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{{About|energy per unit volume|energy per unit mass or energy density of foods|specific energy}}
This is a preview for the new '''MathML rendering mode''' (with SVG fallback), which is availble in production for registered users.


'''Energy density''' is the amount of [[energy]] stored in a given system or region of space per unit [[volume]] or [[mass]], though the latter is more accurately termed [[specific energy]].  Often only the ''useful'' or extractable energy is measured, which is to say that chemically inaccessible energy such as [[rest mass]] energy is ignored.<ref>{{cite web|url=http://physics.nist.gov/Pubs/SP811/sec04.html |title=The Two Classes of SI Units and the SI Prefixes |work=NIST Guide to the SI |publisher= |accessdate=2012-01-25}}</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]] and therefore do include mass energy as well as energy densities associated with the pressures described in the next paragraph.
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Energy per unit volume has the same physical units as [[pressure]], and in many circumstances is a [[synonym]]: for example, the energy density of a magnetic field may be expressed as (and behaves as) a physical pressure, and the energy required to compress a compressed gas a little more may be determined by multiplying the difference between the gas pressure and the external pressure by the change in volume. In short, pressure is a measure of the [[enthalpy]] per unit volume of a system. A pressure gradient has a potential to perform work on the surroundings by converting enthalpy until equilibrium is reached.
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==Introduction to energy density==
'''MathML'''
There are many 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, chemical, electrochemical, and electrical.
:<math forcemathmode="mathml">E=mc^2</math>


Chemical reactions are used by animals to derive energy from food, and by automobiles to derive energy from gasoline. Electrochemical reactions are used by most mobile devices such as laptop computers and mobile phones to release the energy from batteries.
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===Energy densities of common energy storage materials===
'''source'''
{{Unreferenced section|date=October 2013}}
:<math forcemathmode="source">E=mc^2</math> -->
The following is a list of the thermal energy densities of commonly used or well-known energy storage materials; it doesn't include uncommon or experimental materials. Note that this list does not consider the mass of reactants commonly available such as the oxygen required for combustion or the energy efficiency in use.


The following unit conversions may be helpful when considering the data in the table: 1&nbsp;[[Joule|MJ]] ≈ 0.28&nbsp;[[Kilowatt hour|kWh]] ≈ 0.37&nbsp;[[Horsepower-hour|HPh]].
<span style="color: red">Follow this [https://en.wikipedia.org/wiki/Special:Preferences#mw-prefsection-rendering link] to change your Math rendering settings.</span> You can also add a [https://en.wikipedia.org/wiki/Special:Preferences#mw-prefsection-rendering-skin Custom CSS] to force the MathML/SVG rendering or select different font families. See [https://www.mediawiki.org/wiki/Extension:Math#CSS_for_the_MathML_with_SVG_fallback_mode these examples].


{| class="wikitable sortable" style="text-align: center;"
==Demos==
! Storage material !! Energy type !! Specific energy (MJ/kg) !! Energy density (MJ/L) !! Direct uses
|-
| style="text-align:left;"| '''[[Uranium]] (in [[Breeder reactor|breeder]])''' || [[Nuclear power|Nuclear]] fission || 80,620,000<ref name="whatisnuclear" />|| 1,539,842,000 ||  Electric power plants (nuclear reactors), industrial process heat (to drive chemical reactions, water desalination, etc)
|-
| style="text-align:left;"| '''[[Thorium-based nuclear power|Thorium]] (in [[Breeder reactor|breeder]])''' || [[Nuclear power|Nuclear]] fission || 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 |accessdate=2014-04-17}}</ref> || 929,214,000 || Electric power plants (nuclear reactors), industrial process heat
|-
| style="text-align:left;"| '''[[Tritium decay|Tritium]]''' || [[Nuclear power|Nuclear]] decay || 583,529 || ? || Electric power plants (nuclear reactors), industrial process heat
|-
| style="text-align:left;"| '''[[compressed hydrogen|Hydrogen (compressed)]] at 70&nbsp;MPa)''' || [[Chemical energy#Chemical energy|Chemical]] || 142 || 5.6 || Rocket engines, automotive engines, grid storage & conversion
|-
| style="text-align:left;"| '''[[methane]] or [[natural gas]]''' || [[Chemical energy#Chemical energy|Chemical]] || 55.5 || 0.0364 || Cooking, home heating, automotive engines, lighter fluid
|-
| style="text-align:left;"| '''[[Diesel fuel|Diesel]] / [[Fuel oil]]''' || Chemical || 48 || 35.8 || Automotive engines, power plants<ref name=AFDC>{{cite web|last1=Alternative Fuels Datacenter|url=http://www.afdc.energy.gov/fuels/fuel_comparison_chart.pdf|website=energy.gov|accessdate=9 September 2014|title=Fuel Properties Comparison}}</ref>
|-
| style="text-align:left;"| '''[[Liquefied petroleum gas|LPG]] (including [[Propane]] / [[Butane]])''' || Chemical || 46.4 || 26 || Cooking, home heating, automotive engines, lighter fluid
|-
| style="text-align:left;"| '''[[Jet fuel]]''' || Chemical || 46 || 37.4 || Aircraft
|-
| style="text-align:left;"| '''[[Gasoline]] (petrol)''' || Chemical || 44.4 || 32.4 || Automotive engines, power plants
|-
| style="text-align:left;"| '''[[Fat]] (animal/vegetable)''' || Chemical || 37 || 34 || Human/animal nutrition
|-
| style="text-align:left;"| '''[[Ethanol fuel]]''' (E100) || Chemical || 26.4 || 20.9 || Flex-fuel, racing, stoves, lighting
|-
| style="text-align:left;"| '''[[Coal]]''' || Chemical || 24 ||  || Electric power plants, home heating
|-
| style="text-align:left;"| '''[[Methanol fuel]]''' (M100) || Chemical || 19.7 || 15.6 || Racing, model engines, safety
|-
| style="text-align:left;"| '''[[Carbohydrate]]s (including sugars)''' || Chemical || 17 ||  || Human/animal nutrition
|-
| style="text-align:left;"| '''[[Protein in nutrition|Protein]]''' || Chemical || 16.8 ||  || Human/animal nutrition
|-
| style="text-align:left;"| '''[[Wood fuel|Wood]]''' || Chemical || 16.2 ||  || Heating, outdoor cooking
|-
| style="text-align:left;"| '''[[Trinitrotoluene|TNT]]''' || Chemical || 4.6 ||  || Explosives
|-
| style="text-align:left;"| '''[[Gunpowder]]''' || Chemical || 3 ||  || Explosives
|-
| style="text-align:left;"| '''[[Lithium battery]] (non-rechargeable)'''|| [[electrochemical cell|Electrochemical]] || 1.8 || 4.32 || Portable electronic devices, flashlights
|-
| style="text-align:left;"| '''[[Lithium-ion battery]]''' || Electrochemical || 0.36<ref>{{cite web|title=Overview of lithium ion batteries|url=http://www.panasonic.com/industrial/includes/pdf/Panasonic_LiIon_Overview.pdf|publisher=Panasonic|archiveurl=http://web.archive.org/web/20111107060525/http://www.panasonic.com/industrial/includes/pdf/Panasonic_LiIon_Overview.pdf|archivedate=Nov 7, 2011|date=Jan 2007|deadurl=no}}</ref>&ndash;0.875 || 0.9&ndash;2.63 || Laptop computers, mobile devices, some modern electric vehicles
|-
| style="text-align:left;"| '''[[Alkaline battery]]''' || Electrochemical || 0.67 || 1.8 || Portable electronic devices, flashlights
|-
| style="text-align:left;"| '''[[Nickel-metal hydride battery]]''' || Electrochemical || 0.288 || 0.504&ndash;1.08 || Portable electronic devices, flashlights
|-
| style="text-align:left;"| '''[[Lead-acid battery]]''' || Electrochemical || 0.17 || 0.56 || Automotive engine ignition
|-
| style="text-align:left;"| '''[[Supercapacitor]]''' || Electrical ([[electrostatics|electrostatic]]) ||0.018 ||  || Electronic circuits
|-
| style="text-align:left;"| '''Electrostatic [[capacitor]]''' || Electrical (electrostatic) || 0.000036 ||  || Electronic circuits
|}


{| class="wikitable sortable" style="text-align: center;"
Here are some [https://commons.wikimedia.org/w/index.php?title=Special:ListFiles/Frederic.wang demos]:
|+ Energy capacities of common storage forms
|-
! Storage device !! Energy type !! Energy content (MJ) !! Typical mass !! Specific energy (MJ/kg) !!  W × H × D (mm)!! Uses
|-
| style="text-align:left;"| '''Automotive [[lead-acid battery]]''' || Electrochemical || 2.6 || 15&nbsp;kg || 0.17 || 230 × 180 × 185 || Automotive starter motor and accessories
|-
| style="text-align:left;" | '''Sandwich'''<ref>{{Cite web|url = http://caloriecount.about.com/calories-ham-cheese-sandwich-i21116|title = Calories in Ham And Cheese Sandwich|date = |accessdate = 22 May 2014|website = |publisher = |last = |first = }}</ref> || Chemical || 1.47  || 145&nbsp;grams || 10.13 ||  100 × 100 × 8 || Human nutrition <!-- STOP!!! DON'T REMOVE THIS WITHOUT PROVIDING AN ALTERNATIVE CITED EXAMPLE OF HUMAN NUTRITIONAL ENERGY -->
|-
| style="text-align:left;"| '''Alkaline [[AA battery]]''' || Electrochemical || 0.0154 || 23&nbsp;g || 0.616 || 14.5 × 50.5 × 14.5 || Portable electronic equipment, flashlights
|-
| style="text-align:left;" | '''Lithium-ion battery '''<ref>{{Cite web|url = http://docs-europe.electrocomponents.com/webdocs/0cf3/0900766b80cf37fc.pdf|title = Nokia BL-5C datasheet|date = |accessdate = |website = |publisher = |last = |first = }}</ref> || Electrochemical || 0.0129 || 20&nbsp;g || 0.645 || 54.2 × 33.8 × 5.8 || Mobile phones
|}


==Energy density in energy storage and in fuel==
[[File:Energy density.svg|thumb|400px|float|Selected energy densities plot]]


In [[energy storage]] applications the energy density relates the [[mass]] of 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. 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.
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The greatest energy source by far is mass 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]] (.1%), [[nuclear fusion]] (1%),{{Citation needed|date=September 2012}} or the annihilation of some or all of the matter in the volume ''V'' by matter-[[antimatter]] collisions (100%).  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.
==Test pages ==


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 (2011), sustained [[fusion power]] production continues to be elusive. Fission of uranium and thorium in [[nuclear power]] plants will be available for a long time due to the vast supply of the element on earth,{{Citation needed|date=March 2013}} though the full potential of this source can only be realised 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 |accessdate=2010-05-07}}</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|archiveurl=http://web.archive.org/web/20100506022627/http://www.eia.doe.gov/emeu/aer/pecss_diagram.html|archivedate=2010-05-06 |title=U.S. Energy Information Administration (EIA) - Annual Energy Review |publisher=Eia.doe.gov |date=2009-06-26 |accessdate=2010-05-07}}</ref> but have a much lower energy density. Burning local [[biomass]] fuels supplies household energy needs ([[Biomass Cook Stoves|cooking fires]], [[oil lamp]]s, etc.) worldwide.
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Energy density (how much energy you can carry) does not tell you about [[energy conversion efficiency]] (net output per input) or [[embodied energy]] (what the energy output costs to provide, as [[energy industry|harvesting]], [[refinery|refining]], distributing, and dealing with [[pollution]] all use energy). Like any process occurring on a large scale, intensive energy use impacts the world.  For example, [[climate change]], [[nuclear waste]] storage, and [[deforestation]] may be some of the consequences of supplying our growing energy demands from carbohydrate fuels, nuclear fission, or biomass.
*[[Inputtypes|Inputtypes (private Wikis only)]]
 
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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 we pull it out.  To maximize both specific energy and energy density, one can compute the [[specific energy density]] of a substance by multiplying the two values together, where the higher the number, the better the substance is at storing energy efficiently.
==Bug reporting==
 
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Gravimetric and volumetric energy density of some fuels and storage technologies (modified from the [[Gasoline]] article):
:Note: 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.
:Note: Also it is important to realise that generally the density values for chemical fuels do not include the weight of oxygen required for combustion. This is typically two oxygen atoms per carbon atom, and one per two hydrogen atoms. The [[atomic weight]] of carbon and oxygen are similar, while hydrogen is much lighter than oxygen. Figures are presented 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 already include their own oxidiser (such as gunpowder and TNT), where the mass of the oxidiser in effect adds dead 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.
 
{{cleanup|section|date=October 2008}}<!-- table does not sort correctly: second and third columns fail to sort large numbers and some of the number ranges; cannot determine cause, maybe the spans and the tmn templates (non-functioning according to [[Help:Sort]])? -->
 
<!-- table is split into two: first true energy densities including all needed oxidisers; second energy densities excluding oxidisers -->
 
===Energy densities ignoring external components===
This table lists energy densities of systems that require external components, such as oxidisers or a heat sink or source. These figures do not take into account the mass and volume of the required components as they are assumed to be freely available and present in the atmosphere. Such systems cannot be compared with self-contained systems. These values may not be computed at the same reference conditions. Most of them seem to be [[higher heating value]] (HHV).
<!-- To ensure this table sorts correctly: avoid using "-" or unicode dash in columns with numbers; ensure each row has a single numeric value, use <span style="display:none">0</span> 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. -->
{|class="wikitable sortable" style="text-align: right;"
|+ Energy densities of energy media
!Storage type
!Specific energy (MJ/kg)
!Energy density (MJ/L)
!Peak recovery efficiency %
!Practical recovery efficiency %
|-
|align=left | [[Antimatter]] || {{nowrap|1.80 10<sup>11</sup>}} || {{nowrap|9.266032 10<sup>104</sup>}} || ||
|-
|align=left | [[Liquid hydrogen|Hydrogen, liquid]]<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> || 141.86 || 8.491 || ||
|-
|align=left | [[Compressed gaseous hydrogen|Hydrogen, at 690 bar and 15°C]]<ref name="H2"/> || 141.86|| 4.5 || ||
|-
|align=left|[[Gaseous hydrogen|Hydrogen, gas]]<ref name="H2"/> || 141.86|| 0.01005 || ||
|-
|align=left | [[Diborane]]<ref>Greenwood, Norman N.; Earnshaw, Alan (1997), Chemistry of the Elements (2nd ed) (page 164)</ref> || 78.2 || || ||
|-
|align=left|[[Beryllium]] ||67.6||125.1|| ||
|-
|align=left|[[Lithium borohydride]] ||65.2||43.4|| ||
|-
|align=left|[[Boron]]<ref>{{cite web|url=http://www.eagle.ca/~gcowan/boron_blast.html#TOC |title=Boron: A Better Energy Carrier than Hydrogen? (28 February 2009) |publisher=Eagle.ca |accessdate=2010-05-07}}</ref>  ||58.9||137.8|| ||
|-
|align=left|[[Methane]] (1.013&nbsp;bar, 15&nbsp;°C) ||55.6||0.0378 || ||
|-
|align=left|[[Natural gas]] |||53.6<ref name="ngau">Envestra Limited. [http://www.natural-gas.com.au/about/references.html Natural Gas]. Retrieved 2008-10-05.</ref>||0.0364|| ||
|-
|align=left|[[Liquefied natural gas|LNG]] (NG at −160&nbsp;°C)|||53.6<ref name="ngau"/>||22.2|| ||
|-
|align=left|[[Compressed natural gas|CNG]] (NG compressed to 250&nbsp;bar/~3,600&nbsp;psi) || 53.6<ref name="ngau"/> || 9 ||
|-
|align=left | [[Liquefied petroleum gas|LPG]] [[propane]]<ref name="IOR">IOR Energy. [http://web.archive.org/web/20100924142555/http://www.ior.com.au/ecflist.html List of common conversion factors (Engineering conversion factors)]. Retrieved 2008-10-05.</ref> || 49.6 || 25.3 || ||
|-
|align=left| [[Liquefied petroleum gas|LPG]] [[butane]]<ref name="IOR"/> || 49.1 || 27.7 || ||
|-
|align=left|[[Gasoline|Gasoline (petrol)]]<ref name="IOR"/> || 46.4 || 34.2 || ||
|-
|align=left|[[Polypropylene]] plastic||46.4<ref name="aquafoam"/>||41.7|| ||
|-
|align=left|[[Polyethylene]] plastic||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 |publisher= |accessdate=2012-01-25}}</ref>||42.6|| ||
|-
|align=left|[[Crude oil]] (according to the definition of [[ton of oil equivalent]])||46.3||37<ref name="ngau"/>|| ||
|-
|align=left|Residential [[heating oil]]<ref name="IOR"/>||46.2||37.3|| ||
|-
|align=left|[[Diesel fuel]]<ref name="IOR"/>||45.6||38.6|| ||
|-
|align=left|[[100LL]] Avgas ||44.0<ref>{{cite web|url=http://www-static.shell.com/static/aus/downloads/aviation/avgas_100ll_pds.pdf |title=537.PDF |format=PDF |date=June 1993 |accessdate=2012-01-25}}</ref>||31.59|| ||
|-
|align=left|[[Gasohol]] E10 (10% ethanol 90% gasoline by volume)||43.54||33.18|| ||
|-
|align=left|[[Lithium]] ||43.1||23.0|| ||
|-
|align=left|[[Jet fuel|Jet A]] [[aviation fuel]]<ref>{{cite web|url=http://hypertextbook.com/facts/2003/EvelynGofman.shtml |title=Energy Density of Aviation Fuel |publisher=Hypertextbook.com |accessdate=2010-05-07}}</ref>/[[kerosene]]||42.8||33|| ||
|-
|align=left|[[Biodiesel]] oil (vegetable oil)||42.20||33|| ||
|-
|align=left|[[2,5-Dimethylfuran|DMF]] (2,5-dimethylfuran){{Clarify|date=February 2009|need a quote from the cite containing "42" and "37.8" or equivalent in wh/kg and wh/litre}} ||42<ref>{{cite web|author=Nature |url=http://www.nature.com/nature/journal/v447/n7147/abs/nature05923.html |title=Production of dimethylfuran for liquid fuels from biomass-derived carbohydrates : Abstract |publisher=Nature |accessdate=2010-05-07}}</ref> ||37.8|| ||
|-
|align=left|[[Polystyrene]] plastic||41.4<ref name="aquafoam"/>||43.5|| ||
|-
|align=left|[[Fatty acid metabolism|Body fat metabolism]]||38||35|||22<ref name="JLE5">{{cite web |author=Justin Lemire-Elmore |title=The Energy Cost of Electric and Human-Powered Bicycles |url=http://www.ebikes.ca/sustainability/Ebike_Energy.pdf |page=5 |quote=properly trained athlete will have efficiencies of 22 to 26% |date=2004-04-13 |accessdate=2009-02-26}}</ref>||
|-
|align=left|[[Butanol fuel|Butanol]]||36.6||29.2|| ||
|-
|align=left|Gasohol [[E85]] (85% ethanol 15% gasoline by volume)||33.1||25.65{{Citation needed|date=October 2014}}|| ||
|-
|align=left|[[Graphite]] ||32.7||72.9|| ||
|-
|align=left|[[Coal]], [[anthracite]]<ref name='fisher'>{{cite web | last = Fisher | first = Juliya | title = Energy Density of Coal | work = The Physics Factbook | url = http://hypertextbook.com/facts/2003/JuliyaFisher.shtml|year=2003|accessdate = 2006-08-25 }}</ref>||32.5||72.4{{dubious|date=January 2012}}||36||
|-
|align=left|[[Silicon]]<ref>[http://web.archive.org/web/20090327030002/http://www.dbresearch.com/PROD/DBR_INTERNET_EN-PROD/PROD0000000000079095.pdf Silicon as an intermediary between renewable energy and hydrogen<!-- Bot generated title -->]</ref> ||32.2||75.1|| ||
|-
|align=left|[[Aluminum]] ||31.0||83.8|| ||
|-
|align=left|[[Ethanol]]||30||24|| ||
|-
|align=left|[[Polyester]] plastic||26.0<ref name="aquafoam"/>||35.6|| ||
|-
|align=left|[[Magnesium]] ||24.7||43.0|| ||
|-
|align=left|[[Coal]], [[Bitumen|bituminous]]<ref name='fisher'/> ||24||20|| ||
|-
|align=left|[[Polyethylene terephthalate|PET]] plastic||23.5 (impure)<ref>{{cite web|url=http://www.payne-worldwide.com/documents/cms/Elite_bloc_msds.pdf |title=Elite_bloc.indd |format=PDF |accessdate=2010-05-07}}</ref> || || ||
|-
|align=left|[[Methanol]]||19.7||15.6|| ||
|-
|align=left|[[Hydrazine]] (toxic) combusted to N<sub>2</sub>+H<sub>2</sub>O||19.5||19.3|| ||
|-
|align=left|Liquid [[ammonia]] (combusted to N<sub>2</sub>+H<sub>2</sub>O)||18.6||11.5|| ||
|-
|align=left|[[PVC]] plastic ([[Polyvinyl chloride#Dioxins|improper combustion toxic]]){{Clarify|date=October 2008}}<!-- what does this mean? Is it 18MJ/kg only if PVC is incompletely burned? -->||18.0<ref name="aquafoam"/>||25.2|| ||
|-
|align=left|[[Wood]]<ref>{{cite web|url=http://www.woodgas.com/fuel_densities.htm|archiveurl=http://web.archive.org/web/20100110042311/http://www.woodgas.com/fuel_densities.htm|archivedate=2010-01-10 |title=Biomass Energy Foundation: Fuel Densities |publisher=Woodgas.com |accessdate=2010-05-07}}</ref> ||18.0 || || ||
|-
|align=left|[[Peat]] [[briquette]]<ref>{{cite web|url=http://www.bnm.ie/files/20061124040716_peat_for_energy.pdf|archiveurl=http://web.archive.org/web/20071119083231/http://www.bnm.ie/files/20061124040716_peat_for_energy.pdf|archivedate=2007-11-19 |title=Bord na Mona, Peat for Energy |publisher=Bnm.ie |accessdate=2012-01-25}}</ref> ||17.7|| || ||
|-
|align=left|[[Fatty acid metabolism|Sugars, carbohydrates, and protein metabolism]]{{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}}||17||26.2&nbsp;([[dextrose]])|||<span style="display:none">22</span>22<ref>{{cite web|url=http://www.ebikes.ca/sustainability/Ebike_Energy.pdf |title=The Energy Cost of Electric and Human-Powered Bicycle |author=Justin Lemire-Elmor |publisher= |date=April 13, 2004 |accessdate=2012-01-25}}</ref> ||
|-
|align=left|[[Calcium]]{{Citation needed|date=November 2008}}||15.9||24.6|| ||
|-
|align=left|[[Glucose]]||15.55||23.9|| ||
|-
|align=left|Dry [[cow dung]] and [[Manure#Uses of manure|cameldung]]||15.5<ref>{{cite web|url=http://www.davdata.nl/math/energy.html |title=energy buffers |publisher=Home.hccnet.nl |accessdate=2010-05-07}}</ref> || || ||
|-
|align=left|[[Coal]], [[lignite]]{{Citation needed|date=November 2008}}<!-- removed " (to 19)" to make sort work -->||14.0|| || ||
|-
|align=left|[[Sodium]] (burned to wet [[sodium hydroxide]])||13.3||12.8|| ||
|-
|align=left|Sod [[peat]] ||12.8|| || ||
|-
|align=left|[[Nitromethane]] ||11.3|| || ||
|-
|align=left|[[Sulfur]] (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]. Pearson Education NZ ISBN 978-0-582-54974-6</ref>  ||9.23||19.11 ||
|-
|align=left|[[Sodium]] (burned to dry [[sodium oxide]])||9.1||8.8|| ||
|-
|align=left | [[Lithium air battery|Battery, lithium-air rechargeable]]||9.0<ref>{{cite journal |url=http://pubs.rsc.org/en/content/articlelanding/2011/ee/c1ee01496j |title=All-carbon-nanofiber electrodes for high-energy rechargeable Li–O2 batteries |first=Robert R. |last=Mitchell |author2=Betar M. Gallant |author3=Carl V. Thompson |author4= Yang Shao-Horn  |journal=Energy & Environmental Science |year=2011 |volume=4 |pages=2952–2958 |doi=10.1039/C1EE01496J}}</ref> || || ||
|-
|align=left|[[Household waste]]<!-- removed " (to 11)" to make sort work -->|||8.0<ref>David E. Dirkse. [http://www.davdata.nl/math/energy.html energy buffers]. "household waste 8..11 MJ/kg"</ref>|| || ||
|-
|align=left|[[Zinc]] ||5.3||38.0|| ||
|-
|align=left|[[Iron]] (burned to [[iron(III) oxide]])||5.2||40.68|| ||
|-
|align=left|[[PTFE|Teflon]] plastic (combustion toxic, but flame retardant)||5.1||11.2|| ||
|-
|align=left|[[Iron]] (burned to [[iron(II) oxide]])||4.9||38.2|| ||
|-
| align=left | [[ANFO]] || 3.7 || ||
|-
|align=left | [[Zinc-air battery|Battery, zinc-air]]<ref name="duracell-za-tech">{{cite web|url=http://www.duracell.com/oem/primary/Zinc/zinc_air_tech.asp|archiveurl=http://web.archive.org/web/20090127030703/http://www.duracell.com/oem/primary/Zinc/zinc_air_tech.asp|archivedate=2009-01-27|accessdate=2009-04-21|publisher=[[Duracell]]|title=Technical bulletin on Zinc-air batteries}}</ref> || 1.59 || 6.02 || ||
|-
|align=left | [[Liquid nitrogen economy|Liquid nitrogen]]{{Clarify|date=November 2008}}<!-- need note on how energy released, ie temperatures and pressures of both endpoints -->||0.77<ref name="Knowlen">C. Knowlen, A.T. Mattick, A.P. Bruckner and A. Hertzberg, [http://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 || ||
|-
|align=left | [[Compressed air]] at 300&nbsp;bar (potential energy) || 0.5 || 0.2 || || >50%{{Citation needed|date=February 2010}}
|-
|align=left|[[Enthalpy of fusion|Latent heat of fusion]] of ice{{Citation needed|date=June 2009}} (thermal)||0.335||0.335|| ||
|-
|align=left|[[Hydroelectricity|Water at 100 m dam height]] (potential energy)||0.001||0.001|| ||<span style="display:none">85</span>85-90%{{Citation needed|date=May 2009}}
|- class="sortbottom"
!Storage type
!Energy density by mass (MJ/kg)
!Energy density by volume (MJ/[[Liter|L]])
!Peak recovery efficiency %
!Practical recovery efficiency %
|}
 
Divide [[joule]] [[metre]]<sup>−3</sup> by 10<sup>9</sup> to get [[Joule|MJ]]/[[Liter|L]]. Divide MJ/L by 3.6 to get [[kWh]]/L.
 
==Energy density of electric and magnetic fields==<!-- This section is linked from [[Special relativity]] -->
[[Electric field|Electric]] and [[magnetic field]]s store energy.  In a vacuum, the (volumetric) energy density (in SI units) is given by
 
:<math> U = \frac{\varepsilon_0}{2} \mathbf{E}^2 + \frac{1}{2\mu_0} \mathbf{B}^2 </math>
 
where '''E''' is the [[electric field]] and '''B''' is the [[magnetic field]].  The solution will be 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 normal (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 '''D''' is the [[electric displacement field]] and '''H''' is the [[Effective magnetic field|magnetizing field]].
 
==See also==
{{Portal|Energy}}
* [[Energy density Extended Reference Table]]
* [[High Energy Density Matter]]
* [[Power density]] and specifically
** [[Power-to-weight ratio]]
* [[Orders of magnitude (specific energy)]]
* [[Figure of merit]]
* [[Energy content of biofuel]]
* [[Heat of combustion]]
* [[Heating value]]
* [[Rechargeable battery]]
* [[Specific impulse]]
* [[Food energy]]
 
==Footnotes==
{{Reflist|colwidth=30em}}
 
==External references==
 
===Density data===
* {{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
 
===Energy storage===
* [http://www.tinaja.com/h2gas01.asp energy fundamentals]
 
===Books===
* ''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
 
{{DEFAULTSORT:Energy Density}}
[[Category:Energy]]
[[Category:Density]]

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