This is meant as a starting point for discussion about the big economic issues that might’ve caused this. One of the many, many reasons I’ll never make it as a political pundit, though, is that when I see a graph like this, I’m inexorably drawn to speculating about aspects of it that really have nothing to do with the intended point. In this particular case, I look at this graphic and ask myself “Why are there so many wind power plants installed in the fourth quarter every year?”
Because, I mean, look at it. For 2010, the green bar representing the fourth quarter is bigger than the other three quarters put together. 2008 and 2009 come close as well, and in all the years where the installations are broken out by quarter, the fourth quarter has the largest bar of any of them. So, why would wind power installation peak in the fourth quarter?
I can come up with a bunch of reasons, but there are two that seem most plausible to me, one demand-related, and the other accounting-related. The fourth quarter is the start of winter in the Northern Hemisphere, and that’s a time when energy use goes way up– more people need to heat their homes, days get short so lights are on for longer hours, etc.If you were running a utility, and adding power plants, you would definitely want them to come on-line in the fourth quarter of the year, so as to meet that increase in demand, so it could be that projects that are mostly constructed in the summer months only get finished and hooked up at the end of the year, because that’s when it makes the most sense.
The other possibility is less interesting, really, which is that it’s just an accounting game. That is, there’s some immediate advantage to be gained in terms of taxes or whatever by having a wind plant come on in December of one year rather than January of the next, so they make a push to finish before the end of the year, skewing the numbers a bit.
If accounting were the whole story, you would expect to see the number of plants coming on-line in the first quarter depressed relative to the others (because those that would naturally have ended up there are hurried along to get them into the previous fiscal year). You might see a bit of that in the data from 2006, 2007, and 2010. Not so much in 2008 and 2009, though– the first-quarter bar for 2008 is about the same size as the other two, and the first-quarter bar for 2009 is the second-largest for the year.
I suspect it’s a combination of those two, plus a couple of other things (in much of the country, you’re unlikely to break ground on new construction in November, which will reduce the number of projects finished however many months it takes to build one of these later, which might account for the low summer numbers, and that sort of thing). I would guess that some of the abnormally large first quarters in 2008 and 2009 were projects that had been intended to finish in the fourth quarter of the previous year, but ran over a few months. The big run-up in 2007-2009 probably reflects oil prices going high enough that wind power started to look like a good idea, and the crash in 2010 is probably a delayed effect from the financial crash in 2008– projects that were started with bubble money have finished, and post-bubble, there was less money for new projects that would’ve finished in 2010.
An interesting question is whether the huge fourth quarter of 2010 is just an accounting effect, or a “bump” in projects started with stimulus money. If the latter, the 2011 total would probably be higher overall, probably with a larger first quarter (catching the projects that were aimed for late 2010 and missed). If the former, I’d expect a really small first quarter of 2011, with the overall pattern looking more like 2006 or 2007.
Of course, I’ll totally forget this long before the relevant data become available to check this. But it’s kind of fun to speculate about this sort of thing, just to see what you can come up with from a sketchy set of data.
(I need to come up with a good way to turn this sort of thing into a classroom exercise, because this is exactly the kind of mental process scientists and engineers should be doing as a matter of course…)