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One-blade wonder

Three Fisher & Paykel veterans have a radical new design for domestic wind generation. It’s a long way from the DishDrawer.

Three Fisher & Paykel veterans have a radical new design for domestic wind generation. It’s a long way from the DishDrawer

On the face of it, dishwashers and wind turbines don’t have much in common.

But one current and two former Fisher & Paykel engineers have used their experience with mass-market consumer products like the DishDrawer to harness wind power for the home.

By year’s end, Dunedin-based Powerhouse Wind directors Wayne O’Hara, Richard Butler and Bill Currie expect the wind turbine they started as a hobby project will become a commercial reality.

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Photograph by Bill Nichol

When they chucked in their day jobs in early 2007 to work on the turbine, Currie was head of engineering services with F&P, while O’Hara worked in the UK for a Cambridge engineering design consultancy specialising in small medical devices such as asthma inhalers. Butler, Fisher & Paykel’s Dunedin engineering manager and another former member of the DishDrawer team, also joined the startup in a part-time role.

O’Hara admits it was a bold step for guys in their late forties. “We realised the older we got the harder it would be, but I didn’t want to get to retirement age or my deathbed and say ‘Gee, I wish I’d done that.’ Our aim is the make the best small wind turbine in the world.”

His fascination with wind power goes back to a childhood love of the windmill-powered water pumps common around Oamaru when he was growing up. Currie also had a strong interest in wind turbines and his Sawyers Bay home is off-grid, partly powered by a Thinair 102, Powerhouse Wind’s revolutionary single-bladed domestic turbine.

Why a single blade? The 1.8 metre blade with two smaller counterweights has all the dynamic advantages of a three-bladed machine, but it’s quieter in operation and cheaper to manufacture (the target price is about $20,000). Large single-bladed turbines have been built before, but the Thinair is the first domestic model.

Traditional multi-blade windmills need to be tilted to catch the wind correctly, are inefficient in high winds and vulnerable to turbulence. Powerhouse’s patented ‘teetering hub’ design automatically adjusts the blade’s angle to accommodate changes in wind speed. The turbine can cope with turbulence around houses and trees, so it doesn’t need to be sited high on a bare hillside.

In really wild weather, O’Hara says, the blade simply ‘parks’ itself horizontally. “It’s a very low stress position, whereas other machines are trying to cope with very high winds, and that’s when they can suffer a lot of damage and fly to bits.”

On sites with average wind speeds of five to six metres per second, the Thinair will generate 3,250kWh per year, enough to meet the energy requirements of a well-designed, energy efficient home. Power generated can be stored in batteries and converted via an inverter into standard AC-electricity supply, or there’s the option of connecting to the national grid.

“It works intelligently so when the house demands electricity it feeds it to the house, and if there’s a surplus, it will feed it into the grid,” says O’Hara.

The ten-metre tower is suited to houses with large sections and, given its size, O’Hara says aesthetics are important. “It has to make a statement and contribute to the look of any well-designed home; it can’t look like a bucket of bolts like some other machines.”

The name Thinair came care of an American competitor. “We were watching a video on YouTube of one of their machines being installed. This American chap was very enthusiastic and said, ‘It’s amazing! We’re going to make energy out of thin air.’”

Powerhouse Wind has received $100,000 funding from the Foundation for Research, Science and Technology, and Thinairs are installed at several Otago homes. Now, O’Hara says they’ve embarked on the key stage: securing investment to get the Thinair into commercial production.

Article illustrationWhen the wind speed rises over 20 metres per second, the rotation of the rotor is stopped, parking the blade, making it less prone to stress and damageThe blade adopts the most efficient operating angle, optimising power for any wind speed. A single blade also allows quieter operation than multi-blade designsTwo counterweights balance the single blade, so that the rotor operates dynamically like a three-bladed machineMost turbines are ugly. Thinair is designed to complement and enhance contemporary homesThe chassis is mounted at least eight metres above ground level, where wind is cleaner and less turbulentElectronics provide sophisticated monitoring and reportingThe chassis is shaped to reduce turbulence as the blade travels through the tower's wind shadowThe patented teetering hub moves in response to the wind, resulting in a lighter rotor assembly and maximising energy generation

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