Life expectancy of a Eoltec Scirocco [Archive]

Rob Beckers

8th January 2009, 08:20

Hi Richard,

As you've probably already figured out I'm biased; We're the importer/distributor for Eoltec in Canada. So, with that in mind....

The Scirocco is a very well-built wind turbine. Very solid, with oversized bearings and slewing-rings. The designers clearly put serious engineering into it; this is not a wind generator where things were sized to "look right", and changed as needed to fix problems (you would be surprised how many commercial small wind turbines are 'designed' that way). The Scirocco used stress-analysis by computer to size components and resolve issues before they crop up in the field. It is also one of the few wind turbines that I know where energy production as predicted by the manufacturer's spreadsheet correlates closely with reality (most manufacturers will overstate expected production, some do so greatly).

According to Eoltec, the design life for the Scirocco is 20 years, if the bearings are greased annually. They have grease nipples, and are accessible when the nose cone is taken off. So, a squirt with a grease gun will do the job. Using a tilt-up tower can make maintenance easier/cheaper.

How well reality will match the 20 year prediction remains yet to be seen; the Scirocco has been in production for around 8 years now. For North America, the longest running Scirocco I was involved in has been up for 2 years now (in Massachusetts), for Canada the Scirocco is very new, with a few running now. There's one more running in Montana that's been up for just over 3 years. In total there are around 150 Sciroccos running all over the world, most in England and Australia.

For any wind turbine, not just the Scirocco, its life also greatly depends on its siting: Put a wind turbine in turbulent air and it will be subject to ever-changing wind speeds and directions, causing it to 'seek' the wind continuously, speed up, slow down. This is very hard on any turbine, and will take years off its life, besides greatly lowering energy production. So, placing a wind turbine in 'clean' air, above turbulence on a high enough tower, will help it to live longer and live up to its production potential.

Many small wind turbines, maybe even most, are placed too low. Putting any turbine (no matter of its size) on a 10 meter (30 feet) tower is not a good idea, yet that is how the largest small wind turbine manufacturer in the world, South West Wind Power, prefers to sell its windmills. Unless you live on the tundra, or right at the edge of the sea on a cliff, there will always be turbulent air at 10 meters height. Towers are expensive, but as always it is an issue of "pay now or pay later".

The rule of thumb, and this is really to be regarded as the absolute minimum height for turbine placement, is 30 feet plus one blade length above any obstacle in a 300 feet radius, with a minimum of 60 feet height. This rule will likely get you in reasonably clean air, but puts the turbine right at the edge, and a little extra height would not be a luxury. Large objects, such as a house, tend to project an area of turbulent air behind them that is twice the object's height, and extend around 15 to 20 times the height of the object behind it (the effect also projects in front of the object, but has a smaller impact there). All these things should be taken into account when siting a turbine if you want it to live long and produce energy.

To write a few words about the other turbine brands you mention: Proven has a reputation of making rock-solid wind turbines. If you have an extremely harsh environment where almost all other turbines will fail prematurely, you want a Proven turbine because they have shown to stand up to abuse. On the down side: They are expensive for their size, and rumor has it that energy production falls quite a bit short of what the manufacturer predicts. The Bergey Excel-S is a mature product, maybe a bit too 'mature' in fact. A solid product, and in its current incarnation its production seems to correlate well with what the manufacturer predicts. On its down side: The inverter has serious issues with over-voltage cut-outs (see Mel Tyree's posts) and Bergey largely denies they are an issue (to be exact, they acknowledge what's happening, but claim it is of minor importance while Mel shows the opposite to be true). That is a manufacturer's attitude I really don't want to see for a $30,000 product.

Hope this helps!

-RoB-

Bryan Rendall

3rd September 2009, 06:43

We are also an Eoltec distributor, but for the UK and Ireland. We have also been heavily involved in the development work, having erected the 2nd prototype in the Orkney Islands of Scotland in 2003.

We probably have the longest running Scirocco's in the world here now, with some of the 2003 prototype components recycled into low cost "pre owned" installations, but with some of the harshest conditions imaginable. One install is on a small island only 200m long by 50m wide, so can be considered truly offshore, and gets salt air irrespective of the wind direction. We also have recorded turbines operating in windspeeds of 44 m/s without any trouble whatsoever, even when the grid failed simultaneously!

Meanwhile, we have had turbines run at 23-25,500 kWh per annum since 2006 - Thats about 3 times the power output we see on more typical UK sites, where 8,000 kWh per annum seems more realistic. In terms of power production, these turbines have done about 9 years worth of power production from an average site, condensed into just 3 years, again without problem. This is our best predictor for longer term lifespan, and holds up well to the 20 year estimate.

Much of the Scirocco is sealed inside very robust enclosures, meaning that things like the blade pitch control mechanism is operating in its own, clean, dry, grease filled environment. The generator is also fully sealed, with both coils and magnets being in a sealed enclosure. The yawing sliprings and brake lever are also inside, away from external influences. All that, oversized bearings and inherent speed control means that we have hardly any trouble with them!

Cheers

Bryan