The Battery Gap: Why Electric Flight Is Short-Range
Batteries are not a little too heavy for aviation. They are off by more than an order of magnitude, and the gap is best seen by putting the same mass of each carrier on the same aircraft.
Energy per kilogram
Jet A carries about 43 megajoules per kilogram. A current lithium-ion pack carries about 0.9. That is a ratio of roughly 48 to 1 before anything else is considered.
Electric drivetrains are far more efficient — around 90% of stored energy reaches propulsion, against roughly 40% for a gas turbine — which claws back a factor of a bit over two. It does not close a gap of forty-eight.
The same ten tonnes, three ways
The range calculator makes the comparison concrete. Take an aircraft needing 3 MJ per kilometre and give it ten tonnes of energy carrier:
- Jet A at 40% efficiency → 172,000 MJ usable, about 57,300 km
- Liquid hydrogen at 55% → 660,000 MJ usable, about 220,000 km
- Battery at 90% → 8,100 MJ usable, about 2,700 km
The battery gets about 5% of the kerosene range from the same mass, with more than twice the drivetrain efficiency working in its favour.
And the weight never goes away
A second problem the numbers above understate. An aircraft burns fuel as it flies and gets lighter — a long-haul jet can land tens of tonnes lighter than it took off, which improves efficiency through the cruise and sets the landing weight.
A battery weighs the same when empty. An electric aircraft therefore carries its full energy mass to the destination and lands at maximum weight every time, which affects structure, brakes and landing gear as well as efficiency.
Where electric flight does work
None of this makes electric aviation pointless — it makes it a short-range technology. Trainers, small commuter aircraft and short regional hops are within reach, and several are flying or in certification.
Those are genuinely useful applications: short sectors are disproportionately fuel-inefficient per kilometre because climb dominates, and they are where electric propulsion's efficiency and low noise matter most. Hybrid configurations, using electric assist for climb, are another route into the same space.
What would have to change
Pack-level specific energy is the number to watch, and the honest framing is that it would need to improve severalfold — not by tens of per cent — for narrowbody-scale electric flight. Progress in the field has been real and steady, and it has not been fast enough to make a difference of that size imminent.
Cell chemistry figures quoted in research are also not pack figures: a pack includes structure, cooling and management, and the usable number is meaningfully lower than the cell number.
Why the comparison is still worth doing
Because the debate is often conducted in adjectives. Running the same aircraft on three carriers, with each one's own realistic efficiency, replaces "batteries are heavy" with a ratio — and a ratio tells you which applications are plausible now and which are not.