For decades we have seen in TV and cinema futures of urban transportation with flying cars or others, we are long overdue of having such a wonderful transportation method. But, is what we really should aim for?
In a world dominated by technology, we rarely stop to think if “just because we can” is actually the way to go, instead of searching for what we really need and should do according to a much larger picture. This takes a very comprehensive and complex analysis, which is probably one of the reasons why we don’t do it, because at the end, what is it that we really need and should do? Are we all in the need for the same?
We evidently need more efficient urban transportation methods (actually we need better city design), to get us faster and safer whenever and wherever we want to go. So far the private car as more or less provided that with some severe by-products, just to name the two most evident ones: ever-growing traffic and air pollution. Traffic is mostly attempt to be solved by adding street area, which is just a positive feedback loop making the problem bigger and more complex to solve (which is linked to the sale of private cars and their also ever-growing number). Air pollution is being tackled by the shifting of combustion engines to electric, this is a good thing (far from enough or ideal), and we are moving in the right direction, far too slow though.
But what about flying cars? Could they solve any of these issues? Imagining that we finally have a safe to use flying car (safety is a very big concern, which requires a complete analysis on its own, not pretended to cover here). If vehicles are privately owned, just like regular cars, we can only expect to eventually see similar traffic problems but in the sky. One may think these vehicles will be self-driven, that would solve the issue. Yes, probably, partially, because there is always a given amount of space that can be filled with enough vehicles.
What about pollution? The latest flying vehicles we have seen in the news are electric, so they claim to be “clean”, and yes, they might be (depending on the electricity generation source some will be cleaner than others). But it is precisely here where I have been having some issues about the actual feasibility of transportation. I am no physicist but knowing basic concepts should be enough. Rolling a car on a street is not exactly the same in energy demand as sustaining it in the air.
Electric vehicles depend on batteries, and here the key is “energy density”. How much energy can you have in an X volume and weight? Tesla has achieved to produce some very impressive energy-dense batteries, and recently I read an article about their possible intervention in air transport, that sparkle my need to do some math and write this article.
Let’s start by saying that Tesla produces different battery sizes; the 100kW/h weights 625 kg and it gives the vehicle a range of around 500km, which is quite impressive. But pushing is not the same as lifting. Probably the main reason why people are reluctant to buy an electric vehicle is range anxiety, the fear to use all the energy and not being able to replenish it as easily and fast as with gasoline. No one seems to be worried about that with the flying car, yet… flying is too exciting as idea.
The commercial aviation sector is expected to grow 7 times in air traffic by 2050, producing 4 times more greenhouse gases than what it does today, are we OK with this? Can electric planes make a difference? Well, we should check first if it is feasible at all.
An Airbus 320 can takeoff weighting 83 tonnes using two engines that produce 27,000 kg of thrust each and carrying 27,000 litres of fuel. Jet fuel as an energy density of 12kW/h per kilogram and 1 litre of jet fuel weights around 0.80 kg, so an A320 full tank has around 259,200 kW/h of energy stored; that would be 2,592 of the 100kW/h Tesla battery packs, or 1,620 tonnes of batteries, which is ridiculous to propose as an electric analogue of an A320.
So far the electric planes are small, super light and carrying just a few passengers in short distances. The same is happening with flying cars, they are extremely light, just for a few passengers and for short distances, and it will surely use all the battery charge, what means that after every few minutes of use it would be necessary to recharge entirely the battery.
Going back to range anxiety, I guess the excitement of flying is more powerful that rationalising these facts. All of this is absolutely fine for prototypes and experiments, the problem comes when you try to imagine a spread service of these vehicles by the thousands, and it is simply not feasible… I know, I know, you may think technology will catch up and we will have super high-density batteries, maybe in 10 or 20 years? I am just asking if we are organising our priorities adequately to tackle the immediate climate emergency we are living.
I hope this makes it clear that massive long haul electric flight is not an option if based in batteries (with current technology). We will probably see super expensive small flying vehicles that a few will be able to buy to go around the neighbourhood, yes private ownership, we are not getting far with that. We should really stop and think what are we capable of and what are we going to do. In this particular scenario, I don’t see large-scale electric flights becoming reality any time soon, therefore, we should let the sector grow and generate those greenhouse gases? What are our options? Cities like Venice and Bruges are already thinking on limiting tourist and as sad, complex and unfair if you want, I think it may be the way to go.
Complex problems don’t have one single solution; there is the need for a series of small, complementary and user-based services. We need to be smarter and less selfish, not thinking in what I would like to have, but rather what I really need.
We need to think how to design our cities, our jobs, our markets, how and where our food is produced and delivered to our house and a myriad of other things in order to generate the type of sustainable living standards that every human on Earth deserves. Looking at the scale and complexity of what is needed it is clear how some people simply don’t know how to and prefer to bury their heads in the sand.