TechnicalUp to date · Jan 15, 2026
Energy Density
The amount of energy stored per unit of weight (gravimetric, Wh/kg) or volume (volumetric, Wh/L). Gasoline has about 12,500 Wh/kg; lithium-ion batteries have about 250-300 Wh/kg — a 40-50x gap.
Why It Matters
Energy density explains why batteries work for cars but not airplanes, why nuclear fuel lasts decades, and why the energy transition is harder for some sectors than others.