Miles Per Gallon Equivalent by Four Different Methods

[dcb]

Originally Posted by NeilBlanchard

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

please try to understand what I am trying to relate here, if you don't understand what I am saying in this paragraph, please ask specific questions about it. It IS the answer to your question. My diesel far exceeds the efficiency of an electric car when the source of the energy systems as a whole is considered, which mpge doesn't do. If we had any sort of algae biodiesel distribution network, electricity would be rank in comparison.

Originally Posted by dcb

...
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.

[NeilBlanchard]

Sure, electricity is "pure" energy and it does not have to be converted to another form of energy in the car. Power plants on average (or even the worst old coal plants) are more efficient than the ICE in every car. So, if the heat conversion is significantly more efficient for electricity, than it is for gasoline -- and electricity is about equal to your diesel in *ideal* conditions, what is your point?

Not only that, but gasoline and diesel have significant overhead:

Have you tried burning crude oil in your car? Where would you even get it from? How much energy goes into finding, then producing, then refining, and transporting the oil and the gasoline / diesel to get it in your tank?

[JasonG]

Neil,

Look at it this way:
For the EV guys, miles per charge is as important as KWH/M. Commercially more so.
How would you feel if I had a genset in an aero trailer and claimed that from a 50AH battery I was achieving a 600 mile range ?

600 M/charge *

[dcb]

Originally Posted by NeilBlanchard

...So, if the heat conversion is significantly more efficient for electricity, than it is for gasoline -- and electricity is about equal to your diesel in *ideal* conditions, what is your point?

electricity mine to wall is ~%30 efficient

gasoline well to pump is ~%83 efficient

I'm not advocating gasoline, there are better, renewable, alternatives than electricity for transportation purposes however, ones that use 1/5 as much land as their solar counterparts, do not suffer range problems, or inefficient weight problems or outrageous cost problems for batteries that are 15 years away.

Regardless, I never said the heat conversion in electricity is significantly more efficient. By the time it gets to your outlet electricity is already down to %30 efficient, then you have to run a motor, and a controller, and charge batteries, and discharge batteries, and shlep those heavy batteries around everywhere, (the more range the more batteries).

Electricity is great in a dollars per mile sense if you ignore the initial costs, but is a lot less efficient than people are prepared to admit.

[UFO]

Originally Posted by NeilBlanchard

Sure, electricity is "pure" energy and it does not have to be converted to another form of energy in the car. Power plants on average (or even the worst old coal plants) are more efficient than the ICE in every car. So, if the heat conversion is significantly more efficient for electricity, than it is for gasoline -- and electricity is about equal to your diesel in *ideal* conditions, what is your point?

Not only that, but gasoline and diesel have significant overhead:

Have you tried burning crude oil in your car? Where would you even get it from? How much energy goes into finding, then producing, then refining, and transporting the oil and the gasoline / diesel to get it in your tank?

dcb was talking specifically about biodiesel. It doesn't come from crude, it is grown.

[mnmarcus]

Good discussion! Disclaimer: I am partial to turbodiesels and hydraulics because they are proven, reliable, "low" tech options.
Here are some links that seem relevant, please point out any errors, etc. The faces are around my thoughts.

From Fat Knowledge: Algae Biodiesel vs. Solar Panels

The solar panel fueled electric car takes a little less that 1/5 the amount of land to run as a algae biodiesel powered car. It is by far the more efficient source of energy for sustainable transportation.

dcb, I wish it was the other way around. Might be 1/5 the cost though!?

From Electro Automotive: FAQ on Electric Car Efficiency & Pollution

Table 4. Operating Efficiency Comparison Between EVs and ICE Vehicles

EVs & Power Plants ICE & Fuel Refining
Processing 39% (Electricity Generation) 92% (Fuel Refining)
Transmission Lines 95% -
Charging 88% -
Vehicle Efficiency 88% 15%
Overall Efficiency 28% 14%

Also from Electro Automotive: FAQ on Electric Car Efficiency & Pollution

Table 5. Fuel Efficiency Comparison Between EVs and ICE Vehicles

Electric-Powered GM EV1
Start with 1 million BTUs
Energy left after generation (39% efficiency) 390,000 BTUs
Energy left after charging losses (88% efficiency) >343,000 BTUs
BTUs per kilowatt-hour 3412 BTUs
Electricity available 100.6 kWhr
Energy efficiency 0.19 kWhr/mile
Miles per million BTUs 529.5 miles
Equivalent mpg 69 mpg

Gasoline-Powered Acura .2TL
Start with >1 million BTUs
Energy left after refining (92% efficiency) 920,000 BTUs
Energy left after transport (95% efficiency) 874,000 BTUs
BTUs per gallon of gasoline 115,400 BTUs
Gallons available 7.6 gallons
Fuel economy> 24 mpg
Miles per million BTUs 182.5 miles
Equivalent mpg 24 mpg

But what is the range? I bet the Acura is farther than 182 mi & the EV isn't even close to 530mi. So I'd point out the energy density is much better with gas. If we compared the drag coefficients between these two cars the gas version would look even better, plus a turbo-diesels ICE is going to be way more efficient than a gasoline ICE...

From Electric vs Gasoline – Which is more cost effective? True Cost – Analyzing our economy, government policy, and society through the lens of cost-benefit

[1] Electrical energy is created by burning fossil fuels in a power plant at 40% efficiency, followed by transmitting it to your house at 93% efficiency, and using it in an electric vehicle at 92% efficiency, providing a total efficiency of around 34% for an electric vehicle. Crude oil refineries operate at 75% efficiency, and gasoline distribution might cause another 6% energy loss. Since internal combustion engines are only 20% efficient (gas?) , total efficiency would be around 14%. Assuming that the natural gas and oil to power our vehicles comes from the same well, we can directly compare these efficiencies, and thus conclude that electric vehicles are significantly more efficient.

So EV is .40*.93*.92=.34 efficiency
GAS is .75* .94 *.2= .20 efficiency
Would turbo-diesel be .75*.94*.41=.29 efficiency?
Does the above example skip the charging losses for the EV?
If .29*X=.34 does that mean the EV is 17% more efficient? -not including moving the batteries around?

[dcb]

Originally Posted by mnmarcus

The solar panel fueled electric car takes a little less that 1/5 the amount of land to run as a algae biodiesel powered car. It is by far the more efficient source of energy for sustainable transportation.

Dang, I screwed that land metric up royally, thx for setting me straight. Land use wise solar wins by a wide margin.

[NeilBlanchard]

I am highly suspicious of the 83% "efficiency" of gasoline -- sweet crude may have been this easy if you only count the refining stage. But crude is getting to be lower quality now, and even tar sands are being considered now. And extraction and transportation are energy intensive and cannot be ignored.

[mnmarcus]

Originally Posted by NeilBlanchard

I am highly suspicious of the 83% "efficiency" of gasoline -- sweet crude may have been this easy if you only count the refining stage. But crude is getting to be lower quality now, and even tar sands are being considered now. And extraction and transportation are energy intensive and cannot be ignored.

Me too! But I'm equally suspicious of ;

"It also helps to have ~85% efficiency (TW4XP) in the car..."

and

"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."

and

"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."

and pretty much every word of this

"EVs reduce CO2 by 11%-100% compared with ICEs and by 24%-65% compared with HEVs, and significantly reduce all other greenhouse gas emissions, using the U.S. grid mix. If all U.S. cars were EVs, we’d reduce global warming emissions even on today’s mostly coal grid. Using electricity strictly from coal, EVs still would reduce CO2 by 0%-59% compared with ICEs (two analyses found 0% change; seven others found reductions of 17%-59%) and might produce 30%-49% more CO2 than HEVs (based on only two analyses) on today’s grid. On the other hand, if electricity comes from solar or wind power, EVs eliminate all emissions. Using natural gas to make electricity, missions fall in between those from coal and renewable power."

But we get numbers from studies and (often in my case) searching the web. Should we just throw out the "bad" and "dirty" pro-gasoline info and ignore anything negative about "good" "clean" electricity?

[IamIan]

Originally Posted by NeilBlanchard

I am highly suspicious of the 83% "efficiency" of gasoline -- sweet crude may have been this easy if you only count the refining stage. But crude is getting to be lower quality now, and even tar sands are being considered now. And extraction and transportation are energy intensive and cannot be ignored.

mnmarcus explained it very well above ... ~83% is just the refining efficiency ... I suspect it also ignores the electrical energy consumption the refineries have ... but it definitely ignores the transportation efficiency losses , usage efficiency losses , etc ... as pointed out above ... in separate studies they come to similar conclusions ... well or mine to wheels ... the BEV is significantly more energy efficient than an ICE... first study BEV about ~2x more efficient , 2nd study BEV about ~2.8x more efficient , 3rd study BEV about ~2.4x more efficient.

Even mnmarcus' studies assume only a ~40% efficient power plant ... modern technology , including co-generation plants ... are far far better than a meager ~40%... which only shifts it even further to the BEV's benefit in terms of energy efficiency.

I strongly suspect that the same fuel , fossil or bio-fuel ... would be more efficient to use in a modern co-generation power plant and a BEV , than just using it in a mobile ICE directly... exactly how much better we would need to get all the data to crunch the numbers.