Solid fuel

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A fire made of charcoal briquettes Coal and Fire.JPG
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 fuels. Common examples of solid fuels include wood, charcoal, peat, coal, hexamine fuel tablets, dry dung, wood pellets, corn, wheat, rice, rye, and other grains. Solid fuels are extensively used in rocketry as solid propellants. [1] Solid fuels have been used throughout human history to create fire [2] and solid fuel is still in widespread use throughout the world in the present day. [3] [4]

Contents

Solid fuel from biomass is regarded as a renewable energy source which can contribute to climate change mitigation efforts. Solid fuel from fossil fuels (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. [5] : 173  In comparison, the term biofuel is nowadays mainly (but not exclusively) used for liquid or gaseous fuels, used for transportation. [6]

Pellet fuels are made from compressed organic matter or biomass. [7] Pellets can be made from any one of five general categories of biomass: industrial waste and co-products, food waste, agricultural residues, energy crops, and untreated lumber. [8] Wood pellets are the most common type of pellet fuel. [9]

This section is an excerpt from Biomass (energy).[ edit ]
Biomass, in the context of energy production, is matter from recently living (but now dead) organisms which is used for bioenergy production. Examples include wood, wood residues, energy crops, agricultural residues including straw, and organic waste from industry and households. [10] Wood and wood residues is the largest biomass energy source today. Wood can be used as a fuel directly or processed into pellet fuel or other forms of fuels. Other plants can also be used as fuel, for instance maize, switchgrass, miscanthus and bamboo. [11] The main waste feedstocks are wood waste, agricultural waste, municipal solid waste, and manufacturing waste. Upgrading raw biomass to higher grade fuels can be achieved by different methods, broadly classified as thermal, chemical, or biochemical.

Wood

Wood fuel can refer to several fuels such as firewood, charcoal, wood chips sheets, 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 tools in the case of picking up dead wood, or few tools. Today, 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 engines and steam turbines that generate electricity. Wood may be used indoors in a furnace, 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). [12]

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. [13]

Peat

Peat fuel is an accumulation of partially 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 ] It has a relatively low calorific value, even after essential drying.

Fossil fuels

Coal

Coal is a combustible black or brownish-black sedimentary rock usually occurring in 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 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 and 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

Coke is a fuel with few impurities and a high carbon content, usually made from coal. It is the solid carbonaceous 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. [12]

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 stoves 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 barbecues to cook food on an open fire.

Solid fuels for special applications

Rocket propellant

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

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 fuels or gaseous fuels, are often cheaper, easier to extract, more stable to transport and in many places are more readily available. [14] [15]

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. [3]

Damage to health and the environment

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. [3]

Solid fuels are composed of organic materials and can contribute to poor air quality. The burning of solid fuels releases more organic aerosol [16] than liquefied petroleum gas and releases many volatile organic compounds, which can contribute to poor air quality through the formation of secondary pollutants such as ground level ozone and secondary organic aerosol. [17] The emissions from solid fuels are major drivers of poor air quality in regions where solid fuels are a dominant fuel source. [18]

See also

Related Research Articles

<span class="mw-page-title-main">Wood gas</span> Syngas fuel created by gasification of biomass

Wood gas is a fuel gas that can be used for furnaces, stoves, and vehicles. During the production process, biomass or related carbon-containing materials are gasified within the oxygen-limited environment of a wood gas generator to produce a combustible mixture. In some gasifiers this process is preceded by pyrolysis, where the biomass or coal is first converted to char, releasing methane and tar rich in polycyclic aromatic hydrocarbons.

<span class="mw-page-title-main">Biofuel</span> Type of biological fuel produced from biomass from which energy is derived

Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels, such as oil. Biofuel can be produced from plants or from agricultural, domestic or industrial biowaste. Biofuels are mostly used for transportation, but can also be used for heating and electricity. Biofuels are regarded as a renewable energy source. The use of biofuel has been subject to criticism regarding the "food vs fuel" debate, sustainability, deforestation, loss of biodiversity, etc.

<span class="mw-page-title-main">Pyrolysis</span> Thermal decomposition of materials at elevated temperatures, often in an inert atmosphere

The pyrolysis process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere.

<span class="mw-page-title-main">Gasification</span> Form of energy conversion

Gasification is a process that converts biomass- or fossil fuel-based carbonaceous materials into gases, including as the largest fractions: nitrogen (N2), carbon monoxide (CO), hydrogen (H2), and carbon dioxide (CO2). This is achieved by reacting the feedstock material at high temperatures (typically >700 °C), without combustion, via controlling the amount of oxygen and/or steam present in the reaction. The resulting gas mixture is called syngas (from synthesis gas) or producer gas and is itself a fuel due to the flammability of the H2 and CO of which the gas is largely composed. Power can be derived from the subsequent combustion of the resultant gas, and is considered to be a source of renewable energy if the gasified compounds were obtained from biomass feedstock.

<span class="mw-page-title-main">Wood fuel</span> Wood used as fuel for combustion

Wood fuel is a fuel such as firewood, charcoal, chips, sheets, 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 tools in the case of picking up dead wood, or few tools, although as in any industry, specialized tools, such as skidders and hydraulic wood splitters, have been developed to mechanize production. Sawmill waste and construction industry by-products also include various forms of lumber tailings.

<span class="mw-page-title-main">Briquette</span> Compressed block of biomass used for fueling a fire

A briquette is a compressed block of coal dust or other combustible biomass material used for fuel and kindling to start a fire. The term derives from the French word brique, meaning brick.

The heating value of a substance, usually a fuel or food, is the amount of heat released during the combustion of a specified amount of it.

<span class="mw-page-title-main">Fuel gas</span> Fuels which under ordinary conditions, are gaseous

Fuel gas is one of a number of fuels that under ordinary conditions are gaseous. Most fuel gases are composed of hydrocarbons, hydrogen, carbon monoxide, or mixtures thereof. Such gases are sources of energy that can be readily transmitted and distributed through pipes.

<span class="mw-page-title-main">Bioenergy</span> Energy made from recently-living organisms

Bioenergy is energy made or generated from biomass, which consists of recently living organisms, mainly plants. Types of biomass commonly used for bioenergy include wood, food crops such as corn, energy crops and waste from forests, yards, or farms. The IPCC defines bioenergy as a renewable form of energy. Bioenergy can either mitigate or increase greenhouse gas emissions. There is also agreement that local environmental impacts can be problematic.

<span class="mw-page-title-main">Pellet fuel</span> Solid fuel made from compressed organic material

Pellet fuels are a type of solid fuel made from compressed organic material. Pellets can be made from any one of five general categories of biomass: industrial waste and co-products, food waste, agricultural residues, energy crops, and untreated lumber. Wood pellets are the most common type of pellet fuel and are generally made from compacted sawdust and related industrial wastes from the milling of lumber, manufacture of wood products and furniture, and construction. Other industrial waste sources include empty fruit bunches, palm kernel shells, coconut shells, and tree tops and branches discarded during logging operations. So-called "black pellets" are made of biomass, refined to resemble hard coal and were developed to be used in existing coal-fired power plants. Pellets are categorized by their heating value, moisture and ash content, and dimensions. They can be used as fuels for power generation, commercial or residential heating, and cooking.

<span class="mw-page-title-main">Waste-to-energy</span> Process of generating energy from the primary treatment of waste

Waste-to-energy (WtE) or energy-from-waste (EfW) is the process of generating energy in the form of electricity and/or heat from the primary treatment of waste, or the processing of waste into a fuel source. WtE is a form of energy recovery. Most WtE processes generate electricity and/or heat directly through combustion, or produce a combustible fuel commodity, such as methane, methanol, ethanol or synthetic fuels, often derived from the product syngas.

Pyrolysis oil, sometimes also known as bio-crude or bio-oil, is a synthetic fuel with limited industrial application and under investigation as substitute for petroleum. It is obtained by heating dried biomass without oxygen in a reactor at a temperature of about 500 °C (900 °F) with subsequent cooling, separation from the aqueous phase and other processes. Pyrolysis oil is a kind of tar and normally contains levels of oxygen too high to be considered a pure hydrocarbon. This high oxygen content results in non-volatility, corrosiveness, partial miscibility with fossil fuels, thermal instability, and a tendency to polymerize when exposed to air. As such, it is distinctly different from petroleum products. Removing oxygen from bio-oil or nitrogen from algal bio-oil is known as upgrading.

<span class="mw-page-title-main">Biomass (energy)</span> Biological material used as a renewable energy source

Biomass, in the context of energy production, is matter from recently living organisms which is used for bioenergy production. Examples include wood, wood residues, energy crops, agricultural residues including straw, and organic waste from industry and households. Wood and wood residues is the largest biomass energy source today. Wood can be used as a fuel directly or processed into pellet fuel or other forms of fuels. Other plants can also be used as fuel, for instance maize, switchgrass, miscanthus and bamboo. The main waste feedstocks are wood waste, agricultural waste, municipal solid waste, and manufacturing waste. Upgrading raw biomass to higher grade fuels can be achieved by different methods, broadly classified as thermal, chemical, or biochemical.

<span class="mw-page-title-main">Biomass heating system</span>

Biomass heating systems generate heat from biomass. The systems may use direct combustion, gasification, combined heat and power (CHP), anaerobic digestion or aerobic digestion to produce heat. Biomass heating may be fully automated or semi-automated they may be pellet-fired, or they may be combined heat and power systems.

<span class="mw-page-title-main">Smokeless fuel</span>

Smokeless fuel is a type of solid fuel which either does not emit visible smoke or emits minimal amounts during combustion. These types of fuel find use where the use of fuels which produce smoke, such as coal and unseasoned or wet wood, is prohibited.

Biogasoline is a type of gasoline produced from biomass such as algae. Like traditionally produced gasoline, it is made up of hydrocarbons with 6 (hexane) to 12 (dodecane) carbon atoms per molecule and can be used in internal combustion engines. However, unlike traditional gasoline/petroleum based fuels, which are mainly composed from oil, biogasolines are made from plants such as beets and sugarcane or cellulosic biomass- substances normally referred to as plant waste.

<span class="mw-page-title-main">Biomass briquettes</span> Fuel source made from green waste

Biomass briquettes are a biofuel substitute made of biodegradable green waste with lower emissions of greenhouses gases and carbon dioxide then traditional fuel sources. This fuel source is used as an alternative for harmful biofuels. Briquettes are used for heating, cooking fuel, and electricity generation usually in developing countries that do not have access to more modern fuel sources. Biomass briquettes have become popular in developed countries due to the accessibility, and eco-friendly impact. The briquettes can be used in the developed countries for producing electricity from steam power by heating water in boilers.

Reactive flash volatilization (RFV) is a chemical process that rapidly converts nonvolatile solids and liquids to volatile compounds by thermal decomposition for integration with catalytic chemistries.

<span class="mw-page-title-main">Fuel</span> Material used to create heat and energy

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.

<span class="mw-page-title-main">Torrefaction</span>

Torrefaction of biomass, e.g., wood or grain, is a mild form of pyrolysis at temperatures typically between 200 and 320 °C. Torrefaction changes biomass properties to provide a better fuel quality for combustion and gasification applications. Torrefaction produces a relatively dry product, which reduces or eliminates its potential for organic decomposition. Torrefaction combined with densification creates an energy-dense fuel carrier of 20 to 21 GJ/ton lower heating value (LHV). Torrefaction makes the material undergo Maillard reactions. Torrefied biomass can be used as an energy carrier or as a feedstock used in the production of bio-based fuels and chemicals.

References

  1. ↑ "Solid". astronautix.com. Archived from the original on August 15, 2016. Retrieved 2017-03-09.
  2. ↑ "Evidence that human ancestors used fire one million years ago". Science Daily . 2012-04-02. Retrieved 2017-03-09.
  3. 1 2 3 "Coal". iea.org. Retrieved 2017-03-09.
  4. ↑ "Coal consumption statistics - Statistics Explained". ec.europa.eu. Retrieved 2017-03-09.
  5. ↑ "Chapter 9: Biofuels for transport". Future energy : improved, sustainable and clean options for our planet. T. M. Letcher (3rd ed.). Amsterdam, Netherlands. 2020. ISBN   978-0-08-102887-2. OCLC   1137604985.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link)
  6. ↑ 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
  7. ↑ "Biomass Energy". Alternate Energy. Retrieved 16 February 2015.
  8. ↑ "Sources of biomass". BIOMASS Energy Centre. Archived from the original on 11 June 2016. Retrieved 16 February 2015.
  9. ↑ "About the Densified Biomass Fuel Report". U.S. EIA. October 17, 2018. Retrieved October 23, 2018.
  10. ↑ "Biomass explained - U.S. Energy Information Administration (EIA)". www.eia.gov. Retrieved 2023-01-24.
  11. ↑ Darby, Thomas. "What Is Biomass Renewable Energy". Real World Energy. Archived from the original on 2014-06-08. Retrieved 12 June 2014.
  12. 1 2 "Solid Fuels". Solid Fuel Technology Institute. 9 February 2014. Retrieved 22 June 2015.
  13. ↑ Smith, K.R. (1993). "Greenhouse gases from biomass and fossil fuel stoves in developing countries: A Manila pilot study". Chemosphere. 26 (1–4): 479–505. Bibcode:1993Chmsp..26..479S. CiteSeerX   10.1.1.558.9180 . doi:10.1016/0045-6535(93)90440-G.
  14. ↑ "The Guide to Solid Fuels" (PDF). Solid Fuel Association. Retrieved 22 June 2015.
  15. ↑ "Guide To Solid Fuel". Coal Products Ltd. Retrieved 22 June 2015.
  16. ↑ Stewart, Gareth J.; Nelson, Beth S.; Acton, W. Joe F.; Vaughan, Adam R.; Farren, Naomi J.; Hopkins, James R.; Ward, Martyn W.; Swift, Stefan J.; Arya, Rahul; Mondal, Arnab; Jangirh, Ritu (2021-02-18). "Emissions of intermediate-volatility and semi-volatile organic compounds from domestic fuels used in Delhi, India" (PDF). Atmospheric Chemistry and Physics. 21 (4): 2407–2426. Bibcode:2021ACP....21.2407S. doi: 10.5194/acp-21-2407-2021 . ISSN   1680-7316.
  17. ↑ Stewart, Gareth J.; Acton, W. Joe F.; Nelson, Beth S.; Vaughan, Adam R.; Hopkins, James R.; Arya, Rahul; Mondal, Arnab; Jangirh, Ritu; Ahlawat, Sakshi; Yadav, Lokesh; Sharma, Sudhir K. (2021-02-18). "Emissions of non-methane volatile organic compounds from combustion of domestic fuels in Delhi, India" (PDF). Atmospheric Chemistry and Physics. 21 (4): 2383–2406. Bibcode:2021ACP....21.2383S. doi: 10.5194/acp-21-2383-2021 . ISSN   1680-7316.
  18. ↑ World Health Organization. "Household air pollution" . Retrieved 2023-01-06.
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