Gravimetric Energy Density

Calculator and formulas for calculating the gravimetric energy density (Specific Energy)

Gravimetric Energy Density Calculator

Calculate specific energy

Calculates the gravimetric energy density (energy per mass). Important parameter for fuels, batteries and energy carriers.

J/kg
J
kg
Result
Energy density:
Energy:
Mass:

Example Calculation

Example: Lithium-Ion Battery
Problem:

A lithium-ion battery with 2 kg mass stores 720,000 J of energy. What is the gravimetric energy density?

Given:
  • Mass m = 2 kg
  • Energy E = 720,000 J = 720 kJ
  • Find: Gravimetric energy density w
Solution:
\[w = \frac{E}{m}\]
\[w = \frac{720{,}000 \text{ J}}{2 \text{ kg}}\]
\[w = 360{,}000 \text{ J/kg} = 360 \text{ kJ/kg}\]
Practical Applications
Energy storage: Batteries, accumulators, capacitors
Fuels: Gasoline, diesel, hydrogen, biomass
Vehicle technology: E-mobility, range, weight
Typical Energy Densities
Fuels
  • Hydrogen: 120 MJ/kg
  • Gasoline: 44 MJ/kg
  • Diesel: 43 MJ/kg
Batteries
  • Li-Ion: 0.4-0.9 MJ/kg
  • Lead-acid: 0.14 MJ/kg
  • NiMH: 0.29 MJ/kg

Formulas for gravimetric energy density

The gravimetric energy density is a measure of energy per unit mass of a substance. SI unit: Joule per kilogram (J/kg). Important parameter for energy carriers and storage systems.

Calculate energy density

Basic formula for specific energy from energy and mass.

\[\displaystyle w = \frac{E}{m}\]
w = Energy density [J/kg]
Calculate energy

Rearrangement to calculate the stored energy.

\[\displaystyle E = w \cdot m\]
E = Energy [J]
Calculate mass

Rearrangement to calculate the required mass.

\[\displaystyle m = \frac{E}{w}\]
m = Mass [kg]
Important Notes
  • Gravimetric energy density is important for mobile applications (weight matters)
  • Distinction between theoretical and practical energy density
  • Fuels typically have higher energy densities than batteries
  • Important factor for range and efficiency of vehicles

Detailed description of gravimetric energy density

Definition and Significance

This function calculates the gravimetric energy density or specific energy. The gravimetric energy density is a measure of energy per unit mass of a substance (SI unit: Joule per kilogram).

Usage Instructions

To calculate, select the value to be calculated using the radio buttons. Then enter the corresponding value and click the 'Calculate' button.

Application Areas

Energy Storage

Batteries, accumulators, capacitors, flywheel storage. Evaluation of storage capacity per unit weight.

Fuels

Gasoline, diesel, hydrogen, biomass, natural gas. Comparison of different energy carriers for transport and heating.

Vehicle Technology

E-mobility, range, weight optimization. Crucial for performance and efficiency of vehicles.

Energy Densities in Comparison

The gravimetric energy density varies greatly between different energy carriers and determines their suitability for different applications:

Very high (>40 MJ/kg)

Hydrogen: 120 MJ/kg
Gasoline: 44 MJ/kg
Diesel: 43 MJ/kg

Medium (1-40 MJ/kg)

Natural gas: 55 MJ/kg
Wood: 15 MJ/kg
Coal: 25 MJ/kg

Low (<1 MJ /kg)

Li-Ion battery: 0.4-0.9 MJ/kg
NiMH battery: 0.29 MJ/kg
Lead-acid battery: 0.14 MJ/kg

Conclusion: Fuels have significantly higher energy densities than batteries, but batteries can deliver energy directly electrically!


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