Editing Solid fuel

{{Short description|Solid material that can be burnt to release energy}}
[[File:Coal and Fire.JPG|thumb|A fire made of charcoal briquettes]]

'''Solid fuel''' refers to various forms of [[solid]] material that can be burnt to release energy, providing heat and light through the process of [[combustion]]. Solid fuels can be contrasted with [[liquid fuels]] and [[gaseous fuel]]s. Common examples of solid fuels include [[wood fuel|wood]], [[charcoal]], [[peat]], [[coal]], [[hexamine fuel tablet]]s, [[dry dung fuel|dry dung]], [[wood pellets]], [[Maize|corn]], [[wheat]], [[rice]], [[rye]], and other [[cereal|grains]]. Solid fuels are extensively used in [[Solid-fuel rocket|rocketry]] as [[Rocket fuel#Solid chemical propellants|solid propellants]].<ref>{{Cite web|url=http://www.astronautix.com/s/solid.html|archive-url=https://web.archive.org/web/20160815174909/http://www.astronautix.com/s/solid.html|url-status=dead|archive-date=August 15, 2016|title=Solid|website=astronautix.com|access-date=2017-03-09}}</ref> Solid fuels have been used throughout human history to create fire<ref>{{Cite web|date=2012-04-02|title=Evidence that human ancestors used fire one million years ago|url=https://www.sciencedaily.com/releases/2012/04/120402162548.htm|access-date=2017-03-09|website=[[Science Daily]]}}</ref> and solid fuel is still in widespread use throughout the world in the present day.<ref name=":0">{{Cite web|url=https://www.iea.org/about/faqs/coal/|title=Coal|website=iea.org|access-date=2017-03-09}}</ref><ref>{{Cite web|url=http://ec.europa.eu/eurostat/statistics-explained/index.php/Coal_consumption_statistics|title=Coal consumption statistics - Statistics Explained|website=ec.europa.eu|language=en|access-date=2017-03-09}}</ref>

Solid fuel from [[Biomass (energy)|biomass]] is regarded as a [[renewable energy]] source which can contribute to [[climate change mitigation]] efforts. Solid fuel from [[fossil fuel]]s (i.e. [[coal]]) is not a renewable energy.

==Types ==

===Biomass===

Biomass that is used for energy production can be processed into solid fuels but also into liquid or gaseous fuels.<ref name=":3">{{Cite book |url=https://www.worldcat.org/oclc/1137604985 |title=Future energy : improved, sustainable and clean options for our planet |date=2020 |others=T. M. Letcher |isbn=978-0-08-102887-2 |edition=3rd |location=Amsterdam, Netherlands |chapter=Chapter 9: Biofuels for transport |oclc=1137604985}}</ref>{{rp|173}} In comparison, the term [[biofuel]] is nowadays mainly (but not exclusively) used for ''liquid'' or ''gaseous'' fuels, used for transportation.<ref name=":4">The EIA states: "Biofuels are transportation fuels such as ethanol and biodiesel that are made from biomass materials." https://www.eia.gov/energyexplained/index.php?page=biofuel_home</ref>

[[Pellet fuel]]s are made from compressed organic matter or biomass.<ref>{{cite web |title=Biomass Energy |url=http://www.altenergy.org/renewables/biomass.html/ |access-date=16 February 2015 |publisher=Alternate Energy}}</ref> Pellets can be made from any one of five general categories of biomass: industrial waste and co-products, [[food waste]], [[Crop residue|agricultural residues]], [[energy crop]]s, and [[Wood preservation#Chemical|untreated lumber]].<ref>{{cite web |title=Sources of biomass |url=http://www.biomassenergycentre.org.uk/portal/page?_pageid=75,15174&_dad=portal&_schema=PORTAL |url-status=dead |archive-url=https://web.archive.org/web/20160611193224/http://www.biomassenergycentre.org.uk/portal/page?_pageid=75,15174&_dad=portal&_schema=PORTAL |archive-date=11 June 2016 |access-date=16 February 2015 |publisher=BIOMASS Energy Centre}}</ref> Wood pellets are the most common type of pellet fuel.<ref>{{Cite web |date=October 17, 2018 |title=About the Densified Biomass Fuel Report |url=https://www.eia.gov/biofuels/biomass/#about |access-date=October 23, 2018 |website=U.S. EIA}}</ref>{{excerpt|biomass (energy)|paragraphs=1|file=no}}

==== Wood ====
{{Further|Wood fuel}}
Wood fuel can refer to several fuels such as [[firewood]], [[charcoal]], ''wood chips'' sheets, [[Wood pellets|pellets]], and [[sawdust]]. The particular form used depends upon factors such as source, quantity, quality and application. In many areas, wood is the most easily available form of fuel, requiring no [[tool]]s in the case of picking up dead wood, or few tools. Today, [[Combustion|burning]] of wood is the largest use of [[energy]] derived from a solid fuel [[biomass]]. Wood fuel can be used for [[cooking]] and [[heating]], and occasionally for fueling [[steam engine]]s and steam [[turbines]] that [[Electricity generation|generate electricity]]. Wood may be used indoors in a furnace, [[Wood-burning stove|stove]], or [[fireplace]], or outdoors in a furnace, [[campfire]], or [[bonfire]]. As with any [[fire]], burning wood fuel creates numerous by-products, some of which may be useful (heat and steam), and others that are undesirable, irritating or dangerous.

When harvested in a [[sustainable fashion]] wood is usually considered to be a renewable solid fuel ([[renewable energy]]).<ref name="soliftec.com">{{cite web |date=9 February 2014 |title=Solid Fuels |url=http://www.soliftec.com/solidfuels.htm |archive-url=https://web.archive.org/web/20111016185516/http://www.soliftec.com/solidfuels.htm |url-status=usurped |archive-date=October 16, 2011 |access-date=22 June 2015 |publisher=Solid Fuel Technology Institute}}</ref>

There is debate as to whether burning wood can be considered carbon neutral, as technically the wood cannot release more carbon than was sequestered during its growth, although this does not take account of other impacts such as deforestation and rotting has on the [[carbon footprint]].<ref>{{Cite journal |last1=Smith |first1=K.R. |year=1993 |title=Greenhouse gases from biomass and fossil fuel stoves in developing countries: A Manila pilot study |journal=Chemosphere |language=en |volume=26 |issue=1–4 |pages=479–505 |bibcode=1993Chmsp..26..479S |citeseerx=10.1.1.558.9180 |doi=10.1016/0045-6535(93)90440-G}}</ref>

==== Peat ====
{{Further|Peat}}
Peat fuel is an accumulation of partially [[Decomposition|decayed]] [[vegetation]] or organic matter that can be burnt once sufficiently dried. It is used widely in the country districts of [[Ireland]] and [[Scotland]] where alternatives are absent or expensive.{{Citation needed|date=January 2023}} It has a relatively low [[calorific value]], even after essential drying.

===Fossil fuels===

==== Coal ====
{{Further|Coal}}
Coal is a [[combustible]] black or brownish-black [[sedimentary rock]] usually occurring in [[Stratum|rock strata]] in layers or veins called coal beds or coal seams. Throughout history, coal has been used as an energy resource, primarily burned for the production of electricity and heat, and is also used for industrial purposes, such as refining metals. Coal is the largest source of energy for the [[Electricity generation|generation of electricity]] worldwide, as well as one of the largest worldwide  The extraction of coal, its use in energy production and its byproducts are all associated with [[Environmental impact of the coal industry|environmental]] and [[Coal worker's pneumoconiosis|health effects]]. Variations such as smokeless coal can be formed naturally in the form of [[anthracite]], a [[metamorphosed]] type of coal with a very high carbon content that gives off a smokeless flame when set alight. It  is an important type of [[smokeless fuel]].

==== Coke ====
{{Further|Coke (fuel)}}
Coke is a fuel with few impurities and a high [[carbon]] content, usually made from [[coal]]. It is the solid [[carbon]]aceous material derived from [[destructive distillation]] of low-ash, low-sulfur [[bituminous coal]]. Cokes made from coal are grey, hard, and [[porous]]. While coke can be formed naturally, the commonly used form is man-made. The form known as [[petroleum coke]], or pet coke, is derived from oil refinery coker units or other cracking processes.<ref name="soliftec.com" />

==== Smokeless fuel ====
{{Further|Smokeless fuel}}
Solid fuels which produce little smoke or volatiles are made from powdered [[anthracite]] coal and supplied in the form of [[briquettes]] usually for domestic use either in [[stove]]s or open fireplaces. The fuel is replacing coal as a fuel for open fires because of the reduction in particulate emissions and its increased efficiency. Smokeless fuel burns at a higher temperature and more slowly than a coal fire. The term also includes [[charcoal]], made by restricted combustion of dry wood and widely used at open air [[barbecue]]s to cook food on an open fire.

===Solid fuels for special applications===

==== Rocket propellant ====
{{Further|Rocket propellant#Solid chemical propellants}}
Solid rocket propellant consists of a solid oxidizer (such as [[ammonium nitrate]]) bound with flakes or powders of energy compounds (such as [[RDX]]) plus binders, plasticizers, stabilizers, and other additives. Solid propellant is much easier to store and handle than liquid propellant. It also has a higher energy density so it does not require as large of a space for the same amount of stored energy.

==Calorific value==
{{more citations needed|date=January 2023}}
The heat available from each type of fuel is variable, and depends on the [[carbon]] and [[hydrogen]] content, as well as non-combustible or ash and water content. One measure of the heat produced by burning is the [[heat of combustion]], an exact measure usually determined using [[bomb calorimetry]] and demanding complete combustion to carbon dioxide and water.

Gaseous fuels like [[methane]] have higher values than solid fuels like [[coal]]. [[Peat]] exhibits the lowest value of all common fuels. Thus methane has an HHV (Higher heating value) of 55.50 MJ/kg, the highest value of common fuels.

[[Diesel fuel]] has an HHV value of 44.80 MJ/kg and [[anthracite]] coal a value of 32.50 MJ/kg. Moisture and ash-free [[firewood]] has a lower value of  21.70 MJ/kg while dry [[peat]] has the lowest value of all common fuels of about 15.00 MJ/kg.

These are somewhat ideal values and the actual heat realized by any fuel will depend on the [[fireplace]] or [[combustion chamber]] used and its design for example. However they do give a useful guide to the heat available from any fuel. Dry wood has roughly two thirds the [[calorific value]] of coal so a greater weight is needed to make the same amount of heat.

==Cost and transport==
Solid fuels, compared to [[liquid fuel]]s or [[gaseous]] fuels, are often cheaper, easier to extract, more stable to transport and in many places are more readily available.<ref name="nwleics.gov.uk">{{cite web|url=http://www.nwleics.gov.uk/files/documents/guide_to_solid_fuels/solid%255Ffuels%252Epdf.pdf|title=The Guide to Solid Fuels|publisher=Solid Fuel Association|access-date=22 June 2015}}</ref>

[[Coal]], in particular, is utilized in the generation of 38% of the world's [[electricity]] because it is less expensive than its liquid and gas counterparts.<ref name=":0" />

== Damage to health and the environment ==
{{Further||Health and environmental impact of the coal industry}}
Solid fuels require more destructive methods to extract/burn and often have higher carbon, nitrate and sulphate emissions. With the exception of sustainable wood/biomass solid fuel is normally considered non-renewable as it requires thousands of years to form.<ref name=":0" />

Solid fuels are composed of organic materials and can contribute to poor [[Air pollution|air quality]]. The burning of solid fuels releases more organic aerosol<ref>{{Cite journal|last1=Stewart|first1=Gareth J.|last2=Nelson|first2=Beth S.|last3=Acton|first3=W. Joe F.|last4=Vaughan|first4=Adam R.|last5=Farren|first5=Naomi J.|last6=Hopkins|first6=James R.|last7=Ward|first7=Martyn W.|last8=Swift|first8=Stefan J.|last9=Arya|first9=Rahul|last10=Mondal|first10=Arnab|last11=Jangirh|first11=Ritu|date=2021-02-18|title=Emissions of intermediate-volatility and semi-volatile organic compounds from domestic fuels used in Delhi, India|url=http://nora.nerc.ac.uk/id/eprint/528382/1/N528382JA.pdf|journal=Atmospheric Chemistry and Physics|language=English|volume=21|issue=4|pages=2407–2426|doi=10.5194/acp-21-2407-2021|bibcode=2021ACP....21.2407S|issn=1680-7316|doi-access=free}}</ref> than [[liquefied petroleum gas]] and releases many [[volatile organic compound]]s, which can contribute to poor [[Air pollution|air quality]] through the formation of secondary pollutants such as [[ground level ozone]] and [[secondary organic aerosol]].<ref>{{Cite journal|last1=Stewart|first1=Gareth J.|last2=Acton|first2=W. Joe F.|last3=Nelson|first3=Beth S.|last4=Vaughan|first4=Adam R.|last5=Hopkins|first5=James R.|last6=Arya|first6=Rahul|last7=Mondal|first7=Arnab|last8=Jangirh|first8=Ritu|last9=Ahlawat|first9=Sakshi|last10=Yadav|first10=Lokesh|last11=Sharma|first11=Sudhir K.|date=2021-02-18|title=Emissions of non-methane volatile organic compounds from combustion of domestic fuels in Delhi, India|url=http://nora.nerc.ac.uk/id/eprint/528809/1/N528809JA.pdf|journal=Atmospheric Chemistry and Physics|language=English|volume=21|issue=4|pages=2383–2406|doi=10.5194/acp-21-2383-2021|bibcode=2021ACP....21.2383S|issn=1680-7316|doi-access=free}}</ref> The emissions from solid fuels are major drivers of poor [[Air pollution|air quality]] in regions where solid fuels are a dominant [[fuel]] source.<ref>{{Cite web |last=World Health Organization |title=Household air pollution |url=https://www.who.int/news-room/fact-sheets/detail/household-air-pollution-and-health |access-date=2023-01-06 |website= |language=en}}</ref>

==See also==
* [[Biomass briquettes]]
* [[Fossil fuel]]
* [[Hindenburg light]]
* [[Nuclear power]]
* [[Synthetic fuel]]

==References==
{{Reflist}}

==External links==
*{{Commons category-inline|Solid fuels}}

{{Authority control}}

[[Category:Solid fuels| ]]