Energy efficiency in transport

Template:Transport The energy efficiency in transport is the useful travelled distance, of passengers, goods or any type of load; divided by the total energy put into the transport propulsion means. The energy input might be rendered in several different types depending on the type of propulsion, and normally such energy is presented in liquid fuels, electrical energy or food energy.<ref>"Efficiency". Retrieved 18 September 2016.</ref><ref name="fueleco">Assessment of Fuel Economy Technologies for Light-duty Vehicles. The National Academies Press. 2011. doi:10.17226/12924. ISBN 978-0-309-15607-3. Retrieved 18 September 2016.</ref> The energy efficiency is also occasionally known as energy intensity.<ref name="DOEgloss">"Glossary of energy-related terms". U.S. Department of Energy. Retrieved 20 September 2016.</ref> The inverse of the energy efficiency in transport is the energy consumption in transport.

Energy efficiency in transport is often described in terms of fuel consumption, fuel consumption being the reciprocal of fuel economy.<ref name=fueleco/> Nonetheless, fuel consumption is linked with a means of propulsion which uses liquid fuels, whilst energy efficiency is applicable to any sort of propulsion. To avoid said confusion, and to be able to compare the energy efficiency in any type of vehicle, experts tend to measure the energy in the International System of Units, i.e., joules.

Therefore, in the International System of Units, the energy efficiency in transport is measured in terms of metre per joule, or m/J, while the energy consumption in transport is measured in terms of joules per metre, or J/m. The more efficient the vehicle, the more metres it covers with one joule (more efficiency), or the fewer joules it uses to travel over one metre (less consumption). The energy efficiency in transport largely varies by means of transport. Different types of transport range from some hundred kilojoules per kilometre (kJ/km) for a bicycle to tens of megajoules per kilometre (MJ/km) for a helicopter.

Via type of fuel used and rate of fuel consumption, energy efficiency is also often related to operating cost ($/km) and environmental emissions (e.g. CO₂/km).

Units of measurement

In the International System of Units, the energy efficiency in transport is measured in terms of metre per joule, or m/J. Nonetheless, several conversions are applicable, depending on the unit of distance and on the unit of energy. For liquid fuels, normally the quantity of energy input is measured in terms of the liquid's volume, such as litres or gallons. For propulsion which runs on electricity, normally kWh is used, while for any type of human-propelled vehicle, the energy input is measured in terms of Calories. It is typical to convert between different types of energy and units.

For passenger transport, the energy efficiency is normally measured in terms of passengers times distance per unit of energy, in the SI, passengers metres per joule (pax.m/J); while for cargo transport the energy efficiency is normally measured in terms of the mass of transported cargo times distance per unit of energy, in the SI, kilograms metres per joule (kg.m/J). Volumetric efficiency with respect to vehicle capacity may also be reported, such as passenger-mile per gallon (PMPG),<ref>"US Railroad Passenger Miles Per Gallon". Archived from the original on 15 March 2007. Retrieved 2 May 2007.</ref> obtained by multiplying the miles per gallon of fuel by either the passenger capacity or the average occupancy.<ref>"Example calculations (Colorado State Exam)". Archived from the original on 10 September 2006. Retrieved 2 May 2007.</ref> The occupancy of personal vehicles is typically lower than capacity by a considerable degree<ref>"Vehicle Occupancy per Vehicle Mile by Daily Trip Purpose". Retrieved 2 May 2007.</ref><ref>"Vehicle Occupancy Per Vehicle Mile by Time of Day and Weekend Status". Archived from the original on 4 June 2007. Retrieved 2 May 2007.</ref> and thus the values computed based on capacity and on occupancy will often be quite different.

Typical conversions into SI unit

	Joules
litre of petrol	0.3x10⁸
US gallon of petrol (gasoline)<ref name=":0">"Energy Content of Fuels (in joules)" (PDF).</ref>	1.3x10⁸
Imp. gallon of petrol (gasoline)	1.6x10⁸
kilocalorie<ref>"Calories – Joules units conversion". unitsconversion.com.ar. Retrieved 24 June 2017.</ref><ref>"Energy Units". aps.org. Retrieved 24 June 2017.</ref>	4.2x10³
kWh<ref name=":0" />	3.6x10⁶
BTU<ref name=":0" />	1.1x10³

Liquid fuels

Energy efficiency is expressed in terms of fuel economy:<ref name=fueleco/>

distance per vehicle per unit fuel volume; e.g., km/L or miles per gallon (US or imperial).
distance per vehicle per unit fuel mass; e.g., km/kg.<ref>Aeroplane Efficiency, Fédération Aéronautique Internationale, "FAI – The World Air Sports Federation"</ref>
distance per vehicle per unit energy; e.g., miles per gallon equivalent (mpg-e).

Energy consumption (reciprocal efficiency)<ref name=DOEgloss/> is expressed terms of fuel consumption:<ref name=fueleco/>

volume of fuel (or total energy) consumed per unit distance per vehicle; e.g. l/100 km or MJ/100 km.
volume of fuel (or total energy) consumed per unit distance per passenger; e.g., l/(100 passenger·km).
volume of fuel (or total energy) consumed per unit distance per unit mass of cargo transported; e.g., l/100 kg·km or MJ/t·km.

Electricity

Electricity consumption:

electrical energy used per vehicle per unit distance; e.g., kWh/100 km.

Producing electricity from fuel requires much more primary energy than the amount of electricity produced.

Food energy

Energy consumption:

calories burnt by the body's metabolism per kilometre; e.g., Cal/km.
calories burnt by the body's metabolism per mile; e.g., Cal/miles.<ref>"Calories Burned Calculator". Runner's World. 5 August 2016. Retrieved 23 June 2017.</ref>

Land Passenger Transport

Table Overview

In the following table the energy efficiency and energy consumption for different types of passenger land vehicles and modes of transport, as well as standard occupancy rates, are presented. The sources for these figures are in the correspondent section for each vehicle, in the following article. The conversions amongst different types of units, are well known in the art.

For the conversion amongst units of energy in the following table, 1 litre of petrol amounts to 34.2 MJ, 1 kWh amounts to 3.6 MJ and 1 kilocalorie amounts to 4184 J. For the car occupation ratio, the value of 1.2 passengers per automobile<ref name=":1">"Average Vehicle Occupancy by Mode and Purpose". nhts.ornl.gov. Retrieved 8 June 2018.</ref> was considered. Nonetheless, in Europe this value slightly increases to 1.4.<ref>"Occupancy rates of passenger vehicles". European Environment Agency. Retrieved 8 June 2018.</ref> The sources for conversions amongst units of measurements appear only of the first row.

Energy Efficiency and Consumption of Land Passenger Transport means
Mode of transport	Energy Efficiency					Energy consumption					Average number of passengers per vehicle	Energy Efficiency	Energy consumption
Mode of transport	mpg(US) of petrol	mpg(imp) of petrol	km/L of petrol	km/MJ	m/J	L(petrol)/ 100 km	kWh/100 km	kCal/km	MJ/100 km	J/m	Average number of passengers per vehicle	(m·pax)/J	J/(m·pax)
Human propelled
Walking				4.55<ref name="brianmac" />	Alpha"]. wolframalpha.com. Retrieved 17 June 2018.</ref>		6.11	52.58<ref>"Convert kWh/100km to kilocalorie per km – Wolfram Alpha". wolframalpha.com. Retrieved 17 June 2018.</ref>	Alpha"]. wolframalpha.com. Retrieved 17 June 2018.</ref>	Alpha"]. wolframalpha.com. Retrieved 17 June 2018.</ref>	1.0	0.00455	220
Velomobile with enclosed recumbent<ref name=":17" />				12.35	0.01235		2.25<ref name=":17" /> (0.50<ref name=":2">"The velomobile: high-tech bike or low-tech car?".</ref><ref name=":3">"Waw:: a practical sports car :: – mobilitylab.be".</ref>)	19.35	8.1	81	1.0	0.01235	81
Bicycle							0.6 <ref> "Energy Efficient Travel: Nothing Beats the Bike". Retrieved 10 February 2024.</ref> (3.1<ref name="brianmac" /> )	27<ref name="brianmac" />	11<ref name="brianmac" />
Motor assist
Electric bicycle				23.21	0.02321		1.2 <ref>"A Study on electric bicycle energy efficiency". Transport Problems. 10 (3): 131–140. doi:10.21307/tp-2015-041.</ref><ref>"Electric Bikes: Survey and Energy Efficiency Analysis" (PDF). Retrieved 23 November 2020.</ref>	10.33	4.3	43	1.0	0.02321	43
Electric kick scooter				24.87	0.02487		1.12<ref name="Xiaomi M365">"Mi Electric Scooter (M365)". Xiaomi. Retrieved 19 September 2018. Power required for a single full charge (0.335kWh) ÷ typical mileage (30km)</ref>	9.61	4.00	40	1.0	0.02487	40
Automobile
Solar Car				14.93	0.01493		1.86<ref name=":4" />	16.01	6.70	67	1.0	0.01493	67
GEM NER				2.65	0.00265		10.50	90.34	37.80	378	1.2<ref name=":1" />	0.00317	315
General Motors EV1				1.21	0.00121		23.00<ref name=":5" />	197.90	82.80	828	1.2<ref name=":1" />	0.00145	690
Chevrolet Volt	99.31	119.27	42.22	1.23	0.00123	2.37	22.50<ref name=":5" />	193.59	81.00	810	1.2<ref name=":1" />	0.00148	675
Daihatsu Charade	83.80	100.63	35.63	1.04	0.00104	2.81	26.67	229.45	96.00	960	1.2<ref name=":1" />	0.00125	800
Volkswagen Polo	61.88	74.31	26.31	0.77	0.00077	3.80<ref name=":6" />	38<ref name=":16">"Energy related conversion factors, page 21" (PDF). 28 July 2023.</ref>	326.97	136.8	1368	1.2<ref name=":1" />	0.00087	1140
SEAT Ibiza 1.4 TDI Ecomotion	61.88	74.31	26.31	0.77	0.00077	3.80<ref name=":7" />	38<ref name=":16" />	326.97	136.8	1368	1.2<ref name=":1" />	0.00087	1140
Renault Clio	33.60	40.32	13.91	0.42	0.00042	7<ref>"Average fuel consumption Spritmonitor.de". Retrieved 24 November 2020.</ref>	66.5	572.18	239.4	2394	1.2<ref name=":1" />	0.00049	1995
Volkswagen Passat	26.76	32.11	11.37	0.33	0.00033	8.79<ref>"Average fuel consumption Spritmonitor.de". Retrieved 23 November 2020.</ref>	83.51	718.53	300.63	3006	1.2<ref name=":1" />	0.00039	2505
Cadillac CTS-V	13.82<ref name="epa2012" />	16.60	5.88	0.17	0.00017	17.02	161.67	1391.01	582.00	5820	1.2<ref name=":1" />	0.00021	4850
Bugatti Veyron	9.79<ref name="epa2012" />	11.75	4.16	0.12	0.00012	24.04	228.33	1964.63	822.00	8220	1.2<ref name=":1" />	0.00015	6850
Nissan Leaf				1.49	0.00149		18.64<ref name=":8" />	160.37	67.10	671	1.2<ref name=":1" />	0.00179	559
Toyota Prius	56.06	67.32	23.83	0.70	0.00070	4.20	39.86<ref name=":9" />	342.97	143.50	1435	1.2<ref name=":1" />	0.00084	1196
Tesla Model S				1.61	0.00161		Tesla"]. forums.tesla.com. Archived from the original on 12 June 2018. Retrieved 8 June 2018.</ref>	148.42	62.10	621	1.2<ref name=":1" />	0.00193	517
Tesla Model 3				1.76	0.00176		15<ref>"2020 Tesla model 3". EPA. Retrieved 23 November 2020.</ref>	129.06	54	540	1.2<ref name=":1" />	0.00222	450
Aptera 2 Series	423	507.99	179.82	5.28	0.00528	0.53	5<ref>Aptera CEO Steve Fambro, archived from the original on 15 December 2021, retrieved 27 June 2021</ref>	43	18	180	1.2<ref name=":1" />	0.00666	150
Aptera solar EV				4.5	0.0045		6.2<ref>Voelcker, John (28 August 2019). "Exclusive: 3-Wheeled Aptera Reboots as World's Most Efficient Electric Car". IEEE Spectrum. IEEE. Retrieved 15 November 2021.</ref><ref>"Electric car that does not need charging: Aptera EV claims 1,600-km total range! Launch in 2021". The Financial Express. 7 December 2020. Retrieved 27 June 2021.</ref>	52.56	22	220
Buses
MCI 102DL3	6.03<ref name=":10" />	7.24	2.56	0.07	0.00007	39.04	370.83	3190.73	1335.00	13350	11.0<ref name=":11" />	0.00082	1214
Proterra Catalyst 40' E2				0.23<ref name=proterra-catalyst>"CATALYST : 40 FOOT BUS PERFORMANCE SPECIFICATIONS" (PDF). Proterra, Inc. June 2019. Retrieved 17 April 2020.</ref><ref group=note>The range used is the midpoint of the effective operating range.</ref>	0.00023		121.54	1044.20	437.60	4376	11.0<ref name=":11" />	0.00319	313
Trains
Urban rail												0.00231	432<ref name=UITP>"Energy Efficiency – Contribution of Urban Rail Systems" (PDF). Union internationale des transports publics. Retrieved 12 June 2018.</ref>
CR400AF (cn)											~65%<ref>Liu, Fanxiao; Sun, Zhanbo; Zhang, Peitong; Peng, Qiyuan; Qiao, Qingjie (2 September 2018). "Analyzing Capacity Utilization and Travel Patterns of Chinese High-Speed Trains: An Exploratory Data Mining Approach". Journal of Advanced Transportation. 2018: e3985302. doi:10.1155/2018/3985302. ISSN 0197-6729.</ref>	0.00475	210 at 350km/h<ref>"China's latest high-speed train consumes only 3.8 KWh per 100 passenger-km - People's Daily Online". en.people.cn. Retrieved 4 May 2022.</ref>
JR East (jp)											~	0.01091	92<ref name=":12" />
CP-Lisbon (pt)											27.7%<ref>Relatório & Contas da CP; página 16; 2012</ref>	0.01304
Basel (ch)											~50.0%<ref name=":15">"Occupancy rates". European Environment Agency. Retrieved 19 June 2018.</ref>	0.00215	465<ref name=":14" />

Land transport means

Walking

A 68 kg (150 lb) person walking at 4 km/h (2.5 mph) requires approximately 210 kilocalories (880 kJ) of food energy per hour, which is equivalent to 4.55 km/MJ.<ref name="brianmac">Mackenzie, Brian. "Energy expenditure for walking and running". Archived from the original on 23 February 2007. Retrieved 4 March 2007.</ref> 1 US gal (3.8 L) of petrol contains about 114,000 British thermal units (120 MJ)<ref name="EPA">EPA (2007). "Appendix B, Transportation Energy Data Book". Retrieved 16 November 2010.</ref> of energy, so this is approximately equivalent to 360 miles per US gallon (0.65 L/100 km).

Velomobile

Velomobiles (enclosed recumbent bicycles) have the highest energy efficiency of any known mode of personal transport because of their small frontal area and aerodynamic shape. At a speed of 50 km/h (31 mph), the velomobile manufacturer WAW claims that only 0.5 kWh (1.8 MJ) of energy per 100 km is needed to transport the passenger (= 18 J/m). This is around 1⁄5 (20%) of what is needed to power a standard upright bicycle without aerodynamic cladding at same speed, and 1⁄50 (2%) of that which is consumed by an average fossil fuel or electric car (the velomobile efficiency corresponds to 4700 miles per US gallon, 2000 km/L, or 0.05 L/100 km).<ref name=":3" /> Real energy from food used by human is 4–5 times more.<ref name=":17">"How to Convert Watts to Calories Burned While Cycling – Gear & Grit". Gear & Grit. 6 January 2017. Retrieved 27 November 2018.</ref> Unfortunately their energy efficiency advantage over bicycles becomes smaller with decreasing speed and disappears at around 10 km/h where power needed for velomobiles and triathlon bikes are almost the same.<ref name=":22">"Power vs speed calculator".</ref>

Bicycle

A standard lightweight, moderate-speed bicycle is one of the most energy-efficient forms of transport. Compared with walking, a 64 kg (140 lb) cyclist riding at 16 km/h (10 mph) requires about half the food energy per unit distance: 27 kcal/km, 3.1 kWh (11 MJ) per 100 km, or 43 kcal/mi.<ref name=brianmac /> This converts to about 732 mpg_‑US (0.321 L/100 km; 879 mpg_‑imp).<ref name="Wolfram Alpha">"Calculation of conversion from dietary calories per mile to miles per gallon gasoline, using the energy density of gasoline listed by Wolfram Alpha". 2011. Retrieved 19 July 2011.</ref> This means that a bicycle will use between 10 and 25 times less energy per distance travelled than a personal car, depending on fuel source and size of the car. This figure does depend on the speed and mass of the rider: greater speeds give higher air drag and heavier riders consume more energy per unit distance. In addition, because bicycles are very lightweight (usually between 7–15 kg) this means they consume very low amounts of materials and energy to manufacture. In comparison to an automobile weighing 1500 kg or more, a bicycle typically requires 100–200 times less energy to produce than an automobile. In addition, bicycles require less space both to park and to operate and they damage road surfaces less, adding an infrastructural factor of efficiency.

Motorised bicycle

A motorised bicycle allows human power and the assistance of a 49 cm³ (3.0 cu in) engine, giving a range of 160 to 200 mpg_‑US (1.5–1.2 L/100 km; 190–240 mpg_‑imp).^{[citation needed]} Electric pedal-assisted bikes run on as little as 1.0 kWh (3.6 MJ) per 100 km,<ref>Lemire-Elmore, Justin (13 April 2004). "The Energy Cost of Electric and Human-Powered Bicycles" (PDF). ebikes.ca.</ref> while maintaining speeds in excess of 30 km/h (19 mph).^{[citation needed]} These best-case figures rely on a human doing 70% of the work, with around 3.6 MJ (1.0 kWh) per 100 km coming from the motor. This makes an electric bicycle one of the most efficient possible motorised vehicles, behind only a motorised velomobile and an electric unicycle (EUC).

Electric kick scooter

Electric kick scooters, such as those used by scooter-sharing systems like Bird or Lime, typically have a maximum range of under 30 km (19 mi) and are commonly limited to a maximum speed of 25 km/h (15.5 mph).<ref name="Xiaomi M365"/> Intended to fit into a last mile niche and be ridden in bike lanes, they require little skill from the rider. Because of their light weight and small motors, they are extremely energy-efficient with a typical energy efficiency of 1.1 kWh (4.0 MJ) per 100 km<ref>"Mi Global Home".</ref> (1904 MPGe 810 km/L 0.124 L/100 km), even more efficient than bicycles and walking. However, as they must be recharged frequently, they are often collected overnight with motor vehicles, somewhat negating this efficiency. The lifecycle of electric scooters is also notably shorter than that of bicycles, often reaching only a single digit number of years.

Electric Unicycle

An electric unicycle (EUC) cross electric skateboard variant called the Onewheel Pint can carry a 50 kg person 21.5 km at an average speed of 20 km/h. The battery holds 148Wh. Without taking energy lost to heat in the charging stage into account, this equates to an efficiency of 6.88Wh/km or 0.688kWh/100 km.^{[citation needed]} Additionally, with regenerative braking as a standard design feature, hilly terrain would have less impact on an EUC compared to a vehicle with friction brakes such as a push bike. This combined with the single wheel ground interaction may make the EUC the most efficient known vehicle at low speeds (below 25 km/h), with the velomobile overtaking the position as most efficient at higher speeds due to superior aerodynamics.

Automobiles

Automobiles are generally inefficient when compared to other modes of transport, due to the relatively high weight of the vehicle compared to its occupants. On a percentage basis, if there is one occupant in an automobile, only about 0.5% of the total energy used is used to move the person in the car, while the remaining 99.5% (about 200 times more) is used to move the car itself.

An important driver of energy consumption of cars per passenger is the occupancy rate of the vehicle. Although the consumption per unit distance per vehicle increases with increasing number of passengers, this increase is slight compared to the reduction in consumption per unit distance per passenger. This means that higher occupancy yields higher energy efficiency per passenger. Automobile occupancy varies across regions. For example, the estimated average occupancy rate is about 1.3 passengers per car in the San Francisco Bay Area,<ref>Maps and Data Archived 12 June 2007 at the Wayback Machine – Metropolitan Transportation Commission for the nine-county San Francisco Bay Area, California</ref> while the 2006 UK estimated average is 1.58.<ref name="ukdft_carocc">"Transport trends: current edition". UK Department for Transport. 8 January 2008. Archived from the original on 22 April 2008. Retrieved 23 March 2008.</ref>

Due to the efficiency of electric motors, electric cars are much more efficient than their internal combustion engine counterparts, consuming on the order of 38 megajoules (38 000 kJ) per 100 km in comparison to 142 megajoules per 100 km for combustion powered cars.<ref>"How green are electric cars?". TheGuardian.com.</ref> However, depending on the way the electricity is generated, the actual primary energy use may be higher.

Driving practices and vehicles can be modified to improve their energy efficiency by about 15%.<ref name="Beusen">Beusen; et al. (2009). "Using on-board logging devices to study the long-term impact of an eco-driving course". Transportation Research D. 14 (7): 514–520. doi:10.1016/j.trd.2009.05.009.</ref><ref name="transport">"Do lower speed limits on motorways reduce fuel consumption and pollutant emissions?". Retrieved 12 August 2013.</ref>

Common efficiency measures

Automobile fuel efficiency is most commonly expressed in terms of the volume of fuel consumed per one hundred kilometres (l/100 km), but in some countries (including the United States, the United Kingdom and India) it is more commonly expressed in terms of the distance per volume fuel consumed (km/L or miles per gallon). This is complicated by the different energy content of fuels such as petrol and diesel. The Oak Ridge National Laboratory (ORNL) states that the energy content of unleaded petrol is 115,000 British thermal unit (BTU) per US gallon (32 MJ/L) compared to 130,500 BTU per US gallon (36.4 MJ/L) for diesel.<ref>"Oak Ridge National Laboratory (ORNL)". Archived from the original on 27 September 2011.</ref>

Life-cycle energy use

Automobiles have significant energy use in their life cycle, not directly attributable to the running of the vehicle. An important consideration is the energy costs of producing the energy form used by the automobile. Bio-fuels, electricity and hydrogen, for instance, have significant energy inputs in their production. Hydrogen production efficiency are 50–70% when produced from natural gas, and 10–15% from electricity.^{[citation needed]} The efficiency of hydrogen production, as well as the energy required to store and transport hydrogen, must to be combined with the vehicle efficiency to yield net efficiency.<ref name="eere">"Vehicle Technologies Office – Department of Energy" (PDF).</ref> Because of this, hydrogen automobiles are one of the least efficient means of passenger transport, generally around 50 times as much energy must be put into the production of hydrogen compared to how much is used to move the car.^{[citation needed]}

Another important factor is the energy needed to build and maintain roads is an important consideration, as is the energy returned on energy invested (EROEI). Between these two factors, roughly 20% must be added to the energy of the fuel consumed, to accurately account for the total energy used.^{[citation needed]}

Finally, vehicle energy efficiency calculations would be misleading without factoring the energy cost of producing the vehicle itself. This initial energy cost can of course be depreciated over the life of the vehicle to calculate an average energy efficiency over its effective life span. In other words, vehicles that take a lot of energy to produce and are used for relatively short periods will require a great deal more energy over their effective lifespan than those that do not, and are therefore much less energy efficient than they may otherwise seem. Hybrid and electric cars use less energy in their operation than comparable petroleum-fuelled cars but more energy is used to manufacture them, so the overall difference would be less than immediately apparent. Compare, for example, walking, which requires no special equipment at all, and an automobile, produced in and shipped from another country, and made from parts manufactured around the world from raw materials and minerals mined and processed elsewhere again, and used for a limited number of years. According to the French energy and environment agency ADEME,<ref>(fr) Life cycle assessment website www.ademe.fr see page 9</ref> an average motor car has an embodied energy content of 20,800 kWh and an average electric vehicle amounts to 34,700 kWh. The electric car requires nearly twice as much energy to produce, primarily due to the large amount of mining and purification necessary for the rare earth metals and other materials used in lithium-ion batteries and in the electric drive motors. This represents a significant portion of the energy used over the life of the car (in some cases nearly as much as energy that is used through the fuel that is consumed, effectively doubling the car's per-distance energy consumption), and cannot be ignored when comparing automobiles to other transport modes. As these are average numbers for French automobiles and they are likely to be significantly larger in more auto-centric countries like the United States and Canada, where much larger and heavier cars are more common. The usage of private vehicles can be significantly decreased and can help to promote sustainable urban growth if more appealing non-motorized transportation options are developed, as well as more comfortable public transportation environments.<ref>Poudenx, Pascal (2008). "The effect of transportation policies on energy consumption and greenhouse gas emission from urban passenger transportation". Transportation Research Part A: Policy and Practice. 42 (6): 901–909. doi:10.1016/j.tra.2008.01.013.</ref>

Example consumption figures

Solar cars are electric vehicles that use little or no externally supplied energy other than from sunlight, charging the batteries from built-in solar panels, and typically use less than 3 kWh per 100 miles (67 kJ/km or 1.86 kWh/100 km). Most of these cars are race cars designed for competition and not for passenger or utility use.<ref name=":4">Squatriglia, Chuck (27 February 2009). "MIT Unveils 90 MPH Solar Race Car". Wired.</ref> However several companies are designing solar cars for public use. As of December 2021, none have yet been released.
The four passenger GEM NEV uses 169 Wh/mi (199 mpg‑e; 10.5 kW⋅h/100 km),<ref name=":5">"Vehicle Technologies Office – Department of Energy" (PDF).</ref> which equates to 2.6 kWh/100 km per person when fully occupied, albeit at only 24 mph (39 km/h).
The General Motors EV1 was rated in a test with a charging efficiency of 373 Wh-AC/mile or 23 kWh/100 km<ref>"Vehicle Technologies Office – Department of Energy" (PDF).</ref> approximately equivalent to 2.6 L/100 km (110 mpg_‑imp; 90 mpg_‑US) for petroleum-fuelled vehicles.
Chevrolet Volt in full electric mode uses 36 kilowatt-hours per 100 miles (810 kJ/km; 94 mpg‑e), meaning it may approach or exceed the energy efficiency of walking if the car is fully occupied with 4 or more passengers, although the relative emissions produced may not follow the same trends if analysing environmental impacts.
The Daihatsu Charade 993cc turbo diesel (1987–1993) won the most fuel efficient vehicle award for going round the United Kingdom consuming an average of 2.82 L/100 km (100 mpg_‑imp). It was surpassed only recently by the VW Lupo 3 L which consumes about 2.77 L/100 km (102 mpg_‑imp). Both cars are rare to find on the popular market. The Daihatsu had major problems with rust and structural safety which contributes to its rarity and the quite short production run.
The Volkswagen Polo 1.4 TDI Bluemotion and the SEAT Ibiza 1.4 TDI Ecomotion, both rated at 3.8 L/100 km (74 mpg_‑imp; 62 mpg_‑US) (combined) were the most fuel efficient petroleum-fuelled cars on sale in the UK as of 22 March 2008.<ref>"Best on CO₂ rankings". UK Department for Transport. Archived from the original on 12 March 2008. Retrieved 22 March 2008.</ref><ref name=":6">"Vehicle details for Polo 3 / 5 Door (from 6 Nov Wk 45>) 1.4 TDI (80PS) (without A/C) with DPF BLUEMOTION M5". UK Vehicle Certification Agency. Archived from the original on 10 February 2009. Retrieved 22 March 2008.</ref><ref name=":7">"Vehicle details for Ibiza ( from 6 NOV Wk 45 > ) 1.4 TDI 80PS Ecomotion M5". UK Vehicle Certification Agency. Archived from the original on 10 February 2009. Retrieved 22 March 2008.</ref>^{[needs update]}
Honda Insight – achieves 60 mpg_‑US (3.9 L/100 km; 72 mpg_‑imp) under real-world conditions.<ref name="NYT2">Jerry Garrett (27 August 2006). "The Once and Future Mileage King". The New York Times.</ref>
Honda Civic Hybrid regularly averages around 45 mpg_‑US (5.2 L/100 km; 54 mpg_‑imp).
2012 Cadillac CTS-V Wagon 6.2 L Supercharged, 14 mpg_‑US (17 L/100 km; 17 mpg_‑imp)<ref name="epa2012">"2016 Best and Worst Fuel Economy Vehicles".</ref>
2012 Bugatti Veyron, 10 mpg_‑US (24 L/100 km; 12 mpg_‑imp)<ref name="epa2012" />
2018 Honda Civic: 36 mpg_‑US (6.5 L/100 km; 43 mpg_‑imp)<ref>"2017 Honda Civic 4DR". EPA. Retrieved 24 May 2018.</ref>
2017 Mitsubishi Mirage: 39 mpg_‑US (6.0 L/100 km; 47 mpg_‑imp)<ref>"2017 Mitsubishi mirage". EPA. Retrieved 24 May 2018.</ref>
2017 Hyundai Ioniq hybrid: 55 mpg_‑US (4.3 L/100 km; 66 mpg_‑imp)<ref>"2017 Hyundai Ioniq". EPA. Retrieved 23 May 2018.</ref>
2017 Toyota Prius: 56 mpg_‑US (4.2 L/100 km; 67 mpg_‑imp) (Eco trim)<ref name=":9">"2017 Toyota Prius Eco". EPA. Retrieved 23 May 2018.</ref>
2018 Nissan Leaf: 30 kWh (110 MJ)/100 mi (671 kJ/km) or 112 MPGe<ref name=":8">"2018 Nissan Leaf". EPA. Retrieved 23 May 2018.</ref>
2017 Hyundai Ioniq EV: 25 kWh (90 MJ)/100 mi (560 kJ/km) or 136 MPGe<ref>"2017 Hyundai Ioniq Electric". EPA. Retrieved 23 May 2018.</ref>
2020 Tesla model 3: 24 kWh (86.4 MJ)/100 mi (540 kJ/km) or 141 MPGe<ref>"2020 Tesla Model 3 Standard Range Plus". www.fueleconomy.gov. Retrieved 23 November 2020.</ref>

Trains

Trains are in general one of the most efficient means of transport for freight and passengers. Advantages of trains include low friction of steel wheels on steel rails, as well as an intrinsic high occupancy rate. Train lines are typically used to serve urban or inter-urban transit applications where their capacity utilization is maximized.

Efficiency varies significantly with passenger loads, and losses incurred in electricity generation and supply (for electrified systems),<ref>"Fuel-Efficiency of Travel in the 20th Century: Appendix-Notes". Archived from the original on 7 June 2004.</ref><ref>"Fuel-Efficiency of Travel in the 20th Century: Appendix-Notes". 6 October 2003. Archived from the original on 6 October 2003. Retrieved 27 November 2021.</ref> and, importantly, end-to-end delivery, where stations are not the originating final destinations of a journey. While electric motors used in most passenger trains are more efficient than internal combustion engines,<ref>"Electric Car Myth Buster — Efficiency". CleanTechnica. 10 March 2018. Retrieved 27 November 2021.</ref> power generation in thermal power plants is limited to (at best) Carnot efficiency<ref>"What is Carnot Efficiency – Efficiency of Carnot Heat Engine – Definition". Thermal Engineering. 22 May 2019. Retrieved 27 November 2021.</ref> and there are transmission losses on the way from the power plant to the train.<ref>Portal, EEP-Electrical Engineering (19 August 2013). "Total Losses in Power Distribution and Transmission Lines | EEP". EEP – Electrical Engineering Portal. Retrieved 27 November 2021.</ref> Switzerland, which has electrified virtually its entire railway network (heritage railways like the Dampfbahn Furka-Bergstrecke being notable exceptions), derives much of the electricity used by trains from hydropower, including pumped hydro storage.<ref>"Energy efficiency | SBB". Company.sbb.ch. Retrieved 27 November 2021.</ref> While the mechanical efficiency of the turbines involved is comparatively high, pumped hydro involves energy losses and is only cost effective as it can consume energy during times of excess production (leading to low or even negative spot prices) and release the energy again during high-demand times.<ref name="EconomistPSH">"Energy storage – Packing some power". The Economist. 3 March 2011. Retrieved 11 March 2012.</ref><ref name="thier">Jacob, Thierry. "Pumped storage in Switzerland - an outlook beyond 2000" (PDF). www.stucky.ch. Archived from the original (PDF) on 7 July 2011. Retrieved 13 February 2012.</ref><ref name="Levine">Levine, Jonah G. (December 2007). "Pumped Hydroelectric Energy Storage and Spatial Diversity of Wind Resources as Methods of Improving Utilization of Renewable Energy Sources" (PDF). University of Colorado. p. 6. Archived from the original (PDF) on 1 August 2014. Retrieved 12 February 2012.</ref><ref name="yang">Yang, Chi-Jen. Pumped Hydroelectric Storage Duke University. Accessed: 12 February 2012.</ref> with some sources claiming up to 87%.<ref name="heco">"Energy Storage". Archived from the original on 18 November 2015. Retrieved 26 February 2017.</ref>

Actual consumption depends on gradients, maximum speeds, and loading and stopping patterns. Data produced for the European MEET project (Methodologies for Estimating Air Pollutant Emissions) illustrate the different consumption patterns over several track sections. The results show the consumption for a German ICE high-speed train varied from around 19 to 33 kW⋅h/km (68–119 MJ/km; 31–53 kW⋅h/mi). The Siemens Velaro D type ICE trains seat 460 (16 of which in the restaurant car) in their 200-meter length edition of which two can be coupled together.<ref>Fact Sheet: Velaro D – Neuer ICE 3 (Baureihe 407) [Fact Sheet: Velaro D – New ICE 3 (407 series)] (PDF) (Report) (in Deutsch). Siemens.</ref> Per Deutsche Bahn calculations, the energy used per 100 seat-km is the equivalent of 0.33 litres (12 imp fl oz) of gasoline (0.33 litres per 100 kilometres (860 mpg_‑imp; 710 mpg_‑US)).<ref>"ICE 3 der Baureihe 407 (Velaro D) von Siemens". www.hochgeschwindigkeitszuege.com. Retrieved 27 November 2021.</ref><ref>"Superzug: ICE 3: der neue Velaro D von Siemens – Bilder & Fotos – WELT". Welt.de. 1 January 1970. Retrieved 27 November 2021.</ref> The data also reflects the weight of the train per passenger. For example, TGV double-deck Duplex trains use lightweight materials, which keep axle loads down and reduce damage to track and also save energy.<ref>"Commission for integrated transport, Short haul air v High speed rail". Archived from the original on 26 April 2007.</ref> The TGV mostly runs on French nuclear fission power plants which are again limited – as all thermal power plants – to Carnot efficiency. Due to nuclear reprocessing being standard operating procedure, a higher share of the energy contained in the original Uranium is used in France than in e.g. the United States with its once thru fuel cycle.<ref>"France's Efficiency in the Nuclear Fuel Cycle: What Can 'Oui' Learn?". IAEA. 4 September 2019. Retrieved 27 November 2021.</ref>

The specific energy consumption of the trains worldwide amounts to about 150 kJ/pkm (kilojoule per passenger kilometre) and 150 kJ/tkm (kilojoule per tonne kilometre) (ca. 4.2 kWh/100 pkm and 4.2 kWh/100 tkm) in terms of final energy. Passenger transportation by rail systems requires less energy than by car or plane (one seventh of the energy needed to move a person by car in an urban context,<ref name=UITP/>). This is the reason why, although accounting for 9% of world passenger transportation activity (expressed in pkm) in 2015, rail passenger services represented only 1% of final energy demand in passenger transportation.<ref>Railway handbook: Energy consumption and CO₂ emissions website of the International Union of Railways (UIC, based in Paris); see figure 15 on page 27, and values on page 86. This document is the result of a joint work between UIC and International Energy Agency (IEA, based in Paris)</ref><ref>Tracking clean energy progress website iea.org</ref>

Freight

Energy consumption estimates for rail freight vary widely, and many are provided by interested parties. Some are tabulated below.

Country	Year	Fuel economy (weight of goods)	Energy Intensity
USA<ref>"Rail News August 2016 – For Railroad Career Professionals From Progressive Railroading magazine".</ref>	2007	185.363 km/L (1 short ton)	energy/mass-distance
USA<ref>"The Economic Impact of America's Freight Railroads" (PDF). Association of American Railroads. July 2019. p. 2.</ref>	2018	473 miles/gallon (1 ton)	energy/mass-distance
UK<ref>"Freight on Rail" (PDF). freightonrail.org.uk.</ref>	—	87 t·km/L	0.41 MJ/t·km (LHV)

Passenger

Country	Year	Train efficiency	Per passenger-km (kJ)	Note
China<ref>""复兴号"上的黑科技:往返一趟京沪省电5000度". news.sina.com.cn. 28 September 2017. Retrieved 14 May 2018.</ref>	2018	9.7 MJ (2.7 kWh) /car-km	137 kJ/passenger-km (at 100% load)	CR400AF@350 km/h Beijing-Shanghai PDL 1302 km average
Japan<ref>Environmental Goals and Results, JR-East Sustainability Report 2005</ref>	2004	17.9 MJ (5.0 kWh)/car-km	350 kJ/passenger-km	JR East average
Japan<ref>JR East Group CSR 2017, JR-East Sustainability Report 2017</ref>	2017	1.49 kWh/car-km	≈92 kJ/passenger-km<ref name=":12">JR East Annual Report 2017, JR-East Annual Report 2017</ref>	JR East Conventional Rail
EC<ref>TGV Duplex assuming 3 intermediate stops between Paris and Lyon.</ref><ref> Estimating Emissions from Railway Traffic Archived 6 December 2006 at the Wayback Machine, page 74</ref>	1997	18 kW⋅h/km (65 MJ/km)
USA<ref>Colorado Railcar double-deck DMU hauling two Bombardier Bi-level coaches</ref><ref>Colorado Railcar: "DMU Performs Flawlessly on Tri-Rail Service Test" Archived 19 March 2007 at the Wayback Machine</ref>		1.125 mpg_‑US (209.1 L/100 km; 1.351 mpg_‑imp)	468 passenger-miles/US gallon (0.503 L/100 passenger-km)
Switzerland<ref>SBB Facts and Figures Traffic Archived 16 May 2012 at the Wayback Machine</ref>	2011	2300 GWhr/yr	470 kJ/passenger-km
Basel, Switzerland<ref name=":14">"European Environment Agency Occupancy Rates, page 3]" (PDF). europa.eu. Archived from the original (PDF) on 13 June 2007. Retrieved 4 March 2007.</ref><ref name=":13">"Combino – Low Floor Light Rail Vehicles Tests, Trials and Tangible Results" (PDF). Siemens. Archived from the original (PDF) on 11 May 2021. Retrieved 27 November 2021.</ref>		1.53 kWh/vehicle-km (5.51 MJ/vehicle-km)	85 kJ/passenger-km (150 kJ/passenger-km at 80% average load)
USA<ref name="ornl26-02" />	2009		2,435 BTU/mi (1.60 MJ/km)
Portugal<ref name="train in Lisbon">"Eficiência energética: carro ou comboio?".</ref>	2011	8.5 kW⋅h/km (31 MJ/km; 13.7 kW⋅h/mi)

Braking losses

Having to accelerate and decelerate a heavy train load of people at every stop is inefficient. Modern electric trains therefore use regenerative braking to return current into the catenary while they brake. The International Union of Railways has stated<ref>"Regenerative braking in trains | Climate Technology Centre & Network | Tue, 11/08/2016".</ref> that full stop service commuter trains reduce emissions by 8-14% by employing regenerative braking, and very dense suburban network trains by ~30%. High-speed electric trains like the N700 Series Shinkansen (the Bullet Train) employs renerative braking, but due to the high speed, UIC estimates regenerative braking to only reduce emissions by 4.5%.

Buses

In July 2005, the average occupancy for buses in the UK was stated to be 9 passengers per vehicle.<ref name=":11">"Passenger Transport (Fuel Consumption)". Hansard. UK House of Commons. 20 July 2005. Retrieved 25 March 2008.</ref>
The fleet of 244 40-foot (12 m) 1982 New Flyer trolley buses in local service with BC Transit in Vancouver, Canada, in 1994/95 used 35,454,170 kWh for 12,966,285 vehicle km, or 9.84 MJ/vehicle km. Exact ridership on trolleybuses is not known, but with all 34 seats filled this equates to 0.32 MJ/passenger km. It is quite common to see people standing on Vancouver trolleybuses. This is a service with many stops per kilometre; part of the reason for the efficiency is the use of regenerative braking.
A commuter service in Santa Barbara, California, USA, found average diesel bus efficiency of 6.0 mpg_‑US (39 L/100 km; 7.2 mpg_‑imp) (using MCI 102DL3 buses). With all 55 seats filled this equates to 330 passenger mpg; with 70% filled, 231 passenger mpg.<ref name=":10">"Demonstration of Caterpillar C-10 Duel-Fuel Engines in MCI 102DL3 Commuter Buses" (PDF). National Renewable Energy Laboratory. January 2000. Retrieved 5 September 2018.</ref>
In 2011 the fleet of 752 buses in the city of Lisbon had an average speed of 14.4 km/h and an average occupancy of 20.1 passengers per vehicle.<ref>Seara.com. "Indicadores de Atividade".</ref>
Battery electric buses combine the electric motive power of a trolleybus, the drawbacks of battery manufacture, weight and lifespan with the routing flexibility of a bus with any onboard power. Major manufacturers include BYD and Proterra.

Other

NASA's Crawler-Transporter was used to haul the Saturn V and Space Shuttle rockets from storage to the launch pad. It uses diesel and has one of the highest fuel consumption rates on record, 150 US gallons per mile (350 L/km; 120 imp gal/mi).<ref>"Crawler-Transporter System".</ref>

Air transport means

Aircraft

A principal determinant of energy consumption in aircraft is drag, which must be in the opposite direction of motion to the craft.

Drag is proportional to the lift required for flight,<ref name=Capehart>Barney L. Capehart (2007). Encyclopedia of Energy Engineering and Technology, Volume 1. CRC Press. ISBN 0-8493-3653-8, ISBN 978-0-8493-3653-9.</ref> which is equal to the weight of the aircraft. As induced drag increases with weight, mass reduction, with improvements in engine efficiency and reductions in aerodynamic drag, has been a principal source of efficiency gains in aircraft, with a rule-of-thumb being that a 1% weight reduction corresponds to around a 0.75% reduction in fuel consumption.<ref name=Capehart />
Flight altitude affects engine efficiency. Jet-engine efficiency increases at altitude up to the tropopause, the temperature minimum of the atmosphere; at lower temperatures, the Carnot efficiency is higher.<ref name=Capehart /> Jet engine efficiency is also increased at high speeds, but above about Mach 0.85 the airframe aerodynamic losses increase faster.
Compressibility effects: beginning at transonic speeds of around Mach 0.85, shockwaves form increasing drag.
For supersonic flight, it is difficult to achieve a lift to drag ratio greater than 5, and fuel consumption is increased in proportion. However, the faster speed inherent to supersonic flight means that the higher fuel burn is counterbalanced by a shorter flight duration.

*Concorde* fuel efficiency comparison (assuming jets are filled to capacity)
Aircraft	Concorde<ref name = 'powerplant'>"CONCORDE SST : Powerplant". www.concordesst.com. Retrieved 27 November 2021.</ref>	Boeing 747-400<ref>"Technical Specifications: Boeing 747–400". Boeing. Retrieved 11 January 2010.</ref>
Passenger-miles/imperial gallon	17	109
Passenger-miles/US gallon	14	91
Litres/100 passenger-km	16.6	3.1

Passenger airplanes averaged 4.8 L/100 km per passenger (1.4 MJ/passenger-km) (49 passenger-miles per gallon) in 1998.^{[citation needed]} On average 20% of seats are left unoccupied. Jet aircraft efficiencies are improving: Between 1960 and 2000 there was a 55% overall fuel efficiency gain (if one were to exclude the inefficient and limited fleet of the DH Comet 4 and to consider the Boeing 707 as the base case).<ref>"National Aerospace Laboratory]" (PDF). transportenvironment.org.</ref> Most of the improvements in efficiency were gained in the first decade when jet craft first came into widespread commercial use. Compared to advanced piston engine airliners of the 1950s, current jet airliners are only marginally more efficient per passenger-mile.<ref>Peeters P.M., Middel J., Hoolhorst A. (2005). Fuel efficiency of commercial aircraft An overview of historical and future trends. National Aerospace Laboratory, The Netherlands.</ref> Between 1971 and 1998 the fleet-average annual improvement per available seat-kilometre was estimated at 2.4%. Concorde the supersonic transport managed about 17 passenger-miles to the Imperial gallon; similar to a business jet, but much worse than a subsonic turbofan aircraft. Airbus puts the fuel rate consumption of their A380 at less than 3 L/100 km per passenger (78 passenger-miles per US gallon).<ref>"The A380: The future of flying". Airbus. Archived from the original on 14 December 2007. Retrieved 22 March 2008.</ref>

The mass of an aircraft can be reduced by using light-weight materials such as titanium, carbon fibre and other composite plastics. Expensive materials may be used, if the reduction of mass justifies the price of materials through improved fuel efficiency. The improvements achieved in fuel efficiency by mass reduction, reduces the amount of fuel that needs to be carried. This further reduces the mass of the aircraft and therefore enables further gains in fuel efficiency. For example, the Airbus A380 design includes multiple light-weight materials.

Airbus has showcased wingtip devices (sharklets or winglets) that can achieve 3.5 percent reduction in fuel consumption.<ref>Bradley, Grant (17 November 2009). "'Shark fin' wings give airline chiefs something to smile about". NZ Herald – via New Zealand Herald.</ref><ref>"A320 plane shark fins small winglets successfully completed the first flight test". Archived from the original on 11 December 2012. Retrieved 10 September 2012.</ref> There are wingtip devices on the Airbus A380. Further developed Minix winglets have been said to offer 6 percent reduction in fuel consumption.<ref name="gizmag">"Minix wing tip device promises 6% gain in fuel efficiency for airliners". 24 June 2010.</ref> Winglets at the tip of an aircraft wing smooth out the wing-tip vortex (reducing the aircraft's wing drag) and can be retrofitted to any airplane.<ref name="gizmag" />

NASA and Boeing are conducting tests on a 500 lb (230 kg) "blended wing" aircraft. This design allows for greater fuel efficiency since the whole craft produces lift, not just the wings.<ref>Ecogeek Article Archived 14 July 2014 at the Wayback Machine</ref> The blended wing body (BWB) concept offers advantages in structural, aerodynamic and operating efficiencies over today's more conventional fuselage-and-wing designs. These features translate into greater range, fuel economy, reliability and life cycle savings, as well as lower manufacturing costs.<ref>"Boeing to Begin Ground Testing of X-48B Blended Wing Body Concept." Archived 19 August 2012 at the Wayback Machine Boeing, 27 October 2006. Retrieved: 10 April 2012.</ref><ref>Lorenz III, Phillip (3 July 2007). "AEDC testing brings unique blended wing aircraft closer to flight". AEDC, U.S. Air Force. Archived from the original on 14 July 2014. Retrieved 10 April 2012.</ref> NASA has created a cruise efficient STOL (CESTOL) concept.

Fraunhofer Institute for Manufacturing Engineering and Applied Materials Research (IFAM) have researched a shark skin imitating paint that would reduce drag through a riblet effect.<ref>Mahony, Melissa. "A sharkskin coating for ships, planes and blades – ZDNet".</ref> Aircraft are a major potential application for new technologies such as aluminium metal foam and nanotechnology such as the shark skin imitating paint.

Propeller systems, such as turboprops and propfans are a more fuel efficient technology than jets. But turboprops have an optimum speed below about 450 mph (700 km/h).<ref>Spakovszky, Zoltan (2009). "Unified Propulsion Lecture 1". Unified Engineering Lecture Notes. MIT. Retrieved 3 April 2009.</ref> This speed is less than used with jets by major airlines today. With the current ^{[needs update]} high price for jet fuel and the emphasis on engine/airframe efficiency to reduce emissions, there is renewed interest in the propfan concept for jetliners that might come into service beyond the Boeing 787 and Airbus A350XWB. For instance, Airbus has patented aircraft designs with twin rear-mounted counter-rotating propfans.<ref>US application 2009020643, Airbus & Christophe Cros, "Aircraft having reduced environmental impact", published 22 January 2009 </ref> NASA has conducted an Advanced Turboprop Project (ATP), where they researched a variable pitch propfan that produced less noise and achieved high speeds.

Related to fuel efficiency is the impact of aviation emissions on climate.

Small aircraft

Motor-gliders can reach an extremely low fuel consumption for cross-country flights, if favourable thermal air currents and winds are present.
At 160 km/h, a diesel powered two-seater Dieselis burns 6 litres of fuel per hour, 1.9 litres per 100 passenger km.<ref>Contact, Experimental Aircraft and Powerplant Newsforum for Designers and Builders, Issue 55, March–April 2000</ref>
at 220 km/h, a four-seater 100 hp MCR-4S burns 20 litres of gas per hour, 2.2 litres per 100 passenger km.
Under continuous motorised flight at 225 km/h, a Pipistrel Sinus burns 11 litres of fuel per flight hour. Carrying 2 people aboard, it operates at 2.4 litres per 100 passenger km.
Ultralight aircraft Tecnam P92 Echo Classic at cruise speed of 185 km/h burns 17 litres of fuel per flight hour, 4.6 litres per 100 passenger km (2 people).<ref>"Tecnam P92 Echo Classic". Tecnam costruzioni aeronautiche s.r.l. Archived from the original on 29 May 2012. Retrieved 22 May 2012.</ref> Other modern ultralight aircraft have increased efficiency; Tecnam P2002 Sierra RG at cruise speed of 237 km/h burns 17 litres of fuel per flight hour, 3.6 litres per 100 passenger km (2 people).<ref>"Tecnam P2002 Sierra De Luxe". Tecnam costruzioni aeronautiche s.r.l. Archived from the original on 8 June 2012. Retrieved 22 May 2012.</ref>
Two-seater and four-seater flying at 250 km/h with old generation engines can burn 25 to 40 litres per flight hour, 3 to 5 litres per 100 passenger km.
The Sikorsky S-76C++ twin turbine helicopter gets about 1.65 mpg_‑US (143 L/100 km; 1.98 mpg_‑imp) at 140 knots (260 km/h; 160 mph) and carries 12 for about 19.8 passenger-miles per gallon (11.9 L per 100 passenger km).^{[citation needed]}

Water transport means

Ships

Queen Elizabeth

Cunard stated that Queen Elizabeth 2 travelled 49.5 feet per imperial gallon of diesel oil (3.32 m/L or 41.2 ft/US gal), and that it had a passenger capacity of 1777.<ref>"Queen Elizabeth 2: Technical Information" (PDF). Cunard Line. Archived from the original (PDF) on 18 March 2009. Retrieved 31 March 2008.</ref> Thus carrying 1777 passengers we can calculate an efficiency of 16.7 passenger miles per imperial gallon (16.9 L/100 p·km or 13.9 p·mpg_–US).

Cruise ships

Template:MS has a capacity of 6,296 passengers and a fuel efficiency of 14.4 passenger miles per US gallon. Voyager-class cruise ships have a capacity of 3,114 passengers and a fuel efficiency of 12.8 passenger miles per US gallon.<ref>"Cruise Ship Gas Mileage". 27 December 2010.</ref>

Emma Maersk

Emma Maersk uses a Wärtsilä-Sulzer RTA96-C, which consumes 163 g/kWh and 13,000 kg/h. If it carries 13,000 containers then 1 kg fuel transports one container for one hour over a distance of 45 km. The ship takes 18 days from Tanjung (Singapore) to Rotterdam (Netherlands), 11 from Tanjung to Suez, and 7 from Suez to Rotterdam,<ref>"Schedules, vessels voyage, ports call dates / Emma Maersk". www.emma-maersk.com. Retrieved 27 November 2021.</ref> which is roughly 430 hours, and has 80 MW, +30 MW. 18 days at a mean speed of 25 knots (46 km/h) gives a total distance of 10,800 nautical miles (20,000 km).

Assuming the Emma Maersk consumes diesel (as opposed to fuel oil which would be the more precise fuel) then 1 kg diesel = 1.202 litres = 0.317 US gallons. This corresponds to 46,525 kJ. Assuming a standard 14 tonnes per container (per teu) this yields 74 kJ per tonne-km at a speed of 45 km/h (24 knots).

Boats

A sailboat, much like a solar car, can locomote without consuming any fuel. A sail boat such as a dinghy using just wind power requires no input energy in terms of fuel. However some manual energy is required by the crew to steer the boat and adjust the sails using lines. In addition energy will be needed for demands other than propulsion, such as cooking, heating or lighting. The fuel efficiency of a single-occupancy boat is highly dependent on the size of its engine, the speed at which it travels, and its displacement. With a single passenger, the equivalent energy efficiency will be lower than in a car, train, or plane.^{[citation needed]}

International transport comparisons

European Public transport

Rail and bus are generally required to serve 'off peak' and rural services, which by their nature have lower loads than city bus routes and inter city train lines. Moreover, due to their 'walk on' ticketing it is much harder to match daily demand and passenger numbers. As a consequence, the overall load factor on UK railways is 35% or 90 people per train:<ref>"ATOC".</ref>

Conversely, airline services generally work on point-to-point networks between large population centres and are 'pre-book' in nature. Using yield management, overall load factors can be raised to around 70–90%. Intercity train operators have begun to use similar techniques, with loads reaching typically 71% overall for TGV services in France and a similar figure for the UK's Virgin Rail Group services.<ref>"Delivering a sustainable railway – Publications – GOV.UK". Archived from the original on 5 September 2007. Retrieved 25 July 2007.</ref>

For emissions, the electricity generating source needs to be taken into account.<ref>"Energy & Emissions Statement" (PDF).</ref><ref>Defra 2008 Guidelines to Defra's GHG Conversion Factors Archived 5 January 2012 at the Wayback Machine</ref> <ref>"Kilograms of CO2 per passenger kilometre for different modes of transport within the UK]" (PDF). aef.org.uk.</ref>

US Passenger transport

The US Transport Energy Data Book states the following figures for passenger transport in 2018. These are based on actual consumption of energy, at whatever occupancy rates there were. For modes using electricity, losses during generation and distribution are included. Values are not directly comparable due to differences in types of services, routes, etc.<ref name="ORNL/TM-2020/1770">Davis, Stacy C.; Robert G. Boundy (2021). Transportation Energy Data Book: Edition 39. US Department of Energy. p. C–10. ORNL/TM-2020/1770 (Edition 39 of ORNL-5198). Retrieved 27 July 2021.</ref>

Transport mode	Average passengers per vehicle	BTU per passenger-mile	MJ per passenger-kilometre
Rail (transit light & heavy)	23.5	1,813	1.189
Rail (intercity Amtrak)	23.3	1,963	1.287
Motorcycles	1.2	2,369	1.553
Air	118.7	2,341	1.535
Rail (commuter)	33.6	2,398	1.572
Cars	1.5	2,847	1.866
Personal trucks	1.8	3,276	2.148
Buses (transit)	7.7	4,578	3.001
Demand response	1.1	14,660	9.61

US Freight transport

The US Transport Energy book states the following figures for freight transport in 2010:<ref name="ornl26-02">Davis, Stacy C.; Susan W. Diegel; Robert G. Boundy (2011). Transportation Energy Data Book: Edition 30. US Department of Energy. pp. Table 2.14. ORNL-6986 (Edition 30 of ORNL-5198). Retrieved 22 February 2012.</ref><ref>"US Environmental protection, 2006". yosemite.epa.gov. Archived from the original on 12 February 2009.</ref><ref>"Energy Efficiency – Transportation sector". U.S. Energy Information Administration (EIA). Archived from the original on 22 September 2008. Retrieved 27 November 2021.</ref><ref>"Chapter 2 Energy". Transportation Energy Data Book. Archived from the original on 12 March 2009. Retrieved 27 November 2021.</ref>

transport mode	Fuel consumption
transport mode	BTU per short ton-mile	kJ per tonne-kilometre
Domestic waterborne	217	160
Class 1 railroads	289	209
Heavy trucks	3,357	2,426
Air freight (approx.)	9,600	6,900

From 1960 to 2010 the efficiency of air freight has increased 75%, mostly due to more efficient jet engines.<ref>"Trends in Fuel Efficiency, Selected Passenger Jet Planes".</ref>

1 gal_-US (3.785 L, 0.833 gal_-imp) of fuel can move a ton of cargo 857 km or 462 nmi by barge, or 337 km (209 mi) by rail, or 98 km (61 mi) by lorry.<ref>Rodrigue, Dr. Jean-Paul (7 December 2017). "Transportation and Energy". Archived from the original on 25 August 2012. Retrieved 15 September 2012.</ref>

Compare:

Space Shuttle used to transport freight to the other side of the Earth (see above): 40 megajoules per tonne-kilometre.
Net energy for lifting: 10 megajoules per tonne-kilometre.

Canadian transport

Natural Resources Canada's Office of Energy Efficiency publishes annual statistics regarding the efficiency of the entire Canadian fleet. For researchers, these fuel consumption estimates are more realistic than the fuel consumption ratings of new vehicles, as they represent the real world driving conditions, including extreme weather and traffic. The annual report is called Energy Efficiency Trends Analysis. There are dozens of tables illustrating trends in energy consumption expressed in energy per passenger km (passengers) or energy per tonne km (freight).<ref>"2010 data". Oee.rncan.gc.ca. Retrieved 19 June 2018.</ref>

French environmental calculator

The environmental calculator of the French environment and energy agency (ADEME) published in 2007 using data from 2005<ref>(fr) ADEME environmental calculator Archived 20 July 2011 at the Wayback Machine which informs about the CO₂ emissions and the primary energy consumption</ref> enables one to compare the different means of transport as regards the CO₂ emissions (in terms of carbon dioxide equivalent) as well as the consumption of primary energy. In the case of an electric vehicle, the ADEME makes the assumption that 2.58 toe as primary energy are necessary for producing one toe of electricity as end energy in France (see Embodied energy: In the energy field).

This computer tool devised by the ADEME shows the importance of public transport from an environmental point of view. It highlights the primary energy consumption as well as the CO₂ emissions due to transport. Due to the relatively low environmental impact of radioactive waste, compared to that of fossil fuel combustion emissions, this is not a factor in the tool. Moreover, intermodal passenger transport is probably a key to sustainable transport, by allowing people to use less polluting means of transport.

German environmental costs

Deutsche Bahn calculates the energy consumption of their various means of transportation.<ref>"Energy efficiency increased | Deutsche Bahn AG". ibir.deutschebahn.com. Retrieved 12 April 2022.</ref>

Type	2018
Regional rail passenger transport (MJ/pkm)	0.85
Long-distance rail passenger transport (MJ/pkm)	0.25
Bus service (MJ/pkm)	1.14
Rail freight transport (MJ/tkm)	0.33
Road freight transport (MJ/tkm)	1.21
Air freight (MJ/tkm)	9.77
Ocean freight (MJ/tkm)	0.09

Note - External costs not included above

To include all the energy used in transport, we would need to also include the external energy costs of producing, transporting and packaging of fuel (food or fossil fuel or electricity), the energy incurred in disposing of exhaust waste, and the energy costs of manufacturing the vehicle. For example, a human walking requires little or no special equipment while automobiles require a great deal of energy to produce and have relatively short product lifespans.

However, these external costs are independent of the energy cost per distance travelled, and can vary greatly for a particular vehicle depending on its lifetime, how often it is used and how it is energized over its lifetime. Thus this article's numbers include none of these external factors.

Footnotes

External links

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