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Encyclopedia > Fuel efficiency
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Fuel efficiency, in its basic sense, is the same as thermal efficiency, meaning the efficiency of a process that converts chemical potential energy contained in a carrier fuel into kinetic energy or work. Overall fuel efficiency may vary per device, which in turn may vary per application, and this spectrum of variance is often illustrated as a continuous energy profile. Non-transportation applications, such as industry, benefit from increased fuel efficiency, especially fossil fuel power plants or industries dealing with combustion, such as ammonia production during the Haber process. Image File history File links Portal. ... The thermal efficiency () is a dimensionless performance measure of a thermal device such as an internal combustion engine, a boiler, or a furnace, for example. ... For other uses, see Fuel (disambiguation). ... The cars of a roller coaster reach their maximum kinetic energy when at the bottom of their path. ... In physics, mechanical work is the amount of energy transferred by a force. ... In standardization, a profile consists of an agreed-upon subset and interpretation of a specification. ... Mohave Generating Station, a 1,580 MW coal power plant near Laughlin, Nevada A fossil fuel power plant is an energy conversion center that burns fossil fuels to produce electricity, designed on a large scale for continuous operation. ... For other uses, see Ammonia (disambiguation). ... The Haber process (also known as Haberâ€“Bosch process) is the reaction of nitrogen and hydrogen, over an iron-substrate, to produce ammonia [1] [2] [3]. The Haber process is important because ammonia is difficult to produce, on an industrial scale. ...

In the context of transportation, "fuel efficiency" more commonly refers to the energy efficiency of a particular vehicle model, where its total output (range, or "mileage" [U.S.]) is given as a ratio of range units per a unit amount of input fuel (gasoline, diesel, etc.). This ratio is given in common measures such as "litres per 100 kilometre" (L/100 km) or "miles per gallon" (mpg). Though the typical output measure is vehicle range, for certain applications output can also be measured in terms of weight per range units (freight) or individual passenger-range (vehicle range / passenger capacity). For the movement of people or objects, see transport. ... Fuel economy monitor from a 2006 Honda Airwave Fuel economy in automobiles is the amount of fuel required to move the automobile over a given distance. ... This article is about the mathematical concept. ... Look up gasoline in Wiktionary, the free dictionary. ... The litre or liter (see spelling differences) is a unit of volume. ... â€œkmâ€ redirects here. ... â€œMilesâ€ redirects here. ... The gallon (abbreviation: gal) is a unit of volume. ... A Frequent Flyer Program is a service offered by many airlines to reward customer loyalty. ... Freight is a term used to classify the transportation of cargo and is typically a commercial process. ...

This ratio is based on a car's total properties, including its engine properties, its body drag, weight, and rolling resistance (friction), and as such may vary substantially from the profile of the engine alone. While the thermal efficiency of petroleum engines has improved in recent decades, this does not necessarily translate into fuel economy of cars, as people in developed countries tend to buy bigger and heavier cars (i.e. SUVs will get less range per unit fuel than an economy car). For other uses, see Engine (disambiguation). ... This is the name given to a freestyle trick performed by a windsurfer (rider). ... Petro redirects here. ... A colorized automobile engine The internal combustion engine is an engine in which the combustion of fuel and an oxidizer (typically air) occurs in a confined space called a combustion chamber. ... Car redirects here. ... A developed country is a country that has achieved (currently or historically) a high degree of industrialization, and which enjoys the higher standards of living which wealth and technology make possible. ... A fourth-generation (2006-) Ford Explorer, the best-selling mid-size SUV in the United States. ... An economy car is an automobile that is designed for low cost operation. ...

Hybrid vehicle designs use smaller combustion engines as electric generators to produce greater range per unit fuel than directly powering the wheels with an engine would, and (proportionally) less fuel emissions (CO2 grams) than a conventional (combustion engine) vehicle of similar size and capacity. For other types of Hybrid Transportation, see Hybrid (disambiguation)#Transportation. ... Air pollution is the modification of the natural characteristics of the atmosphere by a chemical, particulate matter, or biological agent. ... This article or section does not cite its references or sources. ...

"Energy efficiency" is similar to fuel efficiency but the input is usually in units of energy such as British thermal units (BTU), megajoules (MJ), gigajoules (GJ), kilocalories (kcal), or kilowatt-hours (kW·h). The inverse of "energy efficiency" is "energy intensity", or the amount of input energy required for a unit of output such as MJ/passenger-km (of passenger transport), BTU/ton-mile (of freight transport, for long/short/metric tons), GJ/t (for steel production), BTU/(kW·h) (for electricity generation), or litres/100 km (of vehicle travel). This last term "litres per 100 km" is also a measure of "fuel economy" where the input is measured by the amount of fuel and the output is measured by the distance travelled. For example: Fuel economy in automobiles. Distance is a numerical description of how far apart objects are at any given moment in time. ... Fuel economy monitor from a 2006 Honda Airwave Fuel economy in automobiles is the amount of fuel required to move the automobile over a given distance. ...

Given a heat value of a fuel, it would be trivial to convert from fuel units (such as litres of gasoline) to energy units (such as MJ) and conversely. But there are two problems with comparisons made using energy units:

• There are two different heat values for any hydrogen-containing fuel which can differ by several percent (see below). Which one do we use for converting fuel to energy?
• When comparing transportation energy costs, it must be remembered that a kilowatt hour of electric energy may require an amount of fuel with heating value of 2 or 3 kilowatt hours to produce it.

The kilowatt-hour (symbol: kW·h) is a unit for measuring energy. ...

## Energy content of fuel

The specific energy content of a fuel is the heat energy obtained when a certain quantity is burned (such as a gallon, litre, kilogram, etc.). It is sometimes called the "heat of combustion". There exists two different values of specific heat energy for the same batch of fuel. One is the high (or gross) heat of combustion and the other is the low (or net) heat of combustion. The high value is obtained when, after the combustion, the water in the "exhaust" is in liquid form. For the low value, the "exhaust" has all the water in vapor form (steam). Since water vapor gives up heat energy when it changes from vapor to liquid, the high value is larger since it includes the latent heat of vaporization of water. The difference between the high and low values is significant, about 8 or 9%. This accounts for most of the apparent discrepancy in the heat value of gasoline. In the U.S. (and the table below) the high heat values have traditionally been used, but in many other countries, the low heat values are commonly used.

Fuel type      MJ/L      MJ/kg     BTU/Imp gal     BTU/US gal     Research octane
number (RON)
Regular Gasoline / Petrol 34.83 ~47 150,100 125,000 Min 91
Premium Gasoline / Petrol Min 95
Autogas (LPG) (60% Propane + 40% Butane)
Ethanol 23.5 31.1[1] 101,600 84,600 129
Methanol 17.9 19.9 77,600 64,600 123
Gasohol (10% ethanol + 90% gasoline) 33.7 145,200 120,900 93/94
Diesel 38.60 166,600 138,700 N/A (see cetane)
Biodiesel 35.10 39.89 151,600 126,200
Vegetable oil (using 9.00 kcal/g) 34.32 37.66 147,894 123,143
Aviation gasoline 33.5 46.8 144,400 120,200
Jet fuel, naphtha 35.5 46.6 153,100 127,500
Jet fuel, kerosene 37.60 162,100 135,000
Liquefied natural gas 25.3 ~55 109,000 90,800
Liquid hydrogen 9.36 140.4 40,467 33,696

## Fuel economy

Fuel economy is usually expressed in one of two ways: Fuel economy monitor from a 2006 Honda Airwave Fuel economy in automobiles is the amount of fuel required to move the automobile over a given distance. ...

• The amount of fuel used per unit distance; for example, litres per 100 kilometres (L/100 km). In this case, the lower the value, the more economic a vehicle is (the less fuel it needs to travel a certain distance);
• The distance travelled per unit volume of fuel used; for example, kilometres per litre (km/L) or miles per gallon (mpg), where 1 mpg = 0.42514371 km/l. In this case, the higher the value, the more economic a vehicle is (the more distance it can travel with a certain volume of fuel) (This is the more popular notation).

Converting from mpg or to L/100 km (or vice versa) involves the use of the reciprocal function, which is not distributive. Therefore, the average of two fuel economy numbers gives different values if those units are used. If two people calculate the fuel economy average of two groups of cars with different units, the group with better fuel economy may be one or the other. The litre or liter (see spelling differences) is a unit of volume. ... â€œkmâ€ redirects here. ... â€œMilesâ€ redirects here. ... The gallon (abbreviation: gal) is a unit of volume. ... The reciprocal function: y = 1/x. ... In mathematics, and in particular in abstract algebra, distributivity is a property of binary operations that generalises the distributive law from elementary algebra. ...

The formula for converting to miles per US gallon (3.785 L) from L/100 km is $frac{235.2}{x}$, where x is value of L/100km. For miles per Imperial gallon (4.546 L) the formula is $frac{282.5}{x}$.

In Europe, the two standard measuring cycles for "L/100 km" value are motorway travel at 90 km/h and rush hour city traffic. A reasonably modern European supermini may manage motorway travel at 5 L/100 km (47 mpg US) or 6.5 L/100 km in city traffic (36 mpg US), with carbon dioxide emissions of around 140 g/km. Motorway symbol in UK, France and Ireland. ... 1996 Volkswagen Polo, a popular modern European supermini A supermini is a European hatchback car category. ... Motorway symbol in UK, France and Ireland. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ...

An average North American mid-size car travels 27 mpg (US) (9 L/100 km) highway, 21 mpg (US) (11 L/100 km) city; a full-size SUV usually travels 13 mpg (US) (18 L/100 km) city and 16 mpg (US) (15 L/100 km) highway. Pickup trucks vary considerably; whereas a 4 cylinder-engined light pickup can achieve 28 mpg (8 L/100 km), a V8 full-size pickup with extended cabin only travels 13 mpg (US) (18 L/100 km) city and 15 mpg (US) (15 L/100 km) highway. North American redirects here. ... A mid-size car, frequently referred to as an intermediate, is an automobile with a size between that of a compact and a full-size or standard-size car. ... 2001 BMW 750iL The Ford Falcon, a popular Australian full-size car A full-size car is a marketing term used in North America for an automobile larger than a mid-size car. ... This article or section may be confusing or unclear for some readers, and should be edited to rectify this. ... The best selling North American pickup truck, the Ford F-Series. ... The Liberty V8 aircraft engine clearly shows the configuration A V8 engine is a V engine with eight cylinders. ...

An interesting example of fuel economy is the microcar Smart Fortwo cdi, which can achieve up to 3.4 L/100 km (69.2 mpg US) using a turbocharged three-cylinder 41 hp (30 kW) Diesel engine. The Fortwo is produced by DaimlerChrysler and is currently only sold by one company in the United States (see external link ZAP). The current record in fuel economy of production cars is held by Volkswagen, with a special production model of the Volkswagen Lupo (the Lupo 3L) that can consume as little as 3 litres per 100 kilometres (78 miles per US gallon or 94 miles per Imperial gallon). The last Lupo was built in July 2005. A Messerschmitt KR200. ... The Fortwo is the original smart model, launched in 1998 as City Coupe. ... Air foil bearing-supported turbocharger cutaway made by Mohawk Innovative Technology Inc. ... DaimlerChrysler AG (ISIN: DE0007100000) is a German car corporation and the worlds eighth largest car manufacturer. ... VW redirects here. ... The Volkswagen Lupo was a city car manufactured by German automaker Volkswagen from 1998 to 2005. ... The litre or liter (see spelling differences) is a unit of volume. ... â€œkmâ€ redirects here. ... U.S. customary units, commonly known in the United States as English units or standard units, are units of measurement that are currently used in the U.S., in some cases alongside units from SI (the International System of Unitsâ€”the modern metric system). ... The gallon (abbreviation: gal) is a unit of volume. ... This article is about post-1824 imperial units, see also English unit, U.S. customary units or Avoirdupois. ...

Diesel engines often achieve greater fuel efficiency than petrol (gasoline) engines. Diesel engines have energy efficiency of 45% and petrol engines of 30%.[2] That is one of the reasons why diesels have better fuel efficiency that equivalent petrol cars. A common margin is 40% more miles per gallon for an efficient turbodiesel. For example, the current model Skoda Octavia, using Volkswagen engines, has a combined European fuel efficiency of 38.2 mpg for the 102 bhp petrol engine and 53.3 mpg for the 105 bhp — and heavier — diesel engine. The higher compression ratio is helpful in raising efficiency, but diesel fuel also contains approximately 10-20% more energy per unit volume than gasoline.[3] Diesel engines in a museum Diesel generator on an oil tanker A diesel engine is an internal combustion engine which operates using the Diesel cycle. ... tytytrtyty This article is about energy efficiency as a ratio. ...

## Fuel efficiency in microgravity

The energy produced from fuels occurs during combustion. However, how well the fuel burns will affect how much energy is produced. Recent research by the National Aeronautics and Space Administration (NASA) has gained possible insights to increasing fuel efficiency if fuel consumption takes place in microgravity. NASA Logo Listen to this article Â· (info) This audio file was created from the revision dated 2005-09-01, and does not reflect subsequent edits to the article. ... Astronauts on the International Space Station display an example of weightlessness Weightlessness is the experience (by people and objects) during freefall, of having no weight. ...

The common distribution of a flame under normal gravity conditions depends on convection, because soot tends to rise to the top of a flame, such as in a candle, making the flame yellow. In microgravity or zero gravity, such as an environment in outer space, convection no longer occurs, and the flame becomes spherical, with a tendency to become more blue and more efficient. There are several possible explanations for this difference, of which the most likely one given is that the cause is the hypothesis that the temperature is evenly distributed enough that soot is not formed and complete combustion occurs.[4] Experiments by NASA in microgravity reveal that diffusion flames in microgravity allow more soot to be completely oxidised after they are produced than diffusion flames on Earth, because of a series of mechanisms that behaved differently in microgravity when compared to normal gravity conditions.[5] Premixed flames in microgravity burn at a much slower rate and more efficiently than even a candle on Earth, and last much longer.[6] Convection in the most general terms refers to the movement of currents within fluids (i. ... Astronauts on the International Space Station display an example of weightlessness Weightlessness is the experience (by people and objects) during freefall, of having no weight. ... Layers of Atmosphere - not to scale (NOAA)[1] Outer space, sometimes simply called space, refers to the relatively empty regions of the universe outside the atmospheres of celestial bodies. ... For other uses, see Sphere (disambiguation). ... A nearly-turbulent diffusion flame. ... The bright conical flames near the jets of a standard household gas stove are the premixed flame front. ...

## Transportation

### Vehicle efficiency and transportation pollution

Main articles: Gas-guzzler and Vehicle Efficiency Initiative

Fuel efficiency directly affects emissions causing pollution and potentially leading to climate change by affecting the amount of fuel used. However, it also depends on the fuel source used to drive the vehicle concerned. Cars can, for example, run on a number of fuel types other than gasoline, such as natural gas, LPG or biofuel or electricity which creates various quantities of atmospheric pollution. A Gas-guzzler commonly refers to a vehicle that gets poor fuel economy. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... Variations in CO2, temperature and dust from the Vostok ice core over the last 450,000 years For current global climate change, see Global warming. ... A Natural gas vehicle or NGV is a vehicle that uses compressed natural gas (CNG) or, less commonly, liquified natural gas (LNG)) as a clean alternative to other automobile fuels. ... LPG might be an initialism or abbreviation for: Liquified petroleum gas Laboratoire de Planetologie, Grenoble, France Literary Press Group of Canada Landwirtschaftliche Produktionsgenossenschaft (German, obsolete/historical) Long period grating This page concerning a three-letter acronym or abbreviation is a disambiguation page â€” a navigational aid which lists other pages that... For articles on specific fuels used in vehicles, see Biogas, Bioethanol, Biobutanol, Biodiesel, and Straight vegetable oil. ...

A kilogram of petrol, diesel, kerosene and the like in a vehicle leads to approximately 3.15 kg of CO2 emissions, or 2.3 kg/L (19 lb/gal). Additional measures to reduce overall emission includes improvements to the efficiency of air conditioners, lights and tires. Carbon dioxide is an atmospheric gas composed of one carbon and two oxygen atoms. ... Note: in the broadest sense, air conditioning can refer to any form of heating, ventilation, and air-conditioning. ...

There is also a growing movement of drivers who practice ways to increase their MPG and save fuel through driving techniques. They are often referred to as hypermilers. Hypermilers have broken records of fuel efficiency, averaging 109 miles per gallon driving a Prius. In non-hybrid vehicles these techniques are also beneficial. Hypermiler Wayne Gerdes can get 59 MPG in a Honda Accord and 30 MPG in an Acura MDX.[7] Hypermilers are drivers who exceed EPA estimated mileage on their vehicles by modifying their driving habits. ... Prius may refer to: Hitachi Flora Prius, a personal computer. ... The Honda Accord is an automobile manufactured by Honda since 1976, debuting as a compact hatchback and evolving into a intermediate vehicle. ... The Acura MDX (Honda MDX in Japan and Australia) is a mid-size luxury crossover SUV produced by the Japanese automaker Acura since the 2001 model year. ...

Hybrid vehicles can conserve petroleum fuel and therefore be more efficient than conventional vehicles. For other types of Hybrid Transportation, see Hybrid (disambiguation)#Transportation. ...

The most efficient machines for converting energy to rotary motion are electric motors, as used in electric vehicles. However, electricity is not a primary energy source so the efficiency of the electricity production has also to be taken into account. Currently railway trains can be powered using electricity, delivered through an additional running rail, overhead catenary system or by onboard generators used in diesel-electric locomotives as common on the UK rail network. Pollution produced from centralised generation of electricity is emitted at a distant power station, rather than "on site". Some railways, such as the french SNCF and swiss federal railways derive most, if not 100% of their current, from hydroelectric or nuclear power stations, therefore atmospheric pollution from their rail networks is very low. This was reflected in a study by AEA Technology between a Eurostar train and airline journeys between London and Paris, which showed the trains on average emitting 10 times less CO2, per passenger, than planes, helped in part by french nuclear generation which, however, creates its own radioactive waste which air flight does not. So only comparing CO2 is misleading. [8]. This can be changed using more renewable sources for electric generation. An electric vehicle is a vehicle that is propelled by electric motors. ... This is the top-level page of WikiProject trains Rail tracks Rail transport refers to the land transport of passengers and goods along railways or railroads. ... For the railroad term see Overhead lines For its use in ring theory, see Catenary ring. ... A number of vehicles use a diesel-electric powerplant for providing locomotion. ... Radioactive wastes are waste types containing radioactive chemical elements that do not have a practical purpose. ... Renewable energy effectively utilizes natural resources such as sunlight, wind, tides and geothermal heat, which are naturally replenished. ... World-wide electricity production for 1980 to 2005. ...

In the future hydrogen cars may be commercially available. Powered either through chemical reactions in a fuel cell that create electricity to drive very efficient electrical motors or by directly burning hydrogen in a combustion engine (near identically to a natural gas vehicle, and similarly compatible with both natural gas and gasoline); these vehicles promise to have near zero pollution from the tailpipe (exhaust pipe). Potentially the atmospheric pollution could be minimal, provided the hydrogen is made by electrolysis using electricity from nonpolluting sources such as solar, wind, or hydroelectricity. One advantage of fuel cell vehicles is that they can electrolyze water using their own fuel cells, operating in exactly the same closed-loop fashion as any other rechargeable electric battery. Sequel, a fuel cell-powered vehicle from General Motors A hydrogen vehicle is a vehicle that uses hydrogen as its on-board fuel for motive power. ... A fuel cell is an electrochemical device similar to a battery, but differing from the latter in that it is designed for continuous replenishment of the reactants consumed; i. ... A Natural gas vehicle or NGV is a vehicle that uses compressed natural gas (CNG) or, less commonly, liquified natural gas (LNG)) as a clean alternative to other automobile fuels. ... In chemistry and manufacturing, electrolysis is a method of separating chemically bonded elements and compounds by passing an electric current through them. ... Hydroelectricity is electricity produced by hydropower. ...

In any process, it is vitally important to account for all of the energy used throughout, i.e., cradle-to-grave. Thus, in addition to the energy cost of the electricity or hydrogen production, we must also account for transmission and/or storage losses to support large-scale use of such vehicles. For this reason the use of the idea "zero pollution" should be avoided.

## References

1. ^ Calculated from heats of formation. Does not correspond exactly to the figure for MJ/L divided by density.
2. ^ http://www.volvo.com/group/global/en-gb/Volvo+Group/ourvalues/environment/products/dieselengines.htm
3. ^ http://www.fusel.com/diesel_engines.html
4. ^ CFM-1 experiment results, National Aeronautics and Space Administration, April 2005.
5. ^ LSP-1 experiment results, National Aeronautics and Space Administration, April 2005.
6. ^ SOFBAL-2 experiment results, National Aeronautics and Space Administration, April 2005.
7. ^ Gaffney, Dennis. "This Guy Can Get 59 MPG in a Plain Old Accord. Beat That, Punk.", Mother Jones, 2007-01-01. Retrieved on 2007-04-20.
8. ^ European Federation for Transport and Environment

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 1st day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 110th day of the year (111th in leap years) in the Gregorian calendar. ...

Results from FactBites:

 Fuel efficiency (353 words) Airlines are aiming for a further 25% fuel efficiency improvement by 2020. In 2000 IATA airlines adopted a voluntary goal and committed to improving their fuel efficiency by 10% between 2000 and 2010. IATA has launched a fuel action campaign and is working with industry partners to reduce fuel requirements and associated emissions.
 Fuel efficiency - Wikipedia, the free encyclopedia (2226 words) Fuel efficiency sometimes means the same as thermal efficiency or fuel economy. But fuel efficiency can also mean the output one gets for a unit amount of fuel input such as "miles per gallon" for an automobile. This last term "liters per 100 km" is also a measure of "fuel economy" where the input is measured by the amount of fuel and the output is measured by the distance travelled.
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