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I thought to go into some details on Ad 1.

First, on the geographic aspects.

  • Rooftop solar and both domestic and MW-scale wind share a benefit compared to greenfield solar farms of either type (large-scale PV, concentrated PV [CSP] and solarthermal): they take away little or no real estate. Thus, greenfield solar can have a significant contribution only in places with lots of cheap desert-like area available.
  • Unlike Germany, Spain is such an area. Thus, contrary to what you write in the diary, the 2008 Spanish PV boom (see stats upthread) was overwhelmingly in large greenfield farms (and large industrial rooftops), not on private home rooftops. While I don't have actual stats for it, one can add up the 2008 Spanish plants in the World's largest photovoltaic power plants ranking: just the farms 2MW or above add up to 2096 MW, out of the 2700MW total. (Out of the 3400MW added in Germany this year, the same number is just 517 MW.)
  • It also helps that apparently, Spain has no separate FIT rates for greenfield and rooftop (in Germany the first is lower).

Second, all renewable technologies can be considered evolving technologies, for which the price per kWh as a mature technology can only be projected. These projections come with differing certainty, however, given the different stages of evolution these technologies are in. And this is where the relationship of domestic wind and large wind, and that of PV and CSP or solarthermal is inverted: in the eighties already, large wind was an industry producing in large series, while small wind still remained at backyard shop level to this day; while in solar, PV is the well established industry with factory-size series production, and CSP and solarthermal are still in the pioneering phase.

That is, one can infer with some certainty that PV and MW-scale wind will be able to cut prices further according to projections, while CSP, solarthermal and domestic wind have yet to prove their claims. (What could be the risks for CSP or solarthermal? Maintenance/leaks, for example.)

Finally, there is also the issue of the rate of production. It remains to be seen whether CSP or solarthermal plants can be projected, approved, manufactured and installed at an annual rate in the Gigawatts, like large wind and PV showed that they can.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Sun May 2nd, 2010 at 07:35:00 AM EST
[ Parent ]
I don't really understand the difference made here between commercial solar tech and individual solar tech?

Thermic solar exists in different technology, all of them of some use, the simplest being a black-painted water barrel on top of one's house. They are hardly the most expensive.

Solar PV is still economically unsafe at the moment, but the tech is the same for commercial or individual installation, the pannels being standard-sized. The tech difference here is between low yield silicium pannels and high yield GaAs ones. None of these are economically sustainable at the moment, but the research is very active here.

It's the individual/commercial PV that is badly in need of tariff feed-in, because individual thermic solar is used for hot water generation, not electricity. I don't know the economics of industrial thermal (hot water+turbine+generator) but I think it should be similar to gaz turbine generation regarding the capital investment.

Should your diary be understood as a critic of solar PV, both commercial or individual? If so, the question is more on this particular technology than on solar in general.

by Xavier in Paris on Mon May 3rd, 2010 at 08:09:38 AM EST
[ Parent ]
Thermic solar exists in different technology

Indeed, but electricity generating solarthermal, where some fluid medium is heated by mirrors and drives a turbine, is a bit more complex, with a few more cost and maintenance risk factors, and very much at its infacy... Pilot plants of this type exist and operate since the nineties, but claims that the price could soon be reduced to market levels also exist since the nineties, yet nothing has been built for 15 years. Presently, some new plants are built in Spain and the USA, so we'll see whether those ambitions in economics can be realised. Until then, it needs feed-in tariffs, too.

Should your diarybe understood as a critic of solar PV

MfM quite clearly states that he thinks solarthemal is the way to go in the exploitation of solar energy, and criticises PV. (And I challenge those criticisms as unfounded and based on mistaken assumptions.)

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Mon May 3rd, 2010 at 12:37:38 PM EST
[ Parent ]
But would a solarthermal plant as you describe it be really different from, say, a natural gaz turbine plant?

In terms of physics and engineering, I don't see where the difference would lay.

(Obviously in the heating system, but that doesn't have any need for mechanical parts, so low maintenance, and probably simpler than combustion chamber anyway)

by Xavier in Paris on Tue May 4th, 2010 at 12:21:37 PM EST
[ Parent ]
It's not running on steam, which could mean a myriad little technical differences. I'd say lots of extended piping (if the system is such) subject to daily heat expansion could potentially be high maintenance, as can be motors adjusting movable mirrors (if the system is such).

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Tue May 4th, 2010 at 05:42:37 PM EST
[ Parent ]
It's not running on steam, which could mean a myriad little technical differences.

In many, if not most, cases, solar thermal plants do run on steam, the mineral oil or molten salt medium is solely for heat transfer.  Which is why one of the advantages of solar thermal over PV is that it can share a turbine with a natural gas fired plant.  Where there is sufficient insolation and empty space near natural gas fired plants, that should be a boon as natural gas prices rise and solar thermal equipment costs drop.

I'd say lots of extended piping (if the system is such) subject to daily heat expansion could potentially be high maintenance, as can be motors adjusting movable mirrors (if the system is such).

There are actually multiple configurations.  Solar troughs are highly expensive, but also highly efficient.  

Solarmundo fresnel collectors drive down the equipment cost by using flat plate glass collectors that are rotated on an axis.  There's a system of 6 of these that are concentrated on a single pipe.  This is inefficient, but much less expensive, because you don't have to produce curved glass panels.

Finally, the solar power tower concept uses a field of flat plates rotated to concentrate heat on a single focal point.  That means no piping, and superheating at the focal point.

My money is on the solarmundo fresnel collectors, because capital cost matters much more than efficiency when the fuel is free.

What I see is that solar thermal is a natural complement to natural gas fired plants where the insolation exists.  They can share a turbine, and that drive down the initial construction cost, plus the ability to switch over to natural gas in order to heat steam provides a natural backup.  In that case, the point is that the solar thermal installation allows for the conservation of natural gas, not replacing it.  
 

And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg

by ManfromMiddletown (manfrommiddletown at lycos dot com) on Tue May 4th, 2010 at 07:24:40 PM EST
[ Parent ]
Don't forget the need for cooling. Arizona effectively ships, in the form of electricity, a chunk of its valuable water resources to California by using it for evaporative cooling on thermal solar plants.

http://ag.arizona.edu/azwater/awr/septoct08/d3aa3f8e-7f00-0101-0097-9f6724822dfe.html

by asdf on Tue May 4th, 2010 at 09:50:30 PM EST
[ Parent ]
I wonder if there's a way to do steam recapture, forcing the emissions into bedrock, and using the earth itself as a type of heat sink.

And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg
by ManfromMiddletown (manfrommiddletown at lycos dot com) on Tue May 4th, 2010 at 10:05:33 PM EST
[ Parent ]
Maybe, but you don't have to go down very far before it gets pretty hot. Plus, rock and earth are good insulators, so you would need huge amounts of area...
by asdf on Tue May 4th, 2010 at 10:45:26 PM EST
[ Parent ]
industrial thermal (hot water+turbine+generator)

Not hot water: oil or molten salt.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Mon May 3rd, 2010 at 12:39:47 PM EST
[ Parent ]

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