Solar Power Australia

Posted on Mon 06/20/2011 by

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The Australian Government is seeking to introduce legislation to place a cost on Carbon Dioxide (CO2) Emissions. The public is being told that this legislation is a necessary thing to reduce those emissions. This CO2 Tax is supposed to ‘drive’ the shift away from the major source of those emissions, Coal Fired Power Electrical Generation, to sources that do not emit CO2, those Renewable power plants, in the main Wind Power and Solar Power.

To assist with her attempts to ‘win over’ the Australian public to accept this CO2 tax, Australian Prime Minister Julia Gillard last week launched a new Solar Power Plant in a ‘photo op’. The plant is not officially open and delivering power, and it will not be delivering that power until mid 2015, still four years away. The site for this new Solar Plant is in Chinchilla Queensland, hey, out where the Sun shines all the time, eh!

The total cost for the plant is $1.2 Billion.

This launch was just the preliminary step to get this proposal into the eyes of the public, and also an excellent chance to help the Prime Minister looking like she’s doing something about reducing those emissions, and a chance to add some ‘push’ for her Government’s plan to price those emissions.

As part of the launch, Prime Minister Gillard announced that the Government will be kicking in $464 Million of funding, and the Queensland Premier Anna Bligh said the Queensland Government will be kicking in $75 Million, all up 45% of the total cost.

So then, let’s look at this proposal, and for purposes of comparison, let’s compare this proposed new plant with an existing large scale coal fired plant, in this case the large coal fired plant Bayswater, near Musswellbrook in New South Wales.

Baywaster 2640 MW.

Proposed new Solar Plant 250 MW. Priced at $1.2 Billion.

I could just stop there, and leave it at that, because as you can plainly see, if we were to go down this road, you would need 11 of these new Solar Plants, for a total cost of $13.2 Billion, and that’s just to replace the one large scale coal fired power plant.

However, there’s always more to it than just that.

The proposal for this new plant is at this link. The information looks good on the surface, but it’s thin on those technical details, which most of the public would not understand anyway.

So, here, I will attempt to paint a picture of how this plant operates.

There are 2 major forms of Solar Power.

The first is Solar Photovoltaic Power. This method of power generation utilises large panels mounted on heliostats, that track the path of the Sun across the sky. In those panels are a multitude of cells. The Light from the Sun generates power in those small cells, similar to what was used to power those early solar powered calculators. There can be up to thousands of cells on each panel, and thousands of panels in a field, hence large amounts of power can be generated. The drawback of this method of power generation is that electricity can only be generated while the Sun is shining, and data from existing large plants of this nature show that they can only deliver their maximum power for around 3 to 5 hours at best for a full day.

The second form of Solar Power is Concentrating Solar Power. This is also referred to as Concentrated Solar, or Solar Thermal, and also, quite erroneously as Solar Baseload.

This method of power generation can be achieved in a variety of ways, and the three most common forms are as follows.

Solar Power Tower. This method uses large curved mirrors mounted on heliostats again. The reflected light from the Sun from anything up to thousands of these specially manufactured mirrors is focussed onto a single point atop a tower. At that point, a salt compound is passed through that focal point in pipes, and there are a a variety of those salt compounds in use at plants, while similar, are different because of that difference in compound. This compound is heated by the reflected light to a molten state. That molten compound is then used as a heat source to boil water to steam. The steam drives a conventional turbine/generator complex.

Solar Trough. (Version 1) This method also uses large curved mirrors as well, only instead of ‘standing upright’, they are laid flat in long rows. These also track the Sun. At the focal point of the mirrors are pipes, again carrying a compound that is heated to a molten state, the compound again used to boil water for steam to drive the turbine/generator.

Solar Trough. (Version 2) This is similar to version 1, only instead of the salt compound, water is passed through the pipes, boiling it and the resultant steam drives the turbine/generator. This version is the one announced by Prime Minister Gillard last week.

Those first two versions of Concentrating Solar have the one main drawback, that being how long the compound can be kept in a state molten (hot) enough to make the steam required to drive the turbine. While a plant of Nameplate Capacity might state that the theoretical maximum power is that 250MW, the actual power produced is only 150MW, and this would only be for as long as that compound is in that molten state, which would be from around 8AM until around 8PM, a couple of hours after Sunset.

However, if just Solar alone was used to provide power for as long as possible, then that compound has to be kept in a molten state for a longer period of time. To achieve that, the compound is kept aside from actual power production, and then drawn on after Sunset to keep producing power. What this means is that the plant can only produce 50MW of power in total for the whole time of operation, on that longer time basis, and for this, that 50MW of total power can be generated for around 18 to 19 hours a day.

This inherent problem I have explained in an earlier Post with a diagram and explanatory text, and that explanation is at this link.

As you may now also see, the inherent problem with version 2 of the Solar Trough method is that as soon as the Sun sets, the water will not remain hot enough to make steam to drive the turbine. So, this version of Concentrating Solar Power will only be providing power while the Sun is actually shining, and maybe for around one hour at the most after Sunset.

Again, this method also can only produce 150MW maximum of total power delivered, and you can use that same diagram I linked to to see how this happens.

For all three versions of Concentrating Power, there is however a way that they can be used to provide power for a full 24 hours.

This is achieved with the use of a Natural Gas Fired Turbine to provide the drive mechanism for the generator after the compound becomes less than molten to make steam. For this purpose, the Solar means are used to generate the maximum power, that 150MW, and when the compound cannot make steam, the Natural Gas turbine takes over to keep the power at that maximum 150MW, and the Natural Gas turbine could be in use for as much as 12 hours each day.

This auxilliary drive mechanism is also what is employed at the new plant that Prime Minister Gillard announced late last week.

The Solar method boils the water to make the steam to provide that 150MW of power, and when the Sun sets, the Natural gas fired turbine kicks in.

The link that takes you to the information about the plant itself says that the plant will not be used to provide Base Load Power, but only Peaking Power for periods of time of high consumption. It also says that plant only has a life span of 25 years, when those large coal fired plants have a life span of 50 years and can even be extended out to 60 years, and even 75 years.

This version 2 of Concentrating Solar Power Generation is the type of plant that Prime Minister Gillard announced with a flourish late last week.

There are three quite obvious questions that stand out to me with respect to this announcement, and I’m surprised no one bothered to ask them.

1. If this plant can only produce 250MW of power in total, and here, let’s actually quote that higher figure of that 250MW, why did no one put two and two together and correlate it back to large scale coal fired plants, say like Bayswater which can actually deliver its power for the full 24/7/365, and then add up two and two with respect to the cost of 11 equivalent plants just to replace that one coal fired plant. Hint as to the answer. $13.2 Billion.

2. If the only way this plant can go ahead is for Governments to kick in nearly half the up front cost, doesn’t this amount to subsidies, and how does that equate to Bob Brown’s ‘heavily’ subsidised coal fired power, as he refers to it.

3. This one question I would have thought was the most obvious question of all. If this plant is a hybrid of Solar and Natural Gas Fired Power, and if Natural Gas fired power produces CO2 emissions, then this plant also becomes subject to any ‘Price on Carbon’ or CO2 Tax, or an ETS.

So, when you see the Prime Minister announce on virtually every newscast on TV and radio that this is the way forward for Australia, all is not as it seems on the surface.

UPDATE.

Sometimes, the actual power delivered when compared to the maximum power that can actually be generated is a difficult concept to grasp, and because of that, it’s also a difficult thing to try and explain

In the comment below, the commenter received an Email from the proposers of this plant detailing the amounts of power that will probably be delivered from this plant. That total power was between 500 and 600 GigaWattHours (GWH).

From that total we can now work out the Capacity Factor (CF) for this plant. The CF is comparison of power actually delivered to the theoretical maximum power that could be delivered if the plant were to produce its maximum power all the time.

There is a standard calculation for the maximum power, and from that, we can work out the CF.

That formula is NP X 24 X 365.25 X 1000 where NP is the Nameplate Capacity, 24 hours in a day, 365.25 days in a year (leap year included) and 1000 to convert from MW to KWH.

So for this plant, that theoretical maximum power comes in at 2.1915 Billion KWH or 2,191 GWH.

So, if the plant will be delivering between 500 and 600 GWH a year, then that CF is 23 to 27%.

That CF can now be equated to actual time the plant delivers its full power, and that equates to between 5.5 and 6.5 hours a day.

Again, that may also be a difficult thing to understand.

The plant will be delivering differing amounts of power throughout the day for small amounts at a time after Sunrise to small amounts close to Sunset, with maximum amounts close to midday, so here, those amounts of power are ‘levelled out’ to a period of actual time of total power delivery, that 5.5 to 6.5 hours.

UPDATE 2

For the sake of comparison, Bayswater actually delivers 17,500 GWH of power compared to (an average) 550 GWH from this plant.

Now, why I mention this is again for the sake of comparison.

While this Solar Plant has a Nameplate Capacity of 250 MW, Bayswater has a Nameplate Capacity of 2640 MW, which is almost 11 times larger.

However, when you compare the actual power delivered, Bayswater delivers almost 32 times the power to consumers.

See the difference.

So, extrapolating that out, you would need 33 of these solar plants to replace the total power delivered from the ONE Bayswater large scale coal fired plant, and at $1.2 Billion each for that solar plant, that total comes in at just on $40 Billion.

Again, this is just for the sake of comparison, because while Bayswater can supply that power on a 24/7/365 basis, the Solar plants can only deliver that power for around 6 hours a day on average.

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