On the Rise: Solar Thermal Power ?

[Besoeker]

Originally Posted by prashamk

Here's some encouraging update from Hawaii...

20%-40% seems entirely reasonable.
The key to getting the best out of renewables is aneffective energy storage system.

[LMagic007]

Originally Posted by Besoeker

Good. I'm so pleased that you agree with my 25 hours a day assertion. Thank you for your expert input. I feel exonerated from my previous asinine posts about the 12 hour average for sunshine. Our planet will never move the same way again.

Oh no, I meant indeed it seems your whole across the board argument of 50% capacity factor limit for Solar Thermal energy with storage seems nonsensical, as does it seem your follow up examples, that appear to prove nothing and seem inappropriately applied. No input required on my part, you've done an outstanding job without it. If what you have put forward thus far is the best of your argument, I suspect you won't convince many people. I can see right through it and I suspect thus others keenly interested in the technology can too, but the fact that it appears you can't, does make one wonder. For someone who comes across as priding themselves in what they know about this stuff, I am amazed you have put forward this kind of flawed argument. If proven wrong, I will be the first to congratulate you and award you a gold star, but you just haven't proven yourself right. Not that it's purely a matter of right and wrong. Eventually I guess you will see the light. It's not for me to continually explain the errors of your ways, so I will leave it there for now. No doubt you may take issue with this apparent contention. Kind of predictable now, but I really will leave this one in your court and if you feel satisfied with your explanations, good for you.

[Besoeker]

Originally Posted by LMagic007

Oh no, I meant indeed it seems your whole across the board argument of 50% capacity factor limit for Solar Thermal energy with storage seems nonsensical, .

Given that sunshine on average can't be better than 12 hours in 24 it means that the solar collectors will lie idle for 12 hours in 24 - 50% of the time. Their capacity can be used 50% of the time. At best.
What's so difficult to understand about that?

[LMagic007]

Originally Posted by Besoeker

Given that sunshine on average can't be better than 12 hours in 24 it means that the solar collectors will lie idle for 12 hours in 24 - 50% of the time. Their capacity can be used 50% of the time. At best. What's so difficult to understand about that?

Ahh there comes the ambiguity.

Originally Posted by Besoeker

In short, the definition of capacity factor isn't a problem.

Originally Posted by Besoeker

That depends on what is meant by capacity factor.

Nothing difficult, however what you are describing as capacity factor is not entirely how it is described in other circles for turbine based power generation. When I use the term, I am typically referring to plant rated output capacity and not collector capacity. I'm not sure why you are using collector capacity as it's evident that typically with turbine based power generation, regardless of source of energy, capacity factor is applied to rated output or load rather than input. It comes across as misleading, to be using it on input, when it's typically not used that way for turbine based power generation systems.

Solar PV is different, because typically they are installed without storage and the point of generation is the point of capture and rated output and there is generally no intermediary storage process. i.e. it simply goes straight to the grid and the nothing gets stored, unless of course one uses batteries, which is not as common as grid connect.

However with Solar Thermal CSP power generations systems with thermal storage, the point of generation is at the turbine like conventional power stations. It seems essentially you are using the Solar PV method of calculating capacity factor, for a Solar Thermal CSP system with storage, which is inappropriate. Thus yes I reiterate my point that context is important and mutual understanding of terms and language used also important.

Based on the rated turbine output capacity factor paradigm more typically used in more centralized power generation systems, one could theoretically design a high capacity factor Solar Thermal CSP system with the right configuration and located in the right geographic environment. It's just that it would be very expensive to do so and thus generally not advisable. Thus beyond a certain capacity, alternate backup is a better option from a cost point of view in today's dollar costs for various forms of energy. One can throw all sorts of numbers at it, but at the end of the day, it's going to be costs of the day, that predominantly determine what capacity factor will be most affordable and thus most suitable. These comparative cost dynamics are in a constant state of change as the Solar Thermal CSP technology matures and as fossil fuel generation costs increase.

[Besoeker]

Originally Posted by LMagic007

I am typically referring to plant rated output capacity

Output capacity in relation to what?
Even if it is a simple factor you need two quantities.
Which two?

[LMagic007]

Originally Posted by Besoeker

Output capacity in relation to what?
Even if it is a simple factor you need two quantities.
Which two?

Rated power plant output capacity against actual output, all measured over a given period of time. That's a fairly common measurement for capacity factor.

[LMagic007]

As a non contentious side issue, I also think it might be interesting to note, that the way capacity factor is sometimes used, can be somewhat misleading because its application seems to make an assumption that fuel supply is contiguous in supply, which is true to an extent with fossil fuels, however even fossil fuel supplies are not always guaranteed, especially for some nations that import energy and fossil fuels certainly are not indefinite in supply, compared to that supply of renewable energy which is virtually indefinite in supply, but not contiguous. i.e. it's broken by changes in environmental conditions, like weather and day and night etc...

The other pragmatic aspect is affordable market cost. There is not much point in having a fossil fuel power generation system with high capacity factor, if it is cost prohibitive and nobody can afford to pay for it. If you define a period of hundreds of years ( say for example only, the next 200 years ), one might say fossil fuels might trend toward a relatively lower capacity factor, because supply could become more unpredictable and cost very high. On the other hand, it might be said that over the next 200 years, renewable energy costs might fall and the supply become more predictable due to the fact that sun wind and tides and waves will still in all likelihood be as prevalent as they are today.

Thus the combination of time scale, demand and supply at affordable cost might be applicable factors that play into forming a view that might be held about capacity factor. I fully acknowledge the common usage might be seen as annual average capacity factor, but I still think its interesting to bear these other aspects in mind from an overall perspective, particularly in regard to longer term planning.

[Besoeker]

Originally Posted by LMagic007

Rated power plant output capacity against actual output, all measured over a given period of time. That's a fairly common measurement for capacity factor.

Yes, that's fine for just the output stage of the plant.

[LMagic007]

Originally Posted by Besoeker

Yes, that's fine for just the output stage of the plant.

Exactly, but that's what's typically measured when determining plant net capacity factor for a centralized power generation plant. i.e. it's based on the plant output rating against actual output over a given time period. Sure the other factors impact on power out, but that's all reflected in actual power out. Some definitions seem to use an average expected output against rated output over time, but essentially it's typically based on output rather than input or any other stages.

Using collector input as you seem to have used is not generally done to measure capacity factor for turbine based power generation. Measuring solar PV output is different though, because with PV the collector of energy is typically also the power plant with no intermediary storage and no separate power plant, thus whatever the PV collector panel is rated at, is also the rating of the power plant. i.e. the Solar PV collector is the power generation device or plant for comparison purposes.

Solar Thermal with thermal storage and turbine generation is different because its power plant is the turbine being completely separate from the collector and storage. Thus it's the turbine rating against actual or ( average for some definitions ) output over time, that's used to measure the plant net capacity factor for Solar Thermal power plants. No matter how efficient the intermediary stages are, the result is embodied in the actual output, thus that's all they need to measure in determining plant net capacity factor.

[Besoeker]

Originally Posted by LMagic007

Solar Thermal with thermal storage and turbine generation is different because its power plant is the turbine being completely separate from the collector and storage. Thus it's the turbine rating against actual or ( average for some definitions ) output over time, that's used to measure the plant net capacity factor for Solar Thermal power plants. No matter how efficient the intermediary stages are, the result is embodied in the actual output, thus that's all they need to measure in determining plant net capacity factor.

That may well be how it is stated.
It gives the capacity factor for the turbine and alternator, the output stage, but tells you nothing about the plant as a whole.
Is it reasonable to exclude the rest of the power plant?