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= Total transportation energy consumption statistics = It is important to put transportation energy consumption in perspective to global energy consumption.

It is also relevant to consider the relative weight of each transportation mode.

Energy savings potential in transportation
= Energy efficiency comparison by mode of transportation =

Energy consumption units
Many units can be used for expressing energy consumption. All of them relate energy to distance as in liters of fuel per 100 Km or inversely distance to energy as in miles per gallon of fuel.

The most used units in transportation are linked to the fuel used in each system.

To be able to compare different means of transportation the main unit to be used in the article will not be linked to a specific fuel. The kilowatt-hour per 100 kilometres $$[kwh/100km]$$ will be the main unit used through the article. The following table compares this unit to other usual consumption units:

N.B. to elaborate this conversion table the fuel used for litres per 100 kilometres$$[l/100km]$$ and miles per gallon [mpg] is 87 Octane Gasoline (see Gasoline for energy content). The standard US gallon (see Gallon) and the statute mile (see Mile) were used.

Inverse scale

Because mpg and gas consumption are inversely related, mpg can cause illusions.

CO2 Emmisions per distance for motorized transportation modes

A related measure is the amount of carbon dioxide produced as a result of the combustion process, typically measured in grams of CO2 per kilometre (CO2 g/km).

A petrol (gasoline) engine will produce around 2.32 kg of carbon dioxide for each litre of petrol consumed. A typical diesel engine produces 2.66 kg/l

Transportation purposes
This article will differentiate between personal and cargo transport.

A variation of the main unit will be used for each transportation purpose.

For personal transport the energy consumption will be expressed per transported person [kwh/(100km.person)]

For cargo transport the energy consumption will be expressed per unit of mass transported [kwh/(100km.tonne)] where a tonne is 1000 kilograms.

Speed and energy consumption
For the purpose of this article the main goal of transport is to move persons or mass of cargo for a certain distance.

However the time required to cover the distance and the type of speed profile used need to be taken into account when comparing energy consumption to ensure a thorough understanding of the values.

This point is certainly easy when comparing different variants of a given transportation type, i.e. different vehicle models following an Emission test cycle, but may not be possible when comparing different means of transport, i.e. airplane versus ship for cargo.

= Passenger Transport =

Walking/Running
this section is approximate since no accurate source has been found up to date

Data:

1) Human average power consumption can be easily derived from average calorie intake:

Based on a 2400 calorie diet (a food calorie is one kilocalorie or kcal)

$$ 2400 kcal / 24 hr = 100 kcal/hr = 27.8 cal/sec = 116.38 J/s = 116 W$$

2) Peak human power output ranges between 600 and 900 Watts. Actual power consumption for this case is not provided.

3) Walking speed is usually between 3 and 4 kilometres per hour [kph] (see Walking).

4) Running speed is most efficient for 8.3 mph for males and 6.5 miles per hour [mph] for females (13.3 kph and 10.5 kph respectively).

5) Energy consumption by walking was calculated as 100 food calories (Kcal) per mile or 7.2 $$kwh/(100km.person)$$

6) Energy consumption by walking was calculated as 70 food calories (Kcal) per km or 8.1 $$kwh/(100km.person)$$

Approximate energy consumption values:

Walking: to match the calculation provided by the reference, we need to assume eight times the average power consumption (900 W) and a speed of 3.5 kph for walking. The energy consumption is 7.15 $$kwh/(100km.person)$$

Running: Assuming a power consumption doubling the one of walking (1800W) and a speed of 12 kph for running, the energy consumption is 4.2 $$kwh/(100km.person)$$

Cycling
Energy consumption for cycling has been calculated as 35 food calories (Kcal) per mile per person or 2.5 $$kwh/(100km.person)$$

Plausibility check for this value:

Power output for cycling ranges between 250W (sustained) to 1000W sprint

Assuming 30 kph for sustained cycling speed and a power consumption of 1800 W (similar to running) the result is  1.7 $$kwh/(100km.person)$$ So the result from the external reference is plausible.

Animal power
The main animal used for human transportation has been the horse.

 Data:

A good estimation of horse energy consumption is provided by the National Research Council (U.S.)

Depending on the horse heart beat rate the energy consumption goes from 24 to 230 kilocalories per minute or 1.67 to 16.0 kilowatts (for 60 to 180 beats per minute respectively)

The average speed of horses is 16-27 kph for canter and  40 to 48 kph for gallop (see Horse gait)

Approximate energy consumption values:

Assuming 10 kilowatt for a 30 kph speed and one rider on the horse the energy consumption is $$9.25 kwh/(100km.person)$$

Segway
The Segway provides an individual transportation method that combines low weight and electric drive.

The manufacturer provides a white paper in which it is stated that the average consumption is 0.052 kwh/mile or a full charge of 1.04 kwh for an autonomy of 20 miles. Converting into the standard unit used that means $$3.25 kwh/(100km.person)$$ The maximum speed of the Segway is 20 kph

Motorbike
Conventional

The 2009 Honda Supra 125 was the lowest consumption motorbike found. The fuel economy provided is 1.6 $$[l/100km]$$ with a weight of 100 kg and a maximum speed of 120 kph. Using the standard unit this is $$14.2 kwh/(100km.person)$$ Faster (over 250 kph) and heavier (over 200kg) motorcycles have a consumption exceeding 6.0 $$[l/100km]$$

Electric

The XM-3500Li is used as an example for electric motorbikes.

It has a Li-Ion Battery with a capacity of 40 Ah and a nominal voltage of 60V so a total energy of 2.4 kwh. Assuming that 90% of the available energy is usable the total usable energy is 2.16 kwh. The autonomy is 60 miles. With the usable energy and the autonomy we can calculate a fuel economy of $$2.25 kwh/(100km.person)$$. It is unclear under what speed profile the autonomy of 60 miles can be achieved.

The maximum speed is 48 kph and the total weight is 276 pounds.

Passenger car
The energy consumption or the fuel economy of a vehicle is dependent on the vehicle characteristics and the speed profile.

To eliminate the factor of the speed profile standard cycles are used in each of the major markets.

The following sections cover the new car energy consumption, the car fleet average energy consumption and the fuel economy standards.

In the last section several vehicles will be used to calculate energy consumption per distance and passengers making assumptions on cycle and average passenger load.

United States EPA fuel economy ratings

 * 2009

For EPA testing procedures prior to 2008 and after 2008 refer to Fuel economy in automobiles

Fuel economy standards
* highway ** combined

Average vehicle load
The average vehicle load ranges from 1.3 to 1.6 according to several studies

Most sold hybrid vehicle: Toyota Prius
According to the U.S. EPA's revised estimates, the combined fuel consumption for the 2008 Prius is 46 mpgus, making it the most fuel efficient U.S. car of 2008. In the UK, the official fuel consumption figure (combined) for the Prius is 4.3 l/100 km.

Average occupancy

 * In July 2005, the average occupancy for buses in the UK was stated to be 9.

Energy consumption examples

 * The fleet of 244 1982 New Flyer 40 ft trolley buses in local service with BC Transit in Vancouver, BC, Canada in 1994/95 consumed 35454170 kWh for 12966285 vehicle-km, or 9.84 MJ/vehicle-km. Exact ridership on trolleybuses is not known, but with all 34 seats filled this would equate to 0.32 MJ/passenger-km.  It is quite common to see people standing on Vancouver trolleybuses.  Note that this is a local transit service with many stops per km; part of the reason for the efficiency is the use of regenerative braking.


 * A diesel bus commuter service in Santa Barbara, CA, USA found average diesel bus efficiency of 6.0 mpg (using MCI 102DL3 buses). With all 55 seats filled this equates to 330 passenger-mpg, with 70% filled the efficiency would be 231 passenger-mpg.

Train
However, recently intercity train operators have been using similar techniques, with loads reaching typically 71% overall for TGV services in France and a similar figure for the UK's Virgin trains services.


 * Freight: the AAR claims an energy efficiency of over 400 short ton-miles per gallon of diesel fuel in 2004 (0.588 L/100 km per tonne or 235 J/(km·kg))


 * The East Japan Railway Company claims for 2004 an energy intensity of 20.6 MJ/car-km, or about 0.35 MJ/passenger-km


 * a 1997 EC study on page 74 claims 18.00 kWh/train-km for the TGV Duplex assuming 3 intermediate stops between Paris and Lyon. This equates to 64.80 MJ/train-km.  With 80% of the 545 seats filled on average this is 0.15 MJ/passenger-km.


 * Actual train consumption depends on gradients, maximum speeds and stopping patterns. Data was produced for the European MEET project (Methodologies for Estimating Air Pollutant Emissions) and illustrates the different consumption patterns over several track sections. The results show the consumption for a German ICE High speed train varied between around 19 kWh/km to 33 kWh/km. The data also reflects the weight of the train per passenger. For example, the TGV double-deck ‘Duplex’ trains use lightweight materials in order to keep axle loads down and reduce damage to track, this saves considerable energy.


 * A Siemens study of Combino light rail vehicles in service in Basel, Switzerland over 56 days showed net consumption of 1.53 kWh/vehicle-km, or 5.51 MJ/vehicle-km. Average passenger load was estimated to be 65 people, resulting in average energy efficiency of 0.085 MJ/passenger-km.  The Combino in this configuration can carry as many as 180 with standees.  41.6% of the total energy consumed was recovered through regenerative braking.


 * A trial of a Colorado Railcar double-deck DMU hauling two Bombardier Bi-level coaches found fuel consumption to be 128 US gallons for 144 mi, or 1.125 mpg. The DMU has 92 seats, the coaches typically have 162 seats, for a total of 416 seats.  With all seats filled the efficiency would be 468 passenger-mpg, with 70%  filled the efficiency would be 328 passenger-mpg.


 * Note that intercity rail in the U.S. reports 3.17 MJ/passenger-km which is several times higher than reported from Japan. Independent transportation researcher David Lawyer attributes this difference to the fact that the losses in electricity generation may not have been taken into account for Japan and that Japanese trains have a larger number of passengers per car.


 * Modern electric trains like the shinkansen use regenerative braking to return current into the catenary while they brake. This method results in significant energy savings, where-as diesel locomotives (in use on unelectrified railway networks) typically dispose of the energy generated by dynamic braking as heat into the ambient air.


 * This Swiss Railroad company SBB-CFF-FFS cites 0.082 kWh per passenger-km for traction.


 * AEA carried out a detailed study of road and rail for the United Kingdom Department for Transport. Final report


 * Amtrak reports 2005 energy use of 2,935 BTU per passenger-mile, or 39 passenger-miles per gallon


 * The Passenger Rail (Urban and Intercity) and Scheduled Intercity and All Charter Bus Industries Technological and Operational Improvements - FINAL REPORT states that "Commuter operations can dissipate more than half of their total traction energy in braking for stops." and that "We estimate hotel power to be 35 percent (but it could possibly be as high as 45 percent) of total energy consumed by commuter railways." Having to accelerate and decelerate a heavy train load of people at every stop is inefficient despite regenerative braking which can recover typically around 20% of the energy wasted in braking.

Aircraft
A principle determinant of fuel consumption in aircraft is drag, which must be opposed by thrust for the aircraft to progress. Drag increases approximately as the square of lift required for flight, and, as force of lift is directly related to craft weight, to aircraft weight2. Unlike parasitic or form drag, induced drag decreases with the square of velocity, making flight at higher-speeds more efficient (see drag).

As induced drag increases as a power function of weight, mass reduction, along with improvements in engine efficiency and reductions in aerodynamic drag, has been a principle source of efficiency gains in craft, with a rule-of-thumb being that a 1% weight reduction corresponds to around a .75% reduction in fuel consumption. Altitude impacts on both air-drag and engine efficiency, the altitude at which aircraft are permitted to fly greatly influences their fuel consumption. Jet-engine cruising efficiency increases at altitude due to the constraint to maintain a combustible fuel mixture: low-pressure air allows reduced fuel injection while maintaining an adequate fuel:air ratio.

Passenger airplanes averaged 4.8 L/100 km per passenger (1.4 MJ/passenger-km) (49 passenger-miles per gallon) in 1998. Note that on average 20% of seats are left unoccupied. Aircraft efficiencies are improving: Between 1960 and 2000 there has been a 70% overall fuel efficiency gain. As over 80% of the fully-laden take-off weight of a modern aircraft such as the Airbus A380 is craft and fuel, there remains considerable room for future improvements in efficiency.


 * Airbus state that their A380 consumes fuel at the rate of less than 3 L/100 km per passenger. CNN reports that the fuel consumption figures provided by Airbus for the A380, given as 2.9 L/100 km per passenger, are "slightly misleading", because they assume a passenger count of  555, but do not allow for any luggage or cargo.  Typical occupancy figures are unknown at this time.  Furthermore, the A380, unlike other airliners, has special dispensation from the FAA to fly higher than 40000 ft.


 * NASA and Boeing are conducting tests on a 500 lb. "blended wing" aircraft. This design allows for greater fuel efficiency since the whole craft produces lift, not just the wings.


 * The Sikorsky S-76C++ twin turbine helicopter gets about 1.65 mpg at 140 kn and carries 12 for about 19.8 passenger-miles/gal.


 * The Bell 407 single engine turbine helicopter burns 51 gallons per hour at 120 knots carrying 1 pilot and 6 passengers. 2.35 NM per Gal for 14.1 passenger-miles per gallon. If the pilot is counted as a passenger, it's 16.4 people-miles per gallon. Increased altitudes can yield better fuel rates. It has operated at 47 gal/hr.

US Passenger transportation
The US Transportation Energy Data Book states the following figures for Passenger transportation in 2006:

Caveats

 * There is a distinction between vehicle MPGe and passenger MPGe. Most of these entries cite passenger MPGe even if not explicitly stated.  It is important not to compare energy figures that relate to unsimilar journeys. An airline jet cannot be used for an urban commute so when comparing aircraft with cars the car figures must take this into account.


 * There is currently no agreed upon method of comparing electric vehicle efficiency to heat engine (fossil fuel) vehicle efficiency. However, current typical emissions and thermal energy consumption can be compared. Vehicle speed is also an important parameter, and a peer-reviewed evaluation which convolves these criteria may be found at  http://www.bentham-open.org/pages/content.php?TOEFJ/2008/00000001/00000001/11TOEFJ.PDF


 * If the issue is rapid investment in new electric mass transit it is important to use emissions associated with the most polluting fuel because increased demand for electricity increases the use of the most polluting fuel used in generation for the immediate future.


 * Systems that re-use vehicles like trains and buses can't be directly compared to vehicles that get parked at their destination. They use energy to return (less full) for more passengers and must sometimes run on schedules and routes with little patronage.  These factors greatly affect overall system efficiencies.  The energy costs of accumulating load need to be included.  In the case of most mass transit distributing and accumulating load over many stops means that passenger kilometres are inherently a small proportion of vehicle kilometres see Transport Energy Metrics, Lessons from the west Coast Main line Modernisation and figures for London Underground in transport statistics for Great Britain 2003.  Lessons from the west coast mainline modernisation suggest that long passenger rail should operate at less than 40% capacity utilisation and for London underground the figure is probably less than 15%.


 * Most cars run at less than full capacity, with the usual average load being between 1 and 2. Cars are also subject to inefficiencies because of congestion and the need to negotiate road junctions. The impact of transport road building to reduce congestion should always be considered as should the improving efficiency of cars see http://www.hm-treasury.gov.uk/media/9/5/pbr_csr07_king840.pdf,


 * Vehicles are not isolated systems. They usually form a part of larger systems whos design inherently determines energy consumption. Judging the value of transport systems by comparing the performance of their vehicles alone can be misleading. For instance, metro systems may have a poor energy efficiency per passenger kilometer, but their high throughput and low physical footprint makes the existence of high urban population densities viable. Total energy consumption per capita declines sharply as population density increases, since journeys become shorter.


 * For all transportation modes involving the use of equipment the energy required to manufacture, service and recycle the equipment including all of its components must be taken into consideration for the thorough calculation of the energy consumption per distance. This required a quantification of the total energy required for the complete life cycle of the equipment as well as the total distance that will be covered over the lifetime of the equipment.

= Freight Transport =

US Freight transportation
The US Transportation Energy book states the following figures for Freight transportation in 2004:

= References =

= See also =
 * ACEA agreement
 * Alternative propulsion
 * Annual fuel utilization efficiency (AFUE)
 * Association for the Study of Peak Oil and Gas (ASPO)
 * Electric cars
 * Car tuning
 * Carbon diet
 * Carbon dioxide equivalent
 * Corporate Average Fuel Economy (CAFE)
 * EcoAuto (in Canada)
 * Emission standard
 * Energy conservation
 * Energy content of Biofuel
 * Energy density
 * Energy efficiency
 * Fuel economy in automobiles
 * Fuel economy maximizing behaviors
 * Fuel efficiency in transportation
 * Fuel efficiency
 * Fuel saving devices
 * Gallons Per Mile
 * Gas-guzzler
 * Gasoline gallon equivalent
 * Heating value
 * IRIS engine
 * Life cycle assessment
 * Low-energy vehicle
 * Low-rolling resistance tires
 * Marine fuel management
 * Miles per gallon gasoline equivalent
 * Miles per gallon
 * NHTSA
 * Orders of magnitude (power)
 * Passenger miles per gallon
 * International System of Units (SI)
 * Transport efficiency
 * Vehicle Efficiency Initiative
 * Vehicle efficiency
 * World energy resources and consumption


 * Sites or publications such as Consumer Reports, Edmunds.com, and TrueDelta.com offer this service and claim more accurate numbers than those listed by the EPA.

=External links=
 * ECCM Study for rail, road and air journeys between main UK cities
 * Flight Emission Calculator
 * Transport Energy Consumption Discussion Paper 2004 - Prof. Roger Kemp
 * Traction Summary Report 2007- Prof. Roger Kemp
 * Transportation Energy Data Book (U.S.)
 * Fuel Consumption Ratings
 * US Government website on fuel economy
 * UK DfT comparisons on road and rail
 * Matters of scale in transportation
 * RECODRIVE project
 * U.S. Fuel Economy Label (United States Environmental Protection Agency).
 * US EPA Green Vehicle Guide.
 * European Community Directive 93/116/EC — European Commission Directive 93/116/EC of 17.12.1993 adapting to technical progress Council Directive 80/1268/EEC relating to the fuel consumption of motor vehicles
 * graph
 * "Green fuel for the airline industry",
 * Energy and Emissions Statement - 2006/7 ATOC Train Operators
 * Grams of CO2 per transport modes in UK
 * Oak Ridge National Laboratory (ORNL)
 * Hydrogen Internal Combustion Engine (ICE) Vehicle Testing Activities
 * Average car occupancy SFO
 * 2006 average car occupancy in the UK
 * Website where drivers can enter and track their own real-world fuel economy numbers

Category:Energy conservation Category:Fuels Category:Energy in transport Category:Energy use comparisons