Comparing Energy Storage Technologies
How do different energy storage methods compare? Let's use energy density constants to explore this.
The Problem
You want to store 1 GJ of energy. How much mass would you need for different storage methods?
Setup
energy_needed = 1 GJ1.00 GJ {energy}
Calculations
Gasoline
Gasoline has one of the highest practical energy densities:
gasoline_mass = energy_needed / energy_density_gasoline21.7 [20.9, 22.7] kg {mass}
Lithium-Ion Batteries
Modern batteries are much less energy-dense:
battery_mass = energy_needed / energy_density_lithium_battery1100 [840, 1600] kg {mass}
Hydrogen
Hydrogen has excellent gravimetric density but is hard to store:
hydrogen_mass = energy_needed / energy_density_hydrogen8.34 [8.00, 8.70] kg {mass}
Uranium (Fission)
Nuclear fuel is in a completely different league:
uranium_mass = energy_needed / energy_density_uranium1.23e-5 [1.16e-5, 1.32e-5] kg {mass}
Results
To store 1 GJ of energy, you'd need:
| Fuel | Mass Required |
|---|---|
| Gasoline | 21.7 [20.9, 22.7] kg {mass} |
| Li-ion Battery | 1100 [840, 1600] kg {mass} |
| Hydrogen | 8.34 [8.00, 8.70] kg {mass} |
| Uranium-235 | 1.23e-5 [1.16e-5, 1.32e-5] kg {mass} |
Insight
This explains why electric vehicles need such large, heavy battery packs compared to a small gas tank. The ratio of battery to gasoline mass is roughly:
battery_to_gas_ratio = energy_density_gasoline / energy_density_lithium_battery51 [38, 76]
Batteries need about 51 [38, 76]x more mass than gasoline for the same energy!