Wind turbine output declines rapidly over time
The phrase “hide the decline” became notorious during the “ClimateGate” e-mails scandal, when it became clear that scientists at the heart of the IPCC process and the global warming scare were dismayed to find that the real-world data failed to follow the theory. Temperatures went down when the alarmists thought they should be going up. So they took counsel together as to how they should “hide the decline” (their phrase, not mine), in a deliberate attempt to mislead scientific and public opinion. They sought to achieve this through cobbling together two utterly unrelated and inconsistent data sets (recent observed temperatures and historic dendrochronological data).
It took some scientific and statistical detection work by Steve McKintyre and Ross McKitrick and others to demonstrate the scale of the deceit.
But the phrase could equally be applied to a more recent story on the performance of wind turbines. Statistical data show an alarming fall-off in turbine output over ten to fifteen years.
A paper by distinguished environmental economist Professor Gordon Hughes of Edinburgh University shows that in the UK, on-shore wind farm relative output (actual output as a percent of rated maximum) declined from an average 24% at the outset to 15% after ten years and 11% after fifteen years. Danish offshore wind farms declined even more catastrophically, from 39% initially to 15% at age ten. The output of larger turbines (now favoured by the industry) declined more rapidly than that of smaller turbines.
This decline may be attributable to wear and tear on the mechanical parts and bearings, plus degradation of the aerodynamic surfaces of the blades (I daresay those clots of eagles’ blood and feathers don’t help). Degradation of the blades can create instability and vibration, in turn leading to mechanical wear, damage and failure. And offshore, the strong winds and harsh conditions constitute an extraordinarily challenging environment for wind turbines.
The word in the industry is that Operation & Maintenance costs are coming in far higher than planned, at a time when output and life expectancy are coming in much lower. I understand that the industry bases its projections on the broad assumption that design life is of the order of 25 years, and the tacit assumption that output will be maintained over that period. We now know that neither assumption can be sustained.
The Hughes paper, published by www.ref.org.uk, has been available for a year or so, and rather than being lost on a dusty shelf, it seems to be gaining traction. I’ve mentioned it a couple of times. So I was delighted to see that Christopher Booker chose to pick up the story (Dec 8th) in the Sunday Telegraph. He adds another interesting angle. It seems that Professor Hughes showed his work to DECC’s Chief Scientific Officer David MacKay, who found no fault in Hughes’ analysis.
So MacKay knows. Presumably Ed Davey knows. Yet they insist on pursuing their dream of “free wind energy”, even when they know that it is proving vastly more expensive even that their own eye-watering estimates. They talk of reductions in subsidies for on-shore wind energy, but the reductions are small, and in any case will be offset by increases in off-shore subsidies. Just the place where returns are lowest and the output decline is greatest. I think it’s called “reinforcing failure”.