11 January, 2007

Too windy for wind turbines?

Certain witty and erudite public figures here in the UK have an annoying habit of making somewhat ignorant pronouncements on anthropogenic climate change, preferring to deny that it's happening at all rather than talk about the more complicated (and valid) issues of how badly it might affect us (or not), or what mixture of adaptation and mitigation would best serve us. Jeremy Clarkson is one such person. The Radio 2 DJ Terry Wogan is another. Despite his form, I was intrigued by one item of discussion (or, more accurately, lengthy mockery) on his breakfast show this morning, namely that in the stormy weather that we're currently enjoying, 'it's too windy for the wind turbines!' Ha ha ha.

It turns out that wind turbines are shut down at wind speeds above about 65 mph, because the faster rotation of the blades at high wind speeds can either overheat the generator, or cause 'overspeed' problems whereby the blade rotation becomes impossible to control or stop (see p20 of this pdf). This is a simple consequence of optimising the turbines to the usual (slower) wind conditions, but it does raise an important issue. Other forms of renewable energy such as wave and solar are also compromised by stormy weather, meaning that during a serious storm, even without damage to the distribution system a renewables-heavy generation mix could well leave a lot of us without power.

To avoid such problems, you either need enough non-renewable (nuclear, gas, coal) capacity to act as a backup, which places fundamental (low) limits on renewable generation, or you need to somehow store the energy produced by the renewables in better weather. The latter is currently impractical at a large scale, which is one argument in favour of distributed generation (where batteries and heat sinks can be used). However, it seems that people are experimenting with using wind generators to produce hydrogen fuel. Using renewable power to produce energy-rich chemicals would be an interesting way of getting round the problem; in pure speculation mode, I wonder if you could use wind turbines to turn atmospheric CO2 back into hydrocarbons?

7 comments:

Wildtype said...

Holy cow - Wogan's stil around?

Interesting post, HA. Why not just avoid the unpredictability of the weather altogether, and put solar panels up in orbit? Is this impractical? How would you get the energy down to the planet? What's the limiting factor? Who's working on this?

Wildtype said...

Where's the postblogger, by the way? He's not keeled over in a lab somewhere, is he?

CJR said...

There's a concept I haven't heard about in a while... I think the idea was to beam power down to the surface using microwaves. The real issue is that given we barely have the capability to put together structures like the ISS, despite spending countless $billions on it, building giant solar panels is not something that we're going to be capable of doing, much less do economically, for quite a long time.

As for postblogger, I haven't the foggiest. Hopefully he's just on holiday or something.

MissPrism said...

*click*

That was my respect for Wogan going down a notch. I thought he was quite amusing on Eurovision, in a mildly sarky drunken kind of way.

Lab Lemming said...

Or, you can use your wind/solar to pump the water in your hydro systems back up hill, and generate your baseload with recycled hydro power.

As long as you don't live on a half-submerged swamp of topographically devoid continental shelf, this should provide renewable base power.

jc said...

It's a bit unfortunate that the phrase "Hydrogen fuel" has made it into the lexicon because accessible Hydrogen is all locked up in molecules such as H2O, NH3, CH4, and so on. To get the Hydrogen which we can then burn with O2 to get our water back requires energy, so really Hydrogen is more like a battery. But it's a really great battery because it is clean and easily transported. Ultimately we'll need multiple ways to generate electricity to power the grid directly and also break apart Hydrogen compounds so that we can use the Hydrogen as a, well, a fuel. Orbiting solar panels are a good idea for the distant future, but as I pointed out here, it doesn't take too much money or space to get the solar power we need the old fashioned way.

CJR said...

Hi Josh,

I see your point about hydrogen - although remember that coal and oil 'fuel' also required energy to form - the sun (via plants) and then Earth's internal heat just did the heavy lifting for us.