I speak from certain knowledge, that the ESO, after all losses such as condenser and auxiliaries is 38% or better for a typical NSW 660MW generator.

The 500 MW generators are better than 30% - probably close to 35%.

Thus, any difference between my quoted figure and the one you are using must relate to the energy cost of mining and part of the transport cost of coal from the mine. 13% differential for upstream energy uses seems steep to me, but the story is correct:

(1) If we are comparing energy generation technologies, the whole picture should be assessed - upstream energy use during construction and mining, losses during generation and the energy recovered or expended during site restoration at the end of life.

(2) We need to recognise that these figures may be elusive and must be available for audit to ensure that they are truly comparable.

Neither 1 nor 2 above is easy. Gathering reliable figures needs skill, knowledge and professionalism in an area where a lot of money is on the line and some data is held close to the chest and may be commercial-in-confidence.

I will leave brown coal to the Mexicans south of the border.

Phew — these are always difficult things to get across.

The 38% of a NSW coal plant is thermal efficiency of the turbine.

However the plant uses a lot of parasites and embodied energy in order to get coal out of the ground and into the coal power plant.

This is where by 25% comes from — however depending on the plant maybe upto 30%. Victorian Latrobe Valley Brown coal plants are lower as a lot of water is used in drying the brown coal which comes out at 62% moisture content.

This discussion has a positive side, though. It indicates the need for input power (sunlight) to be greater than output power, and that each step along the way is a balancing act, where construction costs (land, materials, labour and energy) may limit the capacity of the overall system.

The figure you quote for energy payback is interesting. It is much shorter than I expected. Nice work.

It is the turbine that runs at 75% capacity factor. The mirror field runs at a lower efficiency that 75% However they are different things.

By trying to measure the capacity factor of the mirror field, you are effectively doing the equivalent of measuring the conversion efficiency of the energy in coal to what is released at the turbine then mmultiplying that by the capacity factor.

So for comparison a NSW coal plant runs at say 75% capacity factor, however the amount of energy in the coal is 4x what is actually delivered. So what you are asking would describe a coal plant as having an annual capacity factor (this is not the right terminology but I’m going along with it for sake of the discussion) of .75 x .25 or 18% No body ever quotes the figure like this.

. However the energy payback ratio or the embeded CO2 per kwh is what counts.

To illustrate this point again say a wind turbine operates at 55% efficiency for the wind passing through the swept area. We do not quote this as .5 x .3 and then claim the annual average capacity factor of this wind turbine will be 15% It is standard to claim that the annual capacity factor of the wind turbine is 30%

And both are very low for CSP. Energy Payback Ratio on one of these CSP plants is in the order of 4 -6 months. That means that of the 30 years the plant should run it will take 1/2 a year to pay off the total cost of building including making steel, concrete, glass etc, and dismantling.

There are some advantages with dismantling though as they generally use concrete steel and glass and it all can be recycled so the energy payback ratio on the subsequent concentrating solar thermal plant that replaces the first one built in 30 years time would be much faster in the order of 1-2 months.

The relative costs of additional storage and additional turbines and the value of additional storage will make each installation different, but the principles are the same.

I have no hands on experience with molten salt, but I have worked with solar thermal trial plants and I am sure that the principles are as I stated.

Whether Torresol has a “standard size”, by which I take it you mean “standard configuration”, I do not know. My main point is in relation to the ability to collect solar energy/heat durng the 12 hour day and store some for the hours of night, thus reducing the need or value of 100% capacity turbines. No plant can operate at 75% of mirror capacity 24/7, because this implies 150% or better efficiency… not possible. I guess that we are on different wavelengths.

If you are a designer or have actual experience of the Torresol plant, I would like to analyse the thermodynamics of the plant you are describing.

So if your turbine costs say 200million and your storage costs $50 million to scale and your tripling the size of the mirror field costs $150 million well you are $200 million ahead.

And with 75% capacity factor power towers the actual fluid running through tower is molten salt, and it is always going from salt to steam - so scaling this is cheap.

I guess then for solar thermal CF only matters WRT the nameplate capacity of the plant, which is fine, but it makes the numbers for working out averages for a huge area much less dependable.

I have heard of someone in Australia talking about test holes for doing just that. I thought it was Ausra at Liddell, but I got a severe dressing down over being wrong on that. So, all I can tell you i that it’s being tested.

While you’re on that bent, have a look at Compressed air energy storage

I’ve often thought from working at Sydney Water about energy efficiency opportunities by avoiding an energy conversion step. I don’t think hydrogen will get far, mostly because there is so many steps, each with inherent losses. So rather than firing a biogas engine to generate electricity and offset imported electricity, why not use the engine to pump water directly? I think CAES has some potential applications with this in mind.

There is thus a balance between collector size and turbine size. I think that, in the “real world” that lies at 75 or 80% of the max input of sun’s heat. To improve the reliability of the overall system, this spare capacity can be directed to heat storage. If there was no such spare heat, there would be none left over to divert to storage and power could only be produced ramping up from after dawn and running down after dusk, and none at all on cloudy or rainy days or when thunderstorms are about or winds are so strong that the collectors are structurally endangered.

If storage was free and 100% efficient (we wish!) then the ideal turbine might be about 15 or 20% of the best insolation, running 24/7, with storage for several rainy days as backup. Hey presto! reliable baseload solar thermal with no need for CCGT as backup (1). Thermal storage costs big money and has losses, so each installation must be optimised(2).

(1) Most solar thermal scenarios include a large additional cost for CCGT backup, because of the unreliable nature of ST with only limited thermal storage - eg Spain’s 7 hours, which doesn’t even get through the night. The CCGT (or OCGT) are useful also for peaking power.

(2) A a conceptual exercise, consider a large field of mirrors backed up by a very large infinite capacity thermal battery and having a large number of turbines, which are only turned on when needed. There would be no need for GT’s because the solar turbine capacity is equal to peak demand. The downside is the cost of the infinite size and infinitely efficient (no losses!) heat battery. That heat store is the equivalent, in engineering terms, of a stockpile full of coal.

Now, why not make that heat store out of a number of underground holes full of superheated pressurised water with a steam blanket on top? The water and earth hold the heat, the overlying soil insulates the heat store and the result is a series of cells of super heat, all waiting to be discharged on demand via the turbines, with condensed spent steam returned to a header tank and, eventually, fed back to recharge the underground heat store.

I am not the first to think of this, but I don’t know of it being trialled.

To me, it is very much do-able, if there is such a word. Probably much better than hot rocks in the long run.

I have made my position very clear on why I will not support nuclear power in Australia. Do you want me to repeat it in summary?

1. Too slow to implement. The UMPNER (Switkowski) report lists 10 years minimum, more likely 15 years to build a plant. If they manage 25 by 2050, this will reduce emissions by 18%. it is not the silver bullet everyone thinks it is.

2. Waste storage is not solved and contains unknown future costs. Ditto decommissioning.

3. Australia essentially has no nuclear expertise. So, the design, materials and people to complete the project will ALL need to be imported. In my experience, the more contractors used on a project, the less control one has over the final price. Australia could well be held ransom to contract variations and protracted legal proceedings for another 10 years past the proposed commissioning date. I note with interest the number of nuclear projects world wide that caught in similar loops. Solar thermal in contrast, uses Australia’s natural advantages in sun, steel and manufacturing capability.

4. The political upheaval to actually get a plant built puts it well outside the scope of useful technologies. We need to reduce emissions sharply in the next 25 years. How long will it take to get Australian law changed to allow nukes? Why bother?

Back to Capacity Factors; I think that system is odd. Seems to me that the mirrors are greatly oversized compared to the turbine. I don’t think a capacity factor that just reports turbine generation is of any use at all. That means a grossly inefficient system, with hundreds of square somethings of mirrors could supply to a 1kW turbine and achieve near perfect capacity factor. I don’t see how this is useful or factual.

Thus, the strategy is to harvest heat during the sunny bits of the day and to generate electrical power, via a slightly smaller and cheaper turbine, during as many hours as possible, based on system load and stored heat.

For example, the solar linear array in the Hunter Valley is not able to run flat out - it is limited by the steam capacity of the system, including the receiving boiler. This occasionally means that a bit of energy goes unused for a couple of hours. If thermal storage was installed on this system, it could theoretically save the excess and use it later.

Hence, the nameplate rating essentially reflects max output rather than max input.

Re nuclear, I note that you have again sidestepped on the basis that this thread is discussing solar. Then why your references to about everything including solar, coal and CCGT? And nuclear? Your references, not mine. You brought them into the debate and then try to claim that they weren’t invited. And not a word about the fact that they are realistic, available and cheapest - again, your own references show this to be so. I reluctantly have come to see that all forms of low-CO2 energy production must be considered if our poor world is to be saved from its inhabitants.

I hope that my on-topic comment above makes good sense to you re nameplate ratings. Installation of generating and despatch capacity to match the max conceivable input for the best hour of the year is uneconomical. Perhaps 80% of peak nett input is closer to the mark, with the rest either time-shifted via storage or wasted by turning a mirror or two away from the sun or by venting surplus steam.

Beware the elephant.

The capacity factor is measured against the nameplate (or more precisely the net output minus plant parasites) of the plants turbine.

So the sun resource for a good location will be giving DNI output for 25% of the year. So in order to recieve a 75% capacity factor you basically triple your mirror field and add a bit more. So you basically spec for 2190+ hours of annual sun, run 1/3 of the mirrorfield for on sun operation. And store 2/3 of the field’s output in latent heat for operating 2/3 of the time when the sun has set and also in the vvery early morning and very late afternoon or early evening when the output of the mirror field falls below 1/3 of the recievers spec.

These plants also have the advantage that they can cycle the cold storage tank ~290C and increase the temperature of that early in the morning / late at night when it is too difficult to achiever the full 565C (or in future versions 650C).

Also Trough plants lose 7% of their collected heat in heat exchange losses from moving the field oil collected heat to salt storage then back to oil and then flashing to steam. Towers actually use molten salt as the working fluid and storage media so there are no heat exchange losses. In fact the battery is greater than 99% efficient. Losing less than 1% in thermal losses over a year of operation.

All these things trough plants cannot do — molten salt tower plants are far superior to trough plants.

Unless their mirror field is massively oversized for their turbine. In which case I still think it’s dishonest.

Depending on the sun resource at a given location the plants can run 90% of the time throttling the turbine from 60%-100% output. They also have the ability for fast start (dispatchable) because they bleed off a small amount of the cold salt 290C to keep the seals on the turbine hot.

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Assessment of Parabolic
Trough and Power Tower Solar Technology Cost and Performance Forecasts
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If you’d like to know more check out the Beyond Zero Emissions website http://beyondzeroemissions.org/

My understanding of CF is that it is actual generation / maximum possible generation. There’s no way that can be greater than the daylight hours / total hours.

It might provide power over night, but not it’s maximum rated power. Might have availability that high, but surely not capacity factors.

John, if you’ve been concentrating you should have noticed 2 things. 1, this is an article about the current status of solar power world wide. It is a comparison to nothing. 2. I made my objections to nuclear pretty clear on the other thread. What do you hope to achieve by baiting me into listing them again?

Youtube of Solar Reserve, Youtube of SENER Torresol Gemasolar

This technology was first proven in a prototype in the French Pyrenees at the thermis tower in 1978 and a commercial scale demonstration Solar II was proven by the US DOE at the Sandia Laboratories which are run in a Joint Venture with Lockheed Martin.

Solar Reserve is owned by UTC which owns Pratt and Whitney and Hamilton Sunstrand — this company built the Apollo space rockets. Those same engineers developed the technology behind the Solar Reserve towers.

Spain dabbled with Nuclear and lost 6 billion euro’s on power plants that were never commssioned. Now SENER one of the companies that built nuclear plants that did actually work is building molten salt power towers. Unlike the nuclear plants they built in the 1980’s they actually want to own the solar thermal plants.

Also with power towers 50% - 66% less molten salt (potassium nitrate / sodium nitrate) is used than trough power plants. And a molten salt power tower is cheaper with storage than without.

These plants run 75% capacity factor - the same as a NSW black coal plant.

Even his own references indicate that this is so. Why do we spend time and space considering fermented pigeon poo and aardvark feather combustion, when there is another, proven, costed, option staring us in the face.

Come on, Evan. Display your biases right up front and centre.

Defend your determination to discuss everything except the elephant in the room.

I didn’t say it was easy, and don’t think it will be. To my knowledge this is a world first (using the reverse of the Haber-Bosch process) and one of a couple of energy storage options being researched by ANU.

The Wizard Whyalla project will prove 2 things; mass production of the Big Dish and heat storage using ammonia. The Big Dish is built off a jig that was built originally at ANU in Canberra. This will test their on-site mass production ability and the accuracy of their jig. Part of the advantage of this parabolic dish is that they have been able to mass produce the individual mirrors identically, then achieve focussing accuracy through the design of the dish. It’s a nice, efficient design-for-manufacture project in my opinion.

However you really must surrender that whimsy about ammonia! The reference to “Wizard Power” needs a link to an authoritative webpage that shows that dissociating and reforming ammonia is easy. I couldn’t find one, nor could I find a reputable reference to Wizard Power.

Instead the link you gave us shows that reforming ammonia is difficult and that the successful processes gave rise to two Nobel Prizes in Chemistry.

Please check your links, it would save your readers a wild goose chase, or worse, give your more credulous readers false hopes.

Nice summary. There is another aspect to large scale solar thermal. In Spain where there are a number of plants there has been a turnaround for local employment. its not just permanent mirror cleaners ( now off welfare benefits) but other staff who would not otherwise be employed.

A proposal put up by Desertec is to provide the EU with energy from across the “sun belt” of N.Africa. This hs some big players putting their names to it although no plant has been built yet.

I tend to agree with Evan that solar PV is still currently just a plain expensive way to generate the MWs. From a pure efficiency point of view it doesn’t matter what the government subsidy is (since it is my tax money), solar PV is $8-13 Million per MW. Usually the capacity factor is maybe 25%. Compare that to $2-3 Million per MW of wind with a capacity factor of 35-40%.

I’m generally opposed to it, particularly from the viewpoint of efficient use of Government funds. There are some technical advantages to point of use generation, but also some disadvantages. I’m no network engineer, but imagine the polarity of a suburb essentially flipping over on a hot sunny day as a cloud passes over, flipping from an energy positive suburb to energy negative and back again.

But my principle objection is just that it’s an inefficient way to deliver the MW, and difficult to quantify in the long term. Under the old scheme, the government was getting 1kW/$8000. That’s a MW for $8,000,000, where ideally it should be closer to $5M/MW. Decentralised generation means an inverter for everyone, and they strongly benefit from economies of scale. Also, as the systems age, maintenance will vary greatly and inverters will break. If you get a system for free, I would argue you are less likely to maintain it properly.

There are some intangibles with rooftop solar though, particularly the ‘I’m part of the process now, so more involved’ aspect. If someone can see electricity generation in their life, they might take more care of it. However, this is negated a little by gross feed in tariffs. Because a household is paid regardless of how much they use there is no incentive to use less power.

All of that said though, I’m spending today organising my free PV install. At least Canberra has decent insolation.

Something I did leave out, partly because it’s a bit complex, but also because there’s not much info about, is the CSIRO syngas project.
Here’s some pics of the infrastructure
http://www.csiro.au/science/Solar-Thermal-Energy-Research.html

The idea is this. Use solar energy to split the hydrogen off methane (nat gas) to form H2 and (I think) ethyne (ethylene, or C2H2). This creates a ‘synthetic gas’ of higher calorific value than normal methane. This high energy gas can be combusted later through a normal gas turbine.

I like this one because of the problems it solves and options it leaves open. If we build gas peaking turbines in the coming years, which is likely and will add flexibility to the grid, this project feeds into it. It becomes a solar battery, which can be used very quickly. A kooky end point of the project could see some BIG towers at the Moombah gas fields, collecting solar power, juicing up the gas as it comes from the ground, then piping it into Adelaide using the existing pipeline. It’s probably years off, like maybe 10, but I can see some awesome possibilities.

There always seems to be a cry for government subsidy when the maths don’t work out, and solar PV or solar thermal, or a mix of thetwo will require enormous subsidies and cfross-linkage (sounds like a transmission system) if they are to provide reliability

The dream of obtaining adequate power for the nation from individual cottage roofs is just that - a dream, and a not very “beautiful” picture (your word, not mine).

I do agree up to a point, though - and that is in relation to incremental additions to the total system capacity. Managed correctly, the ADDITIONAL generating capacity may very well come from roofs, etc and small community installations. Hopefully, the existing power station ites will provide the basic sites for the larger installations and make use of the existing high and low voltage transmission assets.

Additional loads, especially industrial loads, may also be partnered with new small to medium renewable power generating capacity. That would indeed be beautiful, in many ways.

So, KB, we do probably share some objectives. Probably because I am an engineer, I keep a stronger eye on the costs and the physical task. You may not share my conviction that centralised power generation in some form will be needed for a long time to come.

I do hope that you find my contributions, in total, positive.