Talk:Energy efficiency in transport/Archive 2

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Archive 1 Archive 2

Fundamental difference between European and US measures of energy per passenger km

The Europeans (and many proponents of high speed rail) calculate the kWh/km (or mpg^-1) by dividing the energy required to move a train from point from point A to point B by the product of the km and passengers. Americans (or at least DOT) take all the energy used in a year and divide it by the total passenger km (or miles). The European method gives the most favorable estimate, but to my way of thinking the American method gives a more realistic estimate of all the energy needed to operate the system, including the energy necessary to move the train around empty or only partially loaded. The differences in these two calculations give vastly different results. Regardless of units used, listing various energy use per passenger, without including a discussion of this difference undercuts the utility of all values given. This far outweighs nuances in conversion factors.

From this page: High Speed Rail is listed as 0.1 kWh/km, Amtrack gets 5.7 l/km

Converting AMTRAK's 5.7 l/km * 30400BTU/l gasoline equivalent * 2.93*10^-4 kWh/BTU = 51 kwh/km

High Speed Rail = 0.1 kWh elec/km * 3 kwh therm/kwh elec = 0.3 kwh term/km

(The electrical to thermal conversion is necessary to get it back to a primary source energy (electricity is just a carrier). The conversion factor comes from US government Energy Information Agency website and depends somewhat on the mix of sources used to generate electricity and therefore can vary a little country to country. In any case, the point here is not about the two decimal place accuracy of this factor but the huge difference between the the European rail and AMTRAK energy requirements. Now AMTRAK may not be as efficient as European high speed rail, but there is no way that these numbers are comparable. RStillwater (talk) 03:44, 5 June 2009 (UTC)

I think this point has been dealt with, as I couldn't find the 5.7 L/km figure in the article, but I think you'll find the vast difference is not about differences in assessment methods, but the difference between kWh/vehicle-km and kWh/passenger-km. The "0.1" figure equates to typical figures energy consumption per passenger-km for electric rail. The quoted figure for Amtrak in the article is current 1.737 MJ/pass-km which is equal to 0.48 kWh/pass-km - a typical figure for diesel trains.
As for the conversion to thermal energy of the primary fuel, I don't think anyone will dispute that, but I think this is a non-issue. Every report I've ever read on transport and energy of emissions already allow for the energy content of primary fuels used to generate the electricity. The calculation has to be done simply to compare CO2 emissions of different transport modes, which is the major reason for being concerned about relative energy usage in the first place!

The only reason disagreements arise is that for electric rail, there is the possibility of choosing a zero-carbon mode of generation, whereas for diesel there obviously isn't.Peter Barber (talk) 13:28, 23 September 2009 (UTC)

Poorly Chosen Statistics

No way does the Prius average 59 mpg. Just because the EPA sticker says it does doesn't make it true. 41-43 mpg average sounds much more reasonable, especially since the newly revised EPA fuel economy ratings (whose tests are still bogus) lowered them to that level. LostCause 03:45, 26 August 2007 (UTC)

From http://www.fueleconomy.gov the 2010 Prius averages 48.4 mpg based on 80 vehicles. Low is 35, high is 60. The EPA estimate for combined driving is 50 mpg. 65.112.42.84 (talk) 15:42, 27 April 2010 (UTC)

Ships' fuel efficiency figures are grossly misleading

A modern cruise ship seems much different.

I recently took a cruise on the biggest, newest cruise ship "Oasis of the Seas" by Royal Caribbean. As my son criticized the extravagance of it, I made some effort to find out how fuel efficient it actually is. Here's what I wrote my son:

"One of the crew members told me the ship burns about 7 tons of fuel/hour which I calculated 7*5*24= 840 tons a week. Another told me they load 1000 tons of fuel every week. With 6000 guests aboard (also aboard are 2000 service staff and entertainers), it means each guest is responsible for 1/6 ton = 2000/6 lb = 333 lb, or 333/7 = 47 gallons. So our gas mileage per person is 2700 miles/47 gallons = 57 mpg."

Please notice this is much different than the historic data on the page.

Also, the airplane efficiency seems more like a maximum, than like typical airline efficiency. I'll check further into it, but I suspect average ship efficiency is not much different from airline efficiency, unlike the huge differential on the current page. I'm flying tomorrow. I'll see what information I can get from the pilot. Jclaer (talk) 02:34, 2 July 2010 (UTC) Jclaer (talk) 03:12, 18 July 2010 (UTC)

I agree. The efficiency is quoted so low, to the extent that air transport looks great in comparison. Atif.hussain (talk) 14:47, 4 October 2010 (UTC)

Units, Who is comparing what,

If the issue is energy we would do well to use megajoules per passenger kilometre.

If the issue is global warming then CO2 emissions per megajoule can be included as well as a suitable Radiative Forcing Index see Intergovenmental Panel on Climate change research. The RFI increases CO2 emmissions for the effect of the co-emission of other greenhouse gases and for location effects. A figure of 1.5 is suggested for emissions at ground level but of around 3 for emissions above 9km altitude.

Jhmr1000 (talk) 15:49, 16 May 2008 (UTC)

Actually, I think CO2 per passenger mile, or even RFI per passenger mile is the way to go. Transportation is moving people or freight over a given distance. So the denominator of whatever metric is used should always be passenger-miles or ton-miles.
- Jvv62 (talk) 12:38, 3 June 2008 (UTC)
Yes, megajoules/gramsCO
2 per passenger/tonne-kilometre (kW·h/BTU/poundsCO
2 per passenger/tonne/ton-kilometre/miles). JIMp talk·cont 06:12, 21 August 2009 (UTC)
According to this map, all countries except three have adopted the International System of Units. The kilometer is the appropriate unit of distance here. If an author wants imperial units as well, they should be in parentheses. Regards, PeterEasthope (talk) 17:24, 28 January 2011 (UTC)

buses

this article is hard to understand, take the part about buses. Somehow a bus that on average get 6 mpg, suddenly gets 330 mpg when 55 people get on? 71.194.44.209 (talk) 15:31, 11 May 2011 (UTC) I skimmed the cited source and no where did I see miles per gallon per person. It seems this passenger mpg is calculated by someone just multiplying the number of passengers with the mpg. Which I think is wrong for passenger per mile per gallon, because that would be p/m/g or maybe passeger/mpg. which would mean dividing the passengers by the mpg, which gives a much different number. Unless of course it is mpg per passenger, in which case it would be mpg/passengers. which is again is a different number. In anycase it doesn't take into account the weight of the passengers and the effect on the fuel efficiency. 71.194.44.209 (talk) 19:54, 15 May 2011 (UTC)

messy units

This article seems to use the term "mpg" for both Miles per US Gallon and Miles per British Gallon. These are very different units. A US Gallon is 3.9 l and a British gallon is 15% larger at 4.5 l. The ford mondeo listed at 46.3 mpg: is this US company listing in US Gallons, or in British Gallons because its on a UK road? If its US Gallons, the equivalent is 5 l/100km. If its UK gallons, the value is 4.3 l/100km.

We need to sort this out. I propose adding the international l/100km after each measurement. ... Seabhcan 09:37, 23 August 2007 (UTC)

Per WP:MOSNUM conversions should be provided. Of course, if we don't know what we're converting from, it's impossible. JIMp talk·cont 05:26, 21 August 2009 (UTC)

Having just read the article, I would suggest standard units throughout - some places use Mj/passenger-KM while other places use Passenger miles per gallon - when one goes up the other goes down - which is really confusing to readers. Or in lieu of standard units cite the same set units everywhere - e.g. "Passenger airplanes averaged 4.8 L/100 km per passenger (1.4 MJ/passenger-km) (49 passenger-miles per gallon)" —Preceding unsigned comment added by 76.200.112.174 (talk) 14:59, 11 August 2010 (UTC)

I agree. Most of the Wikipedia English articles are a measurement mess. A collection of confusion due to some war between forces wanting 21-st century units and the dinosaurs who want pre-historic units. It is ridiculous to read an article that has SI in half an article and non-SI in the other half. It is time that the editors of Wikipedia smarten up and get rid of the prehistoric units once and for all. If there are some out there who do not understand SI, then too bad, let them learn it! The intelligent majority should not be handicapped by the ignorant minority. — Preceding unsigned comment added by 68.228.181.187 (talk) 12:45, 26 June 2011 (UTC)

I agree too. For this article to have any value, it must be easy for the reader to compare like-for-like. I think there are two types of comparison that are interesting: energy usage per passenger-distance (for public/private transport), and energy usage per weight-distance (for freight -- which this page doesn't yet say much about). The actual units used aren't really important for comparison purposes, although it is important to use a unit of consumption-per-distance rather than distance-per-consumption (eg. MPG) to be able to make fair comparisons (see Fuel economy in automobiles). Since energy efficiency is different for different fuels, it might make more sense to use MJ rather than litres/gallons as the unit of consumption. (Whatever unit is chosen, all assumptions about conversion rate should be clearly stated). So, I'd recommend:

  • Use MJ/passenger-km as a unit of comparison for all public/private transport figures.
  • Also give MPG figures for when presenting examples of raw vehicle efficiency, since this is what most English-speaking readers are probably familiar with (as long as it is clear whether this is in U.S. or imperial gallons)
  • Mention units at the top of the page, and refer the reader to pages giving conversion rates (eg. Fuel economy in automobiles).

AndrewBolt (talk) 08:02, 26 July 2011 (UTC)

Rocket calculation

I suspect the Rocket section contains numerous errors. It says that the rocket burns 1000 t of solid propellant but then says that the total vehicle weight 'being lifted off the ground' (sounds like GROSS mass to me?) is only 100 t. The mass of liquid hydrogen (106 t) is also in excess of the rocket mass (100 t). So either the mass of the vehicle is wrong, or the mass of these fuels is wrong, or else the NET mass of the vehicle is being stated, which I think is misleading. Jdpipe (talk) 06:43, 23 October 2011 (UTC)

Walking

Who did they get to drink the gasoline for the "mpg" figures for walking? Gene Nygaard 15:53, 11 April 2007 (UTC)

The mpg numbers are equivalents, calculated by dividing the number of calories burned by walking by the number of calories in a gallon of gasoline. Keithkml 23:26, 12 April 2007 (UTC)
You can see the Fuel_efficiency_in_transportation#Humans section for an account of how these figures were obtained. Z-d 06:55, 31 October 2007 (UTC)

I agree that it's dubious to include the average food energy burnt during walking as a mpg? If you're going to do this you should track down a study of the average daily carbohydrate intake by frequent walkers vs frequent drivers, and and only use the _difference_ (if any) to calculate "fuel consumption" of walking. -- Patrick Sunter, 19 March 2008. —Preceding unsigned comment added by 121.45.156.238 (talk) 03:02, 19 March 2008 (UTC)

Since it is an article about energy efficiency, all values should be in the same units. Ideally this would be kJ/km, but other units are more convenient in different contexts, such as the kCal used for energy use in humans, or the (fuel consumption rate) MPG. Since they are all variations of the same thing (well, MPG is the inverse of efficiency), they can be converted easily for comparison sake. RevZoe (talk) 20:49, 19 July 2011 (UTC)

Can we have a better reference for the walking and running efficiencies? The given one is a web page of a coach/trainer. Surely there must be some scientific literature. 130.216.54.198 (talk) 20:42, 21 May 2009 (UTC)

The data given for the efficiency of walking is incorrect. 330 kJ = 79 kcal, not 70 kcal. Also, for all human-powered transportation modes (walking, bicycling), the same units should be used, such as kcal/km or kcal/mi. It is better to use kcal instead of kJ (or MJ) because that's what is used to measure food energy and weight loss. 65.112.42.84 (talk) 15:38, 27 April 2010 (UTC)

Anyone know are these the marginal energy usage for walking and bicycling? Ie is the basal energy subtracted out? Or does it include the energy cost of just keeping the person breathing and alive. Also the energy usage for all of these I suspect is the point energy. Figures for energy used in construction and energy used for energy harvesting should also probably be mentioned. LetterRip (talk) 05:22, 8 September 2010 (UTC)

The first two bullets already cover "energy-input vs useful-output" i.e. issues of efficiency are already covered. This means that 360 MPG is the final figure for human walking MPG. It seems totally bogus to me to then multiply that by the efficiency of a car engine. Why do that? Efficiency is already covered and car efficiency has nothing to do with human walking efficiency. Other sites http://davidarcher.blogspot.com/2007/06/400-mpg-or-so.html and http://sammysense.blogspot.com/2007/06/human-mpg.html come in at approximately 400MPG. We are simply getting it wrong with that final bullet point. Davidmcdavid (talk) 18:27, 17 December 2011 (UTC)

Automobiles

The examples given for automobiles are all selected from the most efficient vehicles available. I've added two of the least efficient for balance, but I think it would make more sense to have one or two from each extreme plus a few of the most popular vehicles. Kendall-K1 (talk) 17:50, 11 June 2012 (UTC)

Table of passenger rail efficiencies

I've edited the fourth line of the table (SBB-CFF-FFS) to show data from the SBB website; namely: 2300 GWhr per year and 17749 million passenger-km per year to give: 0.47 MJ/pax-km (0.13 kWhr/pax-km) for 2011. I suggest that the following line (Siemens) be removed as it refers to the same trains (mostly), namely those the SBB bought from Siemens. Also neither of the Siemens references work any longer. The difference of a factor of four between the values 0.47 and the 1.9 MJ/pax-km for Amtrak probably reflects the lower occupancy of the Amtrak cars (only 24 pax/"vehicle") according to table 2-12 of the Transportation Energy Data Book [1] It's also true that the new SBB trains use regenerative braking.

I also worry that many table entries have lost sight of the meaning of significant figures. For example, Do we really think that 209.1 L/100 km for the efficiency of Colorado Rail could not be 209.2 L/100 km ? Better would be: 210 L/100 km. When a number refers to a measurement (or the calculated result of measurements) it carries two elements: its value and an estimate of its uncertainty. "209.1" means we know that value to an accuracy of half a tenth of a percent (0.1 / 210) which is nonsense in this context -- especially if we declare it to be 209.0 the next year and someone extols the "increase" in efficiency gained under their astute management. 16:10, 27 June 2012 (UTCRobLandau (talk) 16:11, 27 June 2012 (UTC)

Agreed 100.0003% on the issue of excess precision. I try to fix these when I can. Sometimes it happens because the original number was given in one units system, converted to another, and then back to the original, gaining precision at every conversion. I usually try to go back to the source, but the Colorado and Amtrak sources are both 404. I'd be happy with rounding all numbers in any given table to two or three (no more) figures. Kendall-K1 (talk) 17:17, 4 July 2012 (UTC)

Small Aircraft

I'm pretty sure the numbers in the "Small Aircraft" section are supposed to be liters per passenger-km, not liters per km, so I undid the change. I'll see if I can find a better way to do this. Kendall-K1 (talk) 17:25, 4 July 2012 (UTC)

what is BTU?

BTU is often mentioned but I couldn't find it defined in the article 149.254.58.223 (talk) 17:37, 11 July 2012 (UTC)

The first use is linked, per the style guidelines. I wouldn't expand the acronym, as most people who are familiar with the term have never heard the expansion. We should prefer standard units when possible, but unfortunately many of the sources are from US government and use arcane units. Kendall-K1 (talk) 14:58, 16 July 2012 (UTC)

Walking and biking

We need better sources for walking and biking. The given source is a personal web site. It references a book that I don't have, and I can't find the numbers it gives in the Google preview. The numbers don't add up. The source given for biking doesn't mention biking. The other source for biking is a units calculator, not a reliable source. This issue was raised in 2008 and it's about time we fix it. Kendall-K1 (talk) 18:49, 30 October 2012 (UTC)

most efficient airplane?

In the aircraft section the article says: "Airbus states a fuel rate consumption of their A380 at less than 3 L/100 km per passenger (78 passenger-miles per US gallon).[24] The Airbus A380 is the most fuel efficient airplane per passenger mile as of 2012." Yet a table shows that the Boeing 747-400 gets 91 passenger miles/US gallon. Doesn't this make it more fuel efficient than the Airbus A380? — Preceding unsigned comment added by 76.208.67.166 (talk) 03:13, 14 September 2012 (UTC)

I took it out. Aside from the problem you raised, the source is from 2007, so it can't possibly have anything to say about the efficiency of aircraft in 2012. Kendall-K1 (talk) 19:01, 30 October 2012 (UTC)

Velomobile

5× the energy efficiency of a bicycle seems a bit high, and is sourced by a manufacturer's web site. Here is a more reliable source that says closer to 3.5×: The velomobile: high-tech bike or low-tech car? Kendall-K1 (talk) 20:06, 7 January 2013 (UTC)

Irony.....

The worldwide consumption of fuel was so great that it justified the introduction of the (oil)supertanker, yet it is (was) the most efficient means of motorized freight transport. It is difficult to find a link with a clear comparison.... still looking.

“….Overall, reported energy consumption levels for water are among the lowest of any transport mode: nothing carries more ton-km for fewer kJ than a fully loaded supertanker at its optimum cruise speed. But, lightly loaded small ships are not much more energy efficient than the other surface modes….” [ ENERGY USE IN THE TRANSPORT SECTOR Julie Fraser Shiva Swaminathan Louis S. Thompson (www.tgaassoc.com/documents/energy-text&figures-dec2007.pdf)]

Also, there ought to be an index where travel time is included in the concept of efficiency. This would give a more relevant comparison with air travel especially.

Pete318 (talk) 17:40, 2 April 2013 (UTC)

wording error

"Other sources give a figure of 1/3.4 (29.5%) of the energy efficiency of a normal bicycle.[7]" i cannot find the original information in the source article, however i assume this must be an error (it also contradicts the previous claim of 20% of the energy requirements of a bicycle) and instead should say "Other sources give a figure of 1/3.4 (29.5%) of the energy consumption of a normal bicycle.[7]"

80.5.128.19 (talk) 13:45, 27 April 2014 (UTC)

List?

this could be adapted into a "list of common modes of transportation by fuel efficiency," or at least the information could be used in making such a page —Preceding unsigned comment added by 67.232.195.213 (talk) 08:23, 8 August 2008 (UTC)

Along these lines I actually think that the name of this article would be better phrased as something like 'Fuel usage efficiency in transportation', since the units mainly used are actually different and are not those of "energy" (i.e.: a liter of jet fuel != a liter of gasoline) MasterCKO (talk) 06:32, 8 November 2014 (UTC)

Hot Air Balloons

I see that the NASA launch-site crawler is extremely fuel hungry. However for human transport hot air balloons may be the most fuel inefficient. The typical balloon will use 20-30 gallons of propane to travel 5-10 miles. A balloon may carry a small number of passengers, but would still be very inefficient per passenger mile.Flight Risk (talk) 01:02, 31 July 2016 (UTC)

Jet Pack

Can a reference for a jet pack be located? 132.188.71.5 (talk) 00:34, 25 August 2015 (UTC)

The Bell Rocket Belt goes 250 m on 19 litres of hydrogen peroxide. There is a table on the article page but it doesn't seem to be sourced. Kendall-K1 (talk) 23:25, 10 August 2016 (UTC)

E-bikes

We could use a paragraph on e-bikes. So far I can only find manufacturer's claims, which I don't want to use. Kendall-K1 (talk) 12:36, 26 August 2016 (UTC)

First image is NOT representative

The first image - a truck - is NOT representative of efficiency! Trucks are simply not an efficient mean of transportation. Seems to me more commercial, like Tesla. 145.64.134.245 (talk) 11:55, 26 August 2016 (UTC)

I don't think there is anything wrong with using a photo of a truck. This is not the "Most efficient modes of transportation" article. But the caption does seem overly promotional and a bit off-topic. And this brings up another point, most of what we have is consumption per passenger-km. There is very little on consumption per tonne-km of freight. We've got a number for trains but nothing on trucks except the photo. Kendall-K1 (talk) 12:31, 26 August 2016 (UTC)
I also just noticed that we have a photo of a Tesla, but nothing about it in the text. Kendall-K1 (talk) 12:38, 26 August 2016 (UTC)

Analysis section

The Analysis section smacks of WP:OR. I am going to remove it unless someone wants to defend it. Kendall-K1 (talk) 05:58, 27 August 2016 (UTC)

Inefficiency / bad title

I realize that J/km (and similar units) are popular for describing energy-efficiency in transportation, but I think somewhere it should be pointed out that J/km (and similar) really measure inefficiency. Taking the lead section as an example, a bicycle with a few hundred J/km (hJ/km) is not less energy-efficient than a helicopter measured in MJ/km. In other words, the MJ/km helicopter is more energy-inefficient than the hJ/km bicycle. Please correct me if I'm wrong.

If that is true, then efficiency would be the inverse, right? Energy-efficiency = km/J ? This seems more logical to me (based on units), because then a more energy-efficient bicycle would be a few km/hJ (10 m/J) which is obviously greater than a km/MJ (mm/J) helicopter... I mean 10 m/J is obviously (I hope) more energy-efficient than 0.001 m/J.

I'm not literally suggesting we change the title of the article, because we can't change the popular/common use of the term/concept/unit. But shouldn't this fact be mentioned somewhere? I don't have any sources to back me up, and I'm not an expert so I didn't edit anything myself... and obviously I have a very poor way of expressing the idea. But can we agree this issue needs to be addressed somewhere in the article, to help people new to the topic understand why smaller values are more efficient? I think I would be confused if I wasn't already familiar with the topic...

Just had an idea: maybe in the lead we could mention more intuitive units, like km/L or mi/gal, and then mention that energy efficiency is also commonly, but misleadingly, measured in reciprocal units, like J/km. How does that sound? Hydradix (talk) 15:15, 17 September 2016 (UTC)

Composite table

I think, overall, this article gives a good description of energy efficiency (per vehicle). But upon review of the current article, I found it hard to compare various modes of transport (walking, bicycling, car, truck, train, airplane, etc.). I think a composite table would be VERY useful for the average reader... but if I did it, it would be original research (I don't know of a reliable second-party source). If anybody has a reliable source, we (at least me) would appreciate a "table of efficiency per vehicle"! Hydradix (talk) 10:22, 18 September 2016 (UTC)

Updated intro

I updated the intro because it really annoyed me that the two common measures of transport efficiency (fuel economy and fuel consumption) were not clearly identified, although the article uses both! I provided reliable sources, but I never found an "official" definition of "efficiency in transportation". In fact, one reliable source (the state of New Jersey) considers "efficiency in transportation" as the number of passengers per vehicle (p/vh?).

Anyway, I want to point out that my edit was not original research! When I use the phrase "Energy efficiency in transportation is often (and confusingly) described in terms of fuel consumption" this is based on my cited source, and other sources not mentioned here (but I did list some of them in another article). In other words, Fuel Consumption is different/confusing from Fuel Economy is not just my opinion... other reliable sources agree.

Finally, I think my new intro now gives a decent general overview, and also summarizes the remainder of the article (efficiency per various modes of transportation). So, can we remove the "need to expand introduction" from this article? Hydradix (talk) 09:16, 18 September 2016 (UTC)

This has been discussed in the past but not much has been done. I think this is a step in the right direction. Kendall-K1 (talk) 12:38, 18 September 2016 (UTC)

Major Oversight

The article is making a mistake by neglecting time. Imagine there are two identical cars that only differ in their engine. One car gets 50mpg @ 50mph. The other car gets 50mpg @ 100mph. Which is more efficient?

Fuel efficiency encompasses more than fuel per distance traveled. It must also encompass the time taken to travel that distance. In other words, conventional "fuel efficiencies" are not comparable between different velocities. A bicyclist getting "600 mpg" is probably not more efficient that an airliner getting "60mpg". What efficiency would the cyclist have at Mach 0.85?

The question seems absurd because a bicycle is several orders of magnitude less efficient than an airliner. A major source of inefficiency on the bicyclist and airliner is aerodynamic drag. A bicyclist has a drag coefficient (Cd) much greater than an airliner. Air drag increases at the square of velocity and linearly with air density. A bicyclist travelling at Mach 0.85 would require an absurd amount of power. Racing motorcycles are much more streamlined and have over 250x the power available, yet even they struggle to reach Mach 0.3.

Despite the bias against air travel, it is probably the most fuel efficient form of transportation used by the masses. Without considering the time component, the comparison of "fuel efficiency" in transportation is meaningless. — Preceding unsigned comment added by LostCause (talk • contribs) 07:11, 23 April 2011 (UTC)

I disagree that there is an oversight. This article is about the concept which most people call "fuel efficiency". You are right that a different measure that considers speed is also interesting, but it belongs in a separate article. I think the unit of "gallons per hour" is one of the most useful, because people make travel decisions based on how long it takes, not how far it is. That means that MPG is very biased towards air travel, not against it. LachlanA (talk) 05:37, 29 April 2011 (UTC)
I totally disagree that there is an oversight. Rather, the unit of Miles/Gallon is a unit of fuel consumption, not efficiency, and so does not really have a place in the article except for general comparison. The proper measure of fuel efficiency is fuel used per set distance, or fuel use per passenger over set distance, or in general energy used per set distance (with or without pasenger). So, the appropriate measure for miles and gallons is Gallons/100 Mile, the amount of fuel used to cover 100 miles. In this case, the car which has 50mpg @ 100mph has 50Gallons/100 miles, and the car with 50mpg @ 50 mph has 100Gallons/100 Miles. Using appropriate measures of efficiency, we see that the actual distance traveled has no bearing on the efficiency of the transportation. RevZoe (talk) 21:21, 19 July 2011 (UTC)
I think you have it backwards. Miles/Gallon is a measure of efficiency. Fuel consumption is measured in Gallons/Mile. Hydradix (talk) 15:15, 17 September 2016 (UTC)
I too disagree that there's an oversight. You assume that time spent traveling is time wasted. Yet travel itself can be worthy. If something gets you somewhere twice as fast, that doesn't necessarily mean it's more efficient. It's only more efficient if the only consideration is arriving at the destination. Some might say that the journey is just as important as the destination, and for those people, a bicycle would be far more efficient in regard to time than an airliner. The worth (or negative worth) of time spent in travel is subjective. — Preceding unsigned comment added by Ianbrettcooper (talk • contribs) 12:14, 13 April 2012 (UTC)
Energy efficiency, fuel efficiency, fuel economy has never dealt with time, only the amount of fuel needed to an amount of work. The car that gets 50 mpg at 100 mph has done the same work as the car that gets 50 mpg at 50 mph. The fact that it does it faster is irrelevant in this situation. If that 100 mph car slowed to 50 mph then it may get 80 mpg (or whatever), at which point we can say it is more fuel efficient. If you bring time into the mix, you are talking time efficiency, and yes, an airplane or fast car will be more time efficient. True fuel efficiency should deal with passenger/distance/energy. According to https://truecostblog.com/2010/05/27/fuel-efficiency-modes-of-transportation-ranked-by-mpg/ You will find an interesting chart. Notice how a freight ship which gets 0.004 mpg is quite efficient if you are able to cram 77,000 passengers on board. Hopefully the bathrooms remain in service. Flight Risk (talk) 19:03, 3 October 2016 (UTC)

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Bicycle efficiency can't be correct.

The article cites 27 kcal/km at 16 km/hr. That's 500 W, which sounds completely unsustainable for a bike commuter.

Walking is also suspect. 4 km/hr is too slow, and 210 kcal/hr is too much.

--Agustín Dall'Alba (talk) 09:00, 7 June 2018 (UTC)

Data about velomobile / bike / walk are based on different categories:

  • walking for 1 hour may take 210 kcal but about 70 kcal of it is needed for just staying alive...
  • bike 27 kcal/km at 16 km/h is correct (on average bike). Power needed is about 50W but human body needs lot more energy from food (low efficiency engine ;)
  • Best velomobiles needs 250W for 50km/h. 1h of such workout need about 2000 cal which Corresponds to about 40 kcal/km

Velomobile is less fuel(food) efficient than bike with this starting conditions - Which is kind of obvious if he have same engine (human) and try to ride 3 times faster...

-- anonymous 23:00, 26 nov 2019 (UTC) — Preceding unsigned comment added by 2A02:A31A:A244:EB00:F187:8DEC:88BA:8925 (talk)

Disputed sources

If the sources are disputed please provide which, and not merely adding a tag to the article. The sources were never disputed unitil I assembled a table and a chart with these figures. I didn't create nor cherry-picked sources, I merely assembled the figures into a table and a chart using the sources already present in the article. Therefore, unless someone says which sources are disputed, I will remove the tag. João Pimentel Ferreira (talk) 09:10, 14 June 2018 (UTC)

Energy efficiency varies by orders of magnitude for the same mode of transport, depending on the assumptions. Therefore it is essential to provide the context in which the numbers were calculated. As an example, in the figure you added in the lead, it seems that airplanes are the worst in terms of energy efficiency. However the Boeing 727 was produced between 1962 and 1984. Fuel efficiency in aviation improved dramatically over the last 50 years (see Fuel economy in aircraft). Aircraft today consume less than a third of the energy cited in long-haul flights (almost same as buses). Same for electric rail: what does it refer to? Context and methodology are essential here. Also "English Wikipedia" cannot be a source for that graph. --Ita140188 (talk) 09:21, 14 June 2018 (UTC)
I suppose you are right, but that has nothing to do with the tags you added to the article and to the tables. The chart doesn't mention that airplanes in general have that amount, the chart explicitly refers that it is the Boing 727, and not "airplanes". I made the chart according to available sources, sources which were already on the article. Therefore your tag of "factual accuracy" does not apply, specially to the table. It applies merely the tag for "additional citations for verification".João Pimentel Ferreira (talk) 13:12, 14 June 2018 (UTC)
And btw, there was NO original research on the table, the sources were already there, the rest is pure math in the conversion amongst units. João Pimentel Ferreira (talk) 13:14, 14 June 2018 (UTC)
I add your figure for Airbus to the chart, but a) your link [1] doesn't work and b) you have to provide average occupancy ratios, and not consumption per seat. João Pimentel Ferreira (talk) 13:29, 14 June 2018 (UTC)
Mine was just an example taken from Fuel economy in aircraft. Sorry I didn't check if the link to the source was still working. It should be noted that aircraft today have generally very high occupancy rates, so I think assuming consumption per seat is justifiable. Anyway, better data and sources are needed for this article, unfortunately I don't have time to do it now. --Ita140188 (talk) 00:00, 15 June 2018 (UTC)
The table has no airplane, so I don't get why you insist in tagging the table. The sources for each mode of transport are in the table, and the other amounts for each row are purely arithmetic conversions. Must I insert a source in the table for every conversion? Don't you know how to convert from L/100km to J/m or mpg, etc.? What do you want exactly? Be specific! João Pimentel Ferreira (talk) 13:24, 15 June 2018 (UTC)
If a source has the amounts in litres and you insert the data in wikipedia in gallons, would you tag it as "original research"? And please, don't come with the airplane again, because I said you are right, but the table you're insistently tagging has no airplanes. João Pimentel Ferreira (talk) 13:32, 15 June 2018 (UTC)
The airplane was an example. As I said in the edit summary there are several values in the table that are unreferenced. Also, per Wikipedia policy, there are calculations that are trivial and obviously allowed, such as liters/gallons, and other that are not, such as calculating the efficiency per passenger with unreferenced occupancy ratios. Also, I have reserves on the meaning of calculating the equivalent petrol consumption of modes such as walking. It can be misleading and questionable, because energy consumption is calculated differently for such different modes. Anyway, there are still entire rows with no reference, such as motorized bicyle, common petrol automobile (what does it even refer to?), GEM NER, Daihatsu Charade, and all the trains, in which 300 people per car is assumed without any reference. These are not trivial assumptions, as this would completely change the results. Also the occupancy for all cars is from the average in the US, which should be specified. Other countries may have very different values.--Ita140188 (talk) 16:46, 15 June 2018 (UTC)


I understand that you have reserves, but that is very simple and it is done all the time by experts, by simply converting kilocalories to Joules and converting litres of gasoline to Joules, independently of the type of locomotion. After all, everything is energy, and you need energy to produce work! Read the first paragraphs of the article because it clarifies such confusion. For the conversion amongst units of energy in the table, 1 litre of gasoline amounts to 34.2 MJ, 1 kWh amounts to 3.6 MJ and 1 kilocalorie amounts to 4184 J. These are very well known values in the art. Even Google makes these quick conversions, here an example. In any case you raised issues that are relevant:

  • The trains occupancy ratios (the source was in the article, I will search for it);
  • Motorised bicycle was also in the article (I'll search for the source);
  • I will remove the "common automobile". It was somehow a mean amongst the automobiles of the table, but I remove though.
  • The occupancy ratio of the car doesn't change much in the world. In Europe is 1.4, but if you have other sources kindly provide them, that I will amend the table. João Pimentel Ferreira (talk) 21:46, 15 June 2018 (UTC)


@Ita140188: I added the sources for conversions amongst units on the first row of the table, using known converters, if doubts still arise kindly let me know. João Pimentel Ferreira (talk) 15:30, 17 June 2018 (UTC)

I am sorry if I haven't been clear. My objection is not on the conversion factors, which are known. The OR tag is about the occupancy factors, especially for trains, which apparently you just estimated. This is the definition of OR. Also you should provide a reliable source that reports a mpg for walking. I still think it can be misleading and is not a good comparison. There are many more assumptions than you think when you calculate that number. --Ita140188 (talk) 00:03, 18 June 2018 (UTC)
Ok, I see your point. I will check the train occupancy ratios, but the Japanese source already mentions it, I suppose, but I will check again. Regarding walking as mpg, you can check for example this.João Pimentel Ferreira (talk) 18:10, 19 June 2018 (UTC)


@Ita140188: please review your source on source [1] (energy efficiency for airplanes) because it points to a bad link, otherwise a un-sourced tag will be added. João Pimentel Ferreira (talk) 01:57, 2 July 2018 (UTC)

Image

@Ita140188: You don't remove a chart with accurate data, just because you don't like the figure of the airplane

  • the sources ARE NOT the wikipedia as such, the sources are the sources which this article refers to
  • the figures of the airplane are correct, since it clearly says which airplane we are talking about
  • the data you provided for the airplane Airbus is per km-seat and and not km-passenger, which is totally different.

Give me the energy efficiency for the Airbus per passenger-km (and not passenger-seat) with respective reliable sources and I redo the chart accordingly. João Pimentel Ferreira (talk) 10:29, 19 August 2018 (UTC)

References have to be mentioned explicitly. What if the article changes in the future? You cannot reference a Wikipedia article even if indirectly you intend to reference the sources in it. For the airplane, it is extremely misleading to put figures that are about 3 times what is normal today. Specifying what aircraft it refers to does not excuse this. A casual observer cannot know that that aircraft was last flying 30 years ago. I will remove the figure until you provide a better one. --Ita140188 (talk) 03:38, 20 August 2018 (UTC)

Electric-assist vehicles. Micromobility?

There seems to be a potential category between human-powered transportation and automobiles--electric-assist bikes, electric kick scooters, that sort of thing. I marked it 'motor assist', but this might not be the best name. I've seen the word 'micromobility' used; I don't know how canonical that is. I picked the Xiaomi M365, the model used by Bird and Spin, as an example, and used the manufacturer's datasheet for range and energy content of the batteries. Hopefully the changes are okay! grendel|khan 02:33, 20 September 2018 (UTC)

Metrics!

This article is all over the place. Data from various sources is just sort of pasted in, without any consistent way to compare them.

First of all, forgive my boldness by trimming your text, but for the sake of clarity I reply by parts. Note that I also agree that the article is a mess in terms of units, that's exactly why I made a huge effort editing the article on the beginning, to make it clear that experts, to avoid such mess, convert all the units into the SI. And if we want to avoid further mess, we should really stick to the International System of Units. João Pimentel Ferreira (talk) 18:04, 7 January 2019 (UTC)

Different kinds of fuels (bunker fuel, diesel, jet fuel, gasoline, aviation gasoline...) have different energy densities, even before 'grades' of the same fuel, miles and kilometers are used practically interchangeably throughout the article.

Different energy densities is a fact, but not so relevant for the question of energy efficiency. That is a typical misunderstanding, since no-one says that an automobile is more efficient just because it has a bigger fuel tank. Energy efficiency is transportation is merely Energy for vehicle's locomotion divided by passenger-distance, in SI, Joule/(pax.km) independently of the fuel density, externalities, costs of production of energy, and everything else. João Pimentel Ferreira (talk) 18:04, 7 January 2019 (UTC)

I nominate "megajoules per kilogram transported, per kilometer" as the core unit. Or something like that. Just off the top of my head.

If you want 'passenger miles', just taking the 'average passenger weight' to derive the same figures from that, if you want to display it along-side. Though I'd almost want a sliding comparison for 'empty' through 'full' capacity, and the ability to override the default 'average passenger weight' and 'maximum passenger' figures. Not that this scales particularly well, since many modes of transport have more cargo capacity than people-carrying seats. Many passenger aircraft/trains/vehicles also carry cargo, muddying the water even further. The same model of aircraft will carry different ratios of passengers and cargo, according to how an airline configures it.

With due respect you make a confusion on the subject. If we're talking about mobility of passengers, the relevant metric is (again in SI) Joule/(pax.km) and for cargo Joule/(kg.m). Every other conversion will only provide more mess. João Pimentel Ferreira (talk) 18:04, 7 January 2019 (UTC)

If someone feels like building a spreadsheet and converting all of this... 'random stuff' into something consistent, it would be a great service to humanity. I wonder if 'Google Docs' would be OK for that, and if Google provides (or could provide) a standard 'Wikipedia-friendly' shared account for such work?

Yeah, we're not supposed to publish 'new research', but posting the math and data sources behind these tables together and letting the community check it for errors would be awfully nice. The same spreadsheet could probably extract the approximate 'carbon footprint' based on what the various fuels break down into, for other Wikipedia articles.

Then you could compare walking, e-bike, ship, airplane, 'BFR', etc. Someone could probably estimate the 'carbon footprint' from the various modes of transportation from the efficiency and kinds of fuel, too.

Believe me, it was much worse before. I made that table on the beginning trying to solve exactly that problem that you mentioned of the spreadsheet, making it universally comparable, in terms of average vehicle capacity and SI units. The math behind is from Wolfram Alpha, and the equations are there with sources to WA, but I'm not sure that everyone of them is correct, but you're welcomed to correct them if you spot an error. I insistently asked Ita140188 to provide me figures for the airplane, since I even had designed a chart, but he didn't even provide me any reliable source for the airplane average capacity and deleted the chart with no debate, violating WP:TALKFIRST, just because on the figure an old Boing 727 airplane was showed (note that I agree that is misleading, but deleting a whole chart is too much). João Pimentel Ferreira (talk) 18:04, 7 January 2019 (UTC)

Though obviously electrical power is all over the place, all by its self. Renewable, coal, hydro, nuclear, etc. may all be coming out of the same plug, according to where you are, and everything consumes/wastes different amounts of energy to push those electrons around. Which also brings 'commodity' fuels into question, since running a particular kind of vehicle off one particular kind of fuel could be as bad as running it off 'diamonds', if extracting cost/mile from the data. — Preceding unsigned comment added by 50.38.66.216 (talk) 23:44, 12 December 2018 (UTC)

As said before, that may be relevant but only as a subtopic, as it goes beyond the core of the vehicle locomotion per se. Regards. João Pimentel Ferreira (talk) 18:04, 7 January 2019 (UTC)
As you mentioned, this is not what Wikipedia is supposed to do, per WP:OR. I agree the article is a mess, but what's needed is to find a reliable source that already did this job and rewrite the article based on that. --Ita140188 (talk) 11:35, 13 December 2018 (UTC)

VW Bluemotion and Seat Ibiza not the most efficient car in the UK in, before, or after 2008!

The Volkswagen Polo 1.4 TDI Bluemotion and Seat Ibiza were not and are not the most efficient common-fuel car available in the UK, not in 2008, not before, and not after. That title belongs to all three generations of the Cdi diesel version of the Smart Fortwo (generation 1: 1998–2007, generation 2: 2007–2014, generation 3: 2014–present). All three generations are equipped with a Mercedes-Benz OM660 engine, bringing consumption down to 3.3 liters per 100 km, and a world record in lowest CO2 emissions. The claim in the article may read "petroleum-based", but diesel is one petroleum product among others. Source both for the low consumption as well as its availability in the UK: [2], source for record low CO2 emission: [3]. --2003:EF:13C6:DC91:38DF:CA22:4A7A:E40D (talk) 07:23, 22 May 2019 (UTC)

Why no infrastructure costs ?

I can't find any figures for rail electrification on the internet. -- John (Daytona2 · Talk · Contribs) 11:52, 4 April 2021 (UTC)

Occupancy rates are wrong, variable, and thus should not be factored into efficiency ratings.

While adding the Aptera solar EV to the table in section, "Land Passenger Transport means", I found a data discrepancy. The car passenger occupancy is listed as 1.2 passengers per car, but the reference shows 1.55 as the mean number of passengers per car. The link above for European countries shows numbers between 1.2 and 2.0. That reference points to a newer EU reference (https://www.eea.europa.eu/data-and-maps/indicators/occupancy-rates-of-passenger-vehicles/occupancy-rates-of-passenger-vehicles) showing the occupancy hovering around 1.45. Fixing this correctly requires recalculating the (m pax)/J and the J/(m pax) table columns. In my opinion, the passenger efficiency should be the maximum rather than the "mean" efficiency, so the number of passenger seats should be used for each vehicle. That would be a more well defined number not subject to changes in social driving habits. What do you think? Fotoguru (talk) 03:19, 17 November 2021 (UTC)

The comparison between bicycles and electric bicycles is flawed

As far as I can tell, the figures for electric bicycles do not include the energy used by the rider and thus does not include the total amount of energy consumed to propel the e-bike. Therefore the figures shown for e-bikes are dubious. BirdValiant (talk) 21:04, 30 June 2022 (UTC)

Confusing explanation for efficiency of trains

The article states “ Trains are in general one of the most efficient means of transport for freight and passengers. An inherent efficiency advantage is the low friction of steel wheels on steel rails compared especially to rubber tires on asphalt ”. This seems wrong to me.

The friction that matters for wheel efficiency is the friction in the bearings, not between the wheel and the ground.

One potential explanation for why trains are so efficient is their small cross sectional area in the direction of travel relative to their volume, reducing the importance of wind resistance. Gabcoh (talk) 03:14, 8 September 2022 (UTC)

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