Green aeroplanes, ho ho

A mind-bogglingly stupid article in the Times came my way. Someone has built a small aeroplane powered by batteries. So far nothing exciting. But then to report the claim Ms Lavrand said that the fuel cost per hour of the Electra was €1 (70p) compared with about €60 for an equivalent petrol-driven machine. The motor and batteries will cost between €10,000 and €15,000, about the same as existing small petrol engines. I don’t believe that a 25 hp engine would be anything like €10,000, nor that the fuel price disparity could be a factor of 60 – it should be the same as for electric/petrol cars; ie, not very much.

Rather more sanely, Hot Topic points to a report saying that NZ “causes” about 10% of its CO2 emissions from long-haul flights. I say “causes” because its not really obvious who to count the emissions against – NZ for being such a nice place that people want to come, or the home country of the people that go. Plane CO2 is the hardest to reduce (electric planes are obviously hopeless) and NZ is a long way away, so this may become a problem for them, in the unlikely event of peoples conciences getting the better of them.


  1. #1 David B. Benson

    Blimp-type craft have been suggested, but we are running out of helium.

    I suggest bracing ocean voyages in sailing ships.

    Enjoy the journey, not just the destination!

  2. #2 Janne

    “…and batteries”. A sizeable bank of high-efficiency batteries will cost you an arm and a leg. The battery bank is the single most expensive thing in an electric car; it shouldn’t be any different in an airplane.

    The fuel price disparity sounds high, but not excessively so. Aviation fuel is significantly more expensive than the stuff you pump into your car (figure twice the price, or even more, depending), then add that things like fuel taxes are a lot higher in Great Britain than in your country. And they’re probably comparing that price with the metered rate for domestic electricity. 60 times doesn’t sound at all unreasonable.

  3. #3 Sam-Hec

    I think it interesting that the plane was of basic wood construction. It’s drag heavy open-cockpit design suggests room for improvement. Improve the design, add thin film PV, and it just might go places.

  4. #4 John Mashey

    Having been occasionally butchered by journalists (and not even on purpose!) I wouldn’t be quite so quick to zing Ms Lavand, who was quoted:

    “”It’s expensive, but you have to think of it like buying the fuel up front,” Ms Lavrand said.”

    Since the earlier comments weren’t quoted, it’s unclear to me if she said them, or part of them, or the writer misunderstood. Why would she say “It’s expensive” if the motor and batteries cost the same as an existing 25HP petrol engine?

    [Who knows, exactly? But nor is it buying the fuel upfront, unless she has some mysterous free source of electricity -W]

  5. #5 Ian Gould

    Apparently turbo-prop aircraft are radically more fuel efficient than contemporary turbofan engines (used in both the Boeing 7xx range and the Airbus).

    Their main drawbacks are they’re slower and noisier than turbofans – but turbo-props were used in large long-distance carriers up until the 1970s and are still used in smaller commuter planes.

  6. #6 WhiteBaerd

    Off the top of my head the fuel difference would likely be in the 20 to 30 range. No aero fuel required. Engine cost is similarly inflated, unless comparison is with the “enhanced” heat dissipation via gold electroplating option. ;)


    Wood at is a fine engineering material. And some aerodynamic clean-up would help, but this isn’t a serious transportation project no mater how thrust is generated. Wind in the hair is a large part of the purpose. 62 kph is fairly close to the minimum needed to needed to sustain flight.

    [Why would electricity be 20 times cheaper than petrol? -W]

  7. #7 Alex

    GE’s propfan demonstrator (an MD90) was around 30% better for fuel efficiency, in the 1980s. That’s without prejudice to savings from different airframe designs, ATC efficiencies and the like.

  8. #8 bigTom

    Ian, I was thinking, what sort of savings could be had by designing and flying airplanes to be considerably slower, say half of the current speed? On the face of it, for a fixed weight the fuel cost per unit distance would scale as the drag (and the inverse of engine efficiency). Its not at all clear to me if lift/drag could be improved much, but you hint that turboprop -essentially very high bypass by using external blades, might be considerable more efficient. Do you have any estimate of the savings?

    As for the electric plane, I have trouble thinking the savings would be better than 2-5x, and the range would be pretty poor.

  9. #9 MikeB

    Janne, the UK does not impose taxes on aviation fuel, any more than than anyone else does, due to the International treaty signed in 1944 (apparently aviation is still a fledgling industry). Of course this advantage (plus the lack of VAT on tickets, etc) partially accounts for the fact that low cost carriers are saying they can charge as low as only about $30 for flights throughout Europe.

    The Times article is wonderfully batty, especially since no one seems to have factored in the weight of even the lightest batteries in enough quantity to make anything more than a quick hop viable.

    Alas, the only way to deal with less oil and need not to burn it is to simply fly less. I like the sailing ship idea…very Last Grain Race!

  10. #10 Steve Reynolds

    >Plane CO2 is the hardest to reduce…

    But not impossible. Liquid H2 has been considered and could be used if necessary. It has the advantage of light fuel weight and disadvantage of a very large and heavy fuel tank.

  11. #11 Gareth

    Personally, I rather like the blimp idea. Kitted out like the flying boats of the first cross Pacific services (nice lounges, sleeping cabins etc), island hopping across the oceans.

    From a tourism perspective, NZ probably needs to concentrate on two tourism sectors: the relatively long stay, high value independent traveller (the sort that stays in upmarket lodges), and the student/backpacker/gap-year traveller. Not so much money in the latter, but they stay longer and do more jumping off bridges with rubber bands tied to their feet.

    It’s worth mentioning biofuels. AFAIR, Richard Branston (always in a pickle) has chucked a lot of money into a US biotech firm that plans to engineer ?algae to make a biofuel with avgas properties. The link’s on HT somewhere, original article in Technology Review.

  12. #12 David B. Benson

    Somewhere (Live Science(?)) there is an article on a 2 meter wingspan float plane powered via solar cells and a battery. If energy gets low, just land and soak it up until charged and ready to go.

    Does this scale up?

    [If you mean, is this an economic way to generate ‘lectric, then presumably the answer is no, or people would use it to power other things -W]

  13. #13 WhiteBeard

    [Why would electricity be 20 times cheaper than petrol? -W]

    Well, they might be figuring the cost of a generator attachment for a bike over some amortization schedule. Maybe it’s the cost of the jumpers to the handiest power pole.

    I assumed the electric rate quote was true, but know the hydrocarbon fuel quote had to be 2 to 5 times too high. Petrol at 7 to 8 L/hr consumption yields that power level. 25hp aero motors are almost all 2-cycle, so they’d need to figure in consumable lubricant. They could get up to the quoted €60/hr fuel burn were they distilling the brandy you’d serve your annoying neighbors when they dropped in to socialize.

  14. #14 David B. Benson

    No, I meant does this little aircraft scale up to a passenger carrying sized airplane.

    Probably not.

  15. #15 Dave Briggs

    The battery bank is the single most expensive thing in an electric car; it shouldn’t be any different in an airplane.

    Oh well. It doesn’t hurt to keep trying. Maybe one day there will be a big battery breakthrough?
    Dave Briggs :~)

  16. #16 Jim Thomerson

    There is a lot of money being spent on developing light, cheap, powerful electic motors. And a lot more being spent on coming up with light, safe, cheap, powerful power sources. Much of this spending is for militry use and will trickle down slowly into the civilian sector. So one should not get too limited to thinking only about what is available today.

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