Compute energy density as energy divided by mass, so batteries and fuels can be compared on a like-for-like basis.
ρ_E = E / m。
| Item | Formula / Rule | Source / Standard |
|---|---|---|
| Gravimetric energy density | Gravimetric energy density in MJ per kilogram measures energy released per unit mass. | ISO 80000-5:2019, thermodynamic quantities and units |
| Lower heating value | The lower heating value excludes the latent heat of vaporisation of water in the flue gas. | ISO 1928:2009, determination of calorific value of solid mineral fuels |
| Battery energy density | Battery energy density is usually expressed in watt-hours per kilogram and depends on the electrode system. | IEC 62660-1:2018, secondary lithium-ion cells for propulsion |