where an EV needs to produce most of its cabin heat when needed and only when needed. But that's likely too complex of a concept for Joe Six. Please note that modern EVs are capturing some of the waste heat form the electronics (they all have liquid cooling for the electronics) and are therefor a bit more efficient at heating than you may realize.

I agree that more info is (almost) always good. But do we have to give them only the bad news? And only the bad news about the EVs? I can easiliy see how my "strident opposition" can seem like I'm offended, or that I take it as criticism. That's not the case, but clearly it often looks like it! I figure the only valid way to offer up info for consumers to compare is to offer up as many of the pros and cons of both techs as possible. But just giving the bad news isn't going to help adoption of a new scary technology that just might save us from ourselves.

[/quote]People yap about "range anxiety." I concern myself with "capacity anxiety," as in capacity I bought and carry around day after day for no good reason.[/QUOTE]
The only people who yap about EV range anxiety are those who've never lived with an EV.

 

I looked at wiki article on cabin cooling and heating of EVs and couldn't find where in the world you are getting your numbers.
What level of fan use?
What is the temp difference between inside and outside?
Why a base load of about 10kw?
For heat, does the driver use cabin heating or heated seats? Heating just the seat is almost as good and vastly more efficient. And again, it will take less power to provide heat on an average Texas winter day than on an average Minnesota winter day.

It boils down to the EPA is responsible for giving a number that represents the efficiency and pollution of the vehicle. Not of the entire chain of where the fuel for the vehicle comes from.

While I agree it is important for people to understand the entire chain, it is not, and never has been the purpose of the EPA numbers.

 

Well, if your basline travel speed is 30 mph, then you're going to get well over the EPA range estimate anyway, so none of this matters. If you're traveling at freeway speeds, and you're driving a car with heat-pump HVAC, you're looking at maybe 15 kW to push the car, and 1 kW for the HVAC (Driving today at 32 degrees ambient with the cabin kept at 70 degrees, I was averaging less than 1 kW of heater use in the Rav4EV. Let's hope we can do better than that 16 years later??). Driving just a VERY little bit slower can easily recover the 1 kW draw from the air resistance (energy to overcome the air is a cube of the velocity, so a little goes a long way).

Obviously the temp and speed extremes will be different. My experience comes from driving in the low 20's to 110 F. I have always been able to regain my full range by driving no more than 2 mph slower than usual.

 

Which is why we need a new measuring stick. Intentional or not, vehicle-only figures for gasoline-powered vehicles are only a small part of the big picture. It's simply not a valid comparison.

 

No, I don't make a habit of seeing "kid's" movies, but I'm not sure Wall E is really a kid's movie, even if kids like it. Anyway, yes, I've seen it, and I loved it.

I also loved Finding Nemo, which does a remarkable job of capturing the "look" of the underwater world, even though the fishes are anthropomorphized. I think it's the way they "got" the light.