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.