For battery tech nerds like me, the battery is a more efficient lithium-iron battery, called Lithium Manganese Iron Phosphate or lmfp. It has a theoretical energy density of 525Wh/L, compared to normal lithium-iron theoretical density of 325Wh/L
For context jet fuel is around 9,720 Wh/L. However, energy density(energy per volume) is less important in aviation than specific energy(energy per mass) as weight is far more likely to be the limiting factor.
A standard lithium ion battery has 100-265 Wh/kg
The article claims 500 Wh/kg in this new battery.
Jet fuel has around 12,000 Wh/kg.
Though this is a major improvement in battery tech, batteries are unlikely to ever improve to the point to even approach the energy storage of liquid fuels.
Batteries cannot run commercial aviation as it currently exists. Battery planes will need to fly slower and shorter. There is no other way.
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.
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.
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.
Energy density has been the number one most important factor since humans started using metal. Wood is good enough to smelt bronze, and with some refinement can get your iron, but not good enough for steel. Steel requires coal, and with some refinement steel is what our world is built on.
Fossil fuels allow cars, planes and more efficient trains and boats. Unless we somehow start utilizing uranium and transuranics electric airplanes are for grifters. Uranium and it’s derivatives are the only thing we have harnessed that even approaches the energy density of fossil fuels.
Trains don’t need to store the energy at all. Pantographs are a mature technology. High speed renewable long haul transportation is a technologically solved problem for all overland routes, it just requires infrastructure investment.
Sure high-speed rails with HVDC lines powering them from coast-to-coast I’m here for it.
Is there a source that says its an LMFP battery?
This article covers it well, including the fact that specific battery chemistries are trade secrets.
The plane in the article is a 4 ton airplane, they mention plans to make an 8 ton commercial aircraft.
The Learjet 31 is 4.4 tons. It seats 8 passengers. The Cessna CitationJet CJ3+ is right around 4 tons with a maximum of 9 passengers.
The future 8 ton aircraft is around the size of the 10-ton Dash 8 Q200 with a maximum of 40 seats.
There are commercial uses for aircraft this small, but these jets are significantly smaller than most commercial aircraft.
Don’t private jets contribute a significant amount of carbon emissions? I remember seeing headlines about how much pollution was being created from Taylor Swift’s non-stop private jet usage. Wouldn’t this tech help at least reduce that kind of pollution?
The carbon comes from the fuel. Burning a ton of jet fuel will release the same amount of carbon regardless of the plane that burns it.
Taylor Swift’s plane is a Dassault Falcon 7X. It weighs around 17 tons and seats 12 to 16 passengers.
Her plane burns 60% less fuel than a 737 MAX 8. However, her plane holds 9% of the passengers of the MAX 8, so its far less efficient per passenger than typical commercial aircraft.
Private planes are not a huge contributor to carbon emissions in comparison to others. They’re bad, obviously. But there are far more commercial airplanes, and they fly much more frequently than private jets.
Private jets get people’s attention. One person being directly responsible for that much carbon is notable is unconscionable. But it’s the scale of transportation overall that is the issue.
Wow, I didn’t realize we’re so inefficient compared to large commercial jets. 60% of the fuel for 9% of the passenger capacity? And I’m guessing most private jets aren’t even at full capacity, probably just a few passengers per flight. If 2 billionaires flying their jets create as much pollution as a full commercial jet, then eliminating their emissions seems like a win to me.
Your original post seems pretty skeptical of the EV plane tech because they are smaller planes. To me it seems like a reasonable way to start - smaller machines and probably easier to sell. And it targets a very fuel inefficient sector. Is there any reason to believe they won’t be able to scale up to full commercial passenger jet sizes?
Her plane is worse than most. Its one of the last trijets in production. Planes with a small number of large engines are more efficient than planes with many small engines, which is why modern planes are all twinjets with wide high-bypass engines.
Airlines care about fuel efficiency. A minor reduction in fuel burn results in increased profits, and they operate large fleets. A small increase in efficiency across an entire fleet is huge. If you own a private jet, you are spending huge amounts of money to have one, the cost of fuel would only be a minor concern.
The solution to private jets is regulation. Private jets don’t need to exist. They don’t need to be replaced by another kind of airplane. The solution is to replace all planes on overland routes with electrified rail. Let the rich buy private railcars for transport.
I’m not skeptical on the concept of small aircraft. I wanted to give context because very few people will picture bush planes and puddle jumpers from the mention of “commercial aviation.”
PS: My calculations for fuel burn were based on comparing the range to the fuel capacity. Those are the numbers I have ready access. Planes are much less efficient when the tanks are full, and swift’s plane has a longer range, so it’s probably not quite as bad as my calculations indicate on comparable flights.
That’s also empty weight on the Learjet, gross weight is higher. This one is presumably that weight with the batteries so I suspect is smaller. Wish there were more details.
All the weights listed were operating empty weight. The battery planes will be even smaller than the planes I listed for comparison.
Weights of planes vary in flight, so I picked the one that disadvantages the point I’m trying to make in the interest of fairness.
An electric Dash-8 equivalent with 20-40 seats would be a game changer on regional routes.
The engines are the highest maintenance and cost items in aircraft. Electric motors should* drastically reduce that. Regional/small use routes are often on razor thin margins, anything to improve those margins will be taken on board very quickly.
*Perhaps battery maintenance replaces that cost with a rough equivalent, I don’t know
So, small aircraft with very low emissions and running costs? We best get used to being shovelled out of airports like cattle
I think that’s a good thing, especially concerning domestic flights.
China is so far ahead
