Energy density 1610231 225707978 2008-07-15T00:36:18Z 64.115.154.242 '''Energy density''' is the amount of [[energy]] stored in a given system or region of space per unit [[volume]], or per unit [[mass]], depending on the context. In some cases it is obvious from context which quantity is most useful: for example, in [[rocketry]], energy per unit mass is the most important parameter, but when studying pressurized gas or [[magnetohydrodynamics]] the energy per unit volume is more appropriate. In a few applications (comparing, for example, the effectiveness of [[hydrogen]] fuel to [[gasoline]]) both figures are appropriate and should be called out explicitly. (Hydrogen has a higher energy density per unit mass than does gasoline, but a much lower energy density per unit volume in most applications.) Energy density per unit volume has the same physical units as [[pressure]], and in many circumstances is an exact [[synonym]]: for example, the energy density of the magnetic field may be expressed as (and behaves as) a physical pressure, and the energy required to compress a gas may be determined by multiplying the pressure of the compressed gas times its change in volume. ==Energy density in energy storage and in fuel== In [[energy storage]] applications, the energy density relates the [[mass]] of an energy store to its stored energy. The higher the energy density, the more energy may be stored or transported for the same amount of mass. In the context of [[fuel]] selection, that energy density of a fuel is also called the [[specific energy]] of that fuel, though in general an [[engine]] using that fuel will yield less energy due to [[inefficiency|inefficiencies]] and [[thermodynamics|thermodynamic]] considerations—hence the [[specific fuel consumption]] of an engine will be greater than the [[reciprocal]] of the specific energy of the fuel. And in general, specific energy and energy density are at odds due to [[charge screening]]. 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. :This table does not take into account the mass and volume of the oxygen required for many of the chemical reactions, as it is assumed to be freely available and present in the atmosphere. In cases where this is not true (such as rocket fuel), oxygen is included as an oxidizer. [[Image:Energy Density.PNG|thumb|50px|right|Energy density of various storage media.]] {| class="wikitable sortable" |- ! align=center | '''Storage type''' ! align=center width=90 | '''Energy density by mass (MJ/kg)''' ! align=center width=90 | '''Energy density by volume (MJ/[[Liter|L]])''' ! align=center width=90 | '''Peak recovery efficiency (%)''' ! align=center width=90 | '''Practical recovery efficiency (%)''' |- |[[Mass-energy equivalence]]||89,876,000,000|| || || |- |[[Binding energy]] of [[Helium-4]] nucleus||683,000,000||8.57x10<sup>24</sup>|| || |- |[[Nuclear fusion]] of hydrogen (energy from the [[sun]])||645,000,000|| || || |- |[[Nuclear fission]] (of [[U-235]]) (Used in [[nuclear power plant]]s)||88,250,000||1,500,000,000|| ||| |- |[[Uranium|Natural uranium]] (99.3% U238, 0.7% U235) in [[fast breeder reactor]][http://petroleum.berkeley.edu/patzek/ce24/Spring2003/heatvalues.htm]||24,000,000|||| ||[https://netfiles.uiuc.edu/mragheb/www/NPRE%20402%20ME%20405%20Nuclear%20Power%20Engineering/High%20Temperature%20Gas%20Cooled%20Reactor%20HTGR.pdf 50%]{{smn}} |- |[[Uranium|Enriched uranium]] (3.5% U235) in [[light water reactor]]||3,456,000|||| ||[[Heat engine#Other criteria of heat engine performance|30%]] |- |[[Nuclear_isomer|Hf-178m2 isomer]]||1,326,000||17,649,060|| || |- |[[Uranium|Natural uranium]] (0.7% U235) in [[light water reactor]]||443,000|||| ||[[Heat engine#Other criteria of heat engine performance|30%]] |- |[[Nuclear_isomer|Ta-180m isomer]]||41,340||689,964|| || |- |[[Liquid hydrogen]]||143||10.1|| || |- |[[Compressed gaseous hydrogen]] at 700 bar [http://www.gov.pe.ca/photos/original/dev_solutions.pdf]||143||5.6|| || |- |[[Gaseous hydrogen]] at room temperature{{Fact|date=May 2007}}||143||0.01079|| || |- |[[Beryllium]] (toxic) (burned in air)||67.6||125.1|| || |- |[[Lithium borohydride]] (burned in air)||65.2||43.4|| || |- |[[Boron]] [http://www.eagle.ca/~gcowan/boron_blast.html#TOC] (burned in air)||58.9||137.8|| || |- |[[Compressed natural gas]] at 200 bar|||53.6 [http://www.natural-gas.com.au/about/reference.html]{{smn}}||10|| || |- |[[Liquefied petroleum gas|LPG]] [[propane]] [http://www.ior.com.au/ecflist.html]||49.6||25.3|| || |- |[[Liquefied petroleum gas|LPG]] [[butane]]||49.1||27.7|| || |- |[[Gasoline]][http://www.eia.doe.gov/kids/energyfacts/science/energy_calculator.html]||46.9||34.6|| || |- |[[Diesel fuel]]/residential [[heating oil]][http://www.eia.doe.gov/kids/energyfacts/science/energy_calculator.html]||45.8||38.7|| || |- |[[Polyethylene]] plastic||46.3 [http://www.aquafoam.com/papers/selection.pdf]{{smn}}||42.6|| || |- |[[Polypropylene]] plastic||46.3 [http://www.aquafoam.com/papers/selection.pdf]{{smn}}||41.7|| || |- |[[Alcohol fuel|gasohol]] (10% ethanol 90% gasoline)||43.54||28.06 (not consistent with detail)|| || |- |[[Lithium]] (burned in air)||43.1||23.0|| || |- |[[Jet fuel|Jet A]] [[aviation fuel]] [http://hypertextbook.com/facts/2003/EvelynGofman.shtml] / [[kerosene]]||42.8||33|| || |- |[[Biodiesel]] oil (vegetable oil)||42.20||33|| || |- |[[2,5-Dimethylfuran|DMF]] (2,5-dimethylfuran) ||42 [http://www.nature.com/nature/journal/v447/n7147/abs/nature05923.html]{{smn}}||37.8|| || |- |[[Crude oil]] (according to the definition of [[ton of oil equivalent]])||41.87||37 [http://www.natural-gas.com.au/about/reference.html]{{smn}}|| || |- |[[Polystyrene]] plastic||41.4 [http://www.aquafoam.com/papers/selection.pdf]{{smn}}||43.5|| || |- |[[Fatty acid metabolism|Body fat metabolism]]||38||35|||<span style="display:none">22</span>22-26%[http://www.ebikes.ca/sustainability/Ebike_Energy.pdf]{{smn}}|| |- |[[Butanol fuel|Butanol]]||36.6||29.2|| || |- |[[Specific orbital energy]] of [[Low Earth orbit]]||33 (approx.){{smn}}|| || || |- |[[Graphite]] (burned in air)||32.7||72.9|| || |- |[[Anthracite]] [[coal]]||32.5||72.4|| |||<span style="display:none">36</span>[[Heat engine#Other criteria of heat engine performance|36%]]{{smn}} |- |[[Silicon]] (burned in air)[http://dbresearch.com/PROD/DBR_INTERNET_EN-PROD/PROD0000000000079095.pdf]||32.2||75.1|| || |- |[[Aluminum]] (burned in air)||31.0||83.8|| || |- |[[Ethanol]]||30||24|| || |- |[[Polyester]] plastic||26.0 [http://www.aquafoam.com/papers/selection.pdf]{{smn}}||35.6|| || |- |[[Magnesium]] (burned in air)||24.7||43.0|| || |- |[[Bitumen|Bituminous]] [[coal]] [http://hypertextbook.com/facts/2003/JuliyaFisher.shtml]||24||20|| || |- |[[Polyethylene terephthalate|PET]] plastic||23.5 (impure) [http://payne-worldwide.com/pdfs/Elite_bloc_msds.pdf]{{smn}}|| || || |- |[[Methanol]]||19.7||15.6|| || |- |[[Hydrazine]] (toxic) combusted to N<sub>2</sub>+H<sub>2</sub>O||19.5||19.3|| || |- |Liquid [[ammonia]] (combusted to N<sub>2</sub>+H<sub>2</sub>O)||18.6||11.5|| || |- |[[PVC]] plastic ([[Polyvinyl chloride#Dioxins|improper combustion toxic]])||18.0 [http://www.aquafoam.com/papers/selection.pdf]{{smn}}||25.2|| || |- |[[Fatty acid metabolism|Sugars, carbohydrates & protein metabolism]]||17||26.2([[dextrose]]){{smn}}|||<span style="display:none">22</span>22-26% [http://www.ebikes.ca/sustainability/Ebike_Energy.pdf]{{smn}}|| |- |[[Dichlorine heptoxide|Cl<sub>2</sub>O<sub>7</sub>]] + [[CH4|CH<sub>4</sub>]] - computed||17.4|| || || |- |[[Lignite]] coal||<span style="display:none">14</span>14-19|| || || |- |[[Calcium]] (burned in air)||15.9||24.6|| || |- |Dry [[cowdung]] and [[Manure#Uses of manure|cameldung]]||15.5 [http://home.hccnet.nl/david.dirkse/math/energy.html]{{smn}}|| || || |- |[[Wood]]||6–17 [http://xtronics.com/reference/energy_density.htm]{{smn}}||<span style="display:none">1.8</span>1.8–3.2{{smn}}|| || |- |Liquid [[hydrogen]] + [[oxygen]] (as [[oxidizer]]) (1:8 (w/w), 14.1:7.0 (v/v))||13.333||5.7|| || |- |[[Sodium]] (burned to wet [[sodium hydroxide]])||13.3||12.8|| || |- |[[Dichlorine heptoxide|Cl<sub>2</sub>O<sub>7</sub>]] decomposition - computed||12.2|| || || |- |[[Nitromethane]]||11.3||12.9|| || |- |[[Household waste]]|||<span style="display:none">8</span>8-11 [http://home.hccnet.nl/david.dirkse/math/energy.html][http://www.biffaward.org/downloads/projectfiles/1826-00237.pdf]{{smn}}|| || || |- |[[Sodium]] (burned to dry [[sodium oxide]])||9.1||8.8|| || |- |[[Dinitroacetylene]] explosive - computed ||7.9|| || |- |[[Octanitrocubane]] explosive - computed||7.4|| || || |- |[[Sodium]] (reacted with chlorine)||7.0349|| || || |- |[[Ammonal]] (Al+[[ammonium nitrate|NH<sub>4</sub>NO<sub>3</sub>]] [[oxidizer]])||6.9||12.7|| || |- |[[Tetranitromethane]] + [[hydrazine]] explosive - computed||6.6|| || || |- |[[Hexanitrobenzene]] explosive - computed||6.5|| || || |- |[[Zinc]] (burned in air)||5.3||38.0|| || |- |[[PTFE|Teflon]] plastic (combustion toxic, but flame retardant)||5.1||11.2|| || |- |[[iron]] (burned to [[iron(III) oxide]])||5.2||40.68|| || |- |[[iron]] (burned to [[iron(II) oxide]])||4.9||38.2|| || |- |[[trinitrotoluene|TNT]]||4.184||6.92|| || |- |Copper [[Thermite]] (Al + [[copper(II) oxide|CuO]] as [[oxidizer]])||4.13||20.9|| || |- |[[Thermite]] (powder Al + [[iron(III) oxide|Fe<sub>2</sub>O<sub>3</sub>]] as [[oxidizer]])||4.00 [http://xtronics.com/reference/energy_density.htm]{{smn}}||18.4|| || |- |[[Compressed air energy storage|compressed air]] at 300 bar (at 12°C), without container||0.512||0.16|| || |- |[[Hydrogen peroxide]] decomposition (as [[monopropellant]])||2.7||3.8|| || |- |[[Nanowire battery|Lithium ion battery with nanowires]]||<span style="display:none">25.4</span>2.54-2.72?{{smn}}||<span style="display:none">29</span> {{smn}}|| ||95%[http://news-service.stanford.edu/news/2008/january9/nanowire-010908.html]{{smn}} |- |- |[[Lithium thionyl chloride battery]] [http://www.nexergy.com/lithium-thionyl-chloride.htm]||2.5|| || || |- |[[Fluoride ion battery]] [http://istc.ru/istc/sc.nsf/html/projects.htm?open&id=2729]||<span style="display:none">1.7</span>1.7-(?){{smn}}||<span style="display:none">2.8(?)</span>2.8(?){{smn}}|| || |- |Regenerative [[Fuel Cell]] (fuel cell with internal Hydrogen reservoir used much as a battery)||1.62 [http://www.llnl.gov/str/Mitlit.html]{{smn}}|| || || |- |[[Hydrazine]](toxic) decomposition (as [[monopropellant]])||1.6||1.6|| || |- |[[Ammonium nitrate]] decomposition (as [[monopropellant]])||1.4||2.5|| || |- |[[Capacitor]] by EEStor (claimed capacity)||1.0 [http://www.technologyreview.com/Biztech/18086/page2/]{{smn}}|| || || |- |[[Molecular spring]]||<span style="display:none">1</span>~1{{smn}}|| || || |- |[[Sodium-sulfur battery]]|| ||1.23 [http://worldenergy.org/wec-geis/publications/default/tech_papers/17th_congress/3_3_05.asp]{{smn}}|| ||85%[http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=5960185]{{smn}} |- |[[Liquid nitrogen economy|Liquid nitrogen]]||0.77<ref name="Knowlen">C. Knowlen, A.T. Mattick, A.P. Bruckner and A. Hertzberg, [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>{{smn}}||0.62|| || |- |[[Lithium ion battery]]<ref name="BatteryspaceCom">A typically available lithium ion cell with an Energy Density of 201 wh/kg [http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2763]</ref>|||<span style="display:none">0.54</span>0.54–0.72{{smn}}|||<span style="display:none">0.9</span>0.9–1.9{{smn}}|| ||95%[http://www.ebikes.ca/sustainability/Ebike_Energy.pdf]{{smn}} |- |[[Lithium sulphur battery]]|||<span style="display:none">0.54</span>0.54-1.44{{smn}}|| || || |- |[[Kinetic energy penetrator]]|||<span style="display:none">1.9</span>1.9-3.4{{smn}}|||<span style="display:none">30</span>30-54{{smn}}|| || |- |[[5.56 × 45 mm NATO]] bullet|||<span style="display:none">0.4</span>0.4-0.8{{smn}}|||<span style="display:none">3.2</span>3.2-6.4{{smn}}|| || |- |[[Zn-air batteries]]|||<span style="display:none">0.4</span>0.40 to 1.7{{smn}}|||<span style="display:none">5.9</span>5.9{{smn}}|| || |- |[[Flywheel energy storage|Flywheel]]||0.5|| || |||<span style="display:none">81</span>81-94%{{Fact|date=January 2008}}{{smn}} |- |[[Latent heat of fusion|Ice]]||0.335||0.335|| || |- |[[Zinc-bromine flow battery]]|||<span style="display:none">0.27</span>0.27–0.306 [http://www.zbbenergy.com/technology.htm]{{smn}}|| || || |- |[[Compressed air energy storage|Compressed air]] at 20 bar (at 12°C), without container||0.27||0.01|| ||64%[http://www.kbbnet.de/]{{smn}} |- |[[Nickel metal hydride battery|NiMH Battery]]||0.22 [http://xtronics.com/reference/energy_density.htm]{{smn}}||0.36|| ||60% [http://ebikes.ca/sustainability/Ebike_Energy.pdf]{{smn}} |- |[[NiCd Battery]]||<span style="display:none">0.14</span>0.14-0.22{{smn}}|| || ||80% [http://ebikes.ca/sustainability/Ebike_Energy.pdf]{{smn}} |- |[[Lead acid battery]]||<span style="display:none">0.09</span>0.09–0.11 [http://xtronics.com/reference/energy_density.htm]{{smn}}|||<span style="display:none">0.14</span>0.14–0.17{{smn}}|| |||<span style="display:none">75</span>75-85%[http://xtronics.com/reference/batterap.htm]{{smn}} |- |[[Compressed air energy storage|Compressed air]] in fiber-wound bottle at 200 bar (at 24°C)||0.1||0.1|| || |- |Commercial lead acid battery pack||<span style="display:none">0.072</span>0.072-0.079 [http://www.azuredynamics.com/energystoragesystems.htm]{{smn}}|| || || |- |[[Vanadium redox battery]]||0.09 [http://www.zsw-bw.de/index.html]{{smn}}||0.1188|| |||<span style="display:none">70</span>70-75%{{smn}} |- |[[Vanadium bromide redox battery]]||0.18 [http://www.vfuel.com.au/]{{smn}}||0.252|| ||81% |- |[[Compressed air energy storage|compressed air]] in steel bottle at 200 bar (at 24°C)||0.04||0.1|| || |- |[[Ultracapacitor]]||0.0206 [http://maxwell.com/ultracapacitors/products/large-cell/bcap3000.asp]{{smn}}||0.050 [http://maxwell.com/ultracapacitors/products/large-cell/bcap3000.asp]|| || |- |[[Supercapacitor]]||0.01|| ||98.5%||90%[http://www2.fs.cvut.cz/web/fileadmin/documents/12241-BOZEK/publikace/2004/Sup-Cap-Energy-Storage.pdf]{{smn}} |- |[[Capacitor]]||0.002 [http://www.doc.ic.ac.uk/~mpj01/ise2grp/energystorage_report/node9.html]{{smn}}|| || || |- |[[Hydroelectricity|Water at 100 m dam height]]||0.001||0.001|| ||<span style="display:none">85</span>85-90%[http://www.tekes.fi/partner/fin/search/nayta_haku.asp?hakuid=25765]{{smn}} |- |[[Spring power]] (clock spring), [[torsion spring]]||0.0003 [http://garagedoor.org/residential/torsion-springs.php]{{smn}}||0.0006|| || |} The highest density sources of energy are [[nuclear fusion|fusion]] and [[fission]]. Fusion includes energy from the sun which will be available for billions of years (in the form of [[sunlight]]) but humans have not learned to make our own sustained fusion power sources. Fission of U-235 in [[nuclear power plants]] will be available for billions of years because of the vast supply of the element on earth [http://www-formal.stanford.edu/jmc/progress/cohen.html]. [[Coal]] and [[petroleum]] are the current primary energy sources in the U.S. 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. 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 creates environmental impacts: for example, [[global warming]], [[nuclear waste]] storage, and [[deforestation]] are a few of the consequences of supplying our growing energy demands from fossil fuels, nuclear fission, or biomass. By dividing by 3.6 the figures for megajoules per kilogram can be converted to kilowatt-hours per kilogram. Unfortunately, the useful energy available by extraction from an energy store is always less than the energy put into the energy store, as explained by the [[laws of thermodynamics]]. No single energy storage method boasts the best in [[specific power]], [[specific energy]], and energy density. [[Peukert's Law]] describes how the amount of energy we get out depends how quickly we pull it out. ==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]]. 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) 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 [[magnetic field#B and H|magnetizing field]]. ==Energy density of empty space== In [[physics]], "[[vacuum energy]]" or "[[zero-point energy]]" is the volumetric energy density of empty space. More recent developments have expounded on the concept of energy in empty space. [[Modern physics]] is commonly classified into two fundamental theories: [[quantum field theory]] and [[general relativity]]. Quantum field theory takes [[quantum mechanics]] and [[special relativity]] into account, and it's a theory of all the forces and particles except [[gravity]]. General relativity is a theory of gravity, but it is incompatible with quantum mechanics. Currently these two theories have not yet been reconciled into one unified description, though research into "[[quantum gravity]]" seeks to bridge this divide. In [[general relativity]], the [[cosmological constant]] is proportional to the energy density of empty space, and can be measured by the curvature of space. It is subsequently related to the age of the universe, and as energy expands outwards with time its density changes. Quantum field theory considers the vacuum ground state not to be completely empty, but to consist of a seething mass of [[virtual particle]]s and [[field (physics)|fields]]. These fields are quantified as probabilities—that is, the likelihood of manifestation based on conditions. Since these fields do not have a permanent existence, they are called vacuum fluctuations. In the [[Casimir effect]], two metal plates can cause a change in the vacuum energy density between them which generates a measurable force. Some believe that vacuum energy might be the "[[dark energy]]" (also called [[quintessence]]) associated with the cosmological constant in general relativity, thought to be similar to a negative force of gravity (or [[antigravity]]). Observations that the expanding universe appears to be accelerating seem to support the [[cosmic inflation]] theory—first proposed by [[Alan Guth]] in 1981—in which the nascent universe passed through a phase of exponential expansion driven by a negative vacuum energy density (positive vacuum pressure). ==Energy density of food== Energy density is the amount of energy ([[kilojoule]]s or [[calorie]]s) per amount of food, with food amount being measured in grams or milliliters of food. Energy density is thus expressed in cal/g, kcal/g, J/g, kJ/g, cal/mL, kcal/mL, J/mL, or kJ/mL. This is the energy released when the food is metabolised by a healthy organism when it ingests the food (see [[food energy]] for calculation) and the food is [[metabolized]] with oxygen, into waste products such as [[carbon dioxide]] and water. Typical values of food energy density for high energy-density foods, such as a hamburger, would be 2.5 kcal/g. Purified fats and oils contain the highest energy densities—about 9 kcal/g. What is popularly referred to as the number of "[[calories]]" in a portion of food is therefore technically the number of ''kilo''calories (''thousands'' of calories) in the portion. ==Miscellaneous== *[[Kinetic energy]] per unit mass: <math>\begin{matrix} \frac{1}{2} \end{matrix} v^2 </math> J/kg, where ''v'' is the [[speed]] in m/s. See also [[Projectile#Typical_projectile_speeds|kinetic energy per unit mass of projectiles]]. *[[Potential energy]] with respect to gravity, close to earth, per unit mass: ca. 9.8 ''h'' J/kg, with ''h'' the height in m. *[[Heat]]: energies per unit mass are [[specific heat capacity]] times [[temperature]] difference, and [[Latent heat|specific melting heat]], and [[Standard enthalpy change of vaporization|specific heat of vaporization]] ==See also== {{EnergyPortal}} *[[Figure of merit]] *[[Energy content of biofuel]] *[[Heat of combustion]] *[[Heating value]] *[[Rechargeable battery]] *[[Specific impulse]] *[[Vacuum energy]] ==External references== ===Zero point energy=== #Eric Weisstein's world of physics: energy density [http://scienceworld.wolfram.com/physics/EnergyDensity.html] #Baez physics: Is there a nonzero cosmological constant? [http://math.ucr.edu/home/baez/physics/Relativity/GR/cosConstant.html]; [http://math.ucr.edu/home/baez/vacuum.html What's the Energy Density of the Vacuum?]. #Introductory review of cosmic inflation [http://arxiv.org/abs/hep-ph/0304257] #An exposition to inflationary cosmology [http://arxiv.org/abs/astro-ph/0005003] ===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://xtronics.com/reference/energy_density.htm table of energy density] *[http://www.tinaja.com/h2gas01.asp energy fundamentals] *[http://users.powernet.co.uk/bearsoft/Field.html Energy Density Field Theory] ===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 ==References== {{Reflist}} [[Category:Fundamental physics concepts]] [[Category:Energy storage]] [[Category:Density]] [[de:Energiedichte]] [[el:Θερμική αξία]] [[fr:Densité de charge]] [[nl:Energiedichtheid]] [[sl:Gostota energijskega toka]] [[fi:Energiatiheys]] [[pt:Densidade de energia]]