By Amelia Tiemann, published at 4th Generation on June 4, 2020
On Thursday, May 28, 2000 pounds of lithium-ion batteries made history. But, indirectly — it was actually the small Cessna Grand Caravan they powered that made history, when the plane became the largest electric aircraft to ever take to the skies.
The eCaravan, as it is dubbed, completed its maiden voyage after flying for about 30 minutes at 100 mph. Weighing four tons, the plane has a 750 horsepower electric motor and a 50 foot wingspan. It can seat nine passengers.
At present, aviation produces 2% of global emissions, and 12% of total transport sector emissions. It is one of the hardest sectors to decarbonize, precisely because batteries are hard to put on planes. They are not particularly energy-dense for their size and weight — which makes them less than ideal inside a small, flying metal object. But the record-breaking flight of the eCaravan suggests fuel-free air travel may be closer than we think.
There are certainly already visible benefits to batteries. The eCaravan, created by Seattle-based firm magniX, used only $6 of electricity instead of $300 of kerosene for its 30 minute flight. And electric motors are lighter, quieter, and purportedly safer than fossil fuel engines. The problem is that the batteries that power the planes are about 30 times heavier than the energy-equivalent amount of kerosene. And at 250W/kg, they simply cannot compete with the energy density of jet fuel, which packs nearly 12,000 W/kg (a 48X difference). This means we are still very far from electrifying standard-sized commercial aircraft.