Miles Per Gallon Equivalent by Four Different Methods

[solarguy]

If you don't have some form of MPGe, how do you decide when it makes ecological sense to switch from diesel/gas to some kind of electric?

Finest regards,

troy

[JasonG]

It's sort of like the * next to Barry Bonds homerun record.
Sure he beat Hank Aaron, but the * will always invalidate it.

Nissan Leaf 227 MPG *

[Allch Chcar]

Originally Posted by dcb

the xprize MPGe is crap

Originally Posted by dcb

I never agreed to it

Your opinion is wrong.

The Lower/Higher Heating Value per gallon of fuel is a proven and commonly accepted number.

So you're just trolling.

Ethanol beat Gasoline nyah nyah

[IamIan]

Just figured I'd throw my 2 bits in... some of which has been touched on a bit in some previous posts.

skip it ... or get comfy.


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MPGe.

The way I see it there are 3 main methods ... each of which has 3 sub-methods.

The 3 main methods are:

#1> Vehicle level comparison ( Pump or outlet to wheels )

#2> Complete cycle ( From raw source materials and initial energy sources to material disposal )

#3> Partial cycle ( include more than the pump / outlet , but don't include the whole cycle )


Each of which has 3 sub-methods:

#A> $ Cost comparison

#B> Energy comparison

#C> Environmental Impact comparison

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This gives us at least 9 distinct methods of determining MPGe ... and virtually unlimited methods to mix and match different scales of each if we try and combine them.

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My personal preferences in order:
#1> Energy comparison
#2> Environmental Impact comparison
#3> Cost Comparison

My personal preferences of main types in order:
#1> Complete cycle
#2> Vehicle level
#3> Partial cycle

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My 2 bits Complete cycle Energy comparison:

For any 'complete' cycle ... My first question is about the initial energy source for the fuel.

Fossil fuels are just a very inefficient method of converting solar energy ... Photosynthesis is less efficient than modern day photovoltaic ... and only a tiny tiny fraction of that energy ends up being converted into fossil fuels ... which then need to be extracted % loss ... transported % loss ... refined % loss ... before they are used in a ICE that is almost never even as high as ~50% efficient.

Compared to converting that same initial solar energy source into electrical energy ... transporting it ... battery cycle ... modern efficient electronics ... modern efficient electric motors ... the RE powered BEV beats the crap out of any fossil fuel option ... I would estimate well over ~300 to 1 advantage for the RE powered BEV.

But with enough data a specific vehicle could be calculated.

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My 2 bits Vehicle level Energy comparison:

Given the average ICE efficiency of ~30% ... with peaks as high as ~50% ... and lows as low in the single digits %.

Given the much higher ~90%+ Efficiency of modern electric drive systems ... and given the much much broader range of higher operating efficiency ... efficiency less effected by cold ... by load ... etc.

This makes the BEV about ~300% more energy efficient compared to the ICE , at the vehicle level... or for a given amount of energy , the BEV I would generally expect to travel about ~3x as far.

BEVs that end up weighing more will have more rolling resistance ... which is linearly related to weight ... so in order to counter the ~300% vehicle level energy efficiency ... the BEV weight would have to increase by close to ~300% ... which even lead sleds don't get that much heavier.

Of course individual vehicles can be measured ... by the energy content of the fuel they use compared to the average distance they travel with that amount of fuel energy... the low efficiency of ICEs pretty much destroys them in this type of comparison.

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Although partial cycles are not a preference of mine ... I do recognize allot of people usually ignore all the losses it took to produce the fossil fuel in the first place.

Even on that level I would suspect a BEV would still come out ahead on a energy efficiency basis.

Short version:
I suspect : A Gasoline fueled power plant would most likely move BEVs ... further per gallon consumed ... than multiple ICE fueled vehicles with the same amount of gasoline.

The massive variation of ICE efficiencies is a killer to that platform ... a stationary centrally located power plant no longer has to worry much about size ... or weight ... a 0.1% efficiency improvement that costs 2 tons of equipment , is usually worth doing.

This means that the more efficient centrally located power generation system will be likely to operate at close to double the energy efficiency of the mobile ICE that has so many other compromises due to weight , size, efficiency fluctuations , etc.... if a co-generation plant ... it might be as high as 3x as efficient.

I suspect , losses in electrical transportation are less per unit energy than the losses of gasoline transportation ... meaning the trucks that drive the gasoline around the country from the refineries ... are far less efficient than the electrical grid... per mile / per unit of energy.

In short ... there are very good reasons we do not run generators at each of our homes ... and have them all powered by gasoline deliveries ... the same is true for why a more efficient centrally located power plant would make better use of the same fuel.

The added bonus ... is that the centrally located power plant , would not need as much refining losses of the initial fossil fuel.

with enough data this could also be calculated for a specific vehicle , and power plant.

[Allch Chcar]

Originally Posted by JasonG

So if we are comparing BTUs, do we add a 1.89 correction factor for alcohol?

An active person outputs 1000-1300 BTUs/hr, so is there a MPGe for HPVs ?

Comparisons can be a slippery slope.

While we are on the topic of slippery slopes, holy crudman of strawmen. Do you even understand what BTUs are or how they relate to MPG?

The correction factor is to compare KW-H using MPG as a guide. If you divide the Lower heating value (in KW-H) of Gasoline by the MPGe you can get the KW-H per mile. It's only to properly gauge everything else against Gasoline, notably Electric Vehicles. Methanol would get a 2.05 correction factor on this scale! We're comparing energy efficiency here not range per gallon. Don't get the two confused here.

And to answer your second question the answer is yes, but what you are referring to is just the waste heat generated not the energy consumption. But it involves converting calories into KW-H.

[IamIan]

Originally Posted by Allch Chcar

And to answer your second question the answer is yes, but what you are referring to is just the waste heat generated not the energy consumption. But it involves converting calories into KW-H.

1 food calorie = 1 ,000 normal calories
1 food calorie = ~0.001163 kW·h
~2,000 food calorie a day diet = ~2.326 kwh / day ( consumed )

[dcb]

Originally Posted by Allch Chcar

...It's only to properly gauge everything else against Gasoline

How is it "proper" to stack the deck for electricity? Or stay in the mental trappings of mpg and gasoline?

Originally Posted by Allch Chcar

..We're comparing energy efficiency here not range per gallon.

Not exactly. Range is part of the calculation and there is little contention there. main issues are:

1. Information is lost in the conversion to the "dumbed down" mpge figure.
you cannot discern the distinct fuel and electric contributions. This could have major effects on your cost per mile assumptions, or your expected environmental impact based on location specific factors and fuel preferences.

2. MPG was a horrible metric. Mass gives a consistent energy content for a given fuel (what planes use), gallons (volume) does not, we should kill mpg while we can.

3. and not least by any measure, Electricity has undergone it's major heat losses at the plant. It has well to walls efficiency of ~%30, where gasoline (possibly better for other liquid fuels like biodiesel) is considered ~%83 efficient. But electricity has not undergone the major carnot cycle transformations, so the deck is stacked for electricity in MPGe. If I take my "%41" efficient tdi, times %83, I get %34 efficiency out of my engine, whereas a %90 efficient electric motor (if it was plugged directly into the wall) would only be %27 efficient. This appears to be a fundamental flaw in the GREET model, there is not a good way to compare electricity (which has already undergone it's major heat loss conversion) to liquid (or gaseous or solid) fuels without looking at the full lifecyle.

[JasonG]

Originally Posted by Allch Chcar

While we are on the topic of slippery slopes, holy crudman of strawmen. Do you even understand what BTUs are or how they relate to MPG?

The correction factor is to compare KW-H using MPG as a guide. If you divide the Lower heating value (in KW-H) of Gasoline by the MPGe you can get the KW-H per mile. It's only to properly gauge everything else against Gasoline, notably Electric Vehicles. Methanol would get a 2.05 correction factor on this scale! We're comparing energy efficiency here not range per gallon. Don't get the two confused here.

And to answer your second question the answer is yes, but what you are referring to is just the waste heat generated not the energy consumption. But it involves converting calories into KW-H.

Thans Allch Char. My math was off. I meant 2.05 it seems.

I agree with you that E rules. Properly made it beats dino fuel by a landslide. The bad part is in this comparison it cuts your MPG by half. But we're still comparing gallons.

[NeilBlanchard]

The X-Prize spreadsheet does fully account for the BTU content of E10, and E85 (that the winning Edison2 car used), and for diesel, and for hybrids, and for electricity.

How does counting all the BTU's in each form of energy carried onboard the vehicle, give an advantage to any one of them?

For what it is worth, many folks on the Electric Vehicle Discussion List (email listserve) feel that the X-Prize emissions rules were biased against electric vehicles; because they have to account for the embedded energy; while none of the liquid fuels had to add this.

It also helps to have ~85% efficiency (TW4XP) in the car vs 34% (for the VLC).

[bwilson4web]

Originally Posted by RobertSmalls

...and why EVs alone are of doubtful environmental benefit.

As more of us, myself included, are transitioning to plug-in vehicles of some type or another, the controversial topic of mpge is being discussed with increasing frequency. . . .

I don't have a 'dog in that fight,' the value of MPGe, but I do have an interest in PHEV in no small part because our 1.5L engine 2003 and 1.8L engine 2010 Prius are getting nearly the same MPG with 10 years of technical advances between them. Also, there was a King County Washington report after a year of NHW20, PHEV Prius operation that saw rather modest MPG improvement in their fleet MPG.

I think PHEV can improve Prius performance if the control laws maximize the remaining, inefficient regions. This is different from trying to come up with an MPGe figure because it presumes a different application of the extra energy. But to test this hypothesis, I have to make a PHEV, in my case, our 2003, NHW11.

Bob Wilson