Wind Blog

The Ferndale wind project will be expanded with 2 Vestas V82’s late this year. The current project has a single V80. What is the difference between these models?

The current V80 has a 1.8 Megawatt (MW) generator with 40 metre blades. That means that its peak production is 1.8 MW when the winds are above about 50 km/hour. It has a cut in wind speed of 4 m/sec (13 km/hour), and a cut out wind speed of 25 m/sec (90 km/hour). So when winds are low, it produces nothing, and then it produces an increasing amount as the winds increase. Above 14 m/sec, the blades pitch to let some of the wind pass, and it generates at 1.8 MW.

The new V82’s have a 1.65 MW generator. Most people assume that this means it will produce less power than the 1.8 MW V80. But in this location, and in most of Ontario, with its wind resource, this is not the case. The V82 has a 41 m blade, and so it has more swept area. In fact, the swept area is more than 250 m larger, or 5%. This means that the turbine will produce more power at low wind speeds. For example, at 7 m/sec wind speed, the V80 will produce 412 KW, and the V82’s will produce 432 KW.

The V82 has a cut in wind speed of 3.5 m/sec. And while this seems to be pretty close the V80’s 4 m/sec, the winds at this location are between 3.5 and 4 m/sec about 6% of the time. The V82 has a cut out wind speed of 20 m/sec, compared to the 25 m/sec for the V80. But the wind speeds are rarely over 20 m/sec. The V80 lost about 90 minutes of production in the last year from wind speeds over 25 m/sec.

The overall impact on production, with the lower cut in wind speed, more agressive power production in low winds, and including loss of production above 20m/sec means the V82 should produce about 4%-5% more power than the V80. And the installed cost of the turbines is about the same.

Another interesting impact from introducing the new models will be its effect on the percentage of time the wind farm is producing at least some power. In the past 12 months, the current turbine produced power 68% of the time. Downtime for maintenance, power outages, high wind events, and low wind events account for the rest of the time. The addition of 2 turbines will naturally improve this number, since we are unlikely to be performing maintenance on all three turbines at once. But the new model turbines will also increase the percentage by the 6% of the time that the wind is between 3.5 and 4 m/sec. Overall, the wind farm is likely to be producing at least some power about 80% of the time.

Utility planners often unfairly criticize wind as an intermittent resource that can’t be relied on. They use this as an argument in favour of building new fossil fuel stations, since they can be powered up and down as needed. But in this small wind farm, you can see that the intermittency is substantially reduced simply by equipment selection.

Of course, diversifying the locations of wind turbines across a large province like Ontario would reduce the intermittency even further, since the winds are at different speeds in different geographical locations. As I write this, the wind speed in Goderich is 26 km/hour, and in Wiarton and Toronto it is 11 km/h, and in Kingston it is 7 km/hour.

Equipment diversity, and geographic diversity can do much to firm the output from wind turbines.

And sometimes, less is more.

This entry was posted on Monday, May 1st, 2006 at 8:21 am and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.