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Old 04-27-2009, 06:22 PM   #21 (permalink)
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Originally Posted by dcb View Post
Who in their right mind would evaluate the energy chain of an EV (or a biodiesel) using such a phrase?!? Try again.
I apologize,as I'm late to the party.I have some articles at home,from the 1990s,on EVs and alternate fuel vehicles and they were strong in emphasizing to the reader,the entire energy thermal efficiency pathway,from wellhead,mine,hydro dam,PV array,nuke,wind turbine,etc.,so we didn't lose sight of the entire energy balance.

At that date,they were talking about electric generation efficiencies of maybe 32% tops,then 7% loss in transmission lines to the household,the battery charger might have somewhere in the 85% efficiency.The battery might be around 80%,the propulsion motor might be 95%,but the controller would eat some of the battery power.

From the power station,to the drive wheel of the EV,the total thermal,or energy efficiency of the EV was less than stellar.

In 1988,the US EPA allowed car makers a CAFE rating of EVs,from200-400 mpg,for figuring fleet mpg on a sales-weighted basis.That doesn't mean they can do it.The GM Sunraycer was rated by Dr.Paul MacCready at 400-mpg as a gasoline car.We're talking curb weight under 400-pounds,maybe 4 square feet of frontal area,and Cd0.12.I agree with Ernie that we need to be firmly grounded in good science when we're throwing quanta around.

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Old 04-27-2009, 07:25 PM   #22 (permalink)
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I can agree that EV is not as green as people like to point it out as, but its far superior chain included than gasoline.

EV worst case scenario.

Coal(22lbs of CO2 per KWhr)-->transmission 10% loss --> charging loss 20%--> battery loss 10%--> drive loss 20%.

Gas normal

refinery 66 lbs of CO2 per GG 80% loss in power(it takes 4 GGE to make 5 GG, out of every gallon you used 80% to make it)--> 5% loss in transit-->50% loss in engine.

start each with 100 kwhr of power

electric yields 50% of the power produced at the plant
gas yields 9.5% of the power delivered to the refinery.

The gas production is under ideal circumstances, not IRL achievable. Also the refinery suffers any limitations at the power plant so saying I am not factoring those in is like saying I could divide everything by 2. The comparison is in the ratio so it won't matter.

I have used this same argument against regulating emissions on gasoline vehicles against hydrocarbons in the form of catalytic converters. Limiting the output of a gasser in any way in order to decrease tailpipe emissions creates more pollution because changing how you use that nine percent has 11 times more effect on the overall system. Lean burn, using some simple techniques to limit NOx and SOx(that increase FE) emits probably about 2x as much pollution as normal on really low AFRs(right around 16) but even if it increases FE in your car only a little it increases the system much more so.
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Old 04-27-2009, 08:28 PM   #23 (permalink)
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Originally Posted by aerohead View Post
... we need to be firmly grounded in good science when we're throwing quanta around.
That does not put us in disagreement, and I have been advocating a standard conversion factor since August. I do think that would be "fair", but I don't think making a move in favor of ICEs in the name of fairness is a good way to frame it. You want to look at the whole energy chain, as really there is no other fair way to compare them.

I'm quite willing to just give citicar guy some slack myself for now too, rather than peel the onion on the energy chain.
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Old 04-28-2009, 04:00 PM   #24 (permalink)
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Originally Posted by Ernie Rogers View Post
I see that the four highest-mileage cars listed on the left margin of the home page are all electric cars, with the exception of the Mustang HP2g (see more on that elsewhere). The data provided in the EV mileage logs indicates the assumed energy content of gasoline. Here are the numbers I found:

Citicar................36.6 kWh per gallon
Electro Metro......36.5?
1992 Metro.........33.6
Fiero EV.............36.6

Except for the third car, one wonders if these people are intent on violating the first law of thermodynamics. I think the most widely-accepted energy content (low heat value) for gasoline for use in an internal combustion engine is 116,090 BTU per gallon. This was adopted by Wang at Argonne Nat'l Laboratory (e.g., the GREET model) and (I think) is the value used for calculations for the Auto X Prize. From my CRC handbook, the conversion factor from kWh to mean BTUs is 3409.5. Dividing these numbers gives a HEAT energy content of gasoline of--

34.05 kWh (heat) per gallon.

I acknowledge that the higher value of approx. 36.6 kWh (heat) per gallon is obtained if you use 125,000 BTU per gallon, but I believe that would be incorrect for referencing to real gasoline in an internal combustion engine that exhausts products as gases.

Let's be kind and assume that the calculations are based on a strict 100% conversion of gasoline heat of combustion to electricity. However, this represents an implicit violation of the second law of thermodynamics, which states that heat cannot be converted entirely to work.

If the EV car owners would like to be entirely fair in representing the efficiency of their cars, then I suggest they agree to abide by both the first law of thermodynamics and the second law. We could be generous and let them use say the theoretical (Carnot) efficiency of a gasoline engine, or possibly a high (power plant+transmission) efficiency for an advanced power system, at about 50%.

In such a case, I would suggest that they use a kWh-gallon equivalence of either 17 or 18 kWh per gallon.

Making this adjustment will allow a much more fair comparison between EVs and highly-efficient IC cars.

Ernie Rogers
Ernie,I was so impressed with the premise of your post, that I dug through my rat's nest,pulled together what I had on EVs,and posted it in the sticky,at the Fossil Free Forum.I hope people will add more current data,then all members and lurkers can get on the same page with respect to what happens between the power source and traction wheel of the EV.Thanks a lot!
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Old 04-28-2009, 04:35 PM   #25 (permalink)
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conversion factor

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Originally Posted by dcb View Post
That does not put us in disagreement, and I have been advocating a standard conversion factor since August. I do think that would be "fair", but I don't think making a move in favor of ICEs in the name of fairness is a good way to frame it. You want to look at the whole energy chain, as really there is no other fair way to compare them.

I'm quite willing to just give citicar guy some slack myself for now too, rather than peel the onion on the energy chain.
dcb,I too would like to be able to get a handle on this can of worms.And I think this is the spirit behind Ernie's thread.If we can get a full accounting with each energy source,and a complete understanding of the chain of events,and their ramifications,in both directions from our utility meter,we'll have the best chance to make the best choices as citizen/consumers.

And I'm all in favor of "bridge" technologies which will get the US off foreign oil.Ed Begley Jr. is big on letting "science" talk.Much of the information needed to make informed decisions is omitted in the public domain.Many "findings" are found to be "Lab-shopped",are not peer-reviewed,are results of "outcome-based research" funded by some sector of the economy,which has a vested interest in the status-quo,or some agenda.

My formal education is a joke,and at age 57 now,I'm still working on self-education.I've lived off the grid for a decade,relying on wind an solar.The days of sustained cloud cover and zero wind,when I had to use a backup gasoline generator taught me some lessons in efficiency.

I'm a big proponent of plug-in electrics,especially powered by renewable sources,and am personally going down that road,however,with 200-million conventional vehicles in the US alone,it's going to take something big to move that off dead center.

I'll grind more numbers as time allows.In the meantime,I'll be leaning on all of you to keep me headed straight.Lets everybody, get that standard conversion put together.
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Old 04-28-2009, 04:53 PM   #26 (permalink)
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I just dumped this on the EV start here thread but I'll drop it here to avoid back and forthing
Since Aero posted the EV chain I'll do the fossil

Out of a 43 gallon drum 19 gallons become gasoline

drum contains 6.1x10^9j and 6-7 gallons form diesel so 26x 1.3x10^8j/(61x10^8+energy consumed in coal to refine(29.8x10^8j))=37.5%

transmission cost of 7%=34.9%

ICE efficiency typically ranges around 30% but we'll say its the max on any gasoline engine system(40% efficient) =14.0%

Transmission cost 10%=12.6%

very generous efficiency of 12.6% for the total ICE system

so the EV is 50% more efficient(chain-wise) than gas. The killer is gas requires a huge chunk of power to convert it from crude to petrol/diesel and you only get 50% back out of it anyway so add the extra costs into an already expensive side. . .
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Old 04-28-2009, 04:58 PM   #27 (permalink)
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Actually. . .its way off. . .the amount of efficiency lost in the coal plant to power the refinery is just as big as it is to generate the ev-power.

Just to get the gasoline from the crude barrell to gasoline the efficiency is 20%. have to incorporate the inefficiency of the coal plant so the power supplied in coal is way more than the power delivered in watts. . .
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Old 04-28-2009, 05:10 PM   #28 (permalink)
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Lets be fair!!!???

Hi Ernie,

I first noticed your headline and my reaction was someone was thinking that EVs were not getting a fair shake in the mpg game. Quite the contrary, it was you in control. (I was sorry to see that Ken Fry seems to have given up his reform efforts in the face of the XPRIZE final rule determination.)

Glad to see you are still a strong force for technical sanity in the "eco" or "green" world. I am convinced that there are few in this world who stayed awake during freshman physics class.

However, I have firmed up my position that the efficiency of coal fired power plants is the governing process efficiency for all plug-ins in USA or any country where the use of coal is not serverely penalized. This efficiency is 33%. Of course, the whole thing is nonsense when it comes to MPG, equivalent or not, since it just can not be upheld in logic, like adding apples and oranges.

It is more important to convert to CO2 emissions. This can be done with some rationality, though usually it is not.

The first question asked is, "What is the mix of power sources?" I maintain that this is irrelevant since only the lowest price source is relevant. All the more desirable forms of production are fully tapped out, and are not available to respond, regardless of who or how they get on line. I now realize that even California, which basically bans coal, is subject to the lowest priced source rule due to economic coupling through the natural gas market.

Economic coupling takes place when California turns off a coal plant and turns on a natural gas plant in its place. The impact of this is an increase in demand for natural gas, though slight, it is a national impact. That increase in natural gas demand would first be felt as a price increase in natural gas; however, as the rest of the power producers of North America sense such a price increase, they will be immediately motivated to increase their use of coal. The price of natural gas will then be returned to its previous equilibrium price. And that increase in the use of coal, any- and every- where in North America, will be the impact of that EV load.

So the CO2 calculation has to proceed on the basis of 33% efficiency as well as the 2X factor of coal CO2 per BTU compared to natural gas. Sure, thrown on 10% for coal transportation since that requires more energy than natural gas transportation. (If you have a better number I would defer to that.)

After all this, the electric vehicle still has merit as an efficient system where regenerative braking is made possible. The hybrid is the better way to make this work than the plug-in. And maybe more importantly, where the electric machinery enables a much more efficient car it is quite another matter. There is nothing bad about a car running on coal fired power if it uses a small fraction of the power that otherwise would be needed. So making the overall car into a low user of energy seems far the better action.

Any progresss in low rr tires?
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Old 04-28-2009, 05:22 PM   #29 (permalink)
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The well to wheels analysis is complicated, but I have confidence in the NRDC-EPRI study which you can easily get at Miastrada Motors - References (I think the full report is reference (3) )

Figure 5-1 shows that converting a gasoline hybrid to plug-in results in more CO2 in a coal powered scenario than the production hybrid.

This result has confounded NRDC and the plug-in guys ever since. The conclusions of the report try mightily to spin things differently. And they assume the world is going to get off coal almost immediately, so the words can be encouraging to plug-in guys.
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Old 04-28-2009, 05:37 PM   #30 (permalink)
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Figure 5-1 shows that converting a gasoline hybrid to plug-in results in more CO2 in a coal powered scenario than the production hybrid.
Here is another good link for that Argonne study:
http://www.transportation.anl.gov/pdfs/TA/273.pdf
It shows EV: U.S. kWH total Greenhouse gasses per mile at less than gas and like 1/2 of crude (page 28). No mention of biodiesel, it is really a moving target and the data is from 2002



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Actually. . .its way off. . .the amount of efficiency lost in the coal plant to power the refinery is just as big as it is to generate the ev-power.

Just to get the gasoline from the crude barrell to gasoline the efficiency is 20%. have to incorporate the inefficiency of the coal plant so the power supplied in coal is way more than the power delivered in watts. . .
Someone is gonna have to draw me a picture Where are we at with the apples and oranges?

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