A Solar Grand Plan

Posted by Kendall Harmon

Read it all from the latest Scientific American.

Filed under: * Culture-WatchClimate Change, WeatherScience & Technology* Economics, PoliticsEnergy, Natural Resources

13 Comments
Posted December 28, 2007 at 4:40 pm [Printer Friendly] [Print w/ comments]



1. libraryjim wrote:

How would they square this plan with those who are standing for preservation of natural lands? 

It seems to me that requiring tracts of land this huge would seriously impact natural habitats, damaging or destroying some, much more so than drilling in ANWR or the Gulf of Mexico off Florida.

And of course we know that over 500 scientists have recently come outin support of Global Warming being a naturally occuring cycle as opposed to a man-made threat. (That’s 500 in addition to those already out there saying this.)

December 28, 5:55 pm | [comment link]
2. robroy wrote:

Whether global warming is a natural cycle or not is irrelevant. The trade deficit is real and is harming our children’s future. Money to muslim countries is funding terrorism and proselytization. This money, as pointed out by a commenter on the discussion, is much less than the farm subsidies doled out for not growing.

December 28, 7:01 pm | [comment link]
3. AnglicanFirst wrote:

I was educated as a physicist and have used the disciplines of physics analytically as an engineer.

In engineering, there is a large chasm between highly innovative concepts and economically achievable results.  Astute engineers also comprehend that there are also unanticipated outcomes in any major innovation.

For example, asbestos was a miracle mineral in the 1920s and today it is a pariah.  Chlorinated hydrocarbons were an answer to fire hazards in electrical power generation and distribution and today they also are pariahs.

Solar power requires surface area.  That is, solar collectors have to be huge if they are to have a huge energy impact. 

Maybe, we should return to nuclear energy and use the over fifty years of experience that we have in its energy generation capability.

There have been problems, mostly those in the former Soviet Union, but the track record of the Western nations is very good.  Not perfect, but very good. 

Within the United States, the Navy can provide the infrastructure for a nuclear energy program.

December 28, 10:41 pm | [comment link]
4. Tom Roberts wrote:

The authors are at best spurious engineers. The environmental impacts of their concepts are also not very well thought out.

IN re engineering:
1. The efficiency figures for PV arrays cited are conservative, but no mention is made of their degradation over time due to weathering of the collector plates (think of how your house and windows collect dust and molds) or internal degradation of the PV array itself through radiation effects. Both of these are well documented for space PVAs, though space is actually more and less benign (no rain or mold, higher radiation). I suspect that rain and dust would be worse than hard radiation over time. So, you have to keep the PVAs clean and replace them every decade or so. That implies $ for maintenance.
2. Putting 1100 psi (73 atmospheres!) air pressure in a cave is absurd, without high costs which this article never discusses. Doing it extensively over many geological condition sets is speculative in the extreme. You don’t get 73 atm with a leak; you get 2 atm with a leak, and most of your energy wasted in pushing gas around.
3. One of the advantages of using water pumping stations and hydro turbines to manage electrical loads is that liquid turbines are inherently more efficient than gas turbines, or virtually any other thermodynamic cycle for that matter. Why this article is pushing compressed air at all is incomprehensible on that thermodynamic basis.
3. Hot salt concept. The authors forgot to mention that you need a bunch of very clean mirrors to do this. Again, rain, dust, and molds tend to make these installations costly to maintain. Add to that the self confessed issues with piping corrosion which must be considered as an inherent safety hazard. This article fails to note such engineering necessities as the need to create high pressure ratios for the extracted steam in order to efficiently run the generating turbines.
4. The comments on AC distribution infrastructure are good, but ignore the fact that there are already competitive alternatives to the solar concepts. What is the big issue for the US electrical system is its politicized nature; e.g. CA has an electrical generating shortage because that state has not permitted sufficient generating facilities. The reasons for this are politically complex; the result is simple. In this case, CA gets what it wants, and I’m not sure that covering Death Valley with PVAs is going to work as….

IN re environmental effects: the concept that vast areas of the SW US are going to be PVA’d without vast environmental and economic disturbance is patently absurd. Consider the resistance in many locales to large wind farms and add to that factor the concept that PVAs make the land underneath an environmental vacuum suitable only for human habitation in the manner of Trantor in I. Asimov’s “Foundation” series.

I haven’t bothered to push the finances portrayed in this article, but I suspect that they might be equally suspicious as well. Fortunately, this type of project doesn’t need financial analysis, as its engineering aspects make it untenable in the first instance.

December 29, 9:20 am | [comment link]
5. Harvey wrote:

By the way, I’ll butt in and ask a question about the manufacture of solar cells.  I believe I read somewhere that the making of such cells requires a lot of “bad” chemistry and proper “waste disposal”.  Did I read it wrong? Comments please!!

December 29, 1:44 pm | [comment link]
6. robroy wrote:

Harvey, look at the comment section of the article. That is addressed. Solar cells are about 0.1 per cent cadmium. Pretty toxic stuff but it is encased in glass. And the article talks about two solar energy methods. Solar cells which convert into electricity which requires cadmium and molten salt collectors which do not. The plan calls for exploring both initially.

December 29, 2:08 pm | [comment link]
7. robroy wrote:

Tom Roberts: I was intrigued by the high pressure storage systems, but the article states that these are being used right now in Germany with an efficiency of lead-acid batteries.

December 29, 2:11 pm | [comment link]
8. Tom Roberts wrote:

... and the system efficiency of lead acid batteries, especially on a large scale, is pretty bad. That is why so much effort for electric cars is being put into better batteries, which are also safe during collisions.
The scale of these installations also has to be considered. Upscaling the turbines usually results in higher generating efficiencies (though Ontario Hydro managed to do just the opposite in their new nuclear plant), but upscaling the storage increases the difficulty of controlling leakage. What works fine using a small steel tank might not work well at all using the caverns that the authors portray.

December 29, 2:19 pm | [comment link]
9. Tom Roberts wrote:

#5- manufacturing the silicon support circuits, on the scale anticipated, would also involve very large amounts of wash water. Now, this is a major unresolved environmental impact of the whole microelectronics industry, and on this scale would be necessary to address. But here you end up with yet another issue to pay to resolve before you get to the great solar paradise.

December 29, 2:22 pm | [comment link]
10. Tom Roberts wrote:

#7- the major obstacle in increasing the efficiency of lead acid batteries is the DC/AC and reverse rectifiers. If you are simply sticking DC into the battery and then taking DC out, without having to produce AC power (which is what a car does), then the batteries are not terrible. Nothing heroic, but not terrible. But rectifiers generally are about 50% efficient at best. So you take something that is not that great and then divide by 2 or more. And if you want to use just DC power, recall that Tesla won that AC/DC squabble with Edison. It will work in your vacation cabin. It won’t power a grid.

December 29, 2:29 pm | [comment link]
11. robroy wrote:

The “compressed air batteries” can directly generate AC current by having the turbine drive an AC generator. AC in, AC out. No rectifiers needed.

December 29, 5:30 pm | [comment link]
12. Tom Roberts wrote:

Indeed, but comparing them to DC lead acid batteries isn’t very flattering, wrt efficiencies. The reason why this occurs is due to the circumscribed cycle paths of gas working fluid heat engines. Without a phase change at the heat exchangers the turbines let a great deal of power out the exhaust.
So putting the electricity into compressed air or lead acid batteries ends up with the same, generally mediocre, efficiency levels when you try to get AC out of the whole cyclic system.

December 29, 5:42 pm | [comment link]
13. RevK wrote:

Ang First,
Could not agree more.  Both solar and wind power are inconsistent and require 1600 times the land area that a 3% nuclear power plant needs for a similar power output.  The Navy has a long track record of safe nuclear power operation - particularly admirable when you consider the enrichment levels at which their reactors work.  Ironically, with the end of the Cold War, the Navy no longer needed so many submarines and nuclear-trained sailors.  There is now a ‘glut’ of nuclear engineers in the U.S.

Harvey,
This is a lot of new technology with regard to solar power - my personal favorite is the roll of solar cells that can be rolled onto your roof like tar-paper and act like shingles.  However, it is still not a cost effective means of energy generation.

West Texas A&M;University has a large portion of their school dedicated to alternative energy including the ‘Alternative Energy Institute.’

December 29, 10:00 pm | [comment link]
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