All entries for Sunday 10 December 2006

December 10, 2006

Wind energy running out of puff

Writing about web page

What a surprise that this story is only two days old yet I found it hard to dig out the information…

Anyway, a report by the Renewable Energy Foundation (a pro-renewables group) has suggested that claims on wind power have been grossly overstated. Most turbines are marketed as having a certain power output (i.e. a 5MW turbine) in much the same way as a nuclear reactor might be referred to as a 1200MW station etc. What this fails to hit home is that this is their rated power at a rated wind speed, and the figure is easily misleading if you’re not in the know and leads to incorrect direct comparisons. The amount of power generated by a turbine is proportional to the cube of the windspeed, i.e. if you’re generating 5MW at 12m/s wind speed then at a still brisk 6m/s you’re generating a pitiful 625kW. The amount of energy over time you can expect to get from a power generator compared to it’s rated power is typically referred to as the capacity factor or utilisation factor. For wind farms, this utilisation factor is very heavily dependent on siting. There’s the background for you.

The report has found that in the wind sector (which is the most active and the one which most noise is being made about), some turbines are being built on sites with a utilisation factor of as little as 9%. For sites in the North of Scotland and offshore (where we should be building turbines, if at all), the utilisation factor is more like 50%. So ramping up wind power in sensible locations, if that is a route we choose to take, would result in the requirement to build a very large (and expensive) grid connection from Northern Scotland and the surrounding offshore area down to England, where most of our electricity is consumed. You see, it’s not simply a case of plugging it into a grid up in Northern Scotland and wishing the electricity to get to South England – we’re talking about Gigawatts of power here, and as there’s currently no need for such a connection to exist to such remote locations, there isn’t one.

Perhaps even more worrying, the report has built a predictive model of how a large scale network would perform using data collected from Ofgem and hour by hour wind data from the Met Office to predict the performance of such a network in the month of January had it existed for years 1994 to 2004. The results, alarmingly, show that even if wind farms were distributed nationwide, the power variation averages 94% of installed capacity due to wind variation, and the average minimum is 3.7% or 0.9GW in a 25GW wind turbine network. Power swings of 70% over a 30 hour period are the norm. Any person with a grasp of the fundamentals of power generation would take a look at the above and come to the same conclusion I did years ago: wind power is a nonsense for taking up baseload and entrusting security of supply to.

The government, however, doesn’t see this. It’s prediciton is that 75% of the 2010 Renewables target, and the majority of the “20% by 2020” target, will be made from windpower. I should point out at this point that the REF’s report is in keeping with the experiences of other EU nations with wind energy, and not a one-off anomaly.

So, where does this leave us? In the same position I thought we were in before I read the report. We currently are in a situation of increasing demand (and likely to increase dramatically further if the government is serious about us giving up internal combustion to move us about), and rising fossil fuel prices. People are running scared about CO2 emissions as if the apocalypse is approaching. The golden alternatives of wind (as by far and away the biggest hope of the renewables sector) and to a lesser extent other alternatives are inadequate and failing to even live up to their hoped-for minute contribution in the energy mix. Yet we still somehow have to meet our energy demands and ensure security of supply. The solution? Well to me it’s patently obvious – sequestration powerplants and nuclear. The sooner we get the doubters out of their daydreams and get on with some construction before it’s too late to replace our aging plant (we’re due to lose all four of our Magnox stations within four years for example), the sooner we will not have to rely heavily on imports from France and other nations, and the sooner electricity prices will escape the rapidly escalating costs of natural gas.

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