Talk:Miles per gallon of gasoline equivalent

Well to Wheel MPGe
In respect to electric energy, the previous material is technically flawed. It is a serious flaw because it falsely shows a degree of superiority of an electric car which is excessive. Electric cars have considerable merit without false claims confusing the issue. While a MPGe concept could be useful for comparing the merits of different fuels used to produce heat, the concept of comparing fuels that produce heat energy with electric energy is not valid and asserts an equivalence that is false. The second law of thermodynamics stands in the way of such a comparison, as clearly explained in Sears, Principles of Physics Series, Mechanics, Heat and Sound, Addison-Wesley Press, 1950. Sears discusses the heat engine that is required to convert heat into mechanical energy. Electrical energy is then produced using that mechanical energy. On this basis it can be seen that there can be a serious flaw in the comparison process.

To avoid making a fraudulent comparison, it is possible to define an average heat engine by which the electricity was produced, and then compare the heat supplied to such an average heat engine with the heat supplied by burning the other listed fuels in whatever system is being considered. Vehicle miles per BTU can then be meaningfully compared and this can be translated into terms of MPGe to achieve a comparison in familiar terms. --70.231.132.254 14:59, 14 December 2007


 * Your argument is flawed in that electricity production is not solely produced via combustion of fuels. It can also be derived from nuclear, hydro, wind, or solar sources.  I think we would need a new term to represent Well to Wheel energy resource consumption and CO2 emissions to fully account for what you are trying to assert.  --D0li0 (talk) 00:25, 14 January 2008 (UTC)

Response to above: I hope I recognized your point about combustion in the edit that I made today. I also think that by making the basis of comparison be the point at which heat is produced, the comparison will be meaningful for all energy types. And the carbon dioxide impacts can be immediately calculated from that point. I would be glad to respond to further comments you might want to post here. I think it is important that we find a way to get this right since it could make a big impact on how people make decisions. I see it as a big problem for people to stampede to electric cars, thinking they are doing a great green thing, and then it will come out that it is not really quite what they thought. Then try to get people to respond to real solutions to the climate change problem. Of course, if the issue is only fuel supplies, conversion to electric power, thereby shifting to coal as the energy source will have a big effect. —Preceding unsigned comment added by 70.231.131.152 (talk) 01:07, 10 March 2008 (UTC)

The non indented comments above were not signed by me, but I am here trying to add my signature. Jim Bullis (talk) 01:07, 11 March 2008 (UTC)

Why 114,100 BTU instead of 125,000 BTU for gasoline? Ephdot (talk) 21:24, 20 March 2008 (UTC)
 * It seems 114,100 BTU is at the low end of the LHV scale for gasoline. It goes up to 116,090 in google searches.  A value of 115,000 BTU seems common, a good compromise and consistent with the GGE page.  It's also used by the ORNL - http://bioenergy.ornl.gov/papers/misc/energy_conv.html   Ephdot (talk) 15:53, 23 March 2008 (UTC)

MPGe Conversion Template
It would be rather handy to have an MPGe conversion template, or to integrate mileage units such as Template:Mpg, Template:Mpg (Imperial), Template:L100km, and Template:Auto mpg into the universal Template:Convert. It should accept the base unit for the vehicles native fuel type such as, miles per kWh for electric, or MPG of Diesel fuel. --D0li0 (talk) 12:57, 14 January 2008 (UTC)

Try: Template:MPGe Ephdot (talk) 03:00, 21 March 2008 (UTC)

broken reference: http://www.eia.gov/oiaf/1605/coefficients.html —Preceding unsigned comment added by Ephdot (talk • contribs) 02:57, 21 March 2008 (UTC)

moved comments
"There is a common argument that electricity could also come from processes that do not burn fossil fuels. It is reasonable to plan a future where wind and solar sources will be there to carry the added load of electric vehicles, but for the present infrastructure without large capital infusions the response to an added electric load will be filled from the existing national generating capacity. So the efficiency of this network of heat engines is relevant to the efficiency comparison."
 * Hearsay. Ephdot (talk) 20:59, 22 March 2008 (UTC)

"As far as the carbon dioxide comparison goes, the fuels of the present infrastructure are relevant. This could be natural gas, which would be not so bad, or it could be from coal. Without rigid government intervention, the choice will be made on an economic basis, and since coal is almost free compared to natural gas, the outcome seems to be pre-determined. Thus, the case seems clear that the appropriate carbon dioxide emissions to attribute to electric vehicles is that of coal fired facilities."
 * Coal is used as a measure because it's just about the worst polluter and equates to current efficiencies of automobiles - about 33%. Nothing supports this argument.  The cost of coal is only part of the equation.  Very dependent on area.  Québec gets all it's power from hydro dams. I think the case was already made.  Ephdot (talk) 20:59, 22 March 2008 (UTC)

"Individuals can, of course, finance or share in the financing of solar or wind facilities, and thus feel satisfied that they are not causing such emissions. With such investment, they can also ignore the heat energy of fuels altogether, and the MPGe of vehicles thus powered would be infinite.  The only difficulty is the economic problem of the time value of the money involved in such financing.  While this is an individual choice, if we are talking about a national policy of encouraging wide acceptance of electric vehicles we have to think about the average person, for whom such costs are a big factor in the car buying decision. "
 * replaced by a more verifiable example. Ephdot (talk) 21:00, 22 March 2008 (UTC)

Avg occupancy
This summary table is from the Fuel efficiency in transportation page.

Can't get this to sort properly...



Max occupancy
This summary table is from the Fuel efficiency in transportation page. 

MPGe?
Researching links to gasoline-equivalent measures...

Should this be about mpgge and not MPGe?

There seems to be better references for mpgge (though only 800+ on google).

http://www.transportation.anl.gov/pdfs/HV/366.pdf

http://www.eere.energy.gov/vehiclesandfuels/pdfs/success/pngv3_23_01.pdf

Haven't checked the links out yet.

Has anybody found l/100 km type of reference, something more in line with SI?

Ephdot (talk) 14:38, 27 March 2008 (UTC)

This link: www.eere.energy.gov/afdc/pdfs/41590.pdf about E85 used MPGE (all caps). Ephdot (talk) 15:00, 27 March 2008 (UTC)


 * I think so.


 * It would seem to me that MPGe or mpgge is a measure of distance per unit of energy therefore the conversion would not be to l/100 km (km/l, m/cm³, etc.) but km/MJ (km/Wh, kWh/100 km, etc.)  This had been my initial reaction and a couple of days of trying to fathom what's going on has only brought me back to this.  I Googled ... 2006TdS-Monte Carlo Results.xls said


 * "MPGe = miles per gallon 'equivalent' : ie if the vehicle used a fuel other than gasoline, the amount of energy is being expressed in terms of gallons of gasoline"


 * The crucial point: "the amount of energy".
 * ... and Googled ...


 * "In a nutshell, that’s why a main AXP figure of merit is miles-per-gallon equivalent (MPGe), a measure that expresses fuel economy in terms of the energy content of a gallon of petroleum-based gasoline. Basically we ask: how much energy was delivered to the vehicle, and how far did it go? We convert the energy to the number of gallons of gasoline containing equivalent energy, and we express the result as miles per gallon."


 * Said Automotive X PRIZE: Computing MPGe for Electric Hybrids. This "gallon" is not 231 cubic inches, it's not a measure of volume at all, no more than the FFF "firkin" is.  It's a measure of energy which cannot be converted to litres.  The SI equivalent will be the Joule ... or better the megajoule or gigajoule.


 * In other words, though some write "MPGe" and others "mpgge", it's the same unit in question. It's miles per gallon gasoline equivalent &equiv; mi/GGE ... distance per unit energy.


 * Move the page to Miles per gallon gasoline equivalent mention both abbreviations but I think I'd prefer "mpgge" for use in articles since in includes the "g" for gasoline making it clear that it's not just a gallon (and clear that it's almost surely a US gallon since the British would have called it a "mpgpe", "p" for petrol ... could be a Canadian gallon, though, eh).


 * As for a l/100 km type of reference. I got 418 Google hits for '"litre of petrol equivalent" OR "liter of gasoline equivalent" OR "litre of gasoline equivalent"'.  225 for '"litre of petrol equivalent" OR "liter of gasoline equivalent" OR "litre of gasoline equivalent" kilometre OR kilometer OR km'.  How's that stand up against 7,250 for "MJ/km", 5,590 for "MJ/100 km", 5,050 for "km/MJ", 1,200 for "km/kWh", 4,510 for "kWh/km" and 5,300 for "kWh/100 km".  Litres of petrol equivalent if ever they crop up in the sources should be converted from.  Let's not convert to such units.


 * Jɪmp 07:16, 28 March 2008 (UTC)
 * As I understand it, MJ/km is a legitimate measure of electrical energy required to move a vehicle. The calorie is the unit of heat which somewhere down the line got replaced by the joule.  This is unfortunate because unlike conversion of electricity to work, conversion of heat to work isn't the same as conversion of work to heat.  Even if you can get X calories of heat from a MJ of electricity doesn't mean the reverse is possible.  In fact, it isn't, something to do with the second law of thermodynamics. Here a good link for the uninitiated: http://www.ftexploring.com/energy/2nd_Law.html  "low-grade heat" gives no useful work.  Good luck boiling water with 50 degree heat at standard pressure...
 * So, mpgge/MPGe is a measurement of vehicle efficiency at converting one Gasoline-Gallon Equivalent of HEAT (BTU or calorie) to useful forward motion for a given vehicle. Ephdot (talk) 20:50, 29 March 2008 (UTC)


 * There are many, many forms of energy. That the SI uses the same unit for all of them is not what I call unfortunate.  Whenever you use a machine to convert from one form to another there's a loss.  Use the same units and the loss becomes clearer ... or at least that's my perspective.  My approach would be to measure energy in megajoules and efficiency in percentage.  Forget the obsolete and ambiguous calorie.  Forget that unfamiliar quasimetric litre of petrol equivalent. Jɪmp 06:55, 30 March 2008 (UTC)
 * Though most conversions aren't 100%, there are only minor losses. 17% (83% max efficiency at 25 degrees and ~50% max practical efficiency) is very significant.  Measuring everything in MJ will lead to stupid (100%) conversions of heat to power as we have already seen.  Unless MJ(th) can be used? Still...  Ephdot (talk) 12:13, 30 March 2008 (UTC)
 * Minor losses are losses nonetheless. If we take the time to point out all losses, it'll be less likely that the major ones are overlooked.  Stupidity is what leads to stupid conversions.  We don't need to measure the ammount of beer bought by a pub in litres per week and the ammount sold by the pub in pints per week to account for the fact that the barmen spill and swill some ... Jɪmp 02:06, 31 March 2008 (UTC)

"MJ(th)" can't be used but there's nothing wrong with "MJ of heat".
 * The whole point of MPGe is to make it simple to compare regular automobile fuel economy by using a common measure based on MPGe (miles per gasoline gallon equivalent), a more universally accepted method is to measure automobile fuel efficiency in L/100 km gasoline equivalent. Otherwise, it's not worth using at all.  Ephdot (talk) 12:50, 31 March 2008 (UTC)

A simple concept made very confusing.
This page is very, very confusing. Unnecessarily so.

I would start this page by mentioning MPGge and then contrast that to whatever you are trying to document here. Lots of people take MPGe to be MPGge.

The thing people are looking for 1 gallon of gasoline = 115,000 BTU. 115,000 BTU/3412 BTU/KWHr = 33.7 KWHrs. Thus a car that uses 150 watt hours per mile has an MPGge of 33.7 KWHr/ gallon / 150 watt hrs per mile = 224 MPGge.
 * Put simply, this conversion is impossible. Conversion of heat energy completely to power is not possible.  The article tries to explain this. Ephdot (talk) 16:31, 20 May 2008 (UTC)

Getting into the well to pump and well to wheels just confuses people. Yes, I know CO2 emissions matter, but this page looks like an environmental ploy. BTW I am a totally green guy. I hope someone cleans all this up. —Preceding unsigned comment added by Elmerfud (talk • contribs) 15:29, 1 May 2008 (UTC)
 * But it IS complicated. Simple conversions are simply wrong.  Ephdot (talk) 16:31, 20 May 2008 (UTC)

The conversion table is a mess and should either be deleted or significantly improved
The table has a number of values that are clearly wrong. For example the equivalents in several rows do not vary with column heading. Gas is natural gas? What is the 14kwh? Natural gas is around 11kWh? There needs to be a column for reference information. 96.252.103.113 (talk) 03:10, 19 May 2009 (UTC)

Sort table
The fancy sort table allows you to shuffle efficiency depending on whether your electricity comes from coal, gas or some perfect fuel. Note that most of the entries don't use electricity so it doesn't really apply. I've coloured the electric ones in blue and labelled them A, B & C. All the others I've labelled 1, 2, 3 ... The first three I've coloured yellow. Note that only the coloured part of the table changes with respect to whether your electricity source is coal, gas or the theoretical maximium. This would be better as two tables. We be able to get rid of a lot of meaningless clutter (the gas and coal entries for modes which don't generate electricity from either). 
 * Notes

J IM ptalk·cont 22:22, 22 August 2009 (UTC)