Ben Southwood is head of policy at the Adam Smith Institute. The UK is quite windy. We need to reduce our carbon emissions. Take these two propositions together and it seems obvious that wind power could be a significant chunk of the solution. We already know that wind-power is costly and nearly always runs way below capacity. But a new paper out today suggests the problem is worse than that – its output is so variable and unreliable that we’d need nearly the same amount of fossil fuel capacity alongside wind just to guarantee supply. The paper, Wind Power Reassessed by Capell Aris, released jointly by the Adam Smith Institute and the Scientific Alliance, looks past the average-efficiency numbers widely available to see how this average is actually arrived at. Dr Aris accessed RAF and civilian data of half-hourly readings at 22 sites across the UK and 21 further sites across Ireland and Northern Europe. Surprisingly, the most common reading implies that wind farms are most often running at 8 per cent of their ‘nameplate’ (ie, their potential capacity), far below the published load factors from the Department of Climate Change. They generate under 20 per cent for 20 weeks of the year and below 10 per cent for nine weeks a year. It’s important to note that these gaps are not confined to summer, when electricity demand is lower; winter gets its fair share as well. These drops aren’t short and sharp (although there are rapid swings of five percentage points at times) and often last for six hours or more. Since it is difficult and costly to store large amounts of energy, the annual 17 hours of above 90 per cent efficiency, and 163 hours of above 80 per cent efficiency, will be of little use. This means that a large wind fleet, say of the 10 gigawatts planned by 2020, would need to be backed up with something reliable, most likely the fossil fuels that wind is designed to replace. If 5 per cent efficiency is all we can practically guarantee from this fleet, then we would need 9.5 gigawatts of fossil-fuel capacity to guarantee the lights don’t go out – the equivalent of two-and-a-half Drax power stations. Even including an estimate for the environmental cost of carbon emissions, the government thinks producing energy with natural gas or nuclear costs about £80 per megawatt-hour, as opposed to £90 to £100 per megawatt-hour for onshore wind. What’s more, this doesn’t make any attempt to estimate the cost people bear by living near structures they dislike. Though the issue is controversial among economists, some evidence suggests that nearby wind farms substantially suppress house prices. For example, a 2013 paper from Stephen Gibbons at the LSE’s Spatial Economics Research Centre found houses within 2 kilometres of visible wind turbines may lose up to 15 per cent of their value. This suggests homeowners would be willing to pay around £600 a year each to avoid having a visible turbine within 2 kilometres of them. This should be a factor in decisions about wind power. There are ways of reducing our carbon emissions without the costly, variable and intermittent supply wind promises. We should consider these before tying such a large fraction of our generation to such a flighty source.
Posted on: Tue, 28 Oct 2014 08:23:41 +0000
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