Bringing Skepticism (and Math) to Electric Vehicle Fuel Numbers
Frequent readers of this blog will know that I am enormously skeptical of most fuel and efficiency numbers for electric vehicles. Electric vehicles can be quite efficient, and I personally really enjoy the driving feel of an electric car, but most of the numbers published for them, including by the government, are garbage. I have previously written a series of articles challenging the EPA's MPGe methodology for electric cars.
In just a bit, I am going to challenge some numbers in a recent WSJ article on electric vehicles, but first let me give you an idea of why I don't trust many people on this topic. Below is a statement from Fueleconomy.gov, which bills itself as the official government source for fuel economy information (this is a public information, not a marketing site). In reference to electric vehicles, it writes this:
Energy efficient. Electric vehicles convert about 59–62% of the electrical energy from the grid to power at the wheels—conventional gasoline vehicles only convert about 17–21% of the energy stored in gasoline to power at the wheels
The implication, then, is that electric vehicles are 3x more energy efficient than cars with gasoline engines. I hope engineers and scientists can see immediately why this statement is total crap, but for the rest, here is the problem in short: Electricity has to be produced, often from a fossil fuel. That step, of converting the potential energy in the fuel to use-able work, is the least efficient step of the entire fuel to work process. Even in the most modern of plants it runs less than a 50% conversion efficiency. So the numbers for the gasoline cars include this inefficient step, but for the electric vehicle it has been shuffled off stage, back to the power plant which is left out of the calculation.
Today I want to investigate this statement, which startled me:
Factor in the $200 a month he reckons he isn't paying for gasoline to fill up his hulking SUV, and Mr. Beisel says "suddenly the [Nissan Leaf] puts $2,000 in my pocket."
Yes, he pays for electricity to charge the Leaf's 24-kilowatt-hour battery—but not much. "In March, I spent $14.94 to charge the car" and a bit less than that in April, he says.
This implies that on a cost-per-mile basis, the EV is over 13x more efficient than gasoline cars. Is this a fair comparison? For those who do not want to read a lot of math, I will preview the answer: the difference in fuel cost per mile is at best 2x, and is driven not by using less fossil fuel (the electric car likely uses a bit more, when you go all the way back to the power plant) but achieves its savings by using lower cost, less-refined fossil fuels (e.g. natural gas in a large power plant instead of gasoline in a car).
Let's start with his estimate of $14.94. Assuming that is the purchased power into his vehicle charger, that the charger efficiency is 90%, and the cost per KwH in Atlanta is around $0.11, this implies that 122.24 use-able KwH are going into the car. Using an estimate of 3.3 miles per KwH for the Leaf, we get 403 miles driven per month or 3.7 cents per mile in electricity costs. This is very good, and nothing I write should imply that the Leaf is not an efficient vehicle. But its efficiency advantage is over-hyped.
Now let's take his $200 a month for his Ford Expedition, which has an MPG around 15. Based on fuel prices in Atlanta of $3.50 a gallon, this implies 57 gallons per month and 857 miles driven. The cost is 23.3 cents per mile.
Already we see one difference -- the miles driven assumptions are different. Either he, like a lot of people, don't have a reliable memory for how much he spent on gas, or he has changed his driving habits with the electric car (not unlikely given the shorter range). Either way, the total dollar costs he quotes are apples and oranges. The better comparison is 23.3 cents per mile for the Expedition vs. 3.7 cents a mile for the Leaf, a difference of about 6x. Still substantial, but already less than half the 13x difference implied by the article.
But we can go further, because in a Nissan Leaf, he has a very different car from the Ford Expedition. It is much smaller, can carry fewer passengers and less cargo, cannot tow anything, and has only 25% of the Expedition's range. With an electric motor, it offers a very different driving experience. A better comparison would be to a Toyota Prius, the c version of which gets 50MPG. It is similar in most of these categories except that it has a much longer range, but we can't fix that comparison, so just keep that difference in mind.
Let's look at the Prius for the same distances we calculated with his Leaf, about 403 miles. That would require 8.1 gallons in a Prius at $3.50, which would be $28.20 in total or 7 cents a mile. Note that while the Leaf still is better, the difference has been reduced to just under 2x. Perhaps more importantly, the annual fuel savings has been reduced from over $2200 vs. the Expedition that drove twice as many miles to $159 a year vs. the Prius driving the same number of miles. So the tradeoff is $159 a year savings but with much limited range (forgetting for a moment all the government crony-candy that comes with the electric car).
$159 is likely a real savings but could be swamped by differences in long-term operating costs. The Prius has a gasoline engine to maintain which the Leaf does not, though Toyota has gotten those things pretty reliable. On the other hand the Leaf has a far larger battery pack than the Prius, and there are real concerns that this pack (which costs about $15,000 to manufacture) may have to be replaced long before the rest of the car is at end of life. Replacing a full battery pack after even 10 years would add about $1200 (based on discounted values at 8%) a year to operating costs, swamping the fuel cost advantage.
Also note that a 2x difference in fuel costs per mile does not imply a 2x difference in fuel efficiency. Gasoline is very expensive vs. other fuels on a cost per BTU basis, due to taxes that are especially high for gasoline, blending requirements, refining intensity, etc.) Gasoline, as one person once said to me way back when I worked at a refinery, is the Filet Mignon of the barrel of oil -- if you can find a car that will feed on rump steak instead, you will save a lot of money even if it eats the same amount of meat. A lot of marginal electric production (and it is the margin we care about for new loads like electric cars) is natural gas, which is perhaps a third (or less) the cost of gasoline per BTU. My guess is that the key driver of this 2x cost per mile difference is not using less fuel per se, but the ability to use a less expensive, less-refined fuel.
Taking a different approach to the same problem, based on the wells-to-wheels methodology described in my Forbes article (which in turn was taken directly from the DOE), the Nissan Leaf has a real eMPG of about 42 (36.5% of the published 115), less than the Prius's at 50. This confirms the findings above, that for fossil fuel generated electricity, the Leaf uses a bit more fossil fuels than the Prius but likely uses much less expensive fuels, so is cheaper to drive. If the marginal electrical fuel is natural gas, the Leaf also likely generates a bit less CO2.
They added small propane heaters to the GM EV1 to take care of the heating issue. Heating with they battery shortens your trip significantly.
They also forget things, like - oh it takes energy to wash the cloth diapers as well. Usually in these analysis something is left out.
Ideally cars would be charged at night when power companies have significant extra energy they are throwing away. Charging at night would essentially be "free" energy, since the energy would normally be wasted anyway.
Smart grid is more for allowing power companies to charge you different rates at different times. Currently without a smart meter there is no way to charge me 50 cents during the day, and only 12 cents at night (Where I live power above 450kwh is charged at 26 cents per kwh - note the average home uses 900kwh's per month)
They also could use it to charge scads more on those power crisis days.
Actually NG out of the ground is radioactive, it needs to be filtered for radioactive substances, demoisturized, and then separated from other gasses which are in the mix includes propane and butane, helium, CO2, and then it gets transported somewhere.
And a substantial amount of economy can be attributed to how you drive –
http://www.bbcamerica.com/top-gear/videos/thirsty-prius/
[admittedly unscientific, but interesting]
"Ideally" and "essentially be 'free' energy" and "charge scards more".
You sound like a progressive non-engineer. First of all, in an ideal world we would not have to deal with any of these problems. In an ideal world, all the women are strong, the men are good loooking, and the children are above average. Wishing it does not make it so.
Utilities do NOT thow away energy at night. They shut down peaking units, and keep rolling capacity at a minimum. If you haven't noticed, solar panels don't work very well at night. So the nuclear units keep running at 100%, and the coal and gas units load follow. If you want to run coal and gas units more heavily at night you need to haul more coal to the plant, which costs money. It costs money to dig it out of the ground, to transport it, and to stockpile it at the plant. That means more trains and miners working longer. Gas is a bit easier, but you still have to have the infrastructure in place (producing wells and pipelines) to get it to the plant.
And smart meters that just charge different rates at different times are not very advanced - I have had one in my house for over 15 years. The "smart grid" is just a way to control your power usage, by turning off stuff that the "smart people" don't think you need to run. You probably think you are one of them, but it is unlikely that you really are.
The only thing that is free is advice from people who know nothing.
So, you spend an enormous amount of effort cutting down on the weight of the vehicle because the battery is so heavy, and you want to extend the range, but they you have to add a propane bottle and tubing and a burner(!) and a control system (drawing electricity from the battery), just to keep the windshield clear. Are people expected to install and de-install the propane tank when they think it will rain? Does the EV1 have an AC capability?
These are NOT practical vehicles. They are indulgent playthings for people with way too much money.
"And, of course, this source does not say whether that is the amount consumed from the grid, or consumed from both the grid and on-site coogeneration."
RXC,
Noted as well. As a "source", said site isn't. Shame, then, to do a bit of google-fu and find that it's treated as an authoritative set of data on an number of other pages...
Not to go too OT, but M2 above raises the same Q I've been shouted down on over the past few years - namely, the output of chemical reactions is pretty well figured out - so where's the "major/amazing/earthshattering" battery tech that we keep hearing about actually coming from?
1) In the last decade there have been only about 10 trips I have done that required more than 200 miles at a time. For most of them I rented a different car anyways.
2) Take one battery out. Put another in. Done. Available fairly soon.
3) Right... On a related note - the newest Prius has a solar powered air conditioner that can be left running while the car is parked.
I really sorry - there are peaker units, but utilities ground considerable energy at night, because they can't shut down the base units.
You know don't just go babbling because you don't like something. I am dubious about electric cars myself, but this is the one advantage that can be seen. They take energy at night when it is wasted.
If your assertion is not correct, why are utilities so gusto to get smart meters in our homes so they charge us twice as much during peak hours. According to you there is no such thing because they just shut off all the inefficient peaker units.
I am not a progressive engineer, I have just read about some facts. You might want to bone up on how utilities really work before dumping on me.
I know they are not practical. Just pointing out what they had to do to get the heat going - cuz heating really burns down the batteries fast.
I have this ford focus, and it gets 26 mpg. I can drive it fast, I can drive it slow I drive it on the highway, or in the city and it always seems to get 26 mpg.
I know it is not suppose to work that way - I find it pretty frustrating. Maybe my driving technique is so bad that the speed doesn't factor into it.
"...utilities ground considerable energy at night..."
What does this mean? You think that they connect the 3-phase output of the generators directly to ground? Do you have any idea how 3-phase power works? I think not. Energy is NOT wasted at night. The main problem with electric cars is that it is very difficult to store electricity. What is generated is used. The utilities tried to build pumped storage systems, which are the only real storage system that is practical, but the progressive enviros shut that down real fast - too many fish damaged andthey didn't like the creation of the reservoirs. Air storage has been proposed, but it has issues with safety and losses from compression and decompression of the gas. Batteries would have to be ENORMOUS. Flywheels that store considerable amount of energy are too dangerous (which is why they aren't used in cars).
I used to evaluate the safety of nuclear power plants for a living. I was in charge of a group that did nuclear thermal-hydraulic and reactor fuel analyses, and evaluated the same analyses done by utilities and reactor vendors. I used to operate nuclear power plants on navy ships.
You have no idea what you are talking about.
Public utilities are already building flywheel systems. But why would you need a flywheel system if you didn't have times with excess generation capacity compared to demand? (in fact the bigger concern is why build flywheels when you can just build more baseline load instead for less cost) You can't just shut down a baseload system for a few hours, and they account for 40% of peak (that is instantaneous peak during the whole year)
I don't care what you call it, The plants are still burning fuel to heat the boilers which spin the turbines. If the energy just stays within the turbine coils, fine, it is still not being used, when it could be. Maybe the electrons are just out for tea in the middle of the night. Grounding a term which also is used to mean throwing away power.
I think we may be talking cross purposes here.
1. Renting a different car means renting one with a combustible engine.
2. Removable batteries were promised "soon" back in 2009.
3. Please drive in Minnesota or even upstate New York during the winter with that attitude. Air conditioning is a luxury when driving but heating is another matter.
I would add another non-starter... recharging electric cars do not solve the problems they profess to solve. The electricity generated to charge the batteries still rely on fossil fuels (or worse... nuclear). People say that we could use "clean" natural gas but that just puts more pressure on fracking. Is this what you want?
Solar and wind aren't going to meet the our demands going forward and they have their own environmental impact. Even worse in my state they are cutting down trees to put in a solar station. This seems counter to what solar is supposed to resolve.
I knew someone on the California Hydrogen Highway project. We argued about the feasibility of hydrogen and its production in reducing our carbon footprint. Naturally I was 'wrong' and yet the stations in California sit empty they spent so much money on it.
Electric cars are a better solution but for a number of similar reasons they won't end up reducing carbon emissions or our dependence on foreign oil.
We will however waste a good deal of time and money on them and other alternatives such as solar (can you say Solyndra).
1) Do you have a point?
2) 4 years is not a long time.
3) You may find this hard to believe, but electric vehicles do come with heat. So please clarify for me what the problem is with "that attitude". Further, please drive in Texas during summer without air conditioning and get back to me on it being a luxury.
As for your other "non-starters": The best possible efficiency of an internal combustion engine is below that of electrical generators. Nuclear is actually much better than fossil fuels. Cutting down some trees to put in solar may seem counter to what solar is supposed to solve, but it is not.
1. My point was one still requires a combustion engine to drive any real distances. I didn't think I needed to be Capt. Obvious. I would also take this opportunity to point out that many people do drive a good number of miles for various reasons. Just because you do not often doesn't mean others are like you.
2. Well the word 'soon' is repeated quite often. Like most religions I suppose 'soon' is a vague enough definition to mean most anything (such as never).
3. Lived in central Texas for years and I had a convertible. I will admit it is more of a dry heat than say Houston but I survived it.
4. Cutting down trees to put solar in is perhaps the most short sighted idea. Trees do more than just take CO2 out of the air. They provide a cooling effect and a habitat for animals.
So do you have anything to say as to whether these things are actually barriers to adoption, or are you going to go off on tangents on every point? It seems you're just arguing for the sake of arguing.
1) recall that the post I was replying to said ability to drive long distances was a barrier to people buying electric vehicles. I pointed out that it isn't. Nothing you have said on this is relevant to whether it is or is not a barrier to buying electric vehicles (or even doing the vast majority of their driving with electric vehicles). It is perhaps relevant to whether we could completely remove all gas powered vehicles from the road today. But no one is making that claim.
2) This issue could be a barrier. The technology to get around it exists today, but is not in use. Whether it is implemented very quickly or over a longer term depends on whether or not it actually is a barrier to people buying electric cars.
3) Okay, so you're saying either we need a convertible or air conditioning? Fine, I'll concede the point as it is irrelevant to whether or not there is heat in electric vehicles (there is). So it is irrelevant to whether there is a barrier to adoption due to cold weather.
4) This is not a barrier to adoption of electric vehicles (and it's also based on false premises: the CO2 removed by a tree is small compared to the CO2 release avoided by having a corresponding amount of solar, the cooling effect of trees is only a local effect - and remember, solar power is turning solar energy into electricity, rather than heat so is also cooling, and as for habitat for animals: I'm betting it's not an ecological hot spot)
No thanks. I wasn't trying to convince you and I made my points earlier. I didn't go off on tangents but was responding to you on each point you made (such as living in Texas).
You may disagree with me and think electric cars are the next big thing. I think in the long run the benefits are not great enough to justify the costs.
We've been down that 'hydrogen' highway before.
1) Good for you. You aren't every driver, though.
2) That is hardly a practical solution. Electric cars have many batteries weighing many dozens of pounds.
3) I will believe a solar powered air conditioner when I see it. Electric heat is something else altogether. Heat isn't an option in severe climates...it is mandatory to sustain life. Electric resistance heat (there isn't anything else) drains a battery in minutes. Imagine being stuck in the middle of nowhere...no power to drive and no heat. That's a death sentence.
Remember - your original claim was about whether there could possibly be significant use of electric vehicles. Not whether every single driver would drive them. So let's judge my comments in light of that.
1) Fairly typical of many city drivers however. Let me guess - you'd probably say no driver would go for zipcar either.
2) http://www.wired.com/autopia/2009/05/better-place/ Not enough interest *yet* to implement this, but the problem can be solved easily and it is practical. You don't have to lift anything heavy to do it.
3) http://www.fastcompany.com/1282877/toyotas-third-generation-prius-hybrid-has-solar-panels-remote-control-air-conditioning Believe it now? "Imagine being stuck in the middle of nowhere..." You have the same problem if your engine dies in a regular car. There's a reason you're supposed to have blankets etc in a northern car during winter. And the fraction of people who drive in the middle of nowhere in the winter in places where it's actually cold enough to worry about this is "not every driver, though" is it? Besides, http://www.technologyreview.com/news/513466/novel-heating-system-could-improve-electric-cars-range/ there are other options than electrical resistance for heating on the horizon. But at present let's be clear - you're talking about a tiny fraction of the population. Anyone who lives in the South would take the air conditioning even if it means they can't drive all the way to Michigan's upper peninsula in January.
Come on 30 seconds with google would save you from saying things don't exist that do.
Having worked power generation for 20 years, I can say that you are incorrect in your assumptions.
No power gets "thrown away." You cannot "overgenerate", it has to go somewhere. Be it batteries, pumped storage, or capacitors, it has to go somewhere.
Grounding is a very specific term in electricity. It does not mean anything close to what you assert.
You are correct, generally baseload plants are not shut down, however they can ramp their output. One of the facilities I worked was over 2500 MW, and we routinely reduced our output to minimums, about 400 MW.
Mr Ed I think you are being disingenuous or not thinking the problem through. What happens to the inputs. When you reduce the outputs in half do you burn half the coal?
Hey, I thought of a decent example. I buy a 5000watt Honda fixed rate generator and turn it on.
After I finish using it, I unplug the equipment from it, but don't turn it off. If you told me at that point it wasn't generating electricity - I would be inclined to defer to your expertise. Yet I am still using energy to run the device at full potential and using the same amount of fuel - so even with no electricity generated - I am still wasting the equivalent of 5000 watts of energy (instantaneous). Wouldn't it be better to plug in an electric car and reclaim this lost / wasted energy?
FYI:
regarding 2) http://www.reuters.com/article/2013/06/21/us-tesla-swap-idUSBRE95K07H20130621 So it's actually 90 seconds. Which beats the heck out of your car.
1 and 3 remain irrelevant since very few people need to drive many hundreds of miles at a time or in cold enough weather that it's an issue.
I just realize you people have got much experience! Thanks for discussion!
used cars
If you use a car engine to make electric power it get about 1/3 the efficiency of a baseline plant. A turbine - about 1/2.
But then a baseline plant is optimized for one thing, the turbine for another and the car engine for a third. Though making electricity with a Honda generator (like a car engine) is done all the time - it is done when you don't have easy access to the power grid.