Sunday, August 16, 2009

Brook-Lang on Solar Photovoltaics

The Brave New Climate debate on the Brook-Lang wind thesis (see also) has largely wound up. Wind advocate Neil Howes, confronted with the seemingly intractable problem of electrical demand during the summer period of weak wind conceeded:
For peak summer demand, mothballed coal plants could be used for a few weeks until the time that another another 400GW of nuclear, 100GW to replace existing and 300GW to replace most of the coal-fired.
Of course the question is, if you are going to build 400 GWs of conventional nuclear generating capacity, enough to supply 80% of American electrical demand, why would you need an expensive wind system?

Barry Brook, has now moved on to the topic of solar photovoltaics (PV), again relying on the research by Peter Lang, presented in a paper titled "Solar Realities. Brook quotes the Abstract of Lang's 17 page paper:
This paper provides a simple analysis of the capital cost of solar power and energy storage sufficient to meet the demand of Australia’s National Electricity Market. It also considers some of the environmental effects. It puts the figures in perspective.

By looking at the limit position, the paper highlights the very high costs imposed by mandating and subsidising solar power. The minimum power output, not the peak or average, is the main factor governing solar power’s economic viability. The capital cost would be 25 times more than nuclear power. The least-cost solar option would require 400 times more land area and emit 20 times more CO2 than nuclear power.

Conclusions: solar power is uneconomic. Government mandates and subsidies hide the true cost of renewable energy but these additional costs must be carried by others.
As you can see Brook and Lang have lined up another Green Myth for trashing. Lang points out the key, and of course extremely obvious realities of solar power:
The key characteristics of solar power that are relevant to this discussion can be summarised as follows:

1. Power output is zero from sunset to sunrise.

2. Power output versus time is a parabolic distribution on a clear day: zero at sunrise and sunset, and maximum at midday.

3. Energy output varies from summer to winter (less in winter than summer).

4. Energy output varies from day to day depending on weather conditions.

5. Maximum daily energy output is on a clear sunny day in summer.

6. Minimum daily energy output is on a heavily overcast day in winter.
Lang then draws the obvious inference:
Backup for solar power is clearly required
Lang focuses on pumped storage systems.

Using empirical data from the Queanbeyan Solar Farm. Lang reports
The Queanbeyan Solar Farm9 has an installed power capacity of 55 kW. The average
power output over 2 years was 7.58 kW. The average capacity factor10 over this
period was 13.7%.
Indeed Lang reported that during two days in a two year period the power output of the Queanbeyan Solar Farm was a dismal 0.8% of its name plat capacity, and that the highest summer output was only 21.9% of rated capacity. The average winter capacityfactor was 9.9%. Lang suggeste:
If we have 90 days of energy storage we will need sufficient solar generating capacity
to be able to generate the 600,000 MWh per day over 90 continuous days (i.e
54,000,000 MWh) with an average solar generating capacity factor of 9.4%.
Suggesting that
Pumped-hydro storage is the least cost option
And noted
To provide the NEM’s [National Electrical Market's] demand from pumped-hydro storage would require pumping 2.3 Sydney-harbour volumes of water up 150 m each day while the sun is shining strongly (a maximum of about 6 hours during winter), and then releasing it to generate electricity each night. This would require pairs of high dams and low dams linked by pipes, pump stations and generating stations. The top dams and the bottom dams would each need a total active storage capacity of 2.3 Sydney harbour volumes of water and would need to have a vertical separation of 150 m on average. The pumps would need the capacity
to pump the volume of water up from the bottom dams to the top dams in about 6 hours in winter.
Lang added
The total area inundated by the reservoirs, for 1 day of energy storage, would
be about 260 km2. For 90 days of storage, 24,000 km2 would be inundated.
Lang calculated the cost of various solar options and concluded
The capital cost of the least-cost solar option is $2,800 billion. That is 2.8 times Australia’s GDP.
in contrast
The cost of providing the NEM’s energy demand with nuclear power would be about $120 billion, or about 4% of the cost of the least-cost, solar power and pumped-hydro
storage option.
Langs conclusions on PV costs are thus in accord with the conclusions of Nuclear Green.

1 comment:

David Walters said...

I think the PV questions is boutique power for homes, at best. PV for central grid power is a joke and, really, *everyone* knows it. The big debate is going to be, Charles, over CSP, which *seems* to have some potential. This will be the big knock down dragged out debate on brave new climate. The only reason any one is building PV "farms" is because about 100% of the cost is simply being thrown at developers to do it.

I published in the Bay Guardian here a short note on the SF 5 MW PV 'farm' they are going to build in The City. I parsed out the costs to $38,000 KW hour installed. Hardly 'leadership' at any level. should htink about posting this to the DK, it WILL generate a response.


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