Technical Note: Sorry for any recent performance issues. We are working on it.
From Russell Seitz:
(with apologies to Jen Sorensen at Slowpoke comics).
But you also say, “However, the 34 kWh = 1 gallon comparison is obviously meant to compare the efficiency of the respective engines in making use of the power supplied at the plug or pump, in units consumers will be familiar with (mpg). And that’s fine by itself, it’s just not meaningful as a guide to CO2 savings.”
Nope, it is not fine because it erroneously does what it pretends to do. Not counting the engine in the electric case makes the electric car look three times better than it should. Hence, without hardly trying, the Nissan Leaf is proudly advertised as getting 99 MPG, when an honest comparison would rate it at 33 MPG. And 33 MPG is about what it merits.
Not only will it get its energy from coal, it will get a lot of it! If you have to get your energy from coal, you should be pushed hard to use very little of it. The EPA is thus shooting itself in the foot, and climate concerned folks should get a grip on this as a seriously damaging trend. Economy concerned folks should also take note, since this is setting up a sequence of events that can only come to a bad end.
138 Bob Sphaerica
No reference is required beyond the evidence presented, and the hard mathematical logic of my explanation.
Please read it carefully, and I think you will see the same inescapable conclusion that I draw.
@Everyone who is talking about electric cars …
It’s impossible, even with fossil fuels, to nail down “efficiency”, especially with all the “Smart Grid” work going on to make cars play nice with the grid.
The reason is that getting cars into the “off-peak” time period will improve overall grid efficiency by allowing more “bulk” power to be produced and less “peak” power to be required. Some of the “demand regulation” work that’s going on will make the grid still more efficient — with fossil fuels — and if the “supply regulation” concept I worked on while at IBM goes anywhere, the electric car could help replace the “peak power plant”, even with high amounts of renewable and intermittent capacity.
And for what it’s worth, the electric car is just about the only load with the potential to make the grid cleaner and more productive — as well as more tolerant of intermittent loads.
#146 David Miller,
I had not opened the subject of ill intentions. I simply concentrated on the profound dumbfoolery of the EPA method of rating cars. And of course, I might have alluded to the profound implications to the climate from such dumbfoolery.
There is more to say about all this.
Yes, as energy production shifts, EVs could become (even) cleaner. I should have specified at #145 that I was only looking at the present U.S. power generation mix. (And also, that the CO2 savings for an actual consumer will depend on the energy mix going into his local grid rather than the national average I used.)
On the other hand, though, I don’t know how energy production will respond to the jump in demand if Americans begin on a large scale to feed their car habit from a plug rather than a pump. I fear it would give fossil-fuel power generation a longer lease.
As for the 32.6 mpg figure — I think it’s high too, compared with the figures given in http://www.fueleconomy.gov/feg/FEG2011.pdf. But in summary, I think EVs come out looking surprisingly good even when one stacks the cards against them a bit by comparing last millennium’s electric power mix with the gasoline-driven car of tomorrow.
I’m thinking in terms of CO2 emissions. So let’s make the comparison “mpc” (miles per kg CO2) instead of mpg. Using the same rough numbers as in my #145, that would be about 4.8 mpc for the electric car on the sticker, 3.7 mpc for the fabulously energy-efficient new ICE car of the BTS table, and 2.6 mpc for the average American car from the same table. This is, again, assuming the actual carbon emissions per kWh of U.S. national power production mix in 1999, rather than some all-coal or all-windmill scenario.
To my way of thinking, the “99 mpg” electric car is not three times less bad than a 33 mpg economic ICE car, because it does not go three times further with the same CO2 emission (as the sticker might cause one to think), and especially not with no CO2 emission at all (as the sticker might also cause impressionable consumers to think). But it does go some 1.3 times further per CO2 emitted than a 33 mpg ICE car, so neither is it equally bad, as you claim it is. And that’s before taking into account the valid points Bob raised.
As always, goes way off-topic via the usual suspect6s who don’t seem to be able to find a suitable alternate blog. TheOilDrum, perhaps?
146 David Miller
I complained that the EPA sticker was flawed and seriously misleading.
I responded to the question how could it be better done.
You concluded that the correct answer is ‘it depends’ and this is the only correct answer in physics.
Thus, we agree that where the EPA says, ’99 MPGequivalent’, this is not correct. But is not correct, not in a random way that would relate to the it depends answer, but it is over the top exageration in a deliberate direction.
And it is openly apparent that while this is not exactly a lie, it is gibberish and it serves to promote the advantages of electric cars in a false way. Call it what you like.
The statement about CO2 is also not a lie, but restricting the ‘zero emissions’ to the tailpipe only and not adding a further quantification of the power plant effect seems to me to be deliberately misleading. And the effect of the electric vehicle is falsely portrayed as a result.
As to CO2, I wonder that nobody seems to have looked at the NRDC-EPRI study where-in Fig. 5-1 fully and completely, and approximately correctly addresses the complete well to wheels CO2 for the various power generating possibilities, so the ‘it depends’ can be up to the reader.
As for the usual OT complaint that inevitably comes up as things get near an important point, one might look at the article and wonder what the thread should be. I say it is about the politically biased news scene, as epitomized by the Faux folks, whatever they call themselves. Yes, the cartoon focuses on climate controversy, but this is inherently very political, and a mishandling of climate related topics like this by the very regulatory authorities that purport to be acting to limit CO2 only serves to damage the general cause.
I further argue that the effect of the EPA sticker will be to lull the public into a false sense of complacency.
Coming to any kind of common agreement about how a MPGe number can be determined is not possible without some common understanding of power generation processes. However, it seems easy to rule out the more ideal sources that are, and always will be, fully used so the idea that these will be part of the mix that responds to new loads is unreasonable. Not even government decrees can provide reserve capacity from nuclear, hydro,wind, or solar sources.
Reasonable people can disagree whether the choice between natural gas and coal will always go to coal. In California, by banning coal, it would seem otherwise. So on this basis there is a validity to an ‘it depends’ between these two options. I have concluded that it will prove to be economically and politically untenable to continue to ban coal, or even favor natural gas to any serious extent. I even contend that to use natural gas for electrical power generation is unconscionable for climate reasons, not because it would not have an immediate benefit, but because there are higher uses for this very desirable fuel. But all this is a bigger discussion.
CM @ 156:
The upside for the electric car is “Zero CO2 emitted, period”, while for the ICE that’s impossible.
And that’s the difference that’s being glossed over by focusing on present technologies and making naked assertions about the future.
As for “the grid”, “the grid” will be Just Fine(tm). The swing between peak and trough in any given day is great enough that EVs won’t be a problem. The good news is that the more the “trough” is filled in, and the “peak” flattened out, the less CO2 per KWh gets emitted.
159 Furry C Herder
Yes indeed, Zero CO2, but not quite ‘period’. You omit the timeline governing such an accomplishment. And it is necessary that there be reserve capacity from solar, wind, hydro, etc.
The IEA says it won’t happen for a long time. But if and when it does, we can agree, the EV will emit nothing, for the most part. When the last coal plant is scrapped, it will be time to start working on EVs of the sort that Nissan is pushing.
But the EPA sticker says the Nissan Leaf will emit zero!!! in big print, and qualifies it in very small print. And it is now!! for sale on the show room floor. By the time the zero emission situation comes to pass, the permanent magnets in the motors will have weakened to a fraction of their needed effectiveness.
The best use of solar outputs would be to put it on the grid to reduce the need for fossil fuel consumption, and where it makes true economic sense, that is a good idea. When you plug-in an inefficient electric car like the Leaf, that power will be pulled away from other uses, and the coal fired electric generators will have to be cranked up a bit.
But thanks for demonstrating the very thing I assert will happen as a result of this sticker.
It is a shame that you have such a “comic” on your site. I thought you were a scientist and had some valid information. Makes you appear to be just another biased bigot ranting, standing behind his degrees.
“It is a shame [...]”
Ah, the fine art of the concern troll. Nice try.
David #157, I took the comic as an invitation to an open thread.
EVs will have zero CO2 emissions when electric power generation does. But
it does not at all follow that there’s no place for EVs in the interim. If ~30% less CO2 per mile traveled is achievable today, that seems pretty compelling.
a shift to EVs would increase overall electricity demand. If they’re charged off-peak, filling in the troughs, I can follow the logic that prices per kWh might fall despite increased demand, as cheap baseload plants supply a larger share of the total. How would it reduce CO2 per kWh? If you don’t feel like drawing me a map, I’d appreciate pointers to relevant reading.
If 30% reduction in CO2 per mile traveled were the present case for the EV, that would be worth something. Only trouble is, that is not the correct number for reduction.
Perhaps you are making the comparison with conventional cars? Then I can see where you get the 30% number.
But if you are comparing with a hybrid, you do not get a 30% reduction, when coal is the fuel for responding to marginal load increases, there is an increase in CO2, and if the cars are carelessly designed, there could be a big increase.
If we take the case of the plug-in hybrid, the basic machinery of the hybrid has to be installed and then extra batteries added at significant cost. This is particularly bad, and there is no argument since the comparison between the basic hybrid and the plug-in hybrid would be an obvious way to think.
For the all electric, the cost of the even larger battery would need to be weighed against the cost of the engine. I contend that the reference should still be the hybrid and not the conventional car running entirely on gasoline without hybrid capability. And we end with an increase in CO2 again.
Are you looking at Fig. 5-1 of the EPRI-NRDC Duval study?
But at least we agree tha that ‘zero CO2′ is nonsense; and perhaps we agree that our EPA should do better.
I overstated. There is still a place for EVs as a way of reducing use of oil. That is a real motivation, and for some, that is the over-riding motivation.
We have not exactly come to agreement that coal will be the basis of response, but when we get there, we should be able to accept that the shift will be from oil to coal.
Re Jim Bullis
took the numbers from:
the engine is 37.6 % efficient
some fraction of engine output goes to the driveline (100 % if no idling/standby and we neglect accessories)
the driveline efficiency is 69.2 %
the fraction of driveline output (at wheel) not lost to braking is 54.0 % Assuming regenerative braking efficiency is the same as the driveline efficiency * motor/generator efficiency (I’ll just assume 95 % here, I’m not really sure), and multiplying by motor efficiency to get the saved energy that displaces engine energy supply to the driveline, and dividing by engine efficiency, we get the fuel saved; subtracting from the fuel input (100 %) and taking the recip-rocal to fuel input and dividing by 100 %, we get a factor by which the efficiency from fuel to wheel has increased.
No idling/standby and no accessories:
no regenerative braking:
fuel to wheel efficiency is .376*.692*.540 = 14.0 %
with regenerative braking:
14.0 % / (1-.376*.692*(1-.540)*.692*.95^2/.376)
= 14.0 % / (1-(.692*.95)^2*(1-.540))
= 14.0 % / 0.801
= 17.5 %
but multiply by 0.8 for gasoline EROEI of 5:1 (is that correct?), we’re back at 14.0 %
For highway driving, assuming no braking:
.376*.692*.8 = 20.8 %
With an electric car we are told the battery to wheel efficiency is 0.75. Assuming power plant and transmission and EROEI of electricity efficiency is 30 % (?), and that braking uses the same fraction of energy supplied to the wheel,
No idling/standby and no accessories:
no regenerative braking:
fuel to wheel non-braking efficiency is 0.3 * 0.75. * .540 = 12.1 %
with regenerative braking (noting the .75 must include the motor efficiency:
12.1 % / (1-.75*(1-.540)*.75*/.75)
= 12.1 % / (1-.75*(1-.540))
= 12.1 % / 0.655 = 18.5 %
for hwy driving, 0.3 * 0.75 = 22.5 %
But that’s not a fair comparison, because this EV must have a more efficient drivetrain than the ICE car. Guessing it’s 0.75/0.95 ~= 0.789 and substituting for 0.692,
HEV no regenerative braking, including EROEI: 12.2 %
with regenerative braking: 16.4 %
hwy: 22.6 %
Not much difference. Of course this probably misses some details and perhaps misunderstands how the HEV is set up. With either HEV or PHEV or EV, some portion of the drivetrain might be skipped by having a motor for each wheel; this in principle could be done without the P.
Of course, if the power plants are made more efficient or have CCS or are cogeneration (or building furnaces are cogeneration or cars’ engines are cogeneration), or if fuel cells make it big (but they could be used at fixed locations and possibly as cogeneration, and the fuel processing necessary to turn gas,coal,oil into has to be taken into account, although if H could be seperated from C while leaving C in solid form, then… (but I think some fuel cells can use CO, and there’s a Li2CO3 battery that can convert electrical energy as C, though I’m unclear on whether it is reversable), then that also changes things.
And this doesn’t take into account the energy use in buidling and maintaining the power plant, the car, the ICE, the battery, the motor, etc.
Back to an earlier point made somewhat by me and also other(s): the question is whether biofuels EROEI and economics and emissions, social impacts, etc, can compete with fuel equivalents of solar, wind, nuclear, etc, and/or coal and or coal with CCS and/or sequestration… and how much can be supplied to cars as opposed to winter heating and power needs to backup solar, etc., or whether fuel cells can be developed (which would change the whole fuel-electricity part)… Etc. (PS as you say, natural gas is better for heating or at least cogeneration. Well, convert furnaces to cogeneration (maybe with TPV) and you’ve got your electricity for your PHEV.)
And (here back to politics of climate change) it looks like you might want to support a price on emissions or some other climate policy to prevent transportation becoming more dependent on coal.
It’s economics. We could potentially save more money by switching a portion of the fleet from pure ICE to ICE-HEVs but even more to PHEVs and sometimes EVs. Will that money get used to build up clean energy infrastructure, in a deal that reduces emissions and eases the way to eventually shrink coal usage, or will it be used otherwise with greater reliance on coal? Of course you can increase efficiency and prolong oil (and reduce price by reducing demand), but that would help with EVs too.
And we’ve been over this before, but: It doesn’t matter if the power specifically used to charge the battery is coming from a particular set of power plants; what matters is if the total system becomes more clean, and PHEVs could be a part of that. _______________________________
166 Patrick 027
That reference to fueleconomy.gov must have been put together by the same folks that put out the EPA rule on MPG.
Demonstrate this for yourself by also clicking on the ‘electric’ tab and see that they believe an electric motor efficiency can be meaningfully compared to an internal combustion engine efficiency. This serves as total disqualification on the subject.
Their analysis is hopelessly confusing. And you misread the driveline efficiency number to further confuse matters.
And on top of it all, there is a lot of confusion even among the more credible folks involved in engine issues.
I am traveling and not in a place to effectively sort this out. And rather than further confuse the issue, for now, I will just rely on the results of Figure 5-1 of the NRDC-EPRI study.
Grams CO2 relate proportionally to kWhr, or BTU, of heat. So if we believe the CO2 per mile from the NRDC-EPRI study, we should get a reasonable statement of total heat as well, since that study is comprehensive from well to wheels, at least it is so stated. Relating this to heat in a gallon of gasoline would be a reasonable way to proceed, and the input to the engine would then be as if it required something more than the initial gallon of gasoline. This should satisfy those who want to count upstream energy loss, and so they should.
CM and Patrick 027 and others interested
To further realize how things have deteriorated in order to promote electric cars look at:
where this particular page shows that even the head of the UK DOE and Climate Control, David MacKay, is willing to distort physics even though he shows he knows better.
Here is an exerpt from that page 27 of his book:
In this book, however, I will usually use a one-to-one conversion rate when comparing different forms of energy. It is not the case that 2.5 kWh of oil is inescapably equivalent to 1 kWh of electricity; that just happens to be the perceived exchange rate in a world-view where oil is used to make electricity. Yes, conversion of chemicalenergy to electrical energy is done with this particular inefﬁcient exchangerate. But electrical energy can also be converted to chemical energy. In an alternative world (perhaps not far-off) with relatively plentiful electricity and little oil, we might use electricity to make liquid fuels; in that world we would surely not use the same exchange rate – each kWh of gasoline would then cost us something like 3 kWh of electricity! I think the timelessand scientiﬁc way to summarize and compare energies is to hold 1 kWh of chemical energy equivalent to 1 kWh of electricity.
There is a lot of good work in this book that is otherwise spoiled by this deliberate distortion, yes, equal to the EPA in violating Laws of Physics.
Think of the grid as a bucket with lots of tubes running out the bottom. The job of the power planner is to keep the bucket full, at least to the level of the highest tube.
There are a number of filler tubes, each with a faucet controlling it. Many of the faucets are all the way on, no matter what happens. Some faucets are part way on. There is a mix of filling faucets.
Now a new tube is installed in the bottom of the bucket and more water runs out into that tube, so something has to be done to increase water coming in at the top.
The faucets that are allready full on can not be turned on further.
Now look to the faucets that are part way on. But there is a meter on these, so there is a cost associated with which of these faucet is turned on more. The sensible economic decision is obviously to choose the lower cost faucet. But the response to the newly added bottom tube is which faucet is turned up. That is the marginal response.
Coal is the fuel feeding the system that is chosen for the marginal response when an EV is plugged in.
Jim Bullis: you seem to be struggling to create an analogy for base load and peaking power. You are struggling a lot – the analogy you provide is really rather muddy and not helpful.
If my interpretation is correct (unlikely, because it doesn’t make much sense) then you claim that plugging in an EV will require a response from a peaking power plant, because the baseload powerplants are turned on full. And then you claim coal is the power in question. But that’s wrong, because coal provides baseload power. Gas is the typical source of peaking power.
Your whole argument is a non-starter anyway, because fighting climate change requires replacing coal and natural gas and gasoline with renewables.
And you really didn’t understand what David MacKay said, did you? That’s not a question. You didn’t understand. Try reading it again, leaving your preconceptions at the door.
Yes, my comparison was with conventional gas-driven cars. I hadn’t got to hybrids yet… But for starters, I could apply the same simple calculation and data used at #145 and #156 to the Prius, which is now rated at 50 MPG combined (FEG 2011). As a non-plugin, it gets all its energy from gasoline, so that’s 8.8 kg CO2 on a 50-mile journey, or ~ 180 g CO2/mile.
That’s better than I get for the higher-rated Leaf (210 g/mile on the present U.S. power mix). But for EVs vs HEVs vs PHEVs, the margins are small enough that the outcome may be decided by all the terms I lazily left out when comparing EVs with hopeless old conventional cars, including emissions from the refining and distribution of gasoline. In the Duval study you mentioned, well-to-tank emissions seem to account for a steady 21-22% of the total emissions from gasoline. Factor that in, and the Prius gets ~ 230 g CO2/mile, which is worse than the Leaf.
But wait – what about transmission losses… and the emissions from getting the coal to the power plant…? I think you can scratch my calculations.
Which brings me to whether the EPA could have done better, as you say. Maybe they could, but remember, they’re not stupid – they’ll have considered the advantages and drawbacks of different approaches. How would you do it? Remember, the label should convey as useful information as possible, as intuitively as possible, in as few figures, explanations and caveats as possible, and they’re only going to make one label for one car model regardless of where it’s bought.
We may not like their MPG-equivalent for EVs. But if the EV label reported miles per kWh, it would be a far smaller number than the MPG, so psychologically it might make conventional cars seem more economic. So perhaps we need some kind of MPGe after all. I’d innovatively suggest a carbon mileage, an MPGe based on miles traveled with the same CO2 emissions as from one gallon of gasoline. But then, should the full well-to-wheels emissions be included, for both gasoline and electricity? Calculated how? Moreover, the emissions from electric power production would not be the same for all consumers. One could use the national average, but noone’s got their garage plugged into a national average grid. We already have“city” and“highway” mileages in small print beside the combined mileage; should the label also indicate coal-state and nuke-state mileages?
In short, I’m beginning to understand why the EPA label focuses on quantities that can be measured solely by testing the actual vehicle the sticker is glued to, and that will be the same for all vehicles no matter what utility they draw their power from: namely, how well they make use of the energy they draw from the pump or the plug; and what comes out of the tailpipe.
But I continue to think it’s not a good guide to the carbon footprint of EVs, and you may be right that they exaggerate the advantage of plug-ins over hybrids. Since the EPA is eager to gather public input on labeling, it would be nice to come up with a better idea.
But I’ve got deadlines looming…
As his OT comments have come to outnumber his readers , Mr. Bullis ought to take his soapbox elsewhere
Thanks for the alert that the comment period is not over. I was under the impression that the rule was final.
Steady loads are met by a in a variety of ways, but all that is required for coal scheduling is a reasonable capability to anticipate loads.
Somebody told you that coal supplies ‘base loads’ which it does, but coal is fairly flexible and can respond to daily scheduling. ‘Base load’ is a not very useful term. Load is variable, and there is a level of load that usually is less than the daily minimums.
MacKay writes a clear and absolute sentence, “I think the timeless and scientiﬁc way to summarize and compare energies is to hold 1 kWh of chemical energy equivalent to 1 kWh of electricity.” What is there in these words that is unclear? Do you understand that it is absolutely a violation of the Laws of Thermodynamics?
172 Russel Seitz,
I gather you have no concern about government that repeals the Laws of Physics.
I hope there are a few more readers than commenters, but this is a hope, not a law.
Re Jim Bullis – I realize you have the opinion that the graphic at http://www.fueleconomy.gov/feg/atv.shtml has the wrong numbers. But I didn’t misread anything; I divided the number at the driveline output by the number at the driveline input and got the driveline efficiency; what did I miss? Of course, if you think I used the wrong approach or numbers to guesstimate regenerative braking, then go ahead and tell me what I should have done. But I tried to make comparisons on an equal footing – and what I came up with (noting the last calculation with the ‘implied’ driveline efficiency of an (P)EV substituted into a non-P HEV) is that the fuel (including EROEI) to wheel efficiency may be about the same (why should that be surprising?), with the ICE-HEV car being possibly slightly better on the hwy and the P-EV doing better in city driving if both have regenerative braking.
The point that the electricity-fuel conversion could change is a good point – if all primary energy were electric and certain applications were served best with fuel, then the conversion would be quite different. I’m not saying that is the future but it’s an approximation of one scenario.
Dream on, Mister Bullis . Your 40 odd posts may far outnumber your interlocutors, but anyone who writes the better part of 27,000 words off topic is unlikely to be deterred by a fleeing audience .
Let me express their thanks for not persuing them
175 Patrick 027
I jumped to the arrow going downward labeled
‘driveline loss’ and overwrite of 5.6% to mean driveline efficiency of 94.6%.
Engine efficiency is certainly confusing.
We have learned from Toyota how to produce a very efficient, relatively speaking, automobile that runs directly on gasoline. I use this as a reference since that is an option in actual production, not just idle blather.
Argonne National Laboratory shows engine efficiency for the Prius, variously, from 35% to 38%. Since this comes from dynamometer tests, I make the slightly tenuous assumption that this is heat input energy divided by output mechanical energy via the engine crankshaft. This goes into a transmission which is now fairly efficient, as opposed to the old fluid transmissions. In modern systems, the mechanical connection to the wheels is around 90% efficient. This is the reason that Toyota uses a ‘synergy drive’ arrangement, so that for much driving, much energy is coupled to the wheels without going through the battery and the electric motor.
As you mention, regenerative braking is of great importance. However, there are big differences in the way this is implemented, where a really good system is complicated and expensive, and some incidental use of this basic energy saving arrangement is cheap and simple. There is no guarantee that an electric vehicle uses regenerative braking at all.
Back to the EPA explanation, their attempt to generalize about all kinds of driving makes it nearly impossible to follow their displayed chart. But their idea of electric motor efficiency is so far off as far as real engineering goes that it seems unlikely we will get much more out of this chart.
I often point out, there is a reason that a heat engine is called an engine and an electric motor is called a motor. The electric motor changes form of energy without doing the heavy lifting of converting from heat to mechanical energy.
When the all electric primary power scenario comes to pass, I will cheerfully melt down every ICE I can find.
Until then, the best we can hope for is to use the least amount of electricity possible. The fake MPGe system encourages sloppy use of electricity. This is in the same league as making oil extra cheap through tax deals like the ‘oil depletion allowance’, whereby the motivation to make vehicles use less energy was squashed and the motivation to make engines any better than what we now think of as normal was also squashed.
Historically, 100 years ago, there was a significant group of companies attempting to develop ‘cycle cars’ which could have led to much reduced use of oil, compared to the cars that we came to know and love instead.
I bet you got confused by MacKay’s way of talking about ‘chemical’ energy as both the heat that comes from burning fuel as a ‘chemical’ reaction, and the ‘chemical energy’ stored in a battery. Getting energy from burning fuel requires a heat engine. Getting energy out of a battery requires only ionic action that does not involve the heavy lifting that can only be done in a heat engine.
MacKay himself was not at all confused.
That is confusing even for those who want to understand stuff.
I’m afraid to ask…. so, Jim Bullis: instead of treating all energy as equal, and setting conversion efficiency aside to be treated separately – what conversion factors would you propose?
Do you see the problem yet? The conversion factor is not a constant. Pretending it is can cause vast confusion. As it seems to have done with you.
Now, if you have a limited problem, then it might be sensible to build in your conversion factor. But in a general discussion of energy, where you don’t particularly want to be concerned with where it came from or where it is going – a joule is a joule.
That’s for high-level discussion. If you look at the detail, you will find that the electricity supply route has lots of losses, just as with gasoline. The difference is that electricity is lost in dribs and drabs all the way down the line, while gasoline is, as you keep harping on about, subject to the inefficiencies of the internal combustion engine. I have noticed, Jim, that you have a tendency to apply factors such as this one-sidedly. You need to assess both energy sources in the same way. You can’t just make one exception for one fuel. Even in your trivial example above, you managed to ignore the battery charging efficiency (let alone everything else).
I don’t think David MacKay is absolutely right about everything. But his reasoning skills and communication skills should be something to aspire to, Jim.
Re ‘OT’ – Well, I was starting to think this was a semi-open thread as someone else had, and/or the car discussion was related via politics of regulating emissions (distinct but connected to climate science); but the original poster just said this car discussion was OT, so I guess that’s that – well, except for very brief responses to other comments (as long as allowed) – on that note:
Re Jim Bullis – summarizing my points:
PHEV vs non-P HEV raw fuel source to wheel efficiency may be roughly the same;
I agree the 99 mpg rating given to the Leaf was ill-thought-out, in a word, wrong, though I can understand CM’s point – if I may paraphrase an implied aspect of it – that they want to communicate to the public in units/phrases they are familiar with (mpge is good; maybe just place 1 mpge ~= 2.5 or 3 mpg(fuel) on the sticker).
Thermodynamics/conversion efficiencies and emissions of a mere subset of the whole system are not the only things that decisions are based on; economics, though dependent on those, depends on other things (and so on for social/environmental matters). 1a. Fuel can be more easily stored than electricity; until room-temperature superconductors (And maybe not even then), electricity must be converted to some other form to be stored and conversion to fuel generally involves a loss. 1b. You want to avoid converting energy (and transporting/transmitting it) back-and-forth needlessly and use energy in a less processed (and more local) form if possible; and economics reflects that. But it must also be noted that 2. some applications (in different places in different conditions) are better served by energy in different forms; some are more flexible than others. 3. And also, the economical availability of different forms of energy (at different places, at different times of year) is not necessarily what we would most want, so 2+3 sometimes we will want to convert one form to another, sometimes more than once. Also 4. Various processes can be linked by byproducts/coproducts and overlaping sets of inputs (cooperation (PS if we reduce our gasoline usage and nothing else changes, gasoline prices would have a relative decrease but some other petroleum products could tend to increase in price), competition) And 4. the ways in which energy is obtained from nature can and will evolve as technology changes, society changes, economies evolve (including: some resources are depleted, others have evolving competing demands) and public policies change, and so while a dominant energy conversion now is primary fuel to electricity at ~ 30 to 40 % efficiency, often without cogeneration; it could be (depending on the amount of biofuel that can be produced at some efficiency and lifecycle emissions and some amount of land/water/etc.) reversed at some time in the future; and to avoid unnecessary conversions, some processes which can be adapted to use electricity would be (some might be now if not for habit – depending on COP and cost of heap pumps, for example). The efficiencies of conversions, though ultimately limited by physics, could change depending on technology (and economics thereof). Developing a range of technologies early on can better enable taking advantage of opportunities and reducing costs later.
In other words, economics (and long-term public policy and strategy) is important.
If you don’t want an emissions tax (or some roughly equivalent policy), or simply don’t believe one will occur, or believe that coal will continue to be the first power plant fuel of choice – because of economics (obviously not because of emissions, and not directly because of thermodynamics, but indirectly via economics), then you must also realize that PHEVs could (depending on non-fuel/electricity costs) become a greater share of the market, with some petroleum usage replaced with electricity, because of the economics (prices won’t shift to stop this until the market share reaches some equilibrium – except for bubbles, of course; greater car efficiency could bring the usage of either form of energy down, this would shift the equilibrium market share (for given total market) as the supply curves have different slopes). This is without faulty EPA stickers. With 1 galon of gasoline ~ 36.6 kWh ~ 12 or 14 kWe at maybe $3 (likely to rise without (or up to a point, even with) changes in efficiency, driving, style, market share and size), thus ~ 25 or 21 cents/kWhe (compare to solar, which is likely to fall), verses ~ 10 cents/kWhe for electricity, even factoring in that based on fuel not including EROEI, the non-P HEV may be a little more efficient, it isn’t THAT much more efficient; so what would you choose?
So why advocate against using the P in PHEV if you aren’t going to advocate against burning the C in coal, or have I misunderstood?
(Okay, that was way longer than I thought it would be, but I think that’s all I have to say without becoming too redundant.)
… the gasoline kWhe is used without conversion from ‘kWhm’ (mechanical) because they are similar enough in this context.
Re 177 Jim Bullis, Miastrada Company says:
I jumped to the arrow going downward labeled
‘driveline loss’ and overwrite of 5.6% to mean driveline efficiency of 94.6%.
Would you agree that my interpretation of the graphic makes more sense?
Good to know that driveline efficiency can be so improved upon.
What do you think/know the efficiency of motor/generator in an ((P)H)EV is?
(kept it short that time!)
Patrick 027 and CM, I think your comments are well done, but in just a small but significant part it sounds like your excusing the EPA for making stuff up so long as their heart is in the right place.
#184 “making stuff up…”
Not solely Rod B.’s province…
> sounds like your excusing the EPA for making stuff up
Rod B, relying on Jim Bullis for the assumption EPA is making stuff up.
Clue: approximation, explained as an approximation, is not a lie.
CM @ 163:
The difference between “base load” and “peak”, ignoring block generation that can ramp up fast enough to have “base” efficiency, is made up by peaking plants. Those plants are less efficient and more polluting. So, by “filling in the troughs” both the cost / KWh and the CO2 emissions / KWh decrease. Still have more production, and still have more CO2 emissions, but the “cost” and “CO2″ numbers improve.
The other advantage is that cars are being designed to be charged in a “smart” manner. When demand is higher than production, line frequency drops. There are appliances which can detect this and respond. The reverse happens when demand is lower than production, etc. There is a lot of work going on in this area — it’s usually lumped under “Smart Grid”, though some of the ideas are rather dumb and others could cause the grid to actually collapse. I especially like the poorly conceived “Smart Grid” ideas that can result in total grid failure.
The problem with the “No! Don’t Do It!” people, like Bullis, is that we have to start doing “it” so that in 2, 5, 10, 20 years, we’re actually “done”, not waiting around. But also, we need to be building and buying electric vehicles because the average life expectancy of a car is much longer than the time its going to take to transition. Or at least, to be able to transition.
If you buy a gasoline powered car =today=, you’ve just made a financial commitment to burn gasoline for about 15 years. One outcome of the Car Quality Wars is that cars last a LOT longer. My Pontiac is 9. My son’s Infiniti is 11. Neither car is ready for the scrap heap, and the cars rolling off the assembly line today have even better quality.
The question becomes this — how many years from now do you expect an electric car to be a viable alternative. Consider the explosive growth in wind and solar, rising costs of gasoline, environmental costs and put “my next car will last more than 10 years” on top of that. The only rational answer I can see is that anyone purchasing a new “commuter car” should be buying a ZEV or a PHEV and possibly “self-fueling” with residential wind or solar. A straight-up ICE makes no sense. Big family mobile or truck or long-distance driver? Sure, go with something that can run on liquid fuels. But if the range is workable in a ZEV or PHEV, go that route.
186 Hank Roberts
An ‘approximation’ that is not at all an approximation, but pretends to be, is deliberate deception.
The problem is all about whether or not the heat engine, used to make the conversion from heat energy to electric energy, is included in the calculation for all forms of propulsion apparatus.
By simply accepting a kWhr of electricity as a measure that is closely related in some way to heat is cheating, not by just an approximation, but by a factor of three. In the example at hand, the Nissan Leaf was rated at 99 MPGe when it should be 33 MPGe. That is not an approximation!!!!!! Even under government imposition of a ban on coal, the error would be more than a factor of two, so in this case the Nissan Leaf would get, maybe a rating of 66 MPGe.
What we see here in this discussion is that the basic problem of the heat loss in heat engines is not something that many otherwise well informed people are aware of.
By the way, it is not a new problem: Edison and Westinghouse substantially disagreed on this, but because efficiency was not very important in the day of very cheap fuel, the world went to the AC system of Westinghouse, which enabled the system of central power plants that we have today. And these generally throw away two thirds of the input energy.
The EPA is a government agency that relies on outside experts, and it appears that the ‘expert’ job has been siezed by unqualified folks, who have various motivations and questionable expertise in some combination.
In physics, there is no meaning to equivalence between heat and electric forms of energy, unless the process is specifies. This is the reason for the ‘it depends’ answer, so when one is trying to set a standard, it is necessary to come to some agreement on the underlying process. But it is especially hard to reach such an agreement when some folks evade, whether by ignorance or a deliberate intent, to evade the idea of marginal response.
The idea of marginal response to new loads is not something I made up. It is a common way of evaluating incremental changes in processes. In systems of taxation it is familiar to many, where the last dollar earned is taxed at a different rate from the overall tax rate. In general, marginal response is a required concept for any analysis involving non-linear processes.
In electric power, one has a ‘mix’ of sources, but as loading goes from zero to high levels, sources are brought on line as load increases. The ideal source options are obviously going to be used wherever possible, thus, something like hydro will be first on line if at all possible. But once the cheap and clean supplies are exhausted, the more expensive and troublesome sources are brought into play.
I contend that it is rational to proceed based on the conclusion that coal will be the basis of marginal response when electric vehicles are plugged in, so coal fired systems are specific processes and these can be specified on a meaningful EPA label, instead of just saying ‘it depends’. And in this situation, an MPGe result can be provided.
Rod B #184 (apologies to everybody else for repeating myself)
Quite the opposite. I was excusing the EPA for trying too hard to be objective, reporting only the measurable properties of the actual vehicle that bears the sticker, without making assumptions about the energy chain behind it.
Not for “making stuff up”. They don’t.
The EV sticker we’ve been discussing gives the correct tailpipe CO2 emissions (zero), and the mileage per charge, which has no doubt been painstakingly measured. The kWh-gallons conversion, which prompted Jim Bullis’s rhetorical hyperbole about repealing laws of physics, actually gives a correct picture of how efficient the EV is at making use of the energy supplied to it, relative to other cars; and it does so in terms meaningful to the average consumer.
Unfortunately, because they exclude power generation, neither figure represents the actual carbon footprint of an EV. I don’t know how many consumers actually risk being misled by this: Those who are likely to consider an EV versus a hybrid these days are probably often motivated and well-informed enough to fill in the gaps for themselves.
I do however worry that this kind of rating could lead to complacency that EVs will solve the climate challenge to the transport sector, when a real solution would also involve driving far fewer miles in far fewer cars than we do at present. The perfect zero-emissions vehicle remains the bicycle.
Thanks for the explanation. But I thought baseload power was typically delivered by coal (and nukes), peak power by gas turbines (and hydro, and with opportunities for solar). If I had to take a wild guess without looking up the numbers (as I haven’t yet), I’d think the immediate effect of shifting more power use to baseload would be more CO2 per kWh, not less.
187 Furry Friend
Yes, it all depends on our different perceptions about how things will unfold.
I have looked at the ‘explosive growth in renewables’ and have concluded it is a glass, not half full, but with barely noticeable dampness on the bottom and seem see the glass to be near to overflowing.
Please let me know when there is reserve capacity, yes, I mean ‘at the ready’ in renewable sources. If you don’t tell me, I will just watch to see when all the coal fired power plants are scrapped.
There is no substitute for a powerful visual experience. Drive up to Kansas City and then take US169 North past the old airport. Look to the right and see giant coal cars filling parallel rail lines, and maybe a complete train of 120 cars coming in, pulled by 6 BNSF locomotives.
Then check the annual reports of BNSF and UP, the two by far largest western railroads, and note that 22% of the revenue of both (2007) was from hauling coal. Then look at NRG Corp annual report for 2008 and note that they have about half their fossil fuel capacity in coal and half in natural gas, but they state that in 2008 that 91% of the electricity they produced was from the coal equipment. They also noted how immensely profitable it was selling power from natural gas, where the customers had no other choice.
As long as the coal trains are rolling, if we care a whit about global warming, we had better try to make that system work. (Catch the Forest plan of comments past.)
I had missed that you made the cartoon post, but now I have noted that you have strong opinions, headed by the title, “What’s Wrong with Science and the Media?”
The core of much of science is physics. And you find that a discussion about a violation of the Laws of Physics by the EPA is OT? Please note that the media widely reports the rulings by the EPA.
Do you really think we will get on track to carry out effective solutions to global warming when we base our actions on fake physics?
And there is no separating energy policy from global warming.
But I do thank you for letting free speech prevail.
Are you characterizing what I say about the EPA as an assumption?
Did you check the EPA sticker? The violation of physics is absolutely determined by that sticker, no assumptions needed.
The relationship between heat in gasoline is absolutely related to kWhr of electricity by hard mathematical logic on the very face of that sticker.
I will pay you 33 cents for every dollar you would like to exchange. (Second Law analogy) Apparently you would find that to be a reasonable approximation.
I will even pay postage. (First Law analogy.)
“a real solution would also involve driving far fewer miles in far fewer cars than we do at present.”
I’m not saying it would be a bad thing but whatever happened to simply driving smaller, lighter, less powerful cars?
All this stuff about converting the car fleet to hybrids or even electric cars reminds me of a certain hydrogen-powered Hummer. There are so many SUVs on the road and that’s your priority? Hybrid and electric designs have a place but the vast majority of cars in the world are cheap cars. Efficient ICE cars are so much cheaper than a Prius and can end up causing less emissions (depending on how much time they spend stuck in traffic jams).
Jim Bullism, see CM’s post above, 30 November 2010 at 2:06 PM
The people you think you’re fighting with are not here.
192, Jim Bullis: There is no substitute for a powerful visual experience. Drive up to Kansas City and then take US169 North past the old airport. Look to the right and see giant coal cars filling parallel rail lines, and maybe a complete train of 120 cars coming in, pulled by 6 BNSF locomotives.
True, but it is probably more informative to read a lot of statistics. Renewables now contribute to generating more than 4% of American total electricity, and with exponential growth that will be a much larger percentage reasonably soon, perhaps 40% in 10 years. If the current rate of R&D in wind and solar are maintained, those coal trains will be half as long before you know it (so to speak), or else heading west toward a boat to China.
The cartoon is dreadful: good for making the in-group feel even more smug while offending the undecideds. In my opinion, anyway.
When you say, ‘you may be right that they exaggerate the advantage of plug-ins over hybrids’ you are misrepresenting what I say.
First, we address the issue of energy efficiency:
The EPA sticker as proposed and published and used for advertising overstates the MPGe for electric vehicles by a factor of three.
In some restrictive situations where natural gas fired, peaking generators, provide the marginal response to new loads, the overstatement could be by a’only’ a factor of two. Where government actually bans coal, and this does not get compensated for by other users of coal, there might be an argument that the exageration is only by a factor of two.
The ‘mix’ has little relationship to the fuel used for marginal response.
Then we address the issue of CO2:
The EPA qualifies emissions to be from the tailpipe, thus contriving to make it appear valid to call the electric vehicle a ‘zero’ emission vehicle.
We have gone on to discuss the CO2 emissions in a more reasonable way, and agree that the electric vehicle would result in reduction of CO2 compared to standard cars of the past. However, the electric vehicle will result in greater CO2 than if the comparison was with existing, mass production, hybrid technology. The exception to this last is if the marginal response to new plug-in loads is from something other than coal fired systems, and in this case, and in only this case, is there any advantage to the electric vehicle, and it is not much. It is so much ‘not much’ that the cost and inconvenience of electric operation, all things considered, seems a very foolish expense. In general, it would be much wiser to buy a good hybrid and skip the EV foolishness.
Proponents of nuclear have not weighed in, and that could actually change things. I prefer measures that would make coal work until renewables or really viable nuclear come to pass.
Forests could take up some of the slack, but we also need vehicles that greatly reduce energy in general. We could even go for all electric plug-in vehicles if the efficiency of the vehicle was greatly improved.
But the EPA sticker in question removes all motivation for real efficiency.
Does the 4% of present electric energy supply come from hydro?
There are some opportunities for expanding that, but it is certainly not an explosive expansion situation.
The percentage increase in wind and solar is a very different thing compared with the growth actually needed to displace coal as the basis of response to new loads.
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