An interesting way to look at electric vehicle efficiency

[Telemakhos]

I thought to post this because of the recent coverage being given to electric-powered aircraft in the aviation press.
It seems as though running cars and airplanes on batteries in order to not burn fossil fuel isn't quite what it's popularly made out to be. This most interesting part of the article for me was the EPA's "MPG equivalent" standard posted on the new vehicle information sticker, and how fraudulent it seems to be.
Anyway, here's the link:
http://pajamasmedia.com/blog/epa-fraud-chevy-volt-nissan-leaf-actually-get-only-23-25-mpg/

 

[Greg Bockelman]

I suppose it depends on how the electricity is generated. If it is generated by coal or natural gas, that is still a fossil fuel. Nuclear produced electricity still has the issue of nuclear waste do deal with. Hydroelectric, solar and wind generated electricity seem to be the "greenest", but even then, someone can find issues with that.

I think electric powered vehicles are part of the future. They have to get their start sometime. Now is that time, I suppose.

 

[Telemakhos]

Hydroelectric, solar and wind generated electricity seem to be the "greenest", but even then, someone can find issues with that.

I think the only thing people have against wind and solar power are that they're both incredibly expensive and inefficient.
Personally, I'd love to see something new come out, but I'm afraid that the new thing we're waiting for will be something totally new, not merely incremental increases in wind and solar technology.
By "totally new," I mean some sci-fi stroke of brilliance coming out of Los Alamos or CERN or that crazy antimatter generator.
Until then, I worry about the wisdom of dumping cash on electric vehicles that get, effectively, 25 MPG on coal-generated electricity.

 

[mantakos]

There is simply no one true way to relate MPG between gas-powered and electric-powered cars.

You could try to relate them based on aerodynamic efficiency, but that ignores the differences in efficiency of power generation.

You could try to relate them in terms of fuel cost, but that ratio depends on gas and electricity prices, and these vary geographically and over time.

You could try to relate them in terms of some kind of environmental cost, e.g. CO2 production, but this depends on how the electricity is generated, and that varies geographically.

I think the most honest thing to do would have been to simply scrap MPG and stamp these cars with an efficiency based on kilowatt-hours. Both "miles per kwh" and the current EPA "mpg _equivalent_" allow comparison between electric cars, neither allow proper comparison between electric and gas, but the EPA system encourages such a comparison when it's not really appropriate.
-harry

 

[Telemakhos]

I think the most honest thing to do would have been to simply scrap MPG and stamp these cars with an efficiency based on kilowatt-hours. Both "miles per kwh" and the current EPA "mpg _equivalent_" allow comparison between electric cars, neither allow proper comparison between electric and gas, but the EPA system encourages such a comparison when it's not really appropriate.
-harry

That's kind of what the article argues. The thing is, though, with the current rating system, gasoline-powered cars get rated on the amount of distance the vehicle will travel with one gallon of gasoline input... whereas electric vehicles are rated by how much electricity is consumed to push the vehicle forward a certain distance, ignoring the generation of the electricity itself.

 

[Ken Ibold]

I have to believe that, over the long run, power generated by a few large plants with structured maintenance is a more efficient strategy than generating power with millions of smaller plants of uncertain maintenance, despite transmission and storage losses.

 

[Greg Bockelman]

I have to believe that, over the long run, power generated by a few large plants with structured maintenance is a more efficient strategy than generating power with millions of smaller plants of uncertain maintenance, despite transmission and storage losses.

Sounds like a national security nightmare to me. Terrorists take out one or two of those and where would we be?

 

[Telemakhos]

I have to believe that, over the long run, power generated by a few large plants with structured maintenance is a more efficient strategy than generating power with millions of smaller plants of uncertain maintenance, despite transmission and storage losses.

I can't say one way or another... my background is English Lit, not engineering of any sort.
I will say that the thought of tens of millions of 900 pound battery packs going into a landfill, or being recycled at astronomical cost, makes me shudder. Not to mention the mining and manufacturing process necessary to create those batteries. It just seems like sort of a bad idea. But again, what do I know?

 

[EdFred]

I have to believe that, over the long run, power generated by a few large plants with structured maintenance is a more efficient strategy than generating power with millions of smaller plants of uncertain maintenance, despite transmission and storage losses.

Except when one large plant goes down (terrorist target anyone?) now you've got millions of useless vehicles.

 

[Ken Ibold]

I can't say one way or another... my background is English Lit, not engineering of any sort.
I will say that the thought of tens of millions of 900 pound battery packs going into a landfill, or being recycled at astronomical cost, makes me shudder. Not to mention the mining and manufacturing process necessary to create those batteries. It just seems like sort of a bad idea. But again, what do I know?

Yeah, it's a dicey proposition. But on the other hand look at all the blue-smoking tuner cars and clunkers streaming in and out of the Wal-Mart parking lot.

There is no free lunch, that much is clear.

 

[Telemakhos]

...blue-smoking tuner cars and clunkers streaming in and out of the Wal-Mart parking lot...

Did you know that a hot cam, a coffee can muffler and a bolt-on wing spoiler will turn a 1993 Acura into a Le Mans contender?
I learned that in a Denny's parking lot years ago whilst observing an unsanctioned burn out competition.

 

[mantakos]

That's kind of what the article argues. The thing is, though, with the current rating system, gasoline-powered cars get rated on the amount of distance the vehicle will travel with one gallon of gasoline input... whereas electric vehicles are rated by how much electricity is consumed to push the vehicle forward a certain distance, ignoring the generation of the electricity itself.

One of the advantages of electric cars is that the chain of "coal -> electricity -> battery -> electric motor -> motion" is more efficient than the chain of "oil -> gasoline -> gas tank -> combustion engine -> motion". It's not too surprising, of course, that we can build a small number of centralized power plants to be more efficient than a large number of inexpensive, mobile gas engines.

So there is an inherent efficiency advantage to electric cars, but the EPA number exaggerates that advantage. Again, there are multiple ways to do this, all of them have problems, all could be argued, so I think the most honest thing probably would have been to side-step the issue entirely. I'm not sure why they didn't do that. It may be that their hands are tied, that legislation would have been required to allow them to do something different (I dunno, just making this up). Alternately, it's possible that they know they're fudging, and their motivation is to take up a promotional stance in favor of electric cars.

From a consumer's perspective, though, it's not necessarily doing them a disservice, as "fuel" costs for an electric are significantly lower than for a comparable gas car, with the difference going well beyond the advantage in efficiency. Of course, the higher purchase prices we see today wipe out that advantage.
-harry

 

[gismo]

Yeah, it's a dicey proposition. But on the other hand look at all the blue-smoking tuner cars and clunkers streaming in and out of the Wal-Mart parking lot.

Even if electric cars were more efficient and/or more environmentally friendly in the long run, I think it's a safe bet that the owners of those blue-smokers and clunkers will be the very last to convert to electrics.

 

[Telemakhos]

From a consumer's perspective, though, it's not necessarily doing them a disservice, as "fuel" costs for an electric are significantly lower than for a comparable gas car, with the difference going well beyond the advantage in efficiency. Of course, the higher purchase prices we see today wipe out that advantage.
-harry

Very true about the fuel cost to consumer. What's not attractive about "filling up" one's car for thirty cents? I do worry, though, that many people are thinking that they are doing the most environmentally responsible thing by purchasing an electric car, while in reality they'd be much better off with a high-MPG conventional engine.
My car, for example, has a small four-cylinder turbocharged motor and gets roughly 35 and a half MPG on the highway. If the article is correct, my car is more efficient than the Nissan Leaf (assuming a coal-fired electricity plant) by a factor of about one and a half.
As an aside, I always thought that if society were to start making laws to increase gas mileage, the first things they should do would be to mandate manual transmissions and correct tire pressure. Then, outlaw useless six cylinder, naturally aspirated engines with huge transmission losses (I'm looking at you, GM).

 

[Anthony]

None of this stuff makes any sense until batter effeciency goes way up. Solar, wind? Very ineffecient as you have to build similar fossil or other reliable energy source as back up one for one. The sun doesn't always shine and the wind doesn't always blow, but you still need the power.

 

[mantakos]

... If the article is correct, my car is more efficient than the Nissan Leaf (assuming a coal-fired electricity plant) by a factor of about one and a half...

I think they're talking out their butts on that one. A Leaf or Volt has significant advantages over a normal sub-compact. It has regenerative braking, like current hybrids, which is a big win in city driving, and it has the inherent efficiency advantages of electricity vs gas, which I believe is in the 20% to 30% ballpark.

So I think they're right on in thinking that their electric car has environmental benefits, even in places where electricity is generated by coal. The downside is that they're paying a steep price for that benefit due to the current high purchase prices, which will hopefully come down in the coming years as technology progresses (particularly batteries) and volume goes up.

And, of course, for those who live in areas served by hydro or nuclear, the environmental benefits are far more significant.
-harry

 

[Telemakhos]

I think they're talking out their butts on that one. A Leaf or Volt has significant advantages over a normal sub-compact.

Whoa, buddy! Who said anything about a sub-compact?
Disagree with me if you want, but don't try to emasculate me!

 

[NC Pilot]

Let's do some math...

34 kW-hrs/100 miles from the sheet

1 Btu = .0002928 kW-hrs

=> it takes 116120 Btu's/100 miles (34/.0002928)

114,000 Btu's / gallon of gas

=> about 1 gallon of gas/100 miles.

Of course that assumes that a gasoline powered car would have 100% efficiency, which it doesn't.

However, this is really comparing apples to potatoes, but I do think his methodology is a little off.

 

[Capt. Geoffrey Thorpe]

Random comments.

"Well to wheels" is what you need to look at for efficiency. What is the cost / energy required to process / transport the oil, generate the electricity, etc.

As for the source of energy - it matters not what the current mix of sources (hydro, solar, coal, etc.) is, but what is the source of any additional electricity - and that is mostly coal, partly natural gas. The renewable sources are already running at 100% - more electricty means more coal.

Cost wise, last time I scribbled on a napkin, I came up with battery power is about equal in cost to $1.30 per gallon gasoline. (Ignoring "overhaul reserves")

Transmissions: A manual would be more efficient than old style automatic transmissions if it were shifted at the optimal points (but in the hands of the avrage doof...). Modern automatic transmissions have been WAY improved. Lock up converters and optimal shift schedules win out over the typical manual trans.

 

[mantakos]

Whoa, buddy! Who said anything about a sub-compact?
Disagree with me if you want, but don't try to emasculate me!

Sorry, you mentioned 35mpg and didn't say "motorcycle", so I just assumed you were driving something emasculating.
-harry

 

[Telemakhos]

Let's do some math...

34 kW-hrs/100 miles from the sheet

I think your math is right on, but again, your math represents the power consumed by the car itself and leaves out the fuel burned to generate the power that powers the car.

 

[Telemakhos]

Sorry, you mentioned 35mpg and didn't say "motorcycle", so I just assumed you were driving something emasculating.
-harry

Negative. It just has an appropriately-sized engine, a five speed, and a good aerodynamic design.
My motorcycle gets better than 44 on the highway.
Never thought I'd have to defend my masculine car honor here!

 

[nyoung]

Eliminate the variable of cost of fuel, and compare in terms of energy.
Miles per gallon
-or-
Miles per kW-hr

That way users can make their own assessments on cost per mile. (Although, that may be too much math for the average user.)

Efficiency aside, electric plug-in or plug-in hybrids have one great feature... Rarely having to go to the gas station. 90% of my daily drives are less than 100 miles. 99% are less than 25 miles. It would be great to be able to plug-in each night, and start off with a full tank each day.

You could try to relate them in terms of fuel cost, but that ratio depends on gas and electricity prices, and these vary geographically and over time.-harry

 

[tonycondon]

hey i like my blue smoking clunker...

 

[gismo]

None of this stuff makes any sense until battery efficiency goes way up. Solar, wind? Very inefficient as you have to build similar fossil or other reliable energy source as back up one for one. The sun doesn't always shine and the wind doesn't always blow, but you still need the power.

AFaIK, battery "efficiency" (percent of power delivered vs consumed during charging) is already pretty high (75-85%). The biggest issues with batteries today that might be improved in the future are the cost, size, and weight for a given energy content.

I've seen studies on wind power that show that the cost per kwh is more than double the average of other sources due to issues like maintenance and the relatively short life expectancy of the equipment.

 

[Anthony]

AFaIK, battery "efficiency" (percent of power delivered vs consumed during charging) is already pretty high (75-85%). The biggest issues with batteries today that might be improved in the future are the cost, size, and weight for a given energy content.

My utility company clients tell me that a big reason they don't use solar is due to the batteries. I assumed efficiency, but it just may be an economic reason.

 

[NC Pilot]

Eliminate the variable of cost of fuel, and compare in terms of energy.
Miles per gallon
-or-
Miles per kW-hr

That way users can make their own assessments on cost per mile. (Although, that may be too much math for the average user.)

It needs to be brought down to cost/mile for the average consumer. There will always be people who don't mind spending more for some product for a perceived "feel good" tingle, most are too busy watching pennies.

Of course, then the government needs to figure out how to tax the electricity that goes into cars to collect highway taxes. That will also level the playing field a little between electric and gas/diesel vehicles.

 

[RotorAndWing]

I'm just waiting for the "Mr. Fusion" adapter to come out and modify my present vehicle. Then all I need to do is stop by any garbage can and "fill up".

 

[Telemakhos]

I'm just waiting for the "Mr. Fusion" adapter to come out and modify my present vehicle.

Don't tell me you actually bought a DeLorean!

 

[Capt. Geoffrey Thorpe]

My utility company clients tell me that a big reason they don't use solar is due to the batteries. I assumed efficiency, but it just may be an economic reason.

Batteries are reasonably efficient (engergy in vs. energy out) but expensive to buy (particularly if you need many megawatt hours worth of storage) and replace every few years.

Solar power works best when the sun is shining. Really.

 

[Pi1otguy]

Efficiency aside, electric plug-in or plug-in hybrids have one great feature... Rarely having to go to the gas station. 90% of my daily drives are less than 100 miles. 99% are less than 25 miles. It would be great to be able to plug-in each night, and start off with a full tank each day.

The plug-in is a huge problem. Unlike in those commercials, I know very few people who regularly park in their garage. Most park on the street, and quite a few households have 3, 4 or 5 cars that are used often. There's no plausible way to plug in all these cars each night.

Similarly, efficient use of electric vehicles requires a level of planning beyond normal driving. How many of us hop in the car only to notice they're running on fumes?

 

[Anthony]

The plug-in is a huge problem. Unlike in those commercials, I know very few people who regularly park in their garage. Most park on the street, and quite a few households have 3, 4 or 5 cars that are used often. There's no plausible way to plug in all these cars each night.

Similarly, efficient use of electric vehicles requires a level of planning beyond normal driving. How many of us hop in the car only to notice they're running on fumes?

That's probably a reason that the Volt and Leaf have hybrid back ups.

 

[Pi1otguy]

I think the only thing people have against wind and solar power are that they're both incredibly expensive and inefficient.

Wind power also kills birds and bats. Apparently large birds see the blades and will fly through not just once, but circle until hit. Bats OTOH, "see" the blades but enter a low pressure zone and explode (sort of).

The expensive part is the fact that there is a lot of opposition to building power lines to transmit power from these sites. A few power companies in CA have been battling for years to get transmission lines built from the "green" solar & wind farms to their customer base, but have faced stiff opposition from environmental groups.

 

[Anthony]

I can't say one way or another... my background is English Lit,

So you're going to grad school, right.

 

[Telemakhos]

A few power companies in CA have been battling for years to get transmission lines built from the "green" solar & wind farms to their customer base, but have faced stiff opposition from environmental groups.

I adore and cherish this type of irony. It gives me warm, fuzzy feelings all over.
Sooner or later, when electric cars become more prevalent, we'll see international protests over filthy lithium mining operations and toxic waste spewing, carcinogenic, whale-murdering battery factories. Greenpeace terrorist/activists will sink ships hauling batteries. Friends of the Earth will come in and demand that powered vehicles in general must be abolished, and we'll use horses and oxen once again for out transportation needs.
At that point, PETA will get involved.
Then we will have come full circle and I will rejoice.

 

[Pi1otguy]

That's probably a reason that the Volt and Leaf have hybrid back ups.

True, but that negates the savings of the plug in capabilities.
BTW, the Leaf is 100% electric.

 

[Telemakhos]

So you're going to grad school, right.

No, I'm doing job applications and not flying more than once a month.
I was laid off, but have no intention of further schooling.
I can't find the damned frowny face emoticon, but if I could, I'd put it here.

 

[EdFred]

So when it's -5°F and I'm driving my electric car, how am I going to keep warm? Oh, you want the car to be warm? Well, turn on the electric heater and you now have a range of 5 miles.

 

[JOhnH]

The sun doesn't always shine and the wind doesn't always blow, but you still need the power.

You are right of course, but there is more to it.

Wind does blow somewhere day and night. And every KW of power that is generated from Wind is one KW that is not generated from a polluting fuel that has probably been purchased from a country that supports terrorists. That is money that could be spent as wages to purchase American made turbines that employ Americans.

And even though solar generators are useless at night; they are useful during the day when demand is at its peak. By contributing solar to the mix we reduce the need to build more fossil fuel plants. And again, every KW produced by solar is one KW that is NOT produced by purchasing fuel from terrorists.

In all the talk about comparing apples to potatoes, we lose sight of the fact that we send billions and billions of dollars overseas every day to purchase a product that pollutes our air and water and finances those that hate us. It sickens me when I see those Arab sheiks with their huge fortunes when the only source of their wealth is oil. I say let them drink their oil. We can replace a huge amount of our oil consumption with natural gas, alternative fuels and nuclear energy. We can use domestic oil where we absolutely need to have an oil product and stop importing it. Even if we can't get all the way there, we must do everything we can to get close or our country will surely perish.

Maybe today's technology is not there yet. But no technology ever emerged fully mature. We have to go through growing pains, use what works and abandon ideas that don't (like corn based ethanol fuel).

 

[SCCutler]

True, but that negates the savings of the plug in capabilities.

Not really - for most driving missions, the plug0-in power will be used, the engine will not; the engine's power is only used when the stored electrons are all used-up.

BTW, the Leaf is 100% electric.

...and, thus, has no "all used-up" contingency.

--

I really like some of the elegant design and engineering that goes into the hybrids and plug-hybrids, but I am unhappy that they are marketed and sold through the use of substantial taxpayer subsidies- that's wrong, and masks the economics of the whole deal.

In addition, the most common hybrid, the Prius, is (in the hands of most drivers I have observed) a dangerous vehicle... because they tool along staring at the status screen in stead of paying attention to driving, and often impede traffic flow in the fast lane. Roughly equivalent to driving while holding a cell phone to the ear. My observation.