What’s the efficiency for turning jet fuel into mechanical work? I’d suspect the efficiency is somewhere around 45% for liquid fuel where it’s nearly 100% for electric. So you’re really trying to reach the equivalent of 5500 Wh/kg.
I got the number from wikipedia. Following the references, the number came from a BP datasheet about Jet A-1, where it is listed on a typical properties table, and the number is the net specific energy, which means it accounts for the inefficiency of the engines. Or at least that’s my assumption.
A factor in favour of jet fuel is that as the plane burns fuel if becomes lighter, thus consuming less fuel. Batteries stay the same weight. The difference between a full plane and an empty plane can be 18 metric tonnes. Super cheap operators tend to carry only a small extra margin of fuel over the amount technically necessary to make a trip, because it makes a real difference.
That means the energy density you need in this comparison isn’t really linear. If you’re doing Taylor Swift flights to the couch and back, you can save a lot of weight by having a minimal amount of fuel in the tank, but with an electric plane you’ll always have to have the full battery in case you need to go somewhere further away.
What’s the efficiency for turning jet fuel into mechanical work? I’d suspect the efficiency is somewhere around 45% for liquid fuel where it’s nearly 100% for electric. So you’re really trying to reach the equivalent of 5500 Wh/kg.
I got the number from wikipedia. Following the references, the number came from a BP datasheet about Jet A-1, where it is listed on a typical properties table, and the number is the net specific energy, which means it accounts for the inefficiency of the engines. Or at least that’s my assumption.
A factor in favour of jet fuel is that as the plane burns fuel if becomes lighter, thus consuming less fuel. Batteries stay the same weight. The difference between a full plane and an empty plane can be 18 metric tonnes. Super cheap operators tend to carry only a small extra margin of fuel over the amount technically necessary to make a trip, because it makes a real difference.
That means the energy density you need in this comparison isn’t really linear. If you’re doing Taylor Swift flights to the couch and back, you can save a lot of weight by having a minimal amount of fuel in the tank, but with an electric plane you’ll always have to have the full battery in case you need to go somewhere further away.