Guest post by Neil Rankine from Groundswell Bass Coast.
On Wednesday (21st March 2012) one of the Wonthaggi wind turbine’s blades was reportedly hit by lightning, causing the blade to split down its length. It’s now hanging from the hub in need of being replaced.
Having one turbine off-line will obviously reduce the amount of electricity the wind farm can produce for a while. Clearly any form of generation will have unforeseen mechanical and other breakdowns so I thought I’d see how often coal plants like Hazelwood in the Valley are generating.
Hazelwood has eight generating units and they always seem to have one off-line for maintenance or repair – sometimes two. The actual figure for achieved generation is a bit under 84% (Google ‘green energy markets hazelwood’).
Coincidently, five turbines out of six still operating at Wonthaggi gives the same figure (83.3%). So the availability of the wind farm is about the same at the moment, as Hazelwood power station. In the long term of course the wind farm will have a higher availability than coal fired generation as there is much less to go wrong.
People often say that governing mechanisms can go wrong with wind farms, another potential cause of blade failure, but the same can, and has happened with coal fired steam turbines.
The difference is that the Wonthaggi wind turbine blade failure takes out 2 megawatts for a month or two while it’s repaired, a turbine failure in the Latrobe Valley could take out 500 megawatts for a year or more.
Of course there’s the old chestnut that wind doesn’t blow all the time and people criticise wind farms for this. But that’s the wrong way to think about wind energy. It’s free fuel energy when it’s available. The other generators can adjust their load to compensate for fluctuations from wind.
The fluctuation over the whole grid is actually small as the wind is usually blowing in one area when not at another. It’s also predictable with good weather forecasting and sensing over wide areas.
Our current coal fired generators can cope with proposed wind farms easily, and when we build them, base load solar thermal generators will work well with wind farms too.
You can check out Dave Clarke’s info on lightning striking turbines at Wind in the Bush, where the photo below comes from.