High-altitude windpower: pie-in-the-sky or sound science?
1st May 2009
Since we don’t have enough land for the renewable technologies we need let’s go stratospheric instead, with a high-altitude solution…
Our researcher envisages kite systems producing a gigawatt of power. That's the same as a nuclear plant. Nukes or kites? I know which I'd prefer.
Naming a sane technology to replace fossil fuels can feel like an exercise in futility. Leaving aside the need to scale back energy use generally, grasping at non-fossil options throws up problems galore: solar cells can be too inefficient, hydro schemes produce methane, ethanol causes hunger, and so on. As those same
energy technologies apply hi-tech adjustments to fix their blemishes (‘clean coal’, ‘nano-solar’, ‘cellulosic biofuels’) each tech upgrade brings yet further problems.
For a sharp dose of reality about this energy-tech quagmire I would recommend a natty little presentation called ‘Climate Change Recalculated’ by inventor Saul Griffith. Griffith counts land – the land required actually to erect all those wind turbines, nano-solar panels and vats of GM algae now being hyped in the press. In doing so he comes up with an aggregate land area for deployment, which he dubs Renewistan. Depending on how much fossil fuel you think we can still safely burn, Renewistan would need to be at least as large as Australia – maybe something more like the size of China – and that is assuming society is prepared to accept nuclear power, genetically modified biofuels and nanotech solar cells.
It’s a dispiriting prospect and it leaves me deeply wanting to believe that Griffith’s day job might offer a lift out of this impasse. Saul Griffith builds kites: specifically huge, fixed-wing kites attached to electric generation systems. His Californian company, Makani Power, intends to deploy these kites kilometres up in the sky to produce electricity. He has received approximately $20 million in funding, mostly from Google, and employs 30 staff, many of them kitesurfers.
Makani is the leader in a new field known as ‘high altitude windpower’, and maybe, just maybe, these kitesurfer dudes are on to something good.
I say that ‘maybe’ very carefully. There are only a handful of high altitude wind developers and they have formidable engineering challenges to surmount. Some propose kites whose movement would drive electricity generators on the ground. Others aim to put actual turbines into the sky. So far such outfits report only a few kilowatts of power, but are aiming for megawatt production within the decade. At least one researcher, Mario Milanese at the Polytechnic University of Turin, Italy, envisages kite systems producing a gigawatt of power at one location. That’s the same as a new nuclear plant, which also takes 10 years to commission. Nukes or
kites? I know which I’d prefer.
This big talk of gigawatt-scale kite-power is based on a real promise. If you have ever felt the sadness of seeing an entire wind farm motionless, take heart that at one kilometre above the Earth the wind blows an average of eight times stronger and much more constantly. Kite farms, unlike windmills, depend on airspace, so theoretically they don’t compete for land. There are problems: getting all that electricity back to Earth with a very long string has consequences – ‘just ask Benjamin Franklin!’ explains atmospheric scientist James McCanney, referencing the legendary experiment where the American founding father almost electrocuted himself flying a kite in a storm.
McCanney holds that high-altitude tethers will invite frequent and dangerous electrical discharges. Developers counter that some areas of the world are less likely to encounter electrical storms, so they will fly their kites there. What else? Birders might reasonably ask whether avian migration routes will be affected. Social justice advocates point out that if these systems are patented (which some are) and centralised (which some might be) they may prove as inequitable as any other
Maybe it’s just the aesthetics of a kite bobbing in the wind that gives me hope – because we know kites; because they are a people’s technology. Through the centuries these everyday constructions of cloth and string have been used for communications, art, ceremony, warfare, transport and more. Like bicycles or water wheels, it is not hard to grasp how they work and can be controlled on a human level. A proprietary multimillion-dollar energy kite might prove a different beast, but for now I’m crossing my fingers and hoping this particular technology can fly.
Jim Thomas is a research programme manager and writer with ETC group
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