Research: Wind power pricier, emits more CO2 than thought
'Windfarm output is never zero. Sometimes it's less'
Oswald is an expert on gas turbines, having worked for many years at Rolls Royce*. He says that most people, in allowing for gas backup to wind farms, assume that the current situation of gas-turbine usage applies. Not so, he says. Gas turbines used to compensate for wind will need to be cheap (as they won't be on and earning money as often as today's) and resilient (to cope with being throttled up and down so much). Even though the hardware will be cheap and tough, it will break often under such treatment; meaning increased maintenance costs and a need for even more backup plants to cover busted backup plants. Thus, the scheme overall will be more expensive than the current gas sector. And since people won't want to thrash expensive, efficient combined-cycle kit like this, less fuel-efficient gear will be used - emitting more carbon than people now assume.
High-efficiency base load plant is not designed or developed for load cycling ... Load cycling CCGT plant will induce thermal stress cracking in hot components ... The other impact on the individual plant is a reduction in the plant’s utilisation. This has an economic consequence, which will encourage operators of generation plants to buy cheaper, lower-efficiency and therefore higher carbon emission plants ... Reduced reliability will require more thermal plant to be installed ...
And it gets worse. All this will hammer the gas grid's pipeline networks and storage hardware too, costing the end consumer even more money - again, something that isn't currently accounted for in wind power schemes.
Power swings from wind will need to be compensated for by power swings from gas-powered plants, which in turn will induce comparable power swings on the gas network as plant ramps up and down. This will have a cost implication for the gas network, an implication that does not seem to have been included in cost of wind calculations ...
In essence, wind plans aren't actually wind plans, according to Oswald. They're gas plans with windfarms used to reduce the amount of gas actually burned in the plants. But he thinks the assumptions now made on costs and emissions reductions to be anticipated are unduly optimistic.
From one perspective, one might argue that this is the exact purpose of renewable plants, namely to reduce fossil fuel burning. However, it does this not by obviating the need for that plant, but instead by reducing the utilisation of power plants which continue to be indispensable. Electricity operators will respond to the reduced utilisation ... high capital [cleaner gas] plant is not justified under low utilisation regimes ... it is critically important that the carbon saving achieved by the whole system is known, understood, and achieved in practice. The effect of this higher carbon calculation does not appear to be mentioned ...
There was one little ray of light for wind power lovers, however. When we asked Oswald for his views on plans to deal with wind variation using car batteries plugged into the grid for charging, he said he hadn't so far factored that into his plans. There are those - Google, the Danes - who think this might be seriously useful if a large amount of road transport went electric. Obviously, that doesn't seem especially likely in a 2020 UK timeframe, but it might not take that much longer if oil prices stay high.
Of course, that in turn would mean a lot more electricity production required - perhaps magnifying the wind variation problem, if the increased 'leccy demand was met with windfarms. And the calm or windy periods might not come just when the electric car users wanted them to.
"It's an interesting dance," says Oswald.
His article (Oswald, J., et al., Will British weather provide reliable electricity? Energy Policy (2008), doi:10.1016/ j.enpol.2008.04.0330) can be downloaded here, though you have to pay for it. ®
* The jet-engine firm, not the unimportant car badge.