Wind turbines only produce electricity when the wind is blowing and, because the wind does not always blow, that obviously means that wind turbines are not always producing electricity.

Detractors (SaskPower is one of them) frequently use this fact to claim that it is not possible to generate more than a very small amount of our electricity using wind turbines. However such claims do not stand up to scrutiny!

In fact there is no reason why wind energy should not provide at least 25 percent of our electricity. As the following shows, wind energy already provides more than a quarter of total power needs of two U.S. states and wind energy growth continues to power ahead.

 
 

So what's going on? 

Every form of generation requires backup capacity to provide for occasions when it is not operational.

Coal and gas plants occasionally 'trip off' the system. On these occasions and due to mechanical or electrical problems, these generators may simply shut down with only a few seconds of warning. There is a huge and hidden, cost to electricity consumers to ensure that there is always sufficient backup capacity available and ready to run, at a moment's notice, to keep the lights on when these unintended mechanical failures happen. 

Even hydro-electricity, which generates 20 percent of Saskatchewan's electricity, is not totally reliable. People in Saskatchewan know only too well that dry conditions sometimes occur and, when they do, there will be insufficient water for hydro-electric generation. That means that hydro electric power stations cannot run and we have to get our electricity from other sources. In other words even hydro-electricity requires backup capacity for occasions when it is not possible to use it.

Due to these factors it should be no surprise that there is already an enormous amount of backup capacity available on the system.

There is a tendency to think that generation runs at full output all the time and that anything less than that is 'inefficient'. However that is not the way that the system works. By way of illustration: the Saskatchewan electricity system has an installed generating capacity of 4,280 Megawatts and this has an average capacity factor of 60 percent.

In other words this is equivalent to saying that 60 percent of our electrical generating stations run at full capacity all the time while the remaining 40 percent is idling in 'back-up' mode all the time.

Or, to put it yet another way, every single generating unit in Saskatchewan has 67 percent backup. Since this is substantially more than marginal wind additions would require it is ridiculous to claim, as SaskPower does, that only wind energy requires backup.

Numerous detailed electro-technical studies have been carried out across North America, in Europe and Asia looking at this issue and what impact the addition of variable wind (and solar) will have.

What all those studies have found is that installing significant amounts of variable wind energy (20 to 25 percent of total electricity generation) does not require additional back up capacity. They find that new wind capacity can rely on the back up provided by the existing 40 percent of 'idle capacity' previously mentioned. 

Those same studies find that the penetration of wind and solar together is much higher than it would be for either one acting alone. This is because in North America (and in Saskatchewan) wind output is at peak from September to May while solar output peaks from June through to August. Pretty handy!

For anyone looking for more detail there is plenty of it. And the following two studies are an excellent place to start - not least because they cover the whole of the U.S. and they were prepared for the U.S. Department of Energy. The one that covers the western half of the U.S. was prepared by GE Energy. It found that "The integration of 35 percent wind and solar into the electric power system will not require extensive infrastructure if changes are made to operational practices".

The point is that we don't need to invest in lots of expensive equipment in order to increase the uptake of wind and solar - we simply need to change the way we do things.

 

 
 

 
 
Posted
AuthorJames Glennie