Fuel
is any material that is burned or altered to obtain energy and to heat or to move an object. [1] Fuel releases its energy either through a chemical reaction means, such as combustion, or nuclear means, such as nuclear fission or nuclear fusion. An important property of a useful fuel is that its energy can be stored to be released only when needed, and that the release is controlled in such a way that the energy can be harnessed to produce work. Examples: Methane, Petrol and Oil.
All carbon-based life forms—from microorganisms to animals and humans—depend on and use fuels as their source of energy. Their cells engage in an enzyme-mediated chemical process called metabolism
that converts energy from food or light into a form that can be used to sustain life. [2] Additionally, humans employ a variety of techniques to convert one form of energy into another, producing usable energy for purposes that go far beyond the energy needs of a human body. The application of energy released from fuels ranges from heat to cooking and from powering weapons to combustion and generation of electricity.
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FUEL TICKETS
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Energy sources
A large majority of currently-known fuels ultimately derive their energy from a small number of sources. Much of the chemical energy produced by life forms, such as
fossil fuels, is derived from the utilization of solar energy through
photosynthesis. Solar energy in turn is generated by the
thermonuclear fusion process at the core of the
Sun. The
radioactive isotopes used as fuel to power nuclear plants were formed in
supernova explosions.
Chemical
Chemical fuels are substances that generate energy by reacting with substances around them, most notably by the process of
oxidation. These substances were the first fuels to be known and used by
humans and are still the primary type of fuel used today.
Biofuels
Biofuel can be broadly defined as solid, liquid, or gas fuel consisting of, or derived from
biomass. Biomass can also be used directly for heating or power—known as
biomass fuel
. Biofuel can be produced from any carbon source that can be replenished rapidly e.g. plants. Many different plants and plant-derived materials are used for biofuel manufacture.
Perhaps the earliest fuel that was employed by humans is wood. Evidence shows controlled fire was used up to 1.5 million years ago at
Swartkrans,
South Africa. It is unknown which hominid species first used fire, as both
Australopithecus
and an early species of
Homo
were present at the sites.
[3] As a fuel, wood has remained in use up until the present day, although it has been superseded for many purposes by other sources. Wood has an
energy density of 10–20
MJ/
kg.
[4]
Recently biofuels have been developed for use in automotive transport (for example
E10 fuel), but there is widespread public debate about how carbon efficient these fuels are.
Fossil fuels
Fossil fuels are
hydrocarbons, primarily
coal and
petroleum (
liquid petroleum or
natural gas), formed from the
fossilized remains of dead plants and animals
[5] by exposure to heat and pressure in the
Earth's
crust over hundreds of millions of years
[6]. In common parlance, the term fossil fuel also includes hydrocarbon-containing
natural resources that are not derived entirely from biological sources, such as
tar sands. These latter sources are properly known as
mineral fuels
.
Modern large-scale industrial development is based on fossil fuel use, which has largely supplanted water-driven mills, as well as the combustion of [wood or
peat for heat. With global modernization in the 20th and 21st centuries, the growth in energy production from fossil fuels, especially
gasoline derived from oil, is one of the causes of major regional and global conflicts and environmental issues. A global movement toward the generation of
renewable energy is therefore under way to help meet the increased global energy needs.
The burning of fossil fuels by humans is the largest source of emissions of
carbon dioxide, which is one of the
greenhouse gases that enhances
radiative forcing and contributes to
global warming. The atmospheric concentration of CO
2, a greenhouse gas, is increasing, raising concerns that solar heat will be trapped and the
average surface temperature of the Earth will rise in response.
Nuclear
Nuclear fuel is any material that is consumed to derive
nuclear energy. Technically speaking this definition includes all matter because any element will under the right conditions release nuclear energy, the only materials that are commonly referred to as nuclear fuels though are those that will produce energy without being placed under extreme duress.
Fission
The most common type of nuclear fuel used by humans is heavy
fissile elements that can be made to undergo
nuclear fission chain reactions in a
nuclear fission reactor;
nuclear fuel
can refer to the material or to physical objects (for example fuel bundles composed of
fuel rods) composed of the fuel material, perhaps mixed with structural,
neutron moderating, or neutron reflecting materials. The most common fissile nuclear fuels are
235U and
239Pu, and the actions of mining, refining, purifying, using, and ultimately disposing of these elements together make up the
nuclear fuel cycle, which is important for its relevance to
nuclear power generation and
nuclear weapons.
Fusion
Fuels that produce energy by the process of
nuclear fusion are currently not utilized by man but are the main source of fuel for stars, the most powerful energy sources in nature. Fusion fuels tend to be light elements such as
hydrogen which will combine easily.
In
stars that undergo
nuclear fusion, fuel consists of
atomic nuclei that can release energy by the absorption of a
proton or
neutron. In most stars the fuel is provided by hydrogen, which can combine together to form
helium through the
proton-proton chain reaction or by the
CNO cycle. When the hydrogen fuel is exhausted, nuclear fusion can continue with progressively heavier elements, although the net energy released is lower because of the smaller difference in nuclear binding energy. Once iron-56 or nickel-56 nuclei are produced, no further energy can be obtained by nuclear fusion as these have the highest nuclear binding energies.
[7]
World trade
World Bank reported that the USA was the top fuel importer in 2005 followed by the EU and Japan.
Use over time
The first use of fuel was the combustion of wood or sticks by
Homo erectus
near 2 million years ago.
[8][page # needed] Throughout the majority of human history fuels derived from plants or animal fat were the only ones available for human use.
Charcoal, a wood derivative, has been used since at least 6,000 BCE for smelting metals. It was only supplanted by
coke, derived from coal, as the forests started to become depleted around the 18th century. Charcoal briquettes are now commonly used as a fuel for
barbecue cooking.
[9]
Coal was first used as a fuel around 1000 BCE in
China. With the
development of the
steam engine in 1769, coal came into more common use as a power source. Coal was later used to drive ships and locomotives. By the 19th century, gas extracted from coal was being used for street lighting in
London. In the 20th century, the primary use of coal is for the generation of
electricity, providing 40% of the world's electrical power supply in 2005.
[10]
See also
- Alcohol fuel
- Alternative fuels
- Ammonia
- Battery (electricity)
- Bitumen-based fuel
- Cryogenic fuel
- Fuel cell
- Fuel oil
- Fuel management systems
- Fuel poverty
- Hydrogen economy
- Hydrogen fuel
- Liquid fuels
- List of energy topics
- Marine fuel management
- Propellant
- Solid fuel
- World energy resources and consumption
Footnotes
- Fuels
- "Metabolism," ''Encyclopaedia Britannica'', retrieved August 17, 2006.
- Bones hint at first use of fire
- Chemical Potential Energy
- Canada's Fossil Fuel Dependency
- Fossil fuel
- The atomic nuclide with the highest mean binding energy
- Origin of Humankind
- Charcoal Briquette
- History of Coal Use
References
- Fuels
- "Metabolism," ''Encyclopaedia Britannica'', retrieved August 17, 2006.
- Bones hint at first use of fire
- Chemical Potential Energy
- Canada's Fossil Fuel Dependency
- Fossil fuel
- The atomic nuclide with the highest mean binding energy
- Origin of Humankind
- Charcoal Briquette
- History of Coal Use