Thursday, 23 March 2017

Never say never... but...

Definitely not electric (image from Wikipedia)
It was a little eyebrow-raising to see that a company called Wright Electric is claiming that they will have electric planes flying between London and Paris in 10 years. While we genuinely should never say 'never' with technology, I think the probability is so low that it would be well worth betting against it.

In part, this is a simple competitive edge issue. If the technology existed, it could certainly only cope with short range hops - hence London to Paris. Unfortunately, this is already a highly competitive route because Eurostar offers a far more pleasant journey than flying with similar or better city centre to city centre times. It's not the ideal route to introduce new flight technology on.

Even if London to Paris is attractive, though, this assumes, though that we have coped with 'if the technology existed.' The big problem here is battery technology. I have no doubt at all that batteries will get better in the next few years. But the difficulty faced by a plane, as opposed to a car, is the sheer weight of batteries to provide the same amount of energy as aviation fuel.

Kerosene packs a fearsome amount of energy into a relatively small mass. This is why the 9/11 attack was so devastating - it was the energy in the planes' burning fuel that hugely increased the impact. To get a feel for the difference, kerosene has around 100 times* the usable energy per unit mass as a typical laptop (or car) battery. A plane simply can't afford to carry the extra mass that would be required to be fuelled by batteries. To make the London to Paris electric plane feasible would require at least a 20 times improvement, and quite possibly a 50 times improvement in the energy density available from batteries. This may well happen at some point. But to have it developed on a timescale that allows commercial planes to be using it in 10 years is incredibly unlikely.

I worked for an airline when we were just starting to put computers into planes for cabin management and entertainment. They always ended up being antiquated devices, because the safety requirements for aviation rightly require a long period of being bedded in - typically the tech was at least 5 years old by the time it got into the sky. This means we would need this kind of improvement in just a handful of years to make a ten year horizon viable. So if anyone's up for a bet and will offer decent odds, I'm happy to take it.

This has been a green heretic production

* This figure is about 7 years old, and as battery technology is always advancing it may well be only 90 times by now, but I don't have the latest figures. But batteries haven't changed much in capacity during this period.


  1. A hybrid propulsion system, with turbines for take off to cruise altitude, and electric fans for cruise could be a possibility for long haul. Turbines could charge batteries, and top up could be provided by photovoltaic cells.
    Battery technology is advancing at a phenomenal rate, lighter, faster charging batteries are appearing regularly. Nissan have a scheme to update battery packs in older Leaf models,with the old batteries being used for household systems where weight and size is less important.

    1. Absolutely - battery technology will make great strides, but it’s the 10 year timescale I’m suggesting is unrealistic, especially given the huge difference in energy density.

    2. For a wholly electric aircraft, I'd have to agree, but for a hybrid aircraft the technology is available now, so ten years could see a commercially viable aircraft in use. Cost might be the only factor that holds it back.