On the Rise: Solar Thermal Power ?

[LMagic007]

Originally Posted by Besoeker

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?

Anything can be reasonable if you reason it to be so. A subjective question I will pass on, being one of futile pursuit. Suffice to say, it's the way it's measured, reasonable or otherwise see it as you wish. If you want to look at other aspects of plant that's up to you, however the commonly used method of deriving net capacity factor is as I have described, in regard to plant rated output, against actual output, over time. That is the capacity factor I have been referring to. Ultimately it's driven by cost, in a world where fossil fuel costs are rising significantly.

[Besoeker]

Originally Posted by LMagic007

Ultimately it's driven by cost, in a world where fossil fuel costs are rising significantly.

Quite so. There is a cost for the solar collectors which depends on their capacity factor and efficacy. There is a cost for the thermal storage part of the plant, a cost that is clearly linked to its total capacity and thermal losses.
Taking the capacity factor of just the output stages in isolation is rather irrelevant for the plant as a whole.

[LMagic007]

Originally Posted by Besoeker

Quite so. There is a cost for the solar collectors which depends on their capacity factor and efficacy. There is a cost for the thermal storage part of the plant, a cost that is clearly linked to its total capacity and thermal losses.

Taking the capacity factor of just the output stages in isolation is rather irrelevant for the plant as a whole.

In my opinion not at all and in fact quite the opposite, because power out at cost embodies all aspects of the plants configuration and operations at cost. Capacity Factor is typically and simply defined on output. i.e. on actual output against rated output over time. That's the way it's done.

Sure costs are determined overall and at various stages in evaluating cost per unit output. Many factors effect cost and it's a given that these factors should be taken into consideration, be it the various stages of the plants energy processing, be it labour and materials, be it the time of day energy is sold, be it whatever input that forms part of the plants operations. These aspects however do not define capacity factor.

The measurement of capacity factor is largely to ascertain the plants ability to provide a reliable power flow to the grid over time and determine what degree of backup might be required. The aspect I raised about cost and capacity factor is that, beyond a certain capacity factor, it no longer becomes cost effective to further increase that capacity factor, due to comparative costs of fossil fuels, relative to the uncertainty factor in regard to unpredictability of weather fluctuations and the impact that has on the dollar cost return on additional collector, concentrator, storage and other components. i.e. the increased probability of idle capital or idle capacity of these components not functioning optimally in terms of cost per unit of energy processed, relative to incremental cost of increased capacity of these components. There is an optimal relationship in cost terms between all aspects of a plants operation. Again though these aspects however do not define capacity factor, but they are relevant in arriving at an optimal capacity factor in dollar cost terms.

Additionally less than optimal operation might occur through, for example excessive storage at full stored thermal capacity, not being fully utilized due to output rating limitation of the generation stage. If the configuration is such that the thermal storage is always at 100% then it's likely that is less than optimal configuration purely in invested dollar cost terms. Thus there is a sweet spot on an economic dollar cost basis where native capacity factor functions best at a given level before backup from other energy sources is utilized, however as previously mentioned, rising fossil fuel prices are likely to shift that capacity factor sweet spot upward and allow for greater capacity factors to become more economical for Solar Thermal with storage along with various forms of storage utilized for other renewable energy technologies.

It would seem to me that it may likely never be cost effective to go beyond a certain native capacity factor with just a single renewable source by simply extending collection and storage for the reasons I explained, which is why I agree certainly from a cost basis, that backup from an alternate source of energy would more likely yield better performing cost models for application of this technology. Thus backup may consist of fossil fuels or other renewables like wind provided by other suppliers.

[Besoeker]

Originally Posted by LMagic007

In my opinion not at all and in fact quite the opposite, because power out at cost embodies all aspects of the plants configuration and operations at cost. Capacity Factor is typically and simply defined on output. i.e. on actual output against rated output over time. That's the way it's done..

Capacity factor, as you define it is "Rated power plant output capacity against actual output, all measured over a given period of time".
As a definition of just the output stage capacity factor, that's fine. But that definition makes no mention of costs and it tells you nothing about the plant as a whole.

A simple, deliberately extreme example to illustrate the point.....

Suppose you had a 20MW collector array feeding a thermal storage facility capable of storing the input from the collectors for a week. The thermal energy is used to produce a rated output of 1MW. This is implemented using three 1 MW turbo-alternators - duty, duty assist, and standby, a scheme often used for a high reliability and availability.
Capacity factor for that part of the plant would approach 100%.

From that capacity factor alone, you can deduce nothing about the plant as a whole.

[LMagic007]

Originally Posted by Besoeker

Capacity factor, as you define it is "Rated power plant output capacity against actual output, all measured over a given period of time". As a definition of just the output stage capacity factor, that's fine.

Hello ? just the output stage ? Capacity Factor has been at the core of the discussion and the output stage is what Net Capacity Factor is measured at.

Originally Posted by Besoeker

But that definition makes no mention of costs and it tells you nothing about the plant as a whole.

Capacity Factor is not meant to discuss costs. It's not a measurement of cost. Capacity Factor does reflect the plant as a whole, as it is a culmination of all relevant input factors and processes that result in power out. As I indicated other aspects of the plants operations in terms of cost are relevant, but not in calculating Capacity Factor. They influence Capacity Factor, but they are not Capacity Factor.

Originally Posted by Besoeker

A simple, deliberately extreme example to illustrate the point.....
Suppose you had a 20MW collector array feeding a thermal storage facility capable of storing the input from the collectors for a week. The thermal energy is used to produce a rated output of 1MW. This is implemented using three 1 MW turbo-alternators - duty, duty assist, and standby, a scheme often used for a high reliability and availability. Capacity factor for that part of the plant would approach 100%. From that capacity factor alone, you can deduce nothing about the plant as a whole.

What happens between inputs, processes and up to output are separate issues of relevance, however that's not Capacity Factor as commonly used when determining a plants net capacity factor. Call those various processes whatever you want, but it's not Net Capacity Factor. Capacity Factor is not about making deductions about the plant as a whole. Capacity Factor is simply about measuring the rated output against actual output over time. All kinds of deductions about all kinds of aspects of the plant can be made, but such deductions are not Capacity Factor. Rather, they are simply deductions about the plant. With that said, Capacity Factor embodies a culmination of the plants power production operations. All the various facets that make up the plant and its operational processes, clearly result in the plant achieving a given Net Capacity Factor. That's fairly self evident.

[Besoeker]

Originally Posted by LMagic007

Capacity Factor is not meant to discuss costs. It's not a measurement of cost. Capacity Factor does reflect the plant as a whole, as it is a culmination of all relevant input factors and processes that result in power out.

It can't reflect the plant as a whole if it just relates to the output stage.
That was the point of my example.
I don't know how to make the explanation any simpler.

[LMagic007]

Originally Posted by Besoeker

It can't reflect the plant as a whole if it just relates to the output stage. That was the point of my example. I don't know how to make the explanation any simpler.

Net Capacity Factor can reflect the plant as a whole and it does. Your explanation is very simple, but that does not negate the fact that capacity factor is a reflection of the whole plant. Net Capacity factor being the resultant feature of the whole plants power generation activity. To achieve power out, you have to have energy in, and process inputs. Everything that goes into the plants configuration and operation, influences its power out and hence Net Capacity Factor. If you change the plant configuration effecting power out in relation to the plants power output rating, that effects Net Capacity factor. The Net Capacity Factor arrived at, is an embodiment of the whole plants power generation activity and thus it reflects the plant as a whole.

[Besoeker]

Originally Posted by LMagic007

Net Capacity Factor can reflect the plant as a whole and it does. Your explanation is very simple but......

But, had you understood it, you would not continue claim that net capacity factor, as you defined it, can represent the plant as a whole.

[LMagic007]

Originally Posted by Besoeker

But, had you understood it, you would not continue claim that net capacity factor, as you defined it, can represent the plant as a whole.

Evidently in your opinion, certainly not in mine. Net Capacity Factor embodies all aspects of the plants power generation activity via it's resultant power output over time. Had you understood that you would not continue to be claiming otherwise.

[Besoeker]

Originally Posted by LMagic007

Evidently in your opinion, certainly not in mine. Net Capacity Factor embodies all aspects of the plants power generation activity.

Not as you have defined it, it doesn't.
"actual output against rated output over time"
The input and any intermediate conversions could be anything - good, bad, or indifferent.
You can't or won't understand/accept that, so the topic is at a dead end.


You seem to have an interest in solar so the following article from a publication I regularly get, might interest you. There are a few other links that may be of interest to other posters too.
Electrical Products & Applications - Flying Too Close to the Sun?