Miles Per Gallon Equivalent by Four Different Methods

[roflwaffle]

There is a little bit but it's a very small amount (about 1/700th of what a coal plant/plants operating over the same 60 year lifespan would emit if I'm reading the post right), which is why I said essentially Carbon free.

[IamIan]

Originally Posted by dcb

batteries don't like high load

The graph is depicting the Peukert Effect.
This can be misleading / confusing to some people.
The battery discharged at 3C does not loose significant amounts of mWh compared to the same battery discharged at 2C... or 1C.

The batteries do not actually hold less energy when you discharge them faster ... Chemical reactions in batteries take time ... the faster you try to pull energy out of a given battery the faster you will seem to initially discharge it ... but if you give the chemical reactions time to catch up ( rest ) you get what some of the old time EVers call .. 'growing amps' ... The chemical energy didn't just appear from no where ... it was there before ... you were just electrically drawling off energy faster than the chemical reaction could keep up.

I will agree however ... that this effect is a dis-advantage of Batteries .. and by proxy BEVs , compared to gaseous and liquid fuels which do not reduce in power output until the tank is next to empty... but while a loss of power toward the end of a batteries capacity is a negative for BEVs ... it is also a separate issue from MPGe.

Originally Posted by dcb

batteries do not necessarily charge efficiently "The coulometric charging efficiency of nickel metal hydride batteries is typically 66%,

This is a often quoted piece of mis-interpreted information.

Even if we ignore other batteries have different cycle efficiencies for charging and discharging.

This 66% number is more accurately the cycle efficiency of some of the common NiMH charge termination methods ... which is not the same as the cycle efficiency of the NiMH battery itself.

Typical NiMH charging systems over charge the battery ... which throws away energy ... kind of like trying to poor a 1 gallon jug of water into a shot glass ... sure you can keep pouring ... but you won't ever fit 1 gallon into that little shot glass ... and the 66% efficiency number is using that kind of testing methods.

If you don't believe me ... feel free to run the test properly for yourself.

NiMH is actually over ~90% cycle efficient... exact number will vary some with specific conditions.

Proper testing includes:
#1> Accurately determine the storage size of a single NiMH cell.
From a full charge, how many mAh will it discharge?

#2> To prevent overcharging ... only put in what you know it can hold.
If your AA NiMH puts out ~2,000 mAh on discharge ... put in ~95% of that ~2,000 mAh during charging... or ~1,900 mAh.

#3> Measure the mAh given during discharge

#4> Repeat the above a minimum of ~3 times.

Every time I have done this ... I have ended up with ~90% cycle efficiency numbers.

Remember for this type of test you are counting the mWh going into and out of the battery ... the efficiency of the charger , and the dis-charger are separate issues , and should be isolated form your battery testing data.

Originally Posted by dcb

So even suggesting that an EV is %90 efficient from the wall is coocoo.

Like most things ... it depends on the specifics.
Temperature ... specific parts ... driving methods , and context ... etc.

But yes over 90% efficiency is achievable today with modern technology you can buy today for a BEV ... If you want I can give you some specific components that will result in over 90% BEV efficiency.

In practice we don't use the best components and people drive in wasteful methods ... so the % will be lower ... just like it will be lower for both the BEV and the ICE... neither one operates all the time at their peak efficiency.

Originally Posted by dcb

I also don't think %15 is a fair number for ICE, it takes the driver and any recent advancements out of the equation. It is entirely possible to operate a car near it's peak efficiency, folks here do it all the time. Even if you look at a reasonably idiot proof efficiency car, the prius, it is rated at %37

The Prius is a very efficienct gasoline ICE ... but it is not possible to operate the vehicle on a yearly bases in the tiny ~39% efficiency window.

After the engine is warmed up ... in it's tiny sweet spot of RPM and torque ... when all the factors align perfectly ... then it gets a maximum of ~39% efficiency... see attached graph bellow ... the ~39% efficiency point is only in the 195 g / kwh part of the graph ... and only after the ICE is warmed up.

Sorry ... but 15% to 20% energy efficiency ... is about what the average ICE averages out throughout the year , for operating energy efficiency ... winter being the worst season.

Originally Posted by dcb

I'm not convinced yet the BEV's dominate in efficiency full cycle.

Full cycle ... ALL methods of using fossil fuels are horribly energy inefficient forms of using solar energy.

In terms of energy efficiency Full Cycle Renewable energy sources for either ICEs or BEVs are greatly more energy efficient than any fossil fuel option.

In terms of Full Cycle energy efficiency RE-BEV is more energy efficient than RE-ICE... ICE efficiency kills it ... plus Photovoltaic cells ( as bad as they are ) are more energy efficient than photosynthesis.

Originally Posted by dcb

range and initial cost and availability make liquid fuels attractive for transportation.

100% agree.

Originally Posted by dcb

Also, the rolling resistance/weight thing. The problem with extra weight is not just extra rolling resistance, but also you only get a small fraction of your acceleration energy back in electric regenerative braking.

Far more than the 0% of friction brakes.

When you add up the energy kwh spent ... you do not have to travel very far distances ... before rolling resistance losses in kwh dominate massively over the kwh used for accelerating.

Additionally ... F = MA ... to increase the energy needed for the same acceleration you would have to increase the weight by the same % ... a ~50% increase in energy for accelerating would require ~50% more total vehicle weight ... it is a linear relationship ... just as rolling resistance is linear with weight as well.

- - - - - - - - - - -

Originally Posted by RobertSmalls

The good news is, for the first time ever, we have EPA efficiency data on a PHEV in electric drive, and when running on fossil fuel.

That is to say, 13.6 KWh = 1 gal, in terms of how far it will drive a Volt.

Excellent point.

In a vehicle with the same aerodynamics ... the same weight ... etc.

The Volt shows at the vehicle level ... a ~2.6x energy advantage to the BEV mode ... as a gallon of Gasoline actually has ~36 kwh.

Which is similar to the other studies already posted.

- - - - - - - - - -

Originally Posted by JasonG

Well tell ya what,
when you build an EV that can pull a 16,000lb trailer at 55 MPH for 350 miles I'll conceed that electric is on equal terms.

Heck, if you can find one that can do either I might

You left it too open ... and too easy... prepare to go back on your claim ... or conceed.


Even with old tech ... using lead acid batteries , etc ... a 1,500 HP BEV Locomotive that runs for 12 hours per charge ... can pull much more than a 16,000 lbs trailer ... a modern version using modern components like Lithium batteries ... would easily be able to run for 4x a long as this Lead Sled.

Here's a picture of the Lead Acid one in Altoona Pa ... they built to test the platform of a BEV Locomotive without a diesel generator.



- - - - - - - - -

Originally Posted by roflwaffle

I don't think anyone is saying that either one is on equal terms. An engine can't beat a motor for reliability or efficiency and a motor can't beat an engine for refueling times or energy storage. Each one has it's advantages and disadvantages.

100% agree.

- - - - - - - - -

Originally Posted by dcb

but that is an arbitrary point in the system, ignoring all the conversion losses to that point (which are many), from the days when all there was was gasoline basically, and puts the alternatives at an unfair disadvantage.

I agree ... it is an arbitrary point in the system ... just like picking the fossil fuel and ignoring the energy efficiency losses from solar energy to produce that fossil fuel it in the first place is also an arbitrary point in the system.

But it is the arbitrary point in the system that our current MPG system is based on... it is the currently widely accepted standard.

We are not likely to change our entire MPG system the public uses, by including the losses up-stream... the public expects 1 gallon pumped to = 1 gallon ... to go 30 miles when they drive 30 miles ... etc... is that an arbitrary point in the full energy cycle ? ... of course ... but that is the way the public does it at this time ... that is the current standardized method.... as flawed as it may be.

[RobertSmalls]

Though the Volt can go as far on 1 gal as it could on 13.6kWh, how far could it go on gas if it weren't a PHEV? The battery weighs 375lbs, the motors aren't light either, and weight added at the design level compounds with heavier components throughout the design.

Also, the Volt is big on the outside, but small on the inside, on account of the passengers having to share space with a battery. This gives the Volt utility comparable with a smaller car. From another perspective, the bulk of the battery is an aerodynamic penalty.

Anyway, running some numbers through this spreadsheet, I find that just knocking the battery down from 375lbs to 50lbs would boost fuel economy to 40mpg, and cutting a 3.5 inches out of the middle of the car and ending up with a smaller hybrid (with the same utility and interior space as a Volt) that weighs as much as a regular Cruze would bump fuel economy up to a respectable 45mpg. It would also bring the price out of the stratosphere and in to the low $20k's, resulting in greater adoption and more total benefit to society at this time.

So, for a vehicle with the interior space of a Volt, a PHEV variant would get 368Wh/mi, and a HEV variant would get 45mpg. In other words, 16.5KWh takes you as far as 1gal. Per the metrics derived in the first post, the two methods of travel have a CO2 footprint that is equal. Looks like Dr. Samaras knew what he was talking about.



If you have a certain number of dollars to spend on environmental concerns, you'd be wrong to spend them on vehicle electrification before you first work on reducing the carbon intensity of your electric supply. The same goes for time you spend advocating for environmental causes.

[IamIan]

Originally Posted by RobertSmalls

Per the metrics derived in the first post, the two methods of travel have a CO2 footprint that is equal. Looks like Dr. Samaras knew what he was talking about.

His work you linked two actually makes a different claim.

Results
Under the U.S. average GHG intensity of electricity, PHEVs
were found to reduce use phase GHG emissions by 38–41%
compared to CVs, and by 7–12% compared to HEVs

He was using 2004 grid emmisions numbers ... the grid gets cleaner over time ... electrification of the transportation PHEVs and BEVs automatically benefit from.

Last ~10 years of Grid numbers are here:
Electric Power Annual - Summary Statistics for the United States

In the last ~10 years
CO2 / kwh has decreased ~11%
SO2 / kwh has decreased ~59%
NOx / kwh has decreased ~66%


The national U.S. fleet MPG went up ~6% in the last ~18 years.
BTS | Table 4-23: Average Fuel Efficiency of U.S. Passenger Cars and Light Trucks

The Grid kwh / mile is getting cleaner significantly faster... ~3.3x faster... than the MPG increases.

So not only is it already ahead today ... it is getting better faster for the future.

Originally Posted by RobertSmalls

If you have a certain number of dollars to spend on environmental concerns, you'd be wrong to spend them on vehicle electrification before you first work on reducing the carbon intensity of your electric supply. The same goes for time you spend advocating for environmental causes.

I am not putting up my own power plant any time soon... few people who live in apartments do.

So I do not have the option of choosing between PHEV and a RE power plant.

But when I get my next vehicle , I will have the choice between PHEV or spending 7% to 12% more GHG for a HEV ... or 38% to 41% more GHG for a CV.

His work also does not look at BEVs at all ... which would do better than the PHEVs in terms of kwh / mile ... and CO2 / mile ... the last metric of $ / mile , is still a bit up in the air for BEVs as the initial cost is still significantly higher, which might counter act allot of the $ / mile savings in fuel and operating costs.

But I do 100% agree with you , in that there is significant benefits to be had from 'greening up' ones electric supply ... but I disagree with saying that someone would be 'wrong' for choosing an option that is 7% to 12% GHG better from the grid , and can benefit later from greener electric supply.

I also personally put energy efficiency above GHG emissions ... they sometimes are one and the same ... but when they differ I usually side with energy efficiency.

[dcb]

the power of KISS

[roflwaffle]

Unfortunately most nuts aren't self adjusting.

[RobertSmalls]

Originally Posted by dcb

adjust the nut

lol! Very true.

Ian, I don't put up power plants either. But I do pay extra for my utility's renewable plan (vote with my dollars), and I try to make my views known to my elected representatives and the general public. If a conversation starts about how ugly windmills are, I'm prepared to explain why I think coal plants are uglier.

The conclusion of the paper that we're referring to is that meaningful GHG reduction from vehicle electrification requires a lower-carbon grid. Pretty much the same as my conclusion.

>Per the metrics derived in the first post, the two methods of travel have a CO2 footprint that is equal.
>>His work you linked two actually makes a different claim.

In the engineering sense, 180g/km is equal to 190g/km, if each of those are plus or minus 20g/km.

Anyway, I stand behind the claim that the extra weight and frontal area resulting from the Volt's battery pack erases the GHG benefit of electrification vs a hybrid with a small battery, when charging with the grid as it stands in the US today.

[NeilBlanchard]

Weight is not as important as you think -- the Jacobs fairing, and the Dolphin, and the Seven, are proof of this. And frontal area is minor compared to the Cd -- if the Cd is 0.2, then the entire frontal area is reduced to 1/5th. Do you really think the Volt has a bigger frontal area because of the 'T' shaped battery pack; or are the transverse 4-banger and it's radiator swamping that?

[IamIan]

Originally Posted by RobertSmalls

Ian, I don't put up power plants either. But I do pay extra for my utility's renewable plan (vote with my dollars), and I try to make my views known to my elected representatives and the general public. If a conversation starts about how ugly windmills are, I'm prepared to explain why I think coal plants are uglier.

+1

Originally Posted by RobertSmalls

The conclusion of the paper that we're referring to is that meaningful GHG reduction from vehicle electrification requires a lower-carbon grid. Pretty much the same as my conclusion.

'meaningful' is of course subjective.

The paper did not include BEVs in it's analysis.

Given the what the paper does show ... a BEV90 will have a lower 'impact' than a PHEV90... which is already with the grid as it was ( in 2004 ) 7-12% better than HEV.

Environmental impact is only one way to determine MPGe.
GHG is only one type of environmental impact.

My personal priorities put energy efficiency MPGe higher / more important than GHG MPGe.

Currently MPG is at the vehicle level , and does not include upstream losses... that is the current standard people think of when they use MPG... if you want a MPGe number to be understandable to the masses you are limited to the same frame work they already use MPG for.

If we want to include up-stream or full cycle losses ... All Fossil Fuels will have horrible energy efficiency numbers... and you have to change the entire way the consuming public currently views MPG... which is not going to happen... the whole point of MPGe is to make it easier for the average consumer to compare MPG they are used to.

Originally Posted by RobertSmalls

In the engineering sense, 180g/km is equal to 190g/km, if each of those are plus or minus 20g/km.

If we are to stay in the same ratio as the paper determined ... a ~12% reduction from 190 g/km is ~167 g/km... That is the difference determined ... and I do not think / agree with ~167 = ~190.

Even at the paper's low end of 7% ... it would be from 190 to ~177 ... I would still not consider those as equal.

Your 180 and 190 is about ~5.5% ... which is even less than the 7% low end range given in the paper.

Originally Posted by RobertSmalls

Anyway, I stand behind the claim that the extra weight and frontal area resulting from the Volt's battery pack erases the GHG benefit of electrification vs a hybrid with a small battery, when charging with the grid as it stands in the US today.

As long as you realize ... Your sited paper disagrees with you... as does the other sited papers to date.

[JasonG]

Originally Posted by IamIan

The graph is depicting the Peukert Effect.
This can be misleading / confusing to some people.
The battery discharged at 3C does not loose significant amounts of mWh compared to the same battery discharged at 2C... or 1C.

The batteries do not actually hold less energy when you discharge them faster ... Chemical reactions in batteries take time ... the faster you try to pull energy out of a given battery the faster you will seem to initially discharge it ... but if you give the chemical reactions time to catch up ( rest ) you get what some of the old time EVers call .. 'growing amps' ... The chemical energy didn't just appear from no where ... it was there before ... you were just electrically drawling off energy faster than the chemical reaction could keep up.

I will agree however ... that this effect is a dis-advantage of Batteries .. and by proxy BEVs , compared to gaseous and liquid fuels which do not reduce in power output until the tank is next to empty... but while a loss of power toward the end of a batteries capacity is a negative for BEVs ... it is also a separate issue from MPGe.



This is a often quoted piece of mis-interpreted information.

Even if we ignore other batteries have different cycle efficiencies for charging and discharging.

This 66% number is more accurately the cycle efficiency of some of the common NiMH charge termination methods ... which is not the same as the cycle efficiency of the NiMH battery itself.

Typical NiMH charging systems over charge the battery ... which throws away energy ... kind of like trying to poor a 1 gallon jug of water into a shot glass ... sure you can keep pouring ... but you won't ever fit 1 gallon into that little shot glass ... and the 66% efficiency number is using that kind of testing methods.

If you don't believe me ... feel free to run the test properly for yourself.

NiMH is actually over ~90% cycle efficient... exact number will vary some with specific conditions.

Proper testing includes:
#1> Accurately determine the storage size of a single NiMH cell.
From a full charge, how many mAh will it discharge?

#2> To prevent overcharging ... only put in what you know it can hold.
If your AA NiMH puts out ~2,000 mAh on discharge ... put in ~95% of that ~2,000 mAh during charging... or ~1,900 mAh.

#3> Measure the mAh given during discharge

#4> Repeat the above a minimum of ~3 times.

Every time I have done this ... I have ended up with ~90% cycle efficiency numbers.

Remember for this type of test you are counting the mWh going into and out of the battery ... the efficiency of the charger , and the dis-charger are separate issues , and should be isolated form your battery testing data.



Like most things ... it depends on the specifics.
Temperature ... specific parts ... driving methods , and context ... etc.

But yes over 90% efficiency is achievable today with modern technology you can buy today for a BEV ... If you want I can give you some specific components that will result in over 90% BEV efficiency.

In practice we don't use the best components and people drive in wasteful methods ... so the % will be lower ... just like it will be lower for both the BEV and the ICE... neither one operates all the time at their peak efficiency.



The Prius is a very efficienct gasoline ICE ... but it is not possible to operate the vehicle on a yearly bases in the tiny ~39% efficiency window.

After the engine is warmed up ... in it's tiny sweet spot of RPM and torque ... when all the factors align perfectly ... then it gets a maximum of ~39% efficiency... see attached graph bellow ... the ~39% efficiency point is only in the 195 g / kwh part of the graph ... and only after the ICE is warmed up.

Sorry ... but 15% to 20% energy efficiency ... is about what the average ICE averages out throughout the year , for operating energy efficiency ... winter being the worst season.



Full cycle ... ALL methods of using fossil fuels are horribly energy inefficient forms of using solar energy.

In terms of energy efficiency Full Cycle Renewable energy sources for either ICEs or BEVs are greatly more energy efficient than any fossil fuel option.

In terms of Full Cycle energy efficiency RE-BEV is more energy efficient than RE-ICE... ICE efficiency kills it ... plus Photovoltaic cells ( as bad as they are ) are more energy efficient than photosynthesis.



100% agree.



Far more than the 0% of friction brakes.

When you add up the energy kwh spent ... you do not have to travel very far distances ... before rolling resistance losses in kwh dominate massively over the kwh used for accelerating.

Additionally ... F = MA ... to increase the energy needed for the same acceleration you would have to increase the weight by the same % ... a ~50% increase in energy for accelerating would require ~50% more total vehicle weight ... it is a linear relationship ... just as rolling resistance is linear with weight as well.

- - - - - - - - - - -



Excellent point.

In a vehicle with the same aerodynamics ... the same weight ... etc.

The Volt shows at the vehicle level ... a ~2.6x energy advantage to the BEV mode ... as a gallon of Gasoline actually has ~36 kwh.

Which is similar to the other studies already posted.

- - - - - - - - - -



You left it too open ... and too easy... prepare to go back on your claim ... or conceed.


Even with old tech ... using lead acid batteries , etc ... a 1,500 HP BEV Locomotive that runs for 12 hours per charge ... can pull much more than a 16,000 lbs trailer ... a modern version using modern components like Lithium batteries ... would easily be able to run for 4x a long as this Lead Sled.

Here's a picture of the Lead Acid one in Altoona Pa ... they built to test the platform of a BEV Locomotive without a diesel generator.



- - - - - - - - -



100% agree.

- - - - - - - - -



I agree ... it is an arbitrary point in the system ... just like picking the fossil fuel and ignoring the energy efficiency losses from solar energy to produce that fossil fuel it in the first place is also an arbitrary point in the system.

But it is the arbitrary point in the system that our current MPG system is based on... it is the currently widely accepted standard.

We are not likely to change our entire MPG system the public uses, by including the losses up-stream... the public expects 1 gallon pumped to = 1 gallon ... to go 30 miles when they drive 30 miles ... etc... is that an arbitrary point in the full energy cycle ? ... of course ... but that is the way the public does it at this time ... that is the current standardized method.... as flawed as it may be.

Nice train, you still don't have an electric pick up that nears my requirements.


---------------------–


I thought the DOE put all of this to bed with their extensive study http://frwebgate.access.gpo.gov/cgi-...4446-filed.pdf

1KWH = 13 GAL U.S.