The Oil Drum

Studies[1] have shown that the capacity factor of wind is around 35% at it's highest.

"The reported annual capacity factor for the UK wind power has varied from 24% to 31%, with a long-term average of around 27% (DUKES, 1998 and DUKES, 2005); these reported figures include downtime due to maintenance, and forced outages due to mechanical failure. In contrast to these reported figures, recent studies (cf. Dale et al., 2004) have tended to use a long-term annual average capacity factor of 35%; this decision is likely based on the higher wind speeds, and hence capacity factors, that are expected from offshore wind power developments, and a bias towards future onshore wind power developments in higher wind speed regions such as Scotland. A pessimistic view of UK capacity factors for wind power has also been put forward by a number of authors, suggesting capacity factor figures of 25% and below (Royal Academy of Engineering, 2003; Sharman, 2005)."

Somewhat lower than the 60% lower estimate you gave for nuclear power. In addition you claim that it is unlikely that 1500 turbines will go down at once. In an area the size of the UK it not that unlikely that an unusual large scale weather event could cause a significant portion of the wind power to go off-line. Since the UK is only connected to Europe by 2 2GW busbars (which incidentally both once went out of service despite being an event considered so unlikely no contingency plan existed, demonstrating that unlikely events do occur) it is effectively an isolated region.

The main problem with wind, however, is not it's capacity factor but the security of supply. On average the wind will supply a given amount of power to the network but this amount cannot be changed as it is dictated by the wind. For instance, there can be no spinning reserve with wind power, in the event of a frequency drop on the network due to a large plant coming off line, the first port of call for maintaining system stability is for the running plants to increase their output, they're supposed to operate slightly less than their rated capacity to do this (whether they actually do or not is another matter). Hydro which is used for peak demand cannot supply emergency power as for the first few fractions of a second of output they cause further strain on the network, which would result in a further drop in frequency and could cause the other generators to become desynchronised. Following taking up the slack by increasing power to the running generators, the spinning reserve is brought online. These are generators which are spun up but not supplying power to the network. The next step following this is to spin up off-line generators, in order to replace the reserve capacity, this can take minutes to hours depending on the type of plant. How would you suggest any of this is achieved with wind or indeed wave power when you have no clue how much wind or waves will be available at any given time? There is more to the security of the electricity network than just the installed capacity. You are correct in stating that storage could solve some of these problems, but this technology is in its early stages.

Further problems with wind are that the best resources bear no particular relation to existing load centres such as cities etc. When you consider that the transmission infrastructure necessary is at least as expensive as the installed capacity this cost can be quite significant.

For what it's worth I don't have anything against wind and wave power, I'm just skeptical that they can supply a secure base supply. In fact, as I'm hoping to start a PhD based on optimising various types of marine energy machines next year, I actually have a distinct bias towards this resource! Therefore, as someone who is going to be doing a little bit of the R&D you mention I feel compelled to warn you that we will be stuck with conventional sources for a while to come.

You also state the required dispatchable power could come from biofuels. There is considerable debate on this board about the viability of biofuels, I personally don't know enough to comment.

[1] Graham Sinden, Characteristics of the UK wind resource: Long-term patterns and relationship to electricity demand, Energy Policy, Volume 35, Issue 1, January 2007, Pages 112-127

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