There has been a lot of publicity recently for the proposition that wind farms don’t in fact deliver on their primary objective of reducing CO2 emissions (whether or not you think emissions reductions are important). This counter-intuitive result arises because intermittent wind requires back-up, usually gas. And because the gas-fired generators are run sporadically to balance the variable wind, they run inefficiently. Each KWh of electricity they produce (on average) costs more, burns more gas, and emits more CO2 than if the plant were run more consistently and efficiently.
Now the Guardian, no less (God bless ’em), leaps to the defence of wind, with their own research. It’s well known, of course, that the Guardian employs a team of highly respected environmental economists.
Let’s look at a key passage from their report:
From analysing National Grid data of more than 4,000 half-hour periods over the last three months, a strong correlation between windiness and a reduction in gas-fired generation becomes clear. The exchange rate is about one for one: a megawatt hour of wind typically meant the UK grid used one less megawatt hour of gas-derived electricity. This means that actual CO2 savings can be calculated from the data with a high degree of accuracy – these are not guesstimates from models, but observations of real-world data
Remember that the gas is there to back-up the wind. So obviously, high winds (provided they’re not so high that the turbines have to be switched off) will generate electricity, and therefore there will be less production from gas. And what does the Guardian’s study find? Why that on windy days, there’s less use of gas. OK, guys, but we knew that already. That’s a given of the system. Indeed, it was designed that way.
Then get that key phrase: “one less megawatt hour of gas-derived electricity”. So (they say) CO2 savings “can be calculated”. So in logical terms they’re now assuming what they’re trying to prove — that any one megawatt hour of gas production uses the same amount of gas, and creates the same emissions, regardless of conditions. But the Hughes/Udo findings are precisely that the efficiency of the gas-fired power station is determined by the pattern of usage. Obviously if the Guardian simply assumes to start with that this is not the case, and that all megawatt hours are the same, they can satisfy themselves that Hughes/Udo are wrong.
They say that “these are observations of real world data”. Yes guys, but the wrong real-world data. You’re measuring the electricity output, and obviously that correlates directly and negatively with wind output. But you’re not measuring the CO2 emissions. So far from proving your point, you’ve not even addressed the question. Your article is a lot of hot air.
They have other priceless observations. Get this:
The intermittency of wind is balanced both by the inertia of the turbines themselves and by multiple wind installations over a wide geographical area.
Intermittency balanced by inertia? So how long do they expect a turbine to keep spinning — and delivering electricity — when the wind stops? Thirty seconds? Maybe 45 if you’re lucky? This is clutching at straws. And the proposition that “the wind is always blowing somewhere” is just not true. Frequently it drops over the whole of the UK, or large parts of Europe.
The Guardian would do well to go away and read Professor Hughes’ work, and see if they can find a logical flaw in it, before they set out on superficial attempts to disprove his conclusion, in terms that show they simply haven’t understood the issue.