Last edited 18 Aug 2017

Types of fuel



[edit] Introduction

Fuels are materials that react with other substances to release heat by way of chemical or nuclear energy:

  • Substances that react with other proximate substances to release energy, through the process of combustion, are known as chemical fuels. These are divided both by their physical properties (as a solid, liquid, or gas), and by how they occur (as a primary or natural fuel, or as a secondary or artificial fuel).
  • Substances that can release nuclear energy by fission or fusion, are known as nuclear fuels.

Humans first used wood as a fuel for combustion nearly 2 million years ago. The most common fuel sources today are hydrocarbons.

[edit] Solid fuel

Solid materials can be used as fuel to burn and release energy through combustion, which provides heat and light. The most common examples of solid fuels are:

  • Wood: Includes firewood, charcoal, woodchips, pellets, sawdust, and so on.
  • Charcoal: Produced by heating wood in the absence of oxygen.
  • Biomass: Natural plant materials, such as wheat, straw and other fibrous material.
  • Peat: Organic matter and decayed vegetation that can be burned when dry.
  • Coal: Combustible sedimentary rock.
  • Coke: High-carbon material derived from coal.
  • Waste: Everyday waste can be converted to a fuel source as long as it does not contain toxic materials.

[edit] Liquid fuel

Liquids can be used to create mechanical energy, although it is the fumes rather than the fluid of liquid fuels that is flammable. Fossil fuels account for the majority of liquid fuels.

[edit] Petroleums

The most common type of liquid fuel is petroleum, formed from dead plants and animals. Examples of petroleum include:

  • Gasoline/petrol: Produced by removing crude oil from petroleum and distilling it in refineries.
  • Diesel: A mixture of aliphatic hydrocarbons extracted from petroleum, and processed to reduce the sulphur level.
  • Kerosene: Extracted from petroleum.

[edit] Natural gas and liquefied petroleum gas

Natural gas can be compressed to a liquid and is much 'cleaner' than other hydrocarbon fuels. However, to maintain the fuel in a liquid state it requires a constant high pressure.

Liquefied petroleum gas (LPG) is a mixture of propane and butane, and is more easily compressed than natural gas.

[edit] Biodiesel

This is a diesel fuel based on vegetable oil or animal fat, although it yields around 10% less energy than conventional diesel.

[edit] Alcohols

The most common types of alcohol fuels are:

  • Methanol: Produced from methane, methanol is the lightest and simplest form of alcohol.
  • Ethanol: Most commonly found in drinks, but can be combined with gasoline for use as a fuel.
  • Butanol: Usually produced by fermenting biomass using bacteria, butanol has a high energy content.

[edit] Hydrogen

Liquefied hydrogen is commonly used as liquid rocket fuel. Large volumes of hydrogen are required for successful combustion.

[edit] Gaseous fuel

Gaseous fuels are distributed through pipes from point of origin to point of use, although some are liquefied for storage. Odorisers are often added to fuel gases so that they can be detected, since an undetected build up of gas can lead to an explosion.

Natural gas (composed mainly of methane) is the most commonly used type, but there are numerous manufactured fuel gases, such as:

  • Coal gas: Derived from coal.
  • Water gas: A mixture of carbon monoxide and hydrogen produced from synthetic gas.
  • Syngas: Synthetic gas consisting of hydrogen, carbon monoxide, and often carbon dioxide.
  • Biogas: A mixture of gases derived from organic matter breaking down in the absence of oxygen.
  • Blast furnace gas: Derived from the manufacture of metallic iron in blast furnaces.

[edit] Calorific values of fuels

The calorific value of a fuel is the total energy released as heat when the substance undergoes combustion. In 2015, the Department for Business, Energy and Industrial Strategy published updated data on the average calorific values of fuels.

Coal 25.7 27
Coke 29.8 29.8
Wood (domestic) 14.7 16.3
Wood (industrial) 19 20.3
Biodiesel 37.2 38.7
Bioethanol 26.8 29.7
Crude oil 43.4 45.7
Petroleum products 43.9 46.2
Ethane 46.6 50.7
Butane and propane (LPG) 46 49.3

For the full list, see

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