Energy efficiency in transport

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.

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.

[15] 1 US gal (3.8 L) of petrol contains about 114,000 British thermal units (120 MJ)[52] of energy, so this is approximately equivalent to 360 miles per US gallon (0.65 L/100 km).

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).

[20] 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.

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.

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 addition, bicycles require less space both to park and to operate and they damage road surfaces less, adding an infrastructural factor of efficiency.

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,[55] 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.

The lifecycle of electric scooters is also notably shorter than that of bicycles, often reaching only a single digit number of years.

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.

Efficiency varies significantly with passenger loads, and losses incurred in electricity generation and supply (for electrified systems),[75][76] and, importantly, end-to-end delivery, where stations are not the originating final destinations of a journey.

Data produced for the European MEET project (Methodologies for Estimating Air Pollutant Emissions) illustrate the different consumption patterns over several track sections.

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.

For example, TGV double-deck Duplex trains use lightweight materials, which keep axle loads down and reduce damage to track and also save energy.

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.

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.

[120] 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.

[123] Aircraft are a major potential application for new technologies such as aluminium metal foam and nanotechnology such as the shark skin imitating paint.

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.

[125] NASA has conducted an Advanced Turboprop Project (ATP), where they researched a variable pitch propfan that produced less noise and achieved high speeds.

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.

As a consequence, the overall load factor on UK railways is 35% or 90 people per train:[132] Conversely, airline services generally work on point-to-point networks between large population centres and are 'pre-book' in nature.

This computer tool devised by the ADEME shows the importance of public transport from an environmental point of view.

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.