Fuel

A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but has since also been applied to other sources of heat energy, such as nuclear energy (via nuclear fission and nuclear fusion).

The heat energy released by reactions of fuels can be converted into mechanical energy via a heat engine. Other times, the heat itself is valued for warmth, cooking, or industrial processes, as well as the illumination that accompanies combustion. Fuels are also used in the cells of organisms in a process known as cellular respiration, where organic molecules are oxidized to release usable energy. Hydrocarbons and related organic molecules are by far the most common source of fuel used by humans, but other substances, including radioactive metals, are also utilized.

Fuels are contrasted with other substances or devices storing potential energy, such as those that directly release electrical energy (such as batteries and capacitors) or mechanical energy (such as flywheels, springs, compressed air, or water in a reservoir).

History

The first known use of fuel was the combustion of firewood by Homo erectus nearly two million years ago.^{[citation needed]} Throughout most of human history only fuels derived from plants or animal fat were used by humans. Charcoal, a wood derivative, has been used since at least 6,000 BCE for melting metals. It was only supplanted by coke, derived from coal, as European forests started to become depleted around the 18th century. Charcoal briquettes are now commonly used as a fuel for barbecue cooking.^{[citation needed]}

With the development of the steam engine in the United Kingdom in 1769, coal came into more common use, the combustion of which releases chemical energy that can be used to turn water into steam.^[5] 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 and 21st centuries, the primary use of coal is to generate electricity, providing 40% of the world's electrical power supply in 2005.^[6]

Fossil fuels were rapidly adopted during the

Chemical fuels are substances that release energy by reacting with substances around them, most notably by the process of combustion.

Chemical fuels are divided in two ways. First, by their physical properties, as a solid, liquid or gas. Secondly, on the basis of their occurrence: primary (natural fuel) and secondary (artificial fuel). Thus, a general classification of chemical fuels is:

Solid fuel

Solid fuel refers to various types of

Liquid fuels

Liquid fuels are combustible or energy-generating molecules that can be harnessed to create mechanical energy, usually producing kinetic energy. They must also take the shape of their container; the fumes of liquid fuels are flammable, not the fluids.

Most liquid fuels in widespread use are derived from the

Some common properties of liquid fuels are that they are easy to transport and can be handled easily. They are also relatively easy to use for all engineering applications and in home use. Fuels like kerosene are rationed in some countries, for example in government-subsidized shops in India for home use.

Conventional

• 
  Locomotive diesel
• 
  Gasoline
• 
  Kerosene
• 
  Petroleum based motor oil
• 
  Residual fuel oil or

  Bunker C oil

Fuel gas

Fuel gas is any one of a number of fuels that are

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 employed by humans is wood. Evidence shows controlled fire was used up to 1.5 million years ago at

Fossil fuels are

Fossil fuels contain high percentages of carbon and include coal, petroleum, and natural gas.^[12] They range from

Nuclear fuel is any material that is consumed to derive nuclear energy. In theory, a wide variety of substances could be a nuclear fuel, as they can be made to release nuclear energy under the right conditions. However, the materials commonly referred to as nuclear fuels are those that will produce energy without being placed under extreme duress. Nuclear fuel can be "burned" by nuclear fission (splitting nuclei apart) or fusion (combining nuclei together) to derive nuclear energy. "Nuclear fuel" can refer to the fuel itself, or to physical objects (for example bundles composed of fuel rods) composed of the fuel material, mixed with structural, neutron moderating, or neutron-reflecting materials.

Nuclear fuel has the highest energy density of all practical fuel sources.

Fission

The most common type of nuclear fuel used by humans is heavy

When some of these fuels are struck by neutrons, they are in turn capable of emitting neutrons when they break apart. This makes possible a self-sustaining chain reaction that releases energy at a controlled rate in a nuclear reactor, or at a very rapid uncontrolled rate in a nuclear weapon.

The most common fissile nuclear fuels are

In contrast to fission, some light nuclides such as tritium (³H) can be used as fuel for nuclear fusion. This involves two or more nuclei combining into larger nuclei. Fuels that produce energy by this method are currently not utilized by humans, but they are the main source of fuel for stars. Fusion fuels are light elements such as hydrogen whose nucleii will combine easily. Energy is required to start fusion by raising the temperature so high that nuclei can collide together with enough energy that they stick together before repelling due to electric charge. This process is called fusion and it can give out energy.

In stars that undergo nuclear fusion, fuel consists of

Liquid fuels for transportation

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Most transportation fuels are liquids, because vehicles usually require high energy density. This occurs naturally in liquids and solids. High energy density can also be provided by an internal combustion engine. These engines require clean-burning fuels. The fuels that are easiest to burn cleanly are typically liquids and gases. Thus, liquids meet the requirements of being both energy-dense and clean-burning. In addition, liquids (and gases) can be pumped, which means handling is easily mechanized, and thus less laborious. As there is a general movement towards a low carbon economy, the use of liquid fuels such as hydrocarbons is coming under scrutiny.

See also

Footnotes

Works cited

• ISBN 978-1-107-05799-9.. AR5 Climate Change 2013: The Physical Science Basis — IPCC
  • IPCC (2013). "Summary for Policymakers" (PDF). IPCC AR5 WG1 2013
    .
• IPCC (2018). Masson-Delmotte, V.; Zhai, P.; Pörtner, H.-O.; Roberts, D.; et al. (eds.). Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty (PDF). Intergovernmental Panel on Climate Change. Global Warming of 1.5 °C —
  .
  • Allen, M. R.; Dube, O. P.; Solecki, W.; Aragón-Durand, F.; et al. (2018). "Chapter 1: Framing and Context" (PDF). IPCC SR15 2018. pp. 49–91.

References

• Ratcliff, Brian; et al. (2000). Chemistry 1. Cambridge University press.
  ISBN 978-0-521-78778-9
  .

Further reading

Wikimedia Commons has media related to Fuels.

• "Directive 1999/94/EC of the European Parliament and of the council of 13 December 1999, relating to the availability of consumer information on fuel economy and CO2 emissions in respect of the marketing of new passenger cars" (PDF). (140 KB).
• Council Directive 80/1268/EEC Fuel consumption of motor vehicles.