A wind turbine for the home

GREEN POWER: Good news for homeowners: with small wind turbines, you will soon be able to generate your own electric power right out in the backyard. The manufacturers produce the rotor blades using nanoparticles from Bayer MaterialScience.

If you have room in your backyard for a cherry or apple tree, you will soon be able to generate power there too.

Just install a wind turbine from Eagle Tuulivoima, hook it up to the power grid and you’re

good to go.

The Finnish company has just begun producing small wind turbines. "We’re starting off with two models:

one with a rated output of two kilowatts and one with five kilowatts," says company founder Juha Siitonen. The product range is to be expan-ded next year to include 10 and 20 kilowatt models. To compare, large systems generate over 1,000 kilowatts, "but ours are big enough for home use."

Oddly enough, the idea of building wind turbines for the home originated in Lahti, an inland city in Finland where only a light breeze usually blows. But it’s also home to Amroy, a company with very special expertise: it incorporates carbon nanotubes (CNT) into plastic resin by a unique method, resulting in a material with signif-icantly improved mechanical properties.

Hybtonite is the name of the reinforced epoxy resin. If it sounds familiar, that’s because it’s a deliberate allusion to the legendary kryptonite of Superman fame. The material’s unusually high strength is attributable to Baytubes brand carbon nanotubes supplied by Bayer MaterialScience. Hybtonite has already demonstrated its toughness in other fields of application.

For example, the material is used to produce ice hockey sticks and skis.

A Bayer MaterialScience customer in China manufactures rotor blades between 40 and 50 meters long from Hybtonite for large wind power plants. So why not use the same material to make small wind turbines?

One day, Amroy employee Kimmo Kaila discussed this idea with his friends Miamari and Juha Siitonen in Lahti, and they were immediately taken with it. So much so that they quit their jobs and founded their own company in 2007: Eagle Tuulivoima. Tuulivoima is the Finnish

word for wind power.

The Siitonens soon learned, however, that you need more than just the right material to make lightweight rotor blades. The generators that convert the rotation into electrical energy proved to be something of a problem. "Conventional devices need about 260 rotations per minute to generate electric power," explains Miamari Siitonen.

In other words, to produce electricity, they need a wind speed of 7 (51-60 km/h) or more. Because weather conditions of this kind are not a daily occurrence, the Finns devised their own solution. The company had an innovative generator engineered that operates efficiently at wind s d thus meets one of the key requirements for mass production.

The smallest system is the two kilowatt turbine. Its rotor blades weigh only 4.5 kilograms, even though they are 2.5 meters long. If they were made of glass fiber reinforced plastic, they would weigh twice as much. These blades would also have a much smaller surface area in contact with the wind.

This means that the blades on the new system produce a higher wind yield. As a result, they are much more efficient. If you have bigger and lighter rotor blades, the first question probably has to be whether they will break more easily in high winds. The answer in this case is no, thanks to the tiny carbon nanotubes incorporated into the plastic compound by supplier Amroy. These little CNTs enable the material to bear high mechanical stresses.

"They also prevent material fatigue and ensure a long service life," emphasizes Amroy CEO Antti Valtakari. This effect stems from both the elongated shape of the carbon structures and the fact that the company chemically anchors them in the plastic. What’s more, it takes the addition of just one percent of CNTs by weight to achieve this performance.

For individual homeowners, this method of alternative power generation naturally is only an attractive option if the price is right.

It is expected to cost less than EUR 10,000 for a two kilowatt wind turbine including installation. The system can generate approximately 4,000 to 8,000 kilowatt hours of electric power annually, although the figure varies from region to region. Miamari Siitonen has calculated that a wind turbine this size can provide a single family home with average consumption with all the electricity it needs. If the turbine produces surplus energy, it can be fed into the public grid, as is commonly done with solar power. Alternatively, the

surplus can be stored.

In targeting customers, the Finns have their eye on more than just environmentally conscious homeowners in the industrial nations. "We are mainly focusing on regions accustomed to a very unreliable power supply, such as India or countries in Africa," Siitonen says. If all goes well, the company may one day be as well known as a certain Finnish mobile communications corporation.