So many times I have seen the comment that Wind Power is cheaper than Coal Fired Power, when it comes to constructing any new type of Power Plant. The comment always comes from someone who is a supporter of Wind Power, and when I attempt to explain how it isn’t a cheaper way to go, I then become the person with an agenda.
It’s easier to believe that one liner that it’s cheaper, than it is to understand why it actually isn’t cheaper. The mistake often made is that this is a theoretical statement based loosely around a set of facts, and it deals with NEW plants that may be constructed, because for existing power generation Coal Fired Power is far cheaper than Wind Power could ever hope to be.
You’ll hear quoted things like EROI (Estimated Return Of Investment) or even LCOE (Levelised Cost Of Electricity) and these provide the headline numbers that make Wind ‘seem’ to be cheaper, and from that, green supporters accept that headline number, without having the understanding as to how those figures were come by.
So then, let me explain how this method of theoretical calculation is arrived at, and how it is manipulated to make it ‘seem’ that any new Wind plant can be made to look cheaper than a Coal Fired plant.
To do that, first you need to understand the end result that all these theoretical calculations are made from. That comes from the actual power that the plant generates over its life span, and from that, they can then calculate how much needs to be charged per unit of electricity to recover all the costs involved.
A typical Wind Plant might have a lifespan of 25 years and a typical Coal Fired plant will have a base lifespan of 50 years.
There is an Industry formula for this power actually delivered for consumption, and that formula is:
NP X 24 X 365.25 X CF
Here, NP stands for Nameplate Capacity. There are 24 hours in a day and 365.25 days in a year, with the leap year taken into account as the .25 extra. CF stands for the Capacity Factor of the plant. This CF is the ratio of power actually generated to the theoretical maximum power if the plant were to run at 100% for the whole year round. For a typical large-scale coal fired plant, while ever it is running it is generating its maximum power. The only down time is for scheduled maintenance, when the plant is not delivering power. When it comes to Wind power though, the generators can only generate their power when the wind is blowing and turning the huge blades that drive the generator.
Typically, for a large-scale coal fired plants, their CF is around 75 to 80%. The newer technology UltraSuperCritical plants currently being constructed all over China are running at a capacity of around 93%, and have been doing that for almost four years since they started going in. As a plant of this type ages, it requires more maintenance, hence more down time each year, so the CF quite naturally lowers, but a figure of 80% is not out of the question as current long term large scale coal fired plants, some in operation for many decades have in fact been running at this level.
With Wind plants however, that capacity is considerably lower. Often quoted at around 30 to 35%, all across the World Wind Power is currently averaging between 15 and 25%.
So for this purpose, I will be using 77.5% for coal fired power, and 25% for Wind power, probably on the low side for large scale coal fired power, and on the high side for wind, but as you will see the end result is surprising to say the least.
While power plants are of many and differing sizes, here, for the purposes of this theoretical exercise, I have used the same initial size for the calculation, and that will be 1000MW. A typical large-scale wind plant might only be of 500MW in size and that will be approximately 170 huge towers. A typical large-scale coal fired plant will be around 2000MW and will have two large generators, so for the purpose of equivalence, here I am using the same starting point, 1000MW.
So using the same calculation for Wind we have the following. (KWH, MWH GWH and TWH are multiples of 1000 used to signify power delivered over time, with the WH meaning WattHours, the K for Kilo, M for Mega, G for Giga, and T for Tera)
1000 X 24 X 365.25 X 0.25 giving a one-year total power delivered of 2191500MWH or 2191.5GWH, and a power delivery over its lifetime (25 years) of 54.8TWH.
For coal-fired power we have this.
1000 X 24 X 365.25 X 0.775 giving us 6793650MWH or 6793.7GWH and a lifetime (50 years) power delivery of 340TWH
So, see the difference here with Coal Fired power delivering 6.2 times more power.
Now, from that end result of the power total, they can then work out how much they can charge per unit of electricity to recover their costs.
Can you see that with coal fired power delivering so much more power over a much longer period of time, then their unit cost for the electricity they deliver is lower, not just lower, but considerably lower?
So, now knowing that, how could the numbers be manipulated to make wind ‘seem’ cheaper, when it is so patently not cheaper?
They play with the data from both forms of generation to artificially lower the cost for wind while at the same time raising the cost of coal fired power by manipulation. So then, let’s look at how they do this.
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© Tony from Oz 2013