View source for Energy density

{{Short description|Energy per volume}}
{{About|energy per unit volume|energy per unit mass|Specific energy}}
{{Infobox physical quantity
| name = Energy density
| unit = [[joule|J]]/[[meter|m]]<sup>3</sup>
| otherunits = J/L, W⋅h/L
| basequantities = m<sup>−1</sup>⋅kg⋅s<sup>−2</sup>
| symbols =
| derivations = ''U'' = [[energy|''E'']]/[[volume|''V'']]
| dimension = wikidata
}}
In [[physics]], '''energy density''' is the amount of [[energy]] stored in a given system or region of space per unit [[volume]]. It is sometimes confused with energy per unit [[mass]] which is properly called ''[[specific energy]]'' or {{em|gravimetric energy density}}.

Often only the ''useful'' or extractable energy is measured, which is to say that inaccessible energy (such as [[rest mass]] energy) is ignored.<ref>{{cite journal|url=http://physics.nist.gov/Pubs/SP811/sec04.html |title=The Two Classes of SI Units and the SI Prefixes |journal=NIST Guide to the SI |access-date=2012-01-25|date=2009-07-02 }}</ref> In [[physical cosmology|cosmological]] and other [[general relativity|general relativistic]] contexts, however, the energy densities considered are those that correspond to the elements of the [[stress–energy tensor|stress-energy tensor]] and therefore do include mass energy as well as energy densities associated with [[pressure]].

Energy per unit volume has the same physical units as pressure and in many situations is [[synonym|synonymous]]. For example, the energy density of a magnetic field may be expressed as and behaves like a physical pressure. Likewise, the energy required to compress a gas to a certain volume may be determined by multiplying the difference between the gas pressure and the external pressure by the change in volume. A [[pressure gradient]] describes the [[potential energy|potential]] to perform [[Work (physics)|work]] on the surroundings by converting [[internal energy]] to work until equilibrium is reached.

==Overview==

There are different types of energy stored in materials, and it takes a particular type of reaction to release each type of energy. In order of the typical magnitude of the energy released, these types of reactions are: [[Nuclear power|nuclear]], [[Chemical energy|chemical]], [[Electrochemistry|electrochemical]], and [[electrical]].

[[Nuclear reaction]]s take place in stars and nuclear power plants, both of which derive energy from the binding energy of nuclei. [[Chemical reaction]]s are used by organisms to derive energy from food and by automobiles to derive energy from gasoline. Liquid hydrocarbons (fuels such as gasoline, diesel and kerosene) are today the densest way known to economically store and transport chemical energy at a large scale (1&nbsp;kg of diesel fuel burns with the oxygen contained in ≈15&nbsp;kg of air). [[Electrochemical reaction]]s are used by most mobile devices such as laptop computers and mobile phones to release energy from batteries.

===Types of energy content===
There are several different types of energy content. One is the theoretical total amount of [[thermodynamic work]] that can be derived from a system, at a given temperature and pressure imposed by the surroundings. This is called [[exergy]]. Another is the theoretical amount of electrical energy that can be derived from [[reactant]]s that are at room temperature and atmospheric pressure. This is given by the change in standard [[Gibbs free energy]]. But as a source of [[heat]] or for use in a [[heat engine]], the relevant quantity is the change in standard [[enthalpy]] or the [[heat of combustion]].

There are two kinds of heat of combustion:
* The higher value (HHV), or gross heat of combustion, includes all the heat released as the products cool to room temperature and whatever water vapor is present condenses.
* The lower value (LHV), or net heat of combustion, does not include the heat which could be released by condensing water vapor, and may not include the heat released on cooling all the way down to room temperature.

A convenient table of HHV and LHV of some fuels can be found in the references.<ref name="engineeringtoolbox">{{cite web|url=https://www.engineeringtoolbox.com/fossil-fuels-energy-content-d_1298.html |title=Fossil and Alternative Fuels - Energy Content (2008).|publisher=Engineering ToolBox |access-date=2018-10-08}}</ref>

==In energy storage and fuels==
[[File:Energy density.svg|thumb|400px|Selected energy densities plot<ref name=tzar2 /><ref name=tzar3 /><ref name=tzar4 /><ref name="fisher">{{cite web
| url=https://hypertextbook.com/facts/2003/JuliyaFisher.shtml
| title=Energy density of coal
| first=Julia
| last=Fisher
| year=2003
| website=The Physics Factbook
| editor-last=Elert
| editor-first=Glenn
| accessdate=2019-07-28}}</ref><ref name=tzar6 /><ref name=tzar7 /><ref name=tzar8 />]]

In [[energy storage]] applications the energy density relates the [[energy]] in an energy store to the volume of the storage facility, e.g. the [[fuel]] tank. The higher the energy density of the fuel, the more energy may be stored or transported for the same amount of volume. Given the high energy density of gasoline, the exploration of alternative media to store the energy of powering a car, such as hydrogen or battery, is strongly limited by the energy density of the alternative medium.  The same mass of lithium-ion storage, for example, would result in a car with only 2% the range of its gasoline counterpart.  If sacrificing the range is undesirable, it becomes necessary to carry that much more fuel.  

The energy density of a fuel per unit mass is called the [[specific energy]] of that fuel. In general an [[engine]] using that fuel will generate less [[kinetic energy]] due to [[inefficiency|inefficiencies]] and [[thermodynamics|thermodynamic]] considerations—hence the [[Thrust specific fuel consumption|specific fuel consumption]] of an engine will always be greater than its rate of production of the kinetic energy of motion.

Energy density differs from [[energy conversion efficiency]] (net output per input) or [[embodied energy]] (the energy output costs to provide, as [[energy industry|harvesting]], [[Oil refinery|refining]], distributing, and dealing with [[pollution]] all use energy). Large scale, intensive energy use impacts and is impacted by [[climate]], [[nuclear waste|waste storage]], and [[deforestation|environmental consequences]].

No single energy storage method boasts the best in [[Power-to-weight ratio|specific power]], [[specific energy]], and energy density. [[Peukert's law]] describes how the amount of useful energy that can be obtained (for a lead-acid cell) depends on how quickly it is pulled out.

Alternative options are discussed for energy storage to increase energy density and decrease charging time.<ref>{{cite journal|last1=Ionescu-Zanetti|first1=C.|last2=et.|first2=al.|s2cid=120910476|title=Nanogap capacitors: Sensitivity to sample permittivity changes|journal=Journal of Applied Physics|date=2005|volume=99|issue=2|pages=024305–024305–5|doi=10.1063/1.2161818|bibcode=2006JAP....99b4305I}}</ref><ref>{{cite journal|last1=Naoi|first1=K.|last2=et.|first2=al.|title=New generation "nanohybrid supercapacitor".|journal=Accounts of Chemical Research|volume=46|issue=5|pages=1075–1083|date=2013|doi=10.1021/ar200308h|pmid=22433167}}</ref><ref>{{cite journal|last1=Hubler|first1=A.|last2=Osuagwu|first2=O.|s2cid=6994736|title=Digital quantum batteries: Energy and information storage in nanovacuum tube arrays|journal=Complexity|date=2010|volume=15|issue=5|pages=NA|doi=10.1002/cplx.20306|doi-access=free}}</ref><ref>{{cite journal|last1=Lyon|first1=D.|last2=et.|first2=al.|title=Gap size dependence of the dielectric strength in nano vacuum gaps|journal=[[IEEE Transactions on Dielectrics and Electrical Insulation]]|date=2013|volume=2|issue=4|pages=1467–1471|doi=10.1109/TDEI.2013.6571470|s2cid=709782}}</ref>

The figure above shows the [[gravimetric]] and [[volumetric]] energy density of some fuels and storage technologies (modified from the [[Gasoline]] article).

Some values may not be precise because of [[isomers]] or other irregularities.  See [[Heating value]] for a comprehensive table of specific energies of important fuels.

Generally the density values for chemical fuels do not include the weight of the oxygen required for combustion. The [[atomic weight|atomic weights]] of carbon and oxygen are similar, while hydrogen is much lighter. Figures are presented in this way for those fuels where in practice air would only be drawn in locally to the burner. This explains the apparently lower energy density of materials that contain their own oxidizer (such as gunpowder and TNT), where the mass of the oxidizer in effect adds weight, and absorbs some of the energy of combustion to dissociate and liberate oxygen to continue the reaction. This also explains some apparent anomalies, such as the energy density of a sandwich appearing to be higher than that of a stick of dynamite.

==List of material energy densities==
{{self-contradictory|Too many disparate sources yield apples-to-oranges values. We should explain why TNT is ''below'' household waste and metallic zinc|date=April 2019}}
{{unreliable sources|section|date=February 2020}}
{{See also|Energy density Extended Reference Table}}
The following unit conversions may be helpful when considering the data in the tables: 3.6&nbsp;[[Joule|MJ]] = 1&nbsp;[[Kilowatt hour|kW⋅h]] ≈ 1.34&nbsp;[[Horsepower-hour|hp⋅h]]. Since 1 J = 10<sup>−6</sup> MJ and 1 m<sup>3</sup> = 10<sup>3</sup> L, divide [[joule]]/[[metre|m]]<sup>3</sup> by 10'''<sup>9</sup>''' to get [[Joule|MJ]]/[[Liter|L]] = GJ/m<sup>3</sup>. Divide MJ/L by 3.6 to get [[kW⋅h]]/L.

=== In chemical reactions (oxidation) ===
{{See also|Energy content of biofuel|Food energy}}
Unless otherwise stated, the values in the following table are [[lower heating value]]s for [[Combustion|perfect combustion]], not counting oxidizer mass or volume. When used to produce electricity in a [[fuel cell]] or to do [[Work (physics)|work]], it is the [[Gibbs free energy]] of reaction (Δ''G'') that sets the theoretical upper limit. If the produced {{H2O}} is vapor, this is generally greater than the lower heat of combustion, whereas if the produced {{chem|H|2|O}} is liquid, it is generally less than the higher heat of combustion. But in the most relevant case of hydrogen, Δ''G'' is 113&nbsp;MJ/kg if water vapor is produced, and 118&nbsp;MJ/kg if liquid water is produced, both being less than the lower heat of combustion (120&nbsp;MJ/kg).<ref>[[CRC Handbook of Chemistry and Physics]], 49th Edition, page D-42.</ref>
{{Table alignment}}
{| class="wikitable sortable defaultright col1left col6left"
|+ Energy released by chemical reactions (oxidation)
! Material
! data-sort-type="number" | Specific energy<br />(MJ/kg)
! data-sort-type="number" | Energy density<br />(MJ/L)
! data-sort-type="number" | Specific energy<br />([[W⋅h/kg]])
! data-sort-type="number" | Energy density<br />(W⋅h/L)
! Comment
|-
| [[Liquid hydrogen|Hydrogen, liquid]]
| data-sort-value="119.93" | 141.86&nbsp;([[Heat of combustion#Higher heating value|HHV]])<br />119.93&nbsp;([[Heat of combustion#Lower heating value|LHV]])
| data-sort-value="8.491" | 10.044&nbsp;(HHV)<br />8.491&nbsp;(LHV)
| data-sort-value="33,313.9" | <span style="display:none">39,405.6</span>39,405.6&nbsp;(HHV)<br />33,313.9&nbsp;(LHV)
| data-sort-value="2,358.6" | 2,790.0&nbsp;(HHV)<br />2,358.6&nbsp;(LHV)
|Energy figures apply '''after''' reheating to 25&nbsp;°C.<ref name="H2">College of the Desert, “Module 1, Hydrogen Properties”, Revision 0, December 2001 [http://energy.gov/sites/prod/files/2014/03/f12/fcm01r0.pdf Hydrogen Properties]. Retrieved 2014-06-08.</ref>
See note above about use in fuel cells.
|-
| [[Compressed hydrogen|Hydrogen, gas]] (681&nbsp;atm, 69&nbsp;MPa, 25&nbsp;°C)
| data-sort-value="119.93" | 141.86&nbsp;(HHV)<br />119.93&nbsp;(LHV)
| data-sort-value="4.500" | 5.323&nbsp;(HHV)<br />4.500&nbsp;(LHV)
| data-sort-value="33,313.9" | <span style="display:none">39,405.6</span>39,405.6&nbsp;(HHV)<br />33,313.9&nbsp;(LHV)
| data-sort-value="1,250.0" | 1,478.6&nbsp;(HHV)<br />1,250.0&nbsp;(LHV)
|Date from same reference as for liquid hydrogen.<ref name="H2" />
High-pressure tanks weigh much more than the hydrogen they can hold. The hydrogen may be around 5.7% of the total mass,<ref name=GCCspecs>{{cite web|url=http://www.greencarcongress.com/2014/11/20141118-mirai.html|title=Toyota FCV Mirai launches in LA; initial TFCS specs; $57,500 or $499 lease; leaning on Prius analogy |author=Mike Millikin|publisher=Green Car Congress|date=2014-11-18|access-date=2014-11-23}}</ref> giving just 6.8 MJ per kg total mass for the LHV.

See note above about use in fuel cells.
|-
| [[Gaseous hydrogen|Hydrogen, gas]] ({{cvt|1|atm|kPa|1|lk=in|disp=or}}, 25&nbsp;°C)
| data-sort-value="119.93" | 141.86&nbsp;(HHV)<br />119.93&nbsp;(LHV)
| data-sort-value="0.01005" | 0.01188&nbsp;(HHV)<br />0.01005&nbsp;(LHV)
| data-sort-value="33,313.9" | <span style="display:none">39,405.6</span>39,405.6&nbsp;(HHV)<br />33,313.9&nbsp;(LHV)
| data-sort-value="2.8" | 3.3&nbsp;(HHV)<br />2.8&nbsp;(LHV)
|<ref name="H2" />
|-
| [[Methane]] (101.3&nbsp;kPa, 15&nbsp;°C)
| 55.6
| data-sort-value="0.0378" | 0.0378
| 15,444.5
| 10.5
|
|-
| [[Liquefied natural gas|LNG]] (NG at −160&nbsp;°C)
| data-sort-value="53.6" | 53.6<ref name="ngau" />
| data-sort-value="22.2" | 22.2
| 14,888.9
| 6,166.7
|
|-
| [[Compressed natural gas|CNG]] (NG compressed to 247&nbsp;atm, 25&nbsp;MPa ≈ {{val|3600|fmt=commas|u=psi}})
| data-sort-value="53.6" | 53.6<ref name="ngau" />
| data-sort-value="9" | 9
| 14,888.9
| 2,500.0
|
|-
| [[Natural gas]]
| data-sort-value="53.6" | 53.6<ref name="ngau">Envestra Limited. [http://www.natural-gas.com.au/about/references.html Natural Gas] {{webarchive|url=https://web.archive.org/web/20081010202138/http://www.natural-gas.com.au/about/references.html |date=2008-10-10 }}. Retrieved 2008-10-05.</ref>
| data-sort-value="0.0364" | 0.0364
| 14,888.9
| 10.1
|
|-
| [[Liquefied petroleum gas|LPG]] [[propane]]
| 49.6
| data-sort-value="25.3" | 25.3
| 13,777.8
| 7,027.8
|<ref name="IOR">IOR Energy. [https://web.archive.org/web/20100825042309/http://www.ior.com.au/ecflist.html List of common conversion factors (Engineering conversion factors)]. Retrieved 2008-10-05.</ref>
|-
| [[Liquefied petroleum gas|LPG]] [[butane]]
| 49.1
| data-sort-value="27.7" | 27.7
| 13,638.9
| 7,694.5
|<ref name="IOR" />
|-
| [[Gasoline|Gasoline (petrol)]]
| 46.4
| data-sort-value="34.2" | 34.2
| 12,888.9
| 9,500.0
|<ref name="IOR" />
|-
| [[Polypropylene]] plastic
| data-sort-value="46.4" | 46.4<ref name="aquafoam" />
| 41.7
| 12,888.9
| 11,583.3
|
|-
| [[Polyethylene]] plastic
| data-sort-value="46.3" | 46.3<ref name="aquafoam">{{cite web |url=http://www.aquafoam.com/papers/selection.pdf |title=ALTERNATE DAILY COVER MATERIALS AND SUBTITLE D - THE SELECTION TECHNIQUE |author=Paul A. Kittle, Ph.D. |access-date=2012-01-25 |archive-url=https://web.archive.org/web/20080527234629/http://www.aquafoam.com/papers/selection.pdf |archive-date=2008-05-27 |url-status=dead }}</ref>
| 42.6
| 12,861.1
| 11,833.3
|
|-
| Residential [[heating oil]]
| 46.2
| data-sort-value="37.3" | 37.3
| 12,833.3
| 10,361.1
|<ref name="IOR" />
|-
| [[Diesel fuel]]
| 45.6
| data-sort-value="38.6" | 38.6
| 12,666.7
| 10,722.2
|<ref name="IOR" />
|-
| [[100LL]] [[Avgas]]
| data-sort-value="44.0" | 44.0<ref>{{cite web|url=http://www-static.shell.com/static/aus/downloads/aviation/avgas_100ll_pds.pdf |title=537.PDF |date=June 1993 |access-date=2012-01-25}}</ref>
| 31.59
| 12,222.2
| 8,775.0
|
|-
| [[Jet fuel]] (e.g. [[kerosene]])
| data-sort-value="42.8" | 43<ref>{{cite web
| url=https://hypertextbook.com/facts/2003/EvelynGofman.shtml
| title=Energy density of aviation fuel
| first=Evelyn
| last=Gofman
| year=2003
| website=The Physics Factbook
| editor-last=Elert
| editor-first=Glenn
| access-date=2019-07-28
}}</ref><ref>{{cite web
 |title=Handbook of Products 
 |publisher=Air BP 
 |url=http://www.bp.com/liveassets/bp_internet/aviation/air_bp/STAGING/local_assets/downloads_pdfs/a/air_bp_products_handbook_04004_1.pdf 
 |url-status=dead 
 |archive-url=https://web.archive.org/web/20110608075828/http://www.bp.com/liveassets/bp_internet/aviation/air_bp/STAGING/local_assets/downloads_pdfs/a/air_bp_products_handbook_04004_1.pdf 
 |archive-date=2011-06-08 
 |pages=11–13 
}}
</ref><ref>{{Citation |url=http://ftp.nirb.ca/01-SCREENINGS/COMPLETED%20SCREENINGS/2016/16XN003-GN-CGS-Tank%20Farm%20Expansion/01-APPLICATION/160204-16XN003-Petroleum%20Products%20Strored%20and%20Dispensed-IA2E.pdf |archive-url=https://web.archive.org/web/20170116182103/http://ftp.nirb.ca/01-SCREENINGS/COMPLETED%20SCREENINGS/2016/16XN003-GN-CGS-Tank%20Farm%20Expansion/01-APPLICATION/160204-16XN003-Petroleum%20Products%20Strored%20and%20Dispensed-IA2E.pdf |url-status=dead |archive-date=16 January 2017 |access-date=15 January 2017 |title=Characteristics of Petroleum Products Stored and Dispensed |page=132 |publisher=Petroleum Products Division - GN }}</ref>
| 35<!-- 43 * .82 -->
|11,944.4
|9,722.2
|Aircraft engine
|-
| [[Gasohol]] E10 (10% ethanol 90% gasoline by volume)
| 43.54
| data-sort-value="33.18" | 33.18
| 12,094.5
| 9,216.7
|
|-
| [[Lithium]]
| 43.1
| 23.0
| 11,972.2
| 6,388.9
|
|-
| [[Biodiesel]] oil (vegetable oil)
| 42.20
| data-sort-value="33" | 33
| 11,722.2
| 9,166.7
|
|-
| [[2,5-Dimethylfuran|DMF]] (2,5-dimethylfuran)
| data-sort-value="42" | 42<ref>{{cite journal|last1=Román-Leshkov|first1=Yuriy|last2=Barrett|first2=Christopher J.|last3=Liu|first3=Zhen Y.|last4=Dumesic|first4=James A.|title=Production of dimethylfuran for liquid fuels from biomass-derived carbohydrates|journal=[[Nature (journal)|Nature]]|date=21 June 2007|volume=447|issue=7147|pages=982–985|doi=10.1038/nature05923|pmid=17581580|bibcode=2007Natur.447..982R|s2cid=4366510}}</ref>
| 37.8
| 11,666.7
| 10,500.0
|{{Clarify|date=February 2009|need a quote from the cite containing "42" and "37.8" or equivalent in W⋅h/kg and W⋅h/L}}
|-
| [[Paraffin wax]]
| 42<ref>{{Cite journal|last=Wiener|first=Harry|date=January 1947|title=Structural Determination of Paraffin Boiling Points|url=https://pubs.acs.org/doi/pdf/10.1021/ja01193a005|journal=Journal of the American Chemical Society|volume=69|issue=1|pages=17–20|doi=10.1021/ja01193a005|pmid=20291038|issn=0002-7863}}</ref>
| data-sort-value="37.8" | 37.8
| data-sort-value="11700" | 11,700
| data-sort-value="10500" | 10,500
|
|-
| [[Crude oil]] ([[tonne of oil equivalent]])
| 41.868
| data-sort-value="37" | 37<ref name="ngau" />
| 11,630
| 10,278
|
|-
| [[Polystyrene]] plastic
| data-sort-value="41.4" | 41.4<ref name="aquafoam" />
| 43.5
| 11,500.0
| 12,083.3
|
|-
| [[Fatty acid|Body fat]]
| 38
| data-sort-value="35" | 35
| 10,555.6
| 9,722.2
|[[Fatty acid metabolism|Metabolism in human body]] (22% efficiency<ref name="JLE5">{{cite web|url=http://www.ebikes.ca/documents/Ebike_Energy.pdf|title=The Energy Cost of Electric and Human-Powered Bicycles|author=Justin Lemire-Elmore|date=2004-04-13|page=5|access-date=2009-02-26|quote=properly trained athlete will have efficiencies of 22 to 26%}}</ref>)
|-
| [[Butanol fuel|Butanol]]
| 36.6
| 29.2
| 10,166.7
| 8,111.1
|
|-
| Gasohol [[E85]] (85% ethanol 15% gasoline by volume)
| 33.1
| data-sort-value="25.65" | 25.65{{Citation needed|date=October 2014}}
| 9,194.5
| 7,125.0
|
|-
| [[Graphite]]
| 32.7
| 72.9
| 9,083.3
| 20,250.0
|
|-
| [[Coal]], [[anthracite]]
| data-sort-value="26" | 26–33
| data-sort-value="34" | 34–43
| data-sort-value="7222.2" | 7,222.2–9,166.7
| data-sort-value="9444.5" | 9,444.5–11,944.5
|Figures represent perfect combustion not counting oxidizer, but efficiency of conversion to electricity is ≈36%<ref name="fisher" />
|-
| [[Silicon]]
| 32.6
| 75.9
| data-sort-value="9056" | 9,056
| data-sort-value="21080" | 21,080
|See Table 1 <ref>{{cite web |title=Silicon as an intermediary between renewable energy and hydrogen |url=https://www.dbresearch.com/PROD/DBR_INTERNET_EN-PROD/PROD0000000000079095.pdf |publisher=Deutsche Bank Research |access-date=16 November 2016|pages=5|archive-url=https://web.archive.org/web/20081116161500/https://www.dbresearch.com/PROD/DBR_INTERNET_EN-PROD/PROD0000000000079095.pdf |archive-date=2008-11-16 }}</ref>
|-
| [[Aluminium]]
| 31.0
| 83.8
| 8,611.1
| 23,277.8
|
|-
| [[Ethanol]]
| 30
| 24
| 8,333.3
| 6,666.7
|
|-
| [[Dimethyl ether|DME]]
| data-sort-value="28.4" | 31.7&nbsp;(HHV)<br />28.4&nbsp;(LHV)
| data-sort-value="19.03" | 21.24&nbsp;(HHV)<br />19.03&nbsp;(LHV)
| data-sort-value="7,888.9" | <span style="display:none">8,805.6</span>8,805.6&nbsp;(HHV)<br />7,888.9&nbsp;(LHV)
| data-sort-value="5,286.1" | 5,900.0&nbsp;(HHV)<br />5,286.1&nbsp;(LHV)
|<ref name="DME1">{{cite web|last=Bossel|first=Ulf|date=July 2003|title=The Physics of the Hydrogen Economy|url=https://www.efcf.com/reports/E05.pdf|url-status=dead|archive-url=https://web.archive.org/web/20060319173951/https://www.efcf.com/reports/E05.pdf|archive-date=2006-03-19|access-date=2019-04-06|publisher=European Fuel Cell News|quote=The Higher Heating Values are 22.7, 29.7 or 31.7 MJ/kg for methanol, ethanol and DME, respectively, while gasoline contains about 45 MJ per kg.}}</ref><ref name="DME2">{{cite web|date=2013-11-18|title=Dimethyl Ether (DME)|url=http://www.etipbioenergy.eu/images/dme-fact-sheet.pdf|access-date=2019-04-06|website=European Biofuels Technology Platform}} DME density and lower heating value were obtained from the table on the first page.</ref>
|-
| [[Polyester]] plastic
| data-sort-value="26.0" | 26.0<ref name="aquafoam" />
| 35.6
| 7,222.2
| 9,888.9
|
|-
| [[Magnesium]]
| 24.7
| 43.0
| 6,861.1
| 11,944.5
|
|-
| [[Phosphorus]] (white)
| data-sort-value="24.30" | 24.30
| data-sort-value="44.30" | 44.30
| data-sort-value="6750" | 6,750
| data-sort-value="12310" | 12,310
|<ref>{{cite book |author1=Green Don |author2=Perry Robert |title=Perry's chemical engineers' handbook |date=2008 |publisher=McGraw-Hill |location=New York |isbn=9780071422949 |edition=8th}}</ref>
|-
| [[Coal]], [[Bitumen|bituminous]]
| data-sort-value="24" | 24–35
| data-sort-value="26" | 26–49
| data-sort-value="6666.7" | 6,666.7–9,722.2
| data-sort-value="7222.2" | 7,222.2–13,611.1
|<ref name="fisher" />
|-
| [[Polyethylene terephthalate|PET]] plastic (impure)
| data-sort-value="23.5" | 23.5<ref>{{cite web|url=http://www.payne-worldwide.com/documents/cms/Elite_bloc_msds.pdf|archive-url=https://web.archive.org/web/20110715061924/http://www.payne-worldwide.com/documents/cms/Elite_bloc_msds.pdf|url-status=dead|archive-date=2011-07-15|title=Elite_bloc.indd|access-date=2010-05-07}}</ref>
| data-sort-value="32.4" | < ~32.4
| 6,527.8
| data-sort-value="9000" | < ~9000
|
|-
| [[Methanol]]
| 19.7
| 15.6
| 5,472.2
| 4,333.3
|
|-
| [[Titanium]] 
| data-sort-value="19.74" | 19.74
| data-sort-value="88.93" | 88.93
| data-sort-value="5480" | 5,480
| data-sort-value="24700" | 24,700
| burned to [[titanium dioxide]]
|-
| [[Hydrazine]] (combusted to N<sub>2</sub>+H<sub>2</sub>O)
| 19.5
| 19.3
| 5,416.7
| 5,361.1
|
|-
| Liquid [[ammonia]] (combusted to N<sub>2</sub>+H<sub>2</sub>O)
| 18.6
| 11.5
| 5,166.7
| 3,194.5
|
|-
| [[Potassium]]
| 18.6
| 16.5
| 5,160
| 4,600
| burned to dry [[potassium oxide]]
|-
| [[PVC]] plastic ([[Polyvinyl chloride#Dioxins|improper combustion toxic]])<!-- what does this mean? Is it 18 MJ/kg only if PVC is incompletely burned? -->
| data-sort-value="18.0" | 18.0<ref name="aquafoam" />
| 25.2
| 5,000.0
| 7,000.0
|{{Clarify|date=October 2008}}
|-
| [[Wood fuel|Wood]]
| 18.0
|
| 5,000.0
|
|<ref>{{cite web|title=Biomass Energy Foundation: Fuel Densities|url=http://www.woodgas.com/fuel_densities.htm|archive-url=https://web.archive.org/web/20100110042311/http://www.woodgas.com/fuel_densities.htm|archive-date=2010-01-10|access-date=2010-05-07|publisher=Woodgas.com}}</ref>
|-
| [[Peat]] [[briquette]]
| 17.7
|
| 4,916.7
|
|<ref>{{cite web|title=Bord na Mona, Peat for Energy|url=http://www.bnm.ie/files/20061124040716_peat_for_energy.pdf|archive-url=https://web.archive.org/web/20071119083231/http://www.bnm.ie/files/20061124040716_peat_for_energy.pdf|archive-date=2007-11-19|access-date=2012-01-25|publisher=Bnm.ie}}</ref>
|-
| [[Fatty acid metabolism|Sugars, carbohydrates, and protein]]
| 17
| data-sort-value="26.2" | 26.2&nbsp;([[dextrose]])
| 4,722.2
| 7,277.8
|[[Fatty acid metabolism|Metabolism in human body]] (22% efficiency<ref>{{cite web|url=http://www.ebikes.ca/documents/Ebike_Energy.pdf|title=The Energy Cost of Electric and Human-Powered Bicycle|author=Justin Lemire-elmore|date=April 13, 2004|access-date=2012-01-25}}</ref>){{Citation needed|date=February 2009|reason=Justin Lemire-Elmore PDF does not specify type of food nor fatty acids nor dextrose, so specific cite needed with page number and precise quotes}}
|-
| [[Calcium]]
| 15.9
| 24.6
| 4,416.7
| 6,833.3
|{{Citation needed|date=November 2008}}
|-
| [[Glucose]]
| 15.55
| 23.9
| 4,319.5
| 6,638.9
|
|-
| Dry [[cow dung]] and [[Manure#Uses of manure|camel dung]]
| data-sort-value="15.5" | 15.5<ref>{{cite web|url=http://www.davdata.nl/math/energy.html |title=energy buffers |publisher=Home.hccnet.nl |access-date=2010-05-07}}</ref>
|
| 4,305.6
|
|
|-
| [[Coal]], [[lignite]]<!-- removed " (to 19)" to make sort work -->
| data-sort-value="10" | 10–20
|
| 2,777.8–5,555.6
|
|{{Citation needed|date=November 2008}}
|-
| [[Sodium]]
| 13.3
| 12.8
| 3,694.5
| 3,555.6
|burned to wet [[sodium hydroxide]]
|-
| [[Peat]]
| 12.8
|
| 3,555.6
|
|
|-
| [[Nitromethane]]
| 11.3
| 12.85
| 3,138.9
| 3,570
|
|-
| [[Manganese]]
| 9.46
| 68.2
| 2,630
| 18,900
| burned to [[manganese dioxide]]
|-
| [[Sulfur]]
| 9.23
| 19.11
| 2,563.9
| 5,308.3
| burned to [[sulfur dioxide]]<ref name="Wignall">Anne Wignall and Terry Wales. [http://www.wignallandwales.co.nz/Chem-12-WB/Sample-chapter.pdf Chemistry 12 Workbook, page 138] {{webarchive|url=https://web.archive.org/web/20110913164216/http://www.wignallandwales.co.nz/Chem-12-WB/Sample-chapter.pdf|date=2011-09-13}}. Pearson Education NZ {{ISBN|978-0-582-54974-6}}</ref>
|-
| [[Sodium]]
| 9.1
| 8.8
| 2,527.8
| 2,444.5
| burned to dry [[sodium oxide]]
|-
| [[Lithium air battery|Battery, lithium-air rechargeable]]
| 9.0<ref>{{cite journal|last1=Mitchell|first1=Robert R.|last2=Gallant|first2=Betar M.|last3=Thompson|first3=Carl V.|last4=Shao-Horn|first4=Yang|author-link4=Yang Shao-Horn|year=2011|title=All-carbon-nanofiber electrodes for high-energy rechargeable Li–O2 batteries|journal=Energy & Environmental Science|volume=4|issue=8|pages=2952–2958|doi=10.1039/C1EE01496J|s2cid=96799565}}</ref>
|
| 2,500.0
|
|Controlled electric discharge
|-
| [[Household waste]]<!-- removed " (to 11)" to make sort work -->
| data-sort-value="8.0" | 8.0<ref>David E. Dirkse. [http://www.davdata.nl/math/energy.html energy buffers]. "household waste 8..11 MJ/kg"</ref>
|
| 2,222.2
|
|
|-
| [[Zinc]]
| 5.3
| 38.0
| 1,472.2
| 10,555.6
|
|-
| [[Iron]]
| 5.2
| 40.68
| 1,444.5
| 11,300.0
| burned to [[iron(III) oxide]]
|-
| [[PTFE|Teflon]] plastic
| 5.1
| 11.2
| 1,416.7
| 3,111.1
|combustion toxic, but flame retardant
|-
| [[Iron]]
| 4.9
| 38.2
| 1,361.1
| 10,611.1
| burned to [[iron(II) oxide]]
|-
| [[Gunpowder]]
| data-sort-value="8" | 4.7–11.3<ref>{{cite book|last1=Lu|first1=Gui-e|last2=Chang|first2=Wen-ping|last3=Jiang|first3=Jin-yong|last4=Du|first4=Shi-guo|title=2011 International Conference on Materials for Renewable Energy & Environment |chapter=Study on the energy density of gunpowder heat source |pages=1185–1187|date=May 2011|doi=10.1109/ICMREE.2011.5930549|publisher=[[Institute of Electrical and Electronics Engineers|IEEE]]|isbn=978-1-61284-749-8|s2cid=36130191}}</ref>
| data-sort-value="9.4" | 5.9–12.9
|
| data-sort-value="2600" | 1,600–3,580
|
|-
| [[Trinitrotoluene|TNT]]
| 4.184
| 6.92
| data-sort-value="1162" | 1,162
| data-sort-value="1920" | 1,920
|
|-
| [[Barium]]
| 3.99
| 14.0
| data-sort-value="1110" | 1,110
| data-sort-value="3890" | 3,890
| burned to [[barium dioxide]]
|-
| [[ANFO]]
| 3.7
|
| 1,027.8
|
|
|}

=== In nuclear reactions ===<!-- To ensure this table sorts correctly: avoid using "-" or unicode dash in columns with numbers; ensure each row has a single numeric value, use data-sort-value="0" | if unknown; do not use ? or {{?}}; do not use "A to B", nor "C (approximately)"; provide a cite for each value. Test changes on several browsers as sort behaviour may vary. -->
{{Table alignment}}
{|class="wikitable sortable defaultright col1left col6left"
|+ Energy released by nuclear reactions
! Material
! data-sort-type="number" | Specific energy<br />(MJ/kg)
! data-sort-type="number" | Energy density<br />(MJ/L)
! data-sort-type="number" | Specific energy<br />([[W⋅h/kg]])
! data-sort-type="number" | Energy density<br />(W⋅h/L)
! Comment
|-
| [[Antimatter]]
| 89,875,517,874 ≈ 90 PJ/kg
| Depends on the density of the antimatter's form
| 24,965,421,631,578 ≈ 25&nbsp;TW⋅h/kg
| Depends on the density of the antimatter's form
| Annihilation, counting both the consumed antimatter mass and ordinary matter mass
|-
| [[Hydrogen]] (fusion)
| data-sort-value="639,780,320"|639,780,320<ref name="ReferenceA">Calculated from fractional mass loss times c squared.</ref> but at least 2% of this is lost to [[neutrino]]s.
| Depends on conditions
| data-sort-value="177,716,755,600"|177,716,755,600
| Depends on conditions
| Reaction 4H→<sup>4</sup>He
|-
| [[Deuterium]] (fusion)<br />
| data-sort-value="571,182,758" | 571,182,758<ref>Calculated from fractional mass loss times c squared. {{cite journal|title=Maximizing specific energy by breeding deuterium|first=Justin |last=Ball|journal=Nuclear Fusion|year=2019|volume=59|issue=10 |pages=106043|doi=10.1088/1741-4326/ab394c|arxiv=1908.00834 |bibcode=2019NucFu..59j6043B |s2cid=199405246 }}</ref>
| Depends on conditions
| data-sort-value="158,661,876,600" | 158,661,876,600
| Depends on conditions
|Proposed [[fusion reactor|fusion scheme]] for D+D→<sup>4</sup>He, by combining D+D→T+H, T+D→<sup>4</sup>He+n, n+H→D and D+D→<sup>3</sup>He+n, <sup>3</sup>He+D→<sup>4</sup>He+H, n+H→D
|-
| [[Deuterium]]+[[tritium]] (fusion)
| data-sort-value="337,387,388"|337,387,388<ref name="ReferenceA"/>
| Depends on conditions
| data-sort-value="93,718,718,800"|93,718,718,800
| Depends on conditions
| D + T → <sup>4</sup>He + n<br>Being developed.
|-
| [[Lithium hydride|Lithium-6 deuteride]] (fusion)
| data-sort-value="268,848,415"|268,848,415<ref name="ReferenceA"/>
| Depends on conditions
| data-sort-value="74,680,115,100"|74,680,115,100
| Depends on conditions
| {{sup|6}}LiD → 2<sup>4</sup>He<br>Used in weapons.
|-
| [[Plutonium-239]]
| 83,610,000
| data-sort-value="1660494600" | 1,300,000,000–1,700,000,000 (Depends on [[Allotropes of plutonium|crystallographic phase]])
| 23,222,915,000
| data-sort-value="461248500000" | 370,000,000,000–460,000,000,000 (Depends on [[Allotropes of plutonium|crystallographic phase]])
|Heat produced in [[Fission reactor]]
|-
| [[Plutonium-239]]
| 31,000,000
| data-sort-value="615660000" | 490,000,000–620,000,000 (Depends on [[Allotropes of plutonium|crystallographic phase]])
| 8,700,000,000
| data-sort-value="171016670000" | 140,000,000,000–170,000,000,000 (Depends on [[Allotropes of plutonium|crystallographic phase]])
| Electricity produced in [[Fission reactor]]
|-
| [[Uranium]]
| data-sort-value="80,620,000" | 80,620,000<ref name="whatisnuclear" />
| data-sort-value="1,539,842,000" | 1,539,842,000
|22,394,000,000
|
|Heat produced in [[breeder reactor]]
|-
| [[Thorium-based nuclear power|Thorium]]
| data-sort-value="79,420,000" | 79,420,000<ref name="whatisnuclear">{{cite web|url=http://www.whatisnuclear.com/physics/energy_density_of_nuclear.html |title=Computing the energy density of nuclear fuel |publisher=whatisnuclear.com |access-date=2014-04-17}}</ref>
| data-sort-value="929,214,000" | 929,214,000
|22,061,000,000
|
|Heat produced in [[breeder reactor]] (Experimental)
|-
| [[Plutonium-238#Decay|Plutonium-238]]
| 2,239,000
| 43,277,631
|621,900,000
|
|[[Radioisotope thermoelectric generator]]. The heat is only produced at a rate of 0.57&nbsp;W/g.
|}

=== Other release mechanisms ===
{{Table alignment}}
{|class="wikitable sortable defaultright col1left col6left" 
|+ Energy released by electrochemical reactions or other means
! Material
! data-sort-type="number" | Specific energy<br />(MJ/kg)
! data-sort-type="number" | Energy density<br />(MJ/L)
! data-sort-type="number" | Specific energy<br />([[W⋅h/kg]])
! data-sort-type="number" | Energy density<br />(W⋅h/L)
! Comment
|-
| [[Zinc-air battery|Battery, zinc-air]]
| 1.59
| 6.02
| 441.7
| 1,672.2
|Controlled electric discharge<ref name="duracell-za-tech">{{cite web|title=Technical bulletin on Zinc-air batteries|url=http://www.duracell.com/oem/primary/Zinc/zinc_air_tech.asp|archive-url=https://web.archive.org/web/20090127030703/http://www.duracell.com/oem/primary/Zinc/zinc_air_tech.asp|archive-date=2009-01-27|access-date=2009-04-21|publisher=[[Duracell]]}}</ref>
|-
| [[Silicon]] (phase change)
| data-sort-value="1.79" | 1.790
| data-sort-value="4.5" | 4.5
| data-sort-value="500" | 500
| data-sort-value="1285" | 1,285
|Energy stored through solid to liquid phase change of silicon<ref name="Meroueh">{{cite journal|last=Meroueh|first=Laureen|year=2020|title=Thermal energy storage in Silicon|doi=10.1016/j.renene.2019.06.036|s2cid=197448761}}</ref>
|-
| [[Strontium bromide|Strontium bromide hydrate]]
| data-sort-value="0.814" | 0.814 <ref name="Fopah-Lele">A. Fopah-Lele, J. G. Tamba [https://www.sciencedirect.com/science/article/pii/S0927024817300703 "A review on the use of {{chem2|SrBr2*6H2O}} as a potential material for low temperature energy storage systems and building applications"], ''Solar Energy Materials and Solar Cells'' '''164''' 175-84 (2017).</ref>
| 1.93
|
| 628
| Thermal energy of phase change at {{cvt|88.6|C|K}}
|-
| [[Liquid nitrogen economy|Liquid nitrogen]]
| data-sort-value="0.77" | 0.77<ref name="Knowlen">C. Knowlen, A.T. Mattick, A.P. Bruckner and A. Hertzberg, [https://web.archive.org/web/20081217082655/http://www.aa.washington.edu/AERP/cryocar/Papers/sae98.pdf "High Efficiency Conversion Systems for Liquid Nitrogen Automobiles"], Society of Automotive Engineers Inc, 1988.</ref>
| 0.62
| 213.9
| 172.2
| Maximum reversible work at 77.4&nbsp;K with 300&nbsp;K reservoir
|-
| [[Sodium–sulfur battery|Sodium sulfur battery]]
| data-sort-value="0.54" | 0.54–0.86
| 
| 150–240
| 
|
|-
| [[Compressed air]] at 30&nbsp;MPa
| 0.5
| 0.2
| 138.9
| 55.6
|Potential energy
|-
| [[Enthalpy of fusion|Latent heat of fusion]] of ice (thermal)
| 0.334
| 0.334
| 93.1
| 93.1
|
|-
| [[Lithium metal battery]]
| 1.8
| 4.32
| 500
| 1,200
|Controlled electric discharge
|-
| [[Lithium-ion battery]]
| data-sort-value="0.36" | 0.36–0.875{{refn|<ref>{{cite web|title=Overview of lithium ion batteries|url=http://www.panasonic.com/industrial/includes/pdf/Panasonic_LiIon_Overview.pdf|publisher=Panasonic|archive-url=https://web.archive.org/web/20111107060525/http://www.panasonic.com/industrial/includes/pdf/Panasonic_LiIon_Overview.pdf|archive-date=November 7, 2011|date=Jan 2007|url-status=live}}</ref><ref>{{cite web|title=Panasonic NCR18650B|url=http://industrial.panasonic.com/lecs/www-data/pdf2/ACA4000/ACA4000CE417.pdf|url-status=dead|archive-url=https://web.archive.org/web/20150722042425/http://industrial.panasonic.com/lecs/www-data/pdf2/ACA4000/ACA4000CE417.pdf|archive-date=2015-07-22}}</ref>}}
| data-sort-value="0.9" | 0.9–2.63
| data-sort-value="100.00" | 100.00–243.06
| data-sort-value="250.00" | 250.00–730.56
|Controlled electric discharge
|-
| [[Lithium-ion battery]] with [[silicon nanowire]] [[anode]]s
| 1.566
| 4.32
| data-sort-value="435" | 435<ref name=":2">{{Cite web |title=Amprius' silicon nanowire Li-ion batteries power Airbus Zephyr S HAPS solar aircraft |url=https://www.greencarcongress.com/2018/12/20181205-amprius.html |access-date=2022-12-31 |website=Green Car Congress}}</ref>
| data-sort-value="1200" | 1,200<ref name=":2" />
| Controlled electric discharge
|-
| [[Flywheel energy storage|Flywheel]]
| data-sort-value="0.36" | 0.36–0.5
| 5.3
|
|
|Kinetic energy
|-
| [[Alkaline battery]]
| data-sort-value="0.5" | 0.48<ref>{{cite web|url=https://lygte-info.dk/review/batteries2012/Duracell%20Ultra%20Power%20AA%20UK.html|title=Test of Duracell Ultra Power AA|website=lygte-info.dk|access-date=2019-02-16}}</ref>
| data-sort-value="1.3" | 1.3<ref name=":8">{{cite web|url=http://data.energizer.com/PDFs/EN91.pdf|title=Energizer EN91 AA alkaline battery datasheet|access-date=2016-01-10}}</ref>
|
|
|Controlled electric discharge
|-
| [[Nickel-metal hydride battery]]
| 0.41<ref name="lygte">{{Cite web|url=https://lygte-info.dk/review/batteries2012/GP%20ReCyko+%20AA%202700mAh%20(Green)%20UK.html|title=Test of GP ReCyko+ AA 2700mAh (Green)|website=lygte-info.dk|access-date=2019-02-16}}</ref>
| data-sort-value="0.504" | 0.504–1.46<ref name="lygte" />
|
|
|Controlled electric discharge
|-
| [[Lead-acid battery]]
| 0.17
| 0.56
| 47.2
| 156
|Controlled electric discharge
|-
| [[Supercapacitor]] ([[Electric double-layer capacitor|EDLC]])
| data-sort-value="0.01" | 0.01–0.030<ref name="maxwell">{{cite web |url=http://www.maxwell.com/images/documents/Product_Comparison_Matrix_3000489_2.pdf |title=Maxwell supercapacitor comparison |access-date=2016-01-10 }}</ref><ref name="ESHSP">{{cite web |url=http://www.nesscap.com/common/download.jsp?dir=product&sfn=MSCWSMXHBBOMXOZ.pdf |title=Nesscap ESHSP series supercapacitor datasheet |access-date=2016-01-10 |archive-url=https://web.archive.org/web/20160329001412/http://www.nesscap.com/common/download.jsp?dir=product&sfn=MSCWSMXHBBOMXOZ.pdf |archive-date=2016-03-29 |url-status= dead}}</ref><ref name="XL60">{{cite web |url=http://www.cooperindustries.com/content/dam/public/bussmann/Electronics/Resources/product-datasheets/bus-elx-ds-10339-xl.pdf |title=Cooper PowerStor XL60 series supercapacitor datasheet |access-date=2016-01-10 }}</ref><ref name=":3">{{cite web|url =http://www.kemet.com/Lists/ProductCatalog/Attachments/504/KEM_S6001_S301.pdf |title=Kemet S301 series supercapacitor datasheet |access-date=2016-01-10 |url-status=dead |archive-url=https://web.archive.org/web/20160304092326/http://www.kemet.com/Lists/ProductCatalog/Attachments/504/KEM_S6001_S301.pdf |archive-date=2016-03-04}}</ref><ref name=":4">{{cite web |url=http://www.nichicon-us.com/english/products/pdfs/e-jjd.pdf |title= Nichicon JJD series supercapatcitor datasheet |access-date=2016-01-10 }}</ref><ref name=":5">{{cite web |title=skelcap High Energy Ultracapacitor |url=http://skeletontech.com/datasheets/skelcap-energy-en.pdf |website=Skeleton Technologies|access-date=13 October 2015|archive-url=https://web.archive.org/web/20160402220331/http://skeletontech.com/datasheets/skelcap-energy-en.pdf|archive-date=2 April 2016|url-status=dead}}</ref><ref name="maxwell2">{{cite web|url=https://www.maxwell.com/images/documents/3V_3400F_datasheet.pdf|title=3.0V 3400F ULTRACAPACITOR CELL DATASHEET BCAP3400 P300 K04/05|access-date=2020-01-12}}</ref>
| data-sort-value="0.05" | 0.006–0.06<ref name="maxwell" /><ref name="ESHSP" /><ref name="XL60" /><ref name=":3" /><ref name=":4" /><ref name=":5" />
| data-sort-value="8.75" | up to 8.57<ref name="maxwell2" />
|
|Controlled electric discharge
|-
| [[Hydroelectricity|Water at 100&nbsp;m dam height]]
| 0.000981
| 0.000978
| 0.272
| 0.272
|Figures represent potential energy, but efficiency of conversion to electricity is 85–90%<ref>{{cite web|url=http://www.mpoweruk.com/hydro_power.htm|title=Hydroelectric Power Generation|website=www.mpoweruk.com|publisher=Woodbank Communications Ltd|access-date=13 April 2018}}</ref><ref>{{cite web|url=http://rivers.bee.oregonstate.edu/elevation-discharge-power-relationship|title=2.1 Power, discharge, head relationship {{!}} River Engineering & Restoration at OSU {{!}} Oregon State University|website=rivers.bee.oregonstate.edu|language=en|access-date=13 April 2018|quote=Let ε = 0.85, signifying an 85% efficiency rating, typical of an older powerplant.}}</ref>
|-
| [[Electrolytic capacitor]]
| data-sort-value="0.00001" | 0.00001–0.0002<ref name=":7">{{Cite web|url = http://www.vishay.com/docs/43009/ste.pdf|title = Vishay STE series tantalum capacitors datasheet|access-date = 2016-01-10}}</ref>
| data-sort-value="0.00001" | 0.00001–0.001<ref name=":7" /><ref>{{Cite web|url = http://www.nichicon-us.com/english/products/pdfs/e-tvx.pdf|title = nichicon TVX aluminum electrolytic capacitors datasheet|access-date = 2016-01-10}}</ref><ref>{{Cite web|url = http://www.nichicon-us.com/english/products/pdfs/e-lgu.pdf|title = nichicon LGU aluminum electrolytic capacitors datasheet|access-date = 2016-01-10}}</ref>
|
|
|Controlled electric discharge
|}

=== In material deformation ===
The mechanical energy storage capacity, or [[Resilience (materials science)|resilience]], of a [[Hookean]] material when it is deformed to the point of failure can be computed by calculating tensile strength times the maximum elongation dividing by two. The maximum elongation of a Hookean material can be computed by dividing stiffness of that material by its ultimate tensile strength. The following table lists these values computed using the Young's modulus as measure of stiffness:
{| class="wikitable sortable"
|+Mechanical energy capacities
!Material
!Energy density by mass
(J/kg)
![[Resilience (materials science)|Resilience]]: Energy density by volume
(J/L)
![[Density]]
(kg/L)
![[Young's modulus]]
(GPa)
!Tensile yield [[Strength of materials|strength]]
(MPa)
|-
|[[Rubber band]]
|1,651–6,605<ref name="Band">{{Cite magazine|url=https://www.wired.com/story/how-much-energy-can-you-store-in-a-rubber-band/|title=How Much Energy Can You Store in a Rubber Band?|magazine=Wired|access-date=2020-01-21|language=en|issn=1059-1028}}</ref>
|2,200–8,900<ref name="Band" />
|1.35<ref name="Band" />
|
|
|-
|Steel, [[ASTM A228]] (yield, 1&nbsp;mm diameter)
|1,440–1,770
|11,200–13,800
|7.80<ref name=":2a">{{cite web|url=http://www.matweb.com/search/datasheettext.aspx?matid=14072|title=MatWeb - The Online Materials Information Resource|website=www.matweb.com|access-date=2019-12-15}}</ref>
|210<ref name=":2a" />
|2,170–2,410<ref name=":2a" />
|-
|Acetals
|908
|754
|0.831<ref>{{Cite web|url=https://pubchem.ncbi.nlm.nih.gov/compound/7765|title=Acetal|last=PubChem|website=pubchem.ncbi.nlm.nih.gov|language=en
|access-date=2019-12-12}}</ref>
|2.8<ref name=":0" />
|65 (ultimate)<ref name=":0" />
|-
|Nylon-6
|233–1,870
|253–2,030
|1.084
|2–4<ref name=":0" />
|45–90 (ultimate)<ref name=":0" />
|-
|[[Beryllium copper|Copper Beryllium]] 25-1/2 HT (yield)
|684
|5,720<ref name=":3a" />
|8.36<ref>{{cite web|url=https://www.ejbmetals.com/p/25/C17200|title=C17200 Alloy Specifications {{!}} E. Jordan Brookes Company|website=www.ejbmetals.com|access-date=2019-12-15}}</ref>
|131<ref name=":3a" />
|1,224<ref name=":3a" />
|-
|Polycarbonates
|433–615
|520–740
|1.2<ref>{{Cite web|url=http://www.polymerprocessing.com/polymers/PC.html|title=polycarbonate information and properties|website=www.polymerprocessing.com|access-date=2019-12-12}}</ref>
|2.6<ref name=":0" />
|52–62 (ultimate)<ref name=":0" />
|-
|ABS plastics
|241–534
|258–571
|1.07
|1.4–3.1<ref name=":0">{{Cite web|url=https://www.engineeringtoolbox.com/young-modulus-d_417.html|title=Young's Modulus - Tensile and Yield Strength for common Materials|website=www.engineeringtoolbox.com|access-date=2019-12-12}}</ref>
|40 (ultimate)<ref name=":0" />
|-
|Acrylic
|
|1,530
|
|3.2<ref name=":0" />
|70 (ultimate)<ref name=":0" />
|-
|[[7075 aluminium alloy|Aluminium 7077-T8]] (yield)
|399
|1,120<ref name=":3a">{{cite web|url=https://materion.com/-/media/files/alloy/newsletters/technical-tidbits/issue-no-22--elastic-resilience.pdf|title=Elastic Resilience|last=Brush Wellman Alloy Products|website=Technical Tidbits|access-date=December 15, 2019}}</ref>
|2.81<ref>{{Cite web|url=http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=MA7075T6|title=ASM Material Data Sheet|website=asm.matweb.com|access-date=2019-12-15}}</ref>
|71.0<ref name=":3a" />
|400<ref name=":3a" />
|-
|Steel, [[Stainless steel|stainless]], 301-H (yield)
|301
|2,410<ref name=":3a" />
|8.0<ref>{{cite web
| url=https://hypertextbook.com/facts/2004/KarenSutherland.shtml
| title=Density of steel
| first1=Karen
| last1=Sutherland
| year=2004
| first2=Monica
| last2=Martin
| website=The Physics Factbook
| editor-last=Elert
| editor-first=Glenn
| access-date=2020-06-18
}}</ref>
|193<ref name=":3a" />
|965<ref name=":3a" />
|-
|[[6061 aluminium alloy|Aluminium 6061-T6]] (yield @ 24&nbsp;°C)
|205
|553
|2.70<ref name=":1">{{Cite web|title=Aluminum 6061-T6; 6061-T651|url=http://www.matweb.com/search/datasheet_print.aspx?matguid=1b8c06d0ca7c456694c7777d9e10be5b|access-date=2021-06-13|website=www.matweb.com}}</ref>
|68.9<ref name=":1" />
|276<ref name=":1" />
|-
|Epoxy resins
|
|113–1,810
|
|2–3<ref name=":0" />
|26–85 (ultimate)<ref name=":0" />
|-
|Douglas fir Wood
|158–200
|96
|.481–.609<ref>{{Cite web|url=https://www.engineeringtoolbox.com/weigt-wood-d_821.html|title=Wood Species - Moisture Content and Weight|website=www.engineeringtoolbox.com|access-date=2019-12-12}}</ref>
|13<ref name=":0" />
|50 (compression)<ref name=":0" />
|-
|Steel, Mild [[Mild steel|AISI 1018]]
|42.4
|334
|7.87<ref name="MildSteel">{{Cite web|url=https://www.azom.com/article.aspx?ArticleID=6115|title=AISI 1018 Mild/Low Carbon Steel|date=2012-06-28|website=AZoM.com|language=en|access-date=2020-01-22}}</ref>
|205<ref name="MildSteel" />
|370 (440 Ultimate)<ref name="MildSteel" />
|-
|[[Aluminium]] (not alloyed)
|32.5
|87.7
|2.70<ref>{{cite web|url=http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=MA6061T6|title=ASM Material Data Sheet|website=asm.matweb.com|access-date=2019-12-12}}</ref>
|69<ref name=":0" />
|110 (ultimate)<ref name=":0" />
|-
|[[Pine]] (American Eastern White, [[Flexural strength|flexural]])
|31.8–32.8
|11.1–11.5
|.350<ref name=":1a">{{cite web|url=http://www.matweb.com/search/datasheetText.aspx?bassnum=PTSAH|title=American Eastern White Pine Wood|website=www.matweb.com|access-date=2019-12-15}}</ref>
|8.30–8.56 (flexural)<ref name=":1a" />
|41.4 (flexural)<ref name=":1a" />
|-
|Brass
|28.6–36.5
|250–306
|8.4–8.73<ref name="MWD">{{cite web|url=https://www.simetric.co.uk/si_metals.htm|title=Mass, Weight, Density or Specific Gravity of Different Metals|website=www.simetric.co.uk|access-date=2019-12-12}}</ref>
|102–125<ref name=":0" />
|250 (ultimate)<ref name=":0" />
|-
|Copper
|23.1
|207
|8.93<ref name="MWD" />
|117<ref name=":0" />
|220 (ultimate)<ref name=":0" />
|-
|Glass
|5.56–10.0
|13.9–25.0
|2.5<ref>{{Cite web|url=https://uk.saint-gobain-building-glass.com/en-gb/architects/physical-properties|title=Physical properties of glass {{!}} Saint Gobain Building Glass UK|website=uk.saint-gobain-building-glass.com|access-date=2019-12-12}}</ref>
|50–90<ref name=":0" />
|50 (compression)<ref name=":0" />
|}

=== In batteries ===
{| class="wikitable sortable" style="text-align: center;"
|+[[Electric battery|Battery]] energy capacities
|-
! Storage device
! data-sort-type="number" | Energy content<br />([[Joule]])
!Energy content<br />([[Kilowatt-hour|W⋅h]])
! Energy type
! data-sort-type="number" | Typical<br />mass (g)
! Typical dimensions<br />(diameter × height in mm)
! data-sort-type="number" | Typical volume (mL)
! data-sort-type="number" | Energy density<br />by volume (MJ/L)
! data-sort-type="number" | Energy density<br />by mass (MJ/kg)
|-
| style="text-align:left;" |[[Alkaline battery|Alkaline]] [[AA battery]]<ref name=":9">{{Cite web|url=http://www.allaboutbatteries.com/Energy-tables.html|title=Battery Energy Tables|archive-url=https://web.archive.org/web/20111204090808/http://www.allaboutbatteries.com/Energy-tables.html|archive-date=2011-12-04|url-status=dead}}</ref>
| data-sort-value="9360" | 9,360
|2.6
| Electrochemical
| 24
| 14.2 × 50
| 7.92
| 1.18
| 0.39
|-
| style="text-align:left;" |[[Alkaline battery|Alkaline]] [[C battery]]<ref name=":9" />
| data-sort-value="34416" |34,416
|9.5
| Electrochemical
| 65
| 26 × 46
| 24.42
| 1.41
| 0.53
|-
| style="text-align:left;" |[[Nickel–metal hydride battery|NiMH]] AA battery
| data-sort-value="9072" |9,072
|2.5
| Electrochemical
| 26
| 14.2 × 50
| 7.92
| 1.15
| 0.35
|-
| style="text-align:left;" |[[Nickel–metal hydride battery|NiMH]] C battery
| data-sort-value="19440" |19,440
|5.4
| Electrochemical
| 82
| 26 × 46
| 24.42
| 0.80
| 0.24
|-
| style="text-align:left;" |[[Lithium-ion battery|Lithium-ion]] [[List of battery sizes|18650 battery]]
| data-sort-value="28800" | 28,800–46,800
|8–13
| Electrochemical
| data-sort-value="44" | 44–49<ref name=":10">{{cite web|url=http://www.best18650battery.com/|title=18650 Battery capacities}}</ref>
| 18 × 65
| 16.54
| 1.74–2.83
| 0.59–1.06
|-
|}

==Nuclear energy sources==<!--esoterica to most readers-->
The greatest energy source by far is matter itself.  This energy, ''E = mc<sup>2</sup>'', where ''m = ρV'', ''ρ'' is the mass per unit volume, ''V'' is the volume of the mass itself and ''c'' is the speed of light.  This energy, however, can be released only by the processes of [[nuclear fission]] (0.1%), [[nuclear fusion]] (1%), or the annihilation of some or all of the matter in the volume ''V'' by matter-[[antimatter]] collisions (100%).{{citation needed|date=November 2018}} Nuclear reactions cannot be realized by chemical reactions such as combustion.  Although greater matter densities can be achieved, the density of a [[neutron star]] would approximate the most dense system capable of matter-antimatter annihilation possible.  A [[black hole]], although denser than a neutron star, does not have an equivalent anti-particle form, but would offer the same 100% conversion rate of mass to energy in the form of [[Hawking radiation]]. In the case of relatively small black holes (smaller than astronomical objects) the power output would be tremendous.

The highest density sources of energy aside from antimatter are [[nuclear fusion|fusion]] and [[Nuclear fission|fission]]. Fusion includes energy from the sun which will be available for billions of years (in the form of sunlight) but so far (2021), sustained [[fusion power]] production continues to be elusive.

Power from fission of uranium and thorium in [[nuclear power]] plants will be available for many decades or even centuries because of the plentiful supply of the elements on earth,<ref>{{cite web|url=http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Uranium-Resources/Supply-of-Uranium/ |title=Supply of Uranium |publisher=world-nuclear.org |date=2014-10-08 |access-date=2015-06-13}}</ref> though the full potential of this source can only be realized through [[breeder reactor]]s, which are, apart from the [[BN-600 reactor]], not yet used commercially.<ref name="cohen">{{cite web |url=http://www-formal.stanford.edu/jmc/progress/cohen.html |title=Facts from Cohen |publisher=Formal.stanford.edu |date=2007-01-26 |access-date=2010-05-07 |archive-url=https://web.archive.org/web/20070410165316/http://www-formal.stanford.edu/jmc/progress/cohen.html |archive-date=2007-04-10 |url-status=dead }}</ref> [[Coal]], [[gas]], and [[petroleum]] are the current primary energy sources in the U.S.<ref>{{cite web|url=http://www.eia.doe.gov/emeu/aer/pecss_diagram.html|archive-url=https://web.archive.org/web/20100506022627/http://www.eia.doe.gov/emeu/aer/pecss_diagram.html|archive-date=2010-05-06 |title=U.S. Energy Information Administration (EIA) - Annual Energy Review |publisher=Eia.doe.gov |date=2009-06-26 |access-date=2010-05-07}}</ref> but have a much lower energy density. Burning local [[biomass]] fuels supplies household energy needs ([[Improved cookstove|cooking fires]], [[oil lamp]]s, etc.) worldwide.

===Thermal power of nuclear fission reactors===
The density of thermal energy contained in the core of a [[light water reactor]] ([[Pressurized water reactor|PWR]] or [[Boiling water reactor|BWR]]) of typically 1 GWe (1,000 MW electrical corresponding to ≈3,000 MW thermal) is in the range of 10 to 100 MW of thermal energy per cubic meter of cooling water depending on the location considered in the system (the core itself (≈30 m<sup>3</sup>), the reactor pressure vessel (≈50 m<sup>3</sup>), or the whole primary circuit (≈300 m<sup>3</sup>)). This represents a considerable density of energy which requires under all circumstances a continuous water flow at high velocity in order to be able to remove the [[heat]] from the core, even after an emergency shutdown of the reactor. The incapacity to cool the cores of three [[boiling water reactor]]s (BWR) at [[Fukushima Daiichi nuclear disaster|Fukushima]] in 2011 after the [[tsunami]] and the resulting loss of the external electrical power and of the cold source was the cause of the meltdown of the three cores in only a few hours, even though the three reactors were correctly shut down just after the [[2011 Tōhoku earthquake and tsunami|Tōhoku earthquake]]. This extremely high power density distinguishes nuclear power plants (NPP's) from any thermal power plants (burning coal, fuel or gas) or any chemical plants and explains the large redundancy required to permanently control the [[Nuclear chain reaction|neutron reactivity]] and to remove the residual heat from the core of NPP's.

==Energy density of electric and magnetic fields==<!-- This section is linked from [[Special relativity]] -->
{{main|Radiant energy density}}
[[Electric field|Electric]] and [[magnetic field]]s store energy.  The (volumetric) energy density is given by

:<math> u = \frac{\varepsilon}{2} \mathbf{E}^2 + \frac{1}{2\mu} \mathbf{B}^2 </math>

where {{math|'''E'''}} is the [[electric field]], {{math|'''B'''}} is the [[magnetic field]], and {{mvar|ε}} and {{mvar|µ}} are the permittivity and permeability of the surroundings respectively. The solution will be (in SI units) in joules per cubic metre. In the context of [[magnetohydrodynamics]], the physics of conductive fluids, the magnetic energy density behaves like an additional [[pressure]] that adds to the [[kinetic theory of gas|gas pressure]] of a [[plasma (physics)|plasma]].

In ideal (linear and nondispersive) substances, the energy density (in SI units) is

:<math> u = \frac{1}{2} ( \mathbf{E} \cdot \mathbf{D} + \mathbf{H} \cdot \mathbf{B} ) </math>

where {{math|'''D'''}} is the [[electric displacement field]] and {{math|'''H'''}} is the [[Effective magnetic field|magnetizing field]].

In the case of absence of magnetic fields, by exploiting [[Herbert Fröhlich|Fröhlich's relationships]] it is also possible to extend these equations to [[anisotropic]] and [[nonlinear]] dielectrics, as well as to calculate the correlated [[Helmholtz free energy]] and [[entropy]] densities.<ref>{{Cite journal | last1 = Parravicini | first1 = J. | doi = 10.1016/j.physb.2018.04.029 | title = Thermodynamic potentials in anisotropic and nonlinear dielectrics | journal = Physica B | volume = 541 | pages = 54–60 | year = 2018 | bibcode = 2018PhyB..541...54P | s2cid = 125817506 }}</ref>

When a pulsed [[laser]] impacts a surface, the [[radiant exposure]], i.e. the energy deposited per unit of surface, may be called '''energy density''' or fluence.<ref>{{cite web |title=Terminology |url=https://www.rltvet.com/terminology.html |website=Regenerative Laser Therapy |language=en}}</ref>

==See also==

{{div col|colwidth=22em}}
* [[Energy content of biofuel]]
* [[Energy density Extended Reference Table]]
* [[Figure of merit]]
* [[Food energy]]
* [[Heat of combustion]]
* [[High-energy-density matter]]
* [[Power density]] and specifically
* [[Power-to-weight ratio]]
* [[Rechargeable battery]]
* [[Solid-state battery]]
* [[Specific energy]]
* [[Specific impulse]]
{{Portal|Energy}}
{{div col end}}

==Footnotes==
{{Reflist|30em|refs= 
* <ref name=tzar2>{{Cite journal |doi = 10.1039/C5EE01659B|title = Nanotechnology enabled rechargeable Li–SO2 batteries: Another approach towards post-lithium-ion battery systems|year = 2015|last1 = Jeong|first1 = Goojin|last2 = Kim|first2 = Hansu|last3 = Park|first3 = Jong Hwan|last4 = Jeon|first4 = Jaehwan|last5 = Jin|first5 = Xing|last6 = Song|first6 = Juhye|last7 = Kim|first7 = Bo-Ram|last8 = Park|first8 = Min-Sik|last9 = Kim|first9 = Ji Man|last10 = Kim|first10 = Young-Jun|journal = Energy & Environmental Science|volume = 8|issue = 11|pages = 3173–3180}}</ref>
* <ref name=tzar3>"Panasonic Develops New Higher-Capacity 18650 Li-Ion Cells." Green Car Congress. N.p., 25 Dec. 2009. Web.</ref> 
* <ref name=tzar4>{{Cite journal |doi = 10.1016/j.aca.2005.11.025|pmid = 17761246|title = New nanomaterials for light weight lithium batteries|year = 2006|last1 = Stura|first1 = Enrico|last2 = Nicolini|first2 = Claudio|journal = Analytica Chimica Acta|volume = 568|issue = 1–2|pages = 57–64| bibcode=2006AcAC..568...57S }}</ref>
* <ref name=tzar6>"Heat Values of Various Fuels - World Nuclear Association." World Nuclear Association. N.p., Sept. 2016. Web.</ref>
* <ref name=tzar7>"Overview of Storage Development DOE Hydrogen Program." Office of Energy Efficiency & Renewable Energy. N.p., May 2000. Web.</ref>
* <ref name=tzar8>{{Cite journal | doi=10.1115/1.4034860| title=Nanotechnology in Batteries| year=2017| last1=Wong| first1=Kaufui| last2=Dia| first2=Sarah| journal=Journal of Energy Resources Technology| volume=139}}</ref>}}

==Further reading==
* ''The Inflationary Universe: The Quest for a New Theory of Cosmic Origins'' by Alan H. Guth (1998) {{ISBN|0-201-32840-2}}
* ''Cosmological Inflation and Large-Scale Structure'' by Andrew R. Liddle, David H. Lyth (2000) {{ISBN|0-521-57598-2}}
* Richard Becker, "Electromagnetic Fields and Interactions", Dover Publications Inc., 1964

==External links==
* {{note|att}}  "Aircraft Fuels." ''Energy, Technology and the Environment'' Ed. Attilio Bisio. Vol. 1. New York: John Wiley and Sons, Inc., 1995. 257–259
* "[http://www1.eere.energy.gov/vehiclesandfuels/pdfs/deer_2002/session1/2002_deer_eberhardt.pdf Fuels of the Future for Cars and Trucks]" – Dr. James J. Eberhardt – Energy Efficiency and Renewable Energy, U.S. Department of Energy – 2002 Diesel Engine Emissions Reduction (DEER) Workshop San Diego, California - August 25–29, 2002
* {{cite web|url=http://www.world-nuclear.org/information-library/facts-and-figures/heat-values-of-various-fuels.aspx|title=Heat values of various fuels – World Nuclear Association|work=www.world-nuclear.org|access-date=4 November 2018}}
* {{cite web|url=https://www.springer.com/cda/content/document/cda_downloaddocument/9781447123712-c2.pdf?SGWID=0-0-45-1293540-p174262962|title=Energy and Energy Types – Springer|access-date=4 November 2018}}

{{Authority control}}

{{DEFAULTSORT:Energy Density}}
[[Category:Energy]]
[[Category:Density]]
[[Category:Volume-specific quantities]]
[[Category:Physical quantities]]