The when and where of wind

Blowing away money – 2 

A common weather pattern in Europe is a prolonged period of very cold, calm weather. Just when the demand for electricity is at its highest to heat homes, the much vaunted wind turbines which dot European farm lands are idle.

This is one of the many problems with wind energy which have kept activists busy denouncing supposed energy company conspiracies, and writing theoretical studies “proving” that the problem is really only a very slight one. Surely the “low wind, cold snap” weather pattern does not affect all of Britain at once? Also, Europe is a very big place. Spread the wind farms over a wide enough area, scatter a few offshore and always some will be operating. We will not examine these European wind wars, with claims and counter claims, here. Australia’s geography and weather patterns are different.

But if the low wind cold snap scenario is common in Europe, how often do hot calm days occur in Australia? Activists will dismiss this question with the assurance that it hardly ever happens. In any case, as activists constantly assert, if the wind falls in a certain area then wind farms outside the area will make up the shortfall. Here we run into the issue of transmission distance. Electricity industry executives point out that generators have a transmission radius. They can transmit electricity only so far over power lines. A wind farm in Queensland cannot fill the gap if the wind in South Australia stops blowing. So then to have any real idea of the effectiveness of wind farms we would need to know just how meteorology interacts with transmission distances.

About the only piece of evidence, one way or another in this part of the wind debate, of which I am aware, is a paper by weather analyst Andrew Miskelly and Tom Quirk, a former deputy chairman of VENCorp which managed Victoria’s transmission network. The paper, Wind Farming in South East Australia (Energy & Environment, 2010), looked at the generation figures for wind farms in South Australia and Victoria at five minute intervals for one month, June 2009. The figures are available from the website of the Australian Market Energy Operator, which now operates the connected grids for Eastern and South Australia. The pair found that when the wind died, it did so right across the two states. Adding in wind from Tasmania helped a little, but there were still problems with calm periods and major fluctuations, particularly in sudden surges of wind which could upset the voltage and frequency balance of networks discussed in the first article.

The paper found that collective average output of the farms was about 30 per cent of installed capacity (this is in line with overseas experience) and, thanks to the spread of wind farms over two states, about 10 per cent of their capacity could be relied on for 90 per cent of the time. That’s not bad for a bunch of wind farms, but still nowhere near good enough for a grid.

Electricity grids are run very conservatively and designed to cope with worst case scenarios. Grid managers cannot ignore the remaining 10 per cent of the time when the wind farms are not producing anything, particularly if they do not know which 10 per cent, nor can laugh off the worst case involving wind generation – a hot, calm day – on the assurance that it does not happen all that often. Considering how much trouble they can get into if the grid blacks out on a hot day, they must plan carefully for the worst, and have a generating reserve on top of that. Given all that it is doubtful that any fossil fuel plants will be shut down because of wind power, even if the results in the paper cited above had been much better.

The problem of sudden surges in wind power destabilising the network has been dealt with by the AMEO declaring in 2007 that all new wind farms of more than 30 megawatt installed capacity would be classified as “semi-despatchable”. This means that rather than accepting the output from wind farms no matter what, the authority will set limits or caps on what it accepts over five minute periods. The caps will change depending on conditions (Semi-dispatch of significant intermittent generation – proposed market arrangements, May 2007).

This would seem to limit the profitability and efficiency of wind farms but another problem remains. What happens when the wind dies away? As noted in an earlier article grid manages have to quickly replace any wind power that suddenly disappears from the grid or have a host of irate consumers on the phone.

The common practice for all networks, long before wind energy came along, is to keep some “spinning” generators – that is, generators operating but perhaps at half power – all ready to be hooked up to the grid at a moment’s notice, if other generators fall out unexpectedly. These are usually gas turbines that can be ramped up to full power very quickly. So how much additional spinning reserves will be required for any wind power delivering energy to the grid at any given moment? How quickly will the wind decline, and how fast can generators be connected and ramped up to full power? Remember that grid managers err on the side of caution.

The only organisation with the detailed knowledge required to answer that question is the AMEO, which reports to the Council of Australian Governments (the state and Federal governments), and it’s not that organisation’s job to comment on such questions. The organisation’s job is to connect wind energy to the system, and make the grid work. But at least some increase in the amount of spinning reserves can be expected.

In other efforts to deflect all this draining criticism of wind energy, activists point to wind forecasting systems. If the grid operators knows in advance just how much energy will be available, and when wind might decline, it can reduce the spinning reserves required. Considerable effort is being expended on wind forecasting systems around the world, but how successful are they? This is another in a long string of questions about wind that are not only unexplored, but mostly unasked. Very few of even the activists who support wind have no idea that such systems are being developed or why they are a good idea, let alone the general public or policy makers.

Results of such a system being tested in Australia handed to me, show that for five minute forecasts the system has an accuracy of more than 95 per cent at certain locations. That is the system will forecast the strength of the wind five minutes ahead and will be right more than 19 times out of 20. This sounds impressive, but then what forecasting accuracy could be achieve by a system that simply declares that the wind will be the same in five minutes as it is now. That simple “status quo” system of forecasting will work well until the wind changes. The figures for one hour ahead, four hours ahead and 24 hours ahead are also impressive at mostly more than 90 per cent, albeit with considerable variations between states, but just how effective this will be in reducing general uncertainty and reserve requirements is a question for the engineers. Another and perhaps crucial problem, related to the problems above, is just how well the system forecasts extreme events, namely storms (when generators also stop producing).

Whatever may come of wind forecasting systems, there is yet another problem with wind farms arising from the need to build them in isolated, windy spots. Transmission lines have to be built out to those spots but built to take full output, for when the generators are operating at full tilt, and not the average. It is akin to building super highways to a remote town to handle traffic that, for most of the time, is at the volume found on a suburban road. This is an enormous, additional expense.

Again even the bulk of the wind activists, let alone the general public, have no idea these problems exist. But then, as noted in my previous article, wind farms are not really intended to save carbon. Instead, they are built as symbols – to make activists feel better, and to reassure voters that the government is trying to do something about green concerns. As we shall see in succeeding articles, the way the system has been set up, it is likely that the books will be automatically arranged to point to illusionary gains in carbon, but the cost of this charade will be much harder to disguise. 

Mark Lawson is a senior journalist on the Australian Financial Review and the author of A Guide To Climate Change Lunacy – bad forecasting, terrible solutions (Connor Court, 2010).

Subscribe to Quadrant magazine here…

See also:

Part 1 of “Blowing away money” is here…

Part 3 of “Blowing away money” is here…

Part 4 of “Blowing away money” is here…