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Per Lindstrand plans 1km-high inflatable solar energy chimney

The engineer who broke numerous ballooning records with Richard Branson is hoping to develop a 1km-tall inflatable chimney that can capture energy from the sun.

Per Lindstrand, whose work in balloon manufacturing led to his world-first Pacific crossing with the Virgin founder, is leading the British attempt in the race to commercialise a 110-year-old idea for a solar updraft tower.

The Swedish-born aeronaut believes the tower, which uses rising air heated by the sun to drive turbines, could provide an alternative to photovoltaic generation in remote areas of seismic activity where maintenance of power lines or solar panels would be difficult.

Lindstrand became involved with the project after he was approached by the ALMA Observatory in Chile’s Atacama desert, which was looking for a greener alternative to its gas and diesel generators that was more robust than solar panels.

Several other groups are working on commercialising solar updraft technology, the idea for which goes back to the early 20th century, but Lindstrand believes bringing his experience in inflatable structures to the table has advantages over concrete, metal or glass models, particularly in desert locations.

‘The problem in this part of the world is the sand is very fine and would very quickly clog up solar panels so you have a very big cleaning job in a place that has no water,’ he told The Engineer.

‘The advantages with inflatables is you manufacture directly from the cutting table; you don’t have things like a metal structure that has to be jigged up and welded so it’s a lot quicker and easier to make things in fabric and to make changes.’

To generate enough power for the ALMA observatory, the chimney will need to be 1km high with a 7km-radius canopy at its base to heat the air to drives the turbines.

Lindstrand said that a similar-sized concrete chimney would cost around $750m (£466m) but that an inflatable one could be made for as little as $20m (£12m).

This should create a 130MW power station with a capacity factor of 24.7 per cent (much higher than solar PV and on a par with wind turbines), producing 281GWh of electricity a year, according to Patrick Cottam, the Lindstrand Technologies engineer who is designing a 3.5m prototype chimney as part of his PhD, supported by the 1851 Commission.

The challenge in constructing a 1km-tall chimney will be in finding a material strong enough to support the high tension forces at the base, with the right flexibility to withstand movement in the wind and the chemical properties to survive many years of exposure to the sun’s ultra-violet light, said Cottam.

‘A lot of it can be dealt with by good design: for example if you put in steel rings it might help stiffen the structure but they make it much more likely the fabric will tear,’ he told The Engineer.

‘You do need to choose the right materials. I suspect some kind of treatment might be necessary as well. It’s the sort of thing that eventually becomes an economic question.’

Other attempts to commercialise solar updraft technology include a prototype built in Spain in the 1980s that generated power for eight years but eventually succumbed to rust and blew over.

More recently, a 200kW chimney began operating in China in 2010 while Australian firm EnviroMission has put forward proposals for a 200MW tower in Arizona in the US.

Australian firm EnviroMission is planning a solar updraft tower in Arizona.


Readers' comments (19)

  • That's more like it a bit of open minded thinking
    The people that knock this sort of thinking are the same as Frank Whittle had to deal with
    Best of luck with it
    The answer is out there

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  • So, what keeps the canopy clean?

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  • Good idea, however you do not have to build such a tall tower if you simply will utilize this new invention from Michaud:


    google that.

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  • Is that radius right? That would almost cover an area the size of Manchester.

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  • Yes, that figure is correct

  • It's an interesting idea. But if I wanted energy in the Atacama desert. wouldn't CSP be a better option?

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  • I hold shares in Enviromission for a variety of reasons. Not the least of which is the fact that they are closer to actually building a tower than any of the other participants in updraft technology. Some of the other updraft (and downdraft) ideas are very interesting but EVM is closer the finish line.

    A flexible tower has been put forward already. Vid here

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  • Another super-chimney link.

    Money is on Enviromission.

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  • Fascinating stuff:
    If the Olympic Industrial Revolution part of the opening ceremony is recalled-loved those inflated chimneys- perhaps there are lessons there. Likewise the Ranque-Hilsch vortex tube -my dissertation in 1963!- is interesting.

    The weaving of fabrics with variable cross section/thickness to accommodate hoop stresses in circular tanks was done in the 80s and
    tri-axial weaving (3 sets of yarns at 60 degrees, not 2 at 90 degrees) was part of the Apollo project.

    Perhaps some merit in revisiting that?

    Mike B

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  • and the Australian government knocked back enviromissions technology in favour of green coal... which failed.... shortsighted.. yet the americans are not so short sighted... lets hope the new Australian government is not so short sighted and gives it a go... or support even as one should...

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  • Good luck Per, go for it!

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  • Hi all,

    My name's Patrick, I'm the research engineer at UCL mentioned in the article. Thanks for all your comments! I will bear them all in mind during my research. I have seen the atmospheric vortex engine, in fact I've met with people from AVEtec who are promoting the technology. I wish them all the best, they've got a good technology on their hands. I'd be worried about the high heat input required to kick-start the vortex. Last time I looked at AVEtec's work, they were building research prototypes where the vortex would not exceed 10m tall. I have a lot of faith they'll get there though.

    And @MikeB: I noticed at the time that the olympic opening ceremony stole our idea! Thanks for your input on fabrics too, I'll be talking to the fabric experts at Lindstrand's and making sure we get the best for our chimney.

    Excuse the shameless plug but if you're interested in further developments I will be posting them on Twitter @PatrickCottam. I promise not to fill your twitter feeds with inane spam.

    Thanks again!

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  • How splendid that individuals in our profession -Engineering- have a vast fund of skills and knowledge that its members are delighted to offer -free gratis and with unlimited enthusiasm to innovative projects. Exactly what our 'blogs' should be doing.

    I shall of course follow your efforts -even though now retired. If there are specific questions that you would like answers to, please contact me:

    I still have good links to the firm(s) who were responsible for those specialty woven fabrics described. In fact I did have the opportunity to attend the Olympic Opening Ceremony Rehearsal (I was a volunteer/ Gamesmaker for the Paralympics)- I am sure you recognised that the chimneys -like most of the other artifacts- were actually drawn-up from the cross-wires that were rigged all over the stadium- but they were inflated from below as they went up! I hope you also noticed the two 'loom-like' objects that were wheeled into the arena at each end and which made 'weaving-like- motions! [An artists impression of the well known mantra 'the hand that rocks the shuttle rules the world.] I am a guide for school parties at Quarry Bank Mill near Manchester -and I try to refer to the opening ceremony to remind visitors of the pivotal influence of textiles and its machinery in the Industrial revolution.

    Mike B

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  • Check out for background on the vortex engine.

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  • while Enviromission are closer to reality. It's clear their CFD is "inaccurate" and the cost is wild for output. Per's idea is a possibility, better than most, but needs to be tested. Michaud's? I've done the sums and it works . . . However, it needs a huge investment to prove concept . . . Yup

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  • Patrick: you only need a heat exchange to a closed seperate vortex, as I'm sure they know.

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  • Would the whole tower need to be constructed in one piece, or could it be constructed as a series of stacked slightly conical " hot air balloons" rather like a builders waste chute with each conical section being a balloon in its own right.

    It would be interesting to know if the structure would be permanently inflated, or rise up each day as the sun heats the tower.

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  • We'll be running a follow-up interview with Per Lindstrand in the January edition of The Engineer covering more detail on the chimney concept.

  • Maybe you need a double chimney ( like a rolled up sock ) which is still inflatable but also extendable
    or retractable in case of to much wind force?
    Of course, you can apply a fast drying concrete coating or magnetic-oil on some parts of the fabric
    to adjust the flexibility.

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  • Like this concept -and would add the following:
    Can I mention the 'Insituform' system -which was (maybe still is) used to replace the inside of corroded (so would you be after 150 years of passing the raw sewage of London and other cities!) brick lined sewer pipes and outfalls. This was instead of digging up, from the surface many miles of pipework in city centres. The system uses a 'head' of water to turn inside-out a sock (such as described by another blogger) within the existing pipe, and then the polyester polymer impregnated material is cured/set once in place by hot water.

    I had a small part in creating an automatic stitching and 'turning' mechanism so that the 'tubes' could be made 'in situ. This was for Nuttalls -one of whose senior Civil Engineers had shared a terrible student apartment in 1962 with the writer! -and knew of my textile experience!

    If ever there was a place for off-the wall and outside-the box and lateral thinking, surely working out how to effectively make a flexible tube one Km long is that!
    Mike B

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  • “Anonymous says, "Is that radius right? That would almost cover an area the size of Manchester.”

    So it could be dual purpose & act as an umbrella, Manchester needs a cover !!!

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