By Anton Lang ~
How often have you heard that Wind power is intermittent, but has anyone ever explained that to you, or shown just how it actually is intermittent, and what it means.
What if you need a dedicated amount of power all the time? Can wind power be relied on to generate that dedicated amount of power?
Over the last Month, I have been detailing the closure of the 53 year old Hazelwood brown coal fired power plant in the State of Victoria here in Australia, and comparing that plants power generation with wind power across the whole of Australia, and that Post is at this link.
The main comparison was with all the wind plants across the whole of Australia, but I was also including the data for just the wind plants in the same State that the Hazelwood plant was in, Victoria. While the Hazelwood plant had a Nameplate of 1600MW originally, its old age meant that it could no longer generate that level of power, but after 53 years it was astonishing that this ancient plant could still actually manage 86% of that original total, and that was 1380MW at its maximum with all 8 Units in operation. Across the whole 31 days immediately prior to its closure, the plant averaged a daily power generation of 1306MW, which gave the plant an effective Capacity Factor of 95% for that Month.
However when compared to just the wind plants in Victoria, the result was even more startling. There are currently 15 of those wind plants, and the oldest of them is the Challicum Hills Wind Plant, now only 14 years old. The total Nameplate for all those wind plants just in the State of Victoria is 1485MW, so there are around 850 of those turbines on poles around the State. That 1485MW nameplate is higher than the 1380MW (the recent maximum) of Hazelwood.
Yet, across those same 31 days in the lead up to the closure of Hazelwood, the average daily generation from all those 15 wind plants with 850 individual generators only came in at only 359MW, and that is just a tiny bit more than what was being generated from just TWO of the ancient Hazelwood’s 8 Units, an astonishing fact. Here you have 850 wind turbines and they can only generate as much power as two 53 year old generators.
However, when you say that the AVERAGE daily power from those wind plants was only 359MW per day, that is a straight line average across those 24 hours, where the power being generated is up and down across the whole day, so it is averaged to that amount.
So then, what does that mean, and can it be directly compared with an equal amount of Nameplate to show you how the wind power is variable, or intermittent?
I mentioned above that the Nameplate for all that wind power is 1485MW, so all we need do is to find an equivalent Nameplate from a (still operating) coal fired power plant and compare directly the power generated on a typical day by both of them, wind, and coal fired.
In the same State of Victoria, and not all that far from the now closed Hazelwood plant is the Loy Yang Power Plant, which also generates its power using brown coal. That Loy Yang Plant has two complexes at the same plant, Loy Yang A, and Loy Yang B. In all, there are six turbine/generator Units, and each of them has a total Nameplate of 525MW, for a total Nameplate for that plant of 3150MW. Now as wind power in Victoria has a total Nameplate of 1485MW, we only need the data from THREE of those Units at Loy Yang, so three generators of 525MW, hence a total of 1575MW, and 15 wind plants with 850 generators totalling 1485MW, and that’s about as close as we can get to equivalent Nameplate in the same State.
So now we have the Same State, and the (approximate) same Nameplate, and all we need to do now is directly compare one with the other, and for that, we will use the same day, Wednesday 29th March 2017, three days ago.
Same State, same Nameplate, and same day.
The image below shows the total power generated by those 850 wind turbines at 15 wind plants.
This image is taken from the Aneroid Wind Data site at this link.
You can see the date at the top, and under the chart are the wind power plants. Here I have only used the wind plants in that State of Victoria, indicated in the legend under the chart, where only the State of Victoria is ticked, and the plants in Victoria are ticked.
The solid black line indicates the sub total for power generated by all those wind plants in the State on that day, and the squiggly coloured lines under that solid black line are the running totals for each individual wind plant.
The Image below (also taken from the same site) details each of those Victorian wind plants, and at right is the total Nameplate for that wind plant, and at the bottom right, the overall total Nameplate for all of them, 1485MW.
The image below (also taken from the same site, and on the same day) details the power generated by those three generators at the Loy Yang coal fired plant, and as you can see under the graph, the only boxes ticked are for Loy Yang B Unit 2, (LOYYB2) Loy Yang A, Units 2 and 3, (LYA2 and LYA3) and the Sub Total box. The solid black line across the top indicates the total power generated, and the coloured lines below, and there are three of them there, indicate the power generated by the three generator Units.
Now, go back to the top image of the power generated by the wind plants. Notice that it goes up and down across that 24 hour period. That is the total power being generated at those points in time across the day. That can be averaged out to a straight line across the page, and that average is 550MW, give or take a little. That actually gives all these wind plants combined a Capacity Factor of 37%, which is good, because the yearly average for wind power is only 30%, so here I have actually picked a day when wind power is doing well, generating more power than the average.
Note that the average is 550MW, and that is slightly more than for just ONE of those three Units at the Loy Yang coal fired plant.
Now look at the second image for power generation from that Loy Yang plant, and note that the total power is a straight line across the page, and is just a fraction higher than 1600MW, just a small amount less than THREE times the power being delivered from all those 15 wind plants with 850 generators.
So here we have wind power on a good day, and it still does not make more power than ONE generator at ONE coal fired power plant.
Okay then, as to that intermittency thing I mentioned at the top of the post.
I have shown here that wind power delivers what can only be referred to as pitifully low power when compared to the same Nameplate for coal fired power, but look closely at that image for wind power generation.
Even though I averaged the power to a straight line across the page for the full 24 hours, note how the power generation went up and down. The maximum on this good day was where it hovered around 900MW for about 4 hours,and note here that even on this very good day for wind power, it still did not even get close to its maximum of that 1485MW total Nameplate. That is because they are spread out across such a vast area, with the wind blowing at optimum in some areas but not in others, and also due in part to the fact that at some of those wind plants, there are turbines that do not work any more, and compare that with the now closed ancient relic, Hazelwood, which after 53 years, could still get all 8 Units operational, while wind power, with all plants younger than 14 years have turbines that don’t work any more.
Of greater importance here, note also the minimum power generated by those 850 turbines at 15 wind plants, only 200MW, and how power generation spent almost 14 hours below the average of that 550MW.
That is the intermittency spoken about when it comes to wind power. It is up and down, and never the same, and no one really has a good idea on when it will be up or down.
Note again how the Nameplate is 1485MW, and yet at times, all those wind plants are only generating 200MW, which is only 13.5% of the maximum.
What happens if this is all you have, and you require the full 1485MW all the time?
Now note the coal fired power generation, and how it delivers the full amount all the time, not up and down, not an average of a third of that requirement, not 900MW, not 200MW, but the full 1600MW all the time.
Wind power is intermittent, not only on a yearly basis, but on a daily basis, and even on an hourly basis.
When wind power falls to 200MW, that power to make up the full requirement has to come from somewhere else, because wind power is not supplying it.
When the average is only one third of the total Nameplate, that power to make up the full requirement has to come from somewhere else, because wind power is not supplying it.
Even at its maximum power delivery for those few hours it actually achieves it, that power to make up the full requirement has to come from somewhere else, because wind power is not supplying it.
So, if you need a dedicated amount of power ALL the time, I have shown here that it cannot be achieved with wind power. It is intermittent at best, and it will always require backup.
Coal fired power, as vilified as it has become, does just that. It generates its full power all the time, and does not require any backup.
Wind Power IS NOT equal to coal fired power, and it never will be.
Anton Lang uses the screen name of TonyfromOz, and he writes at this site, PA Pundits International on topics related to electrical power generation, from all sources, concentrating mainly on Renewable Power, and how the two most favoured methods of renewable power generation, Wind Power and all versions of Solar Power, fail comprehensively to deliver levels of power required to replace traditional power generation. His Bio is at this link.