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<html><iframe src='https://energyeducation.ca/simulations/graphs/energydensity.html' style='width:518px;height:318px;float:right;border:none;margin-left:3px'></iframe></html>

<onlyinclude>'''Gravimetric energy density''', sometimes referred to as '''specific energy''', is the available energy per unit mass of a substance. Gravimetric energy density is typically expressed in Watt-hours per kilogram (Wh/kg), or Megajoules per kilogram (MJ/kg).</onlyinclude><ref name = r6>C. Simpson, "Characteristics of Rechargeable Batteries," ''National Semiconductor''. Texas Instruments Inc., Dallas, 2011.</ref> The gravimetric energy density gives the energy content of a fuel in terms of storage and handling of the substance. However, gravimetric energy density is not only used for fuels; it can also be used to define [[battery]] capacity. This term can be especially useful when talking about materials that need to be stored based on weight, such as batteries in vehicles.<ref name=battery>"Specific Energy and Energy Density of Fuels", Neutrium, 2014. [Online]. Available: https://neutrium.net/properties/specific-energy-and-energy-density-of-fuels/. [Accessed: 09- Nov- 2020].</ref> The graph on the right shows the energy density (in <math>\frac{MJ}{kg}</math>) of a variety of different [[fuel]]s. For example, 1 kg of natural gas has 55 MJ of stored [[chemical energy]]. Another example is [[molecular hydrogen]], which has a gravimetric energy density of 120 MJ/kg, which is about 4 times the energy content per mass compared to gasoline.<ref>"Hydrogen Storage," Hydrogen and Fuel Cell Technologies Office. [Online]. Available: https://www.energy.gov/eere/fuelcells/hydrogen-storage. [Accessed: 06-May-2021]</ref> Knowing the gravimetric energy density of raw materials and fuels is important when designing things like [[battery|batteries]]. Since batteries need to store energy for long periods of time, using materials that have a greater gravimetric energy storage capacity is essential. Visit the page on [[energy density]] for more information about the energy densities of different fuels.

The equation for gravimetric energy density can be seen below.<ref>T. Johnson, D. Dedrick & S. Jorgensen, "Effects of Metal Hydride Properties on the Performance of Hydrogen Storage Systems," 2007. Online. Available: https://www.osti.gov/servlets/purl/1148298.</ref>

<center><math>ρ_{E_G} = \frac{E}{m}</math></center> where:
*<math>ρ_{E_G}</math> is the Gravimetric energy density, an [[intensive property]] of materials
*<math>E</math> is the available [[energy]] (often in megajoules)
*<math>m</math> is the [[mass]] of the substance (in kilograms)

===Gravimetric Energy Density vs. Energy Density===
Gravimetric energy density can be thought of as a more precise definition of [[energy density]]. Energy density is used in every day conversations to describe the energy of a substance per volume '''or''' per mass.<ref name=battery/> In contrast, gravimetric energy density or specific energy are ''only'' used to describe energy per unit mass of a substance.

==For Further Reading==
*[[Power density]]
*[[Energy density]]
*[[Energy density vs power density]]
*[[Specific power]]
*[[Battery]]
*Or explore a [[Special:Random|random page]]
==References==
{{reflist}}

Gravimetric energy density - Revision history

Jmdonev: 1 revision imported

energy>Jmdonev at 22:54, 11 June 2021