[This is Part 1 of "Blowing away money"]
Wind towers heat up green debate
One result of the concern over climate change is the nearly universal adoption, at least among Western countries, of wind energy. Wind generators are spouting on farm land all the way from Norway to Tasmania, Western Australia to Canada.
But this near universal adoption has nothing to do with their efficiency in reducing the amount of carbon emitted by power stations, which is doubtful to say the least. Instead, the phenomena of wind energy is better understood as a political movement and wind turbines seen as political symbols. In that respect they are quite effective.
Governments like them because they are very visible symbols that they are doing something about the green concerns of voters, and they don’t have to raise taxes to pay for them. Voters pay through increased electricity prices. Activists like them because, well, the turbines are harnessing free energy from wind and supplying power direct into a grid. Why wouldn’t they save emissions? Anyone who asserts otherwise must be in the pay of coal or oil companies.
Sadly it’s not that simple. The problem with intermittent energy of all sorts, of which wind energy is by far the largest part, is that the supply and demand of electricity on a power grid has to be balanced at all times. If demand goes up, as it does in the evening when workers come home and start cooking dinner or switch on the television, grid managers have to put more power onto the grid. That usually means connecting generators to it, or directing generators already connected to increase their power. If they don’t then voltages fall throughout the grid and there are brown outs in part of it.
The same thing happens in reverse when consumers go to bed and demand falls. If the resulting unused power is left on the grid it would change the voltage and frequency of the supply, which would greatly upset electrical appliances. At all times the grid managers have to balance supply and demand on the grid, as well as cope with unexpected peaks in demand such as exceptionally hot days when everyone turns on their air conditioner. Electricity cannot be stored on power station scale except by being pumped up hill into dams, and there are all too few dams in Australia. Otherwise it is produced at the same time as it is consumed with nothing left over, no refunds, no returns, no exchanges.
To keep the grid balanced grid managers will use several different types of generators. Big coal and nuclear powered plants operate almost continuously to supply the majority of the power – the base load. The output of those stations changes only slightly over time and they are not shut down lightly.
Then there are the open and closed cycle gas turbines. Open cycle turbines are something like jet engines as they are cheap to build and can be powered up and down easily. Closed cycle turbines are bigger and more efficient than their open cycle brethren, as they recycle part of their heat, but are more difficult to power up and down when demand changes. Then there is hydroelectricity which is the most responsive – that is the easiest to adjust and switch on and off – and so is used for the peaks in demand. It is also the only established energy source that already counts as renewable. If all the 20 per cent renewables target came from hydroelectricity there would be no problem. As matters stand about 4 per cent of power in Australia comes from hydro-electricity, but there is no prospect of that proportion increasing.
Unlike all the other types of turbines discussed, wind energy cannot be turned on and off at request. It turns itself on and off and, so greatly complicates the 24 hour balancing act of managing grids. In effect, having lots of wind energy on the grid means that the grid manager is forced to take a lot of energy from open cycle gas turbines and less from the big coal plants. Further the gas plants will be powered up and down more often, increasing wear and tear and reducing efficiency. Obviously wind will take over some of the generating capacity, but the whole grid system is less efficient because it has to cope with wind.
Then there is the question of spinning reserves. Grid operators always keep operating plants off the grid ready to be hooked up in an emergency, such as one of the conventional power plants failing unexpectedly. Just how much of this “spinning reserve” is kept off line, generating emissions but not producing power depends on the risks involved. What is the risk that an operating plant will have an unexpected “outage”? For large networks with many power stations, the operators will work out the risk of something going wrong and calculate what reserve has to be kept offline to be connected in seconds, five minutes and 15 minutes and so on.
Wind energy comes and goes as it pleases, which increases the risk of outages, and that increases the spinning reserves the grid manager has to keep on hand, generating emissions. So how much additional reserve has to be kept off line to deal with wind? There have been several theoretical studies on this point, with activists insisting that the additional reserve requirement will be small. A 2007 report by the Energy Research Council in the UK, part funded by the pro-green Carbon Trust, dived into these arcane calculations in this area to estimate that backup requirements for wind intermittency adds “ just” 14 to 16 per cent to the cost of wind energy. Note that the report talks about additional costs rather than reserve requirements, and does not go near emission savings. The Royal Academy of Engineering the UK did its own theoretical calculations in yet another report to estimate that reserve requirements would increase the costs of wind by 47 per cent. Engineers are likely to be pessimistic (they say conservative) about new systems, while the Carbon Trust study is hardly likely to play up difficulties, so what real world experience can we point to.
One piece of evidence on this point is the Wind Report 2005 by German power company E.ON Netz GmbH which operates a large number of wind towers on the Baltic Coast. The report states that that because wind is so variable “traditional power stations with capacities equal to 90 per cent of the installed wind power capacity must be permanently online in order to guarantee power supply at all times”. There are a few caveats. The 90 per cent figure, which would completely eliminate any savings in emissions, includes normal reserve requirements whatever they may be (the report doesn’t say). Also, at the time of the report cited above, for various reasons, the company could not access wind farms across Germany, just its own which are concentrated on the Baltic Coast near Denmark. The wind off the Baltic is extremely variable.
This problem has now been rectified but nothing has been said about reserve requirements. In fact, no one operating a grid with substantial amounts of wind in Europe or the US – there are a few – seem to have said anything at all about reserve requirements, apart from E.ON, and no-on has said anything about actual carbon savings. Not only is the issue barely mentioned in the mainstream media, it is seldom cited in the technical publications. This could mean that there is no real question of how much carbon is saved, or it could mean that no one in the much derided energy industry actually operating an energy grid using wind is willing to stick their heads above the parapet to wave real world measurements showing that wind systems far less effective than activists suppose. Yet another possibility is that no-one has bothered to put a figure on wind costs or made realistic measurements of carbon saved because it’s not their job to do so. It’s their job to make the energy grids work, or supply energy to the grid within the law, and if the public want wind systems, then they will hook them up to the system and work around them.
In Australia, no-one in authority has bothered to ask simple questions about actual carbon savings and costs, in part because they don’t realise the problems but also because that is not the point of the exercise. If the public wants wind systems then politicians will give it to them, but arrange it so that the public pays.
One counter argument activists make to all the technical problems that beset wind is that really if the operators spread out wind farms, and adopt specialist forecasting systems, then wind will make a solid contribution. After all, wind must be blowing somewhere in Australia all the time right? Again, as we shall see in another article, it is not that simple.
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).
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