Well, it is, just not real soon. I was really addressing the larger question of the maximum market share for solar, and my point was that if solar production began to exceed daytime demand that there was the potential for some night time demand to move back to the day, where it would normally be, depending on relative costs, of course.

Similarly, morning and evening residential resistance heating peaks are entirely an artifical result of flat pricing (you wake up, and come home from work, and turn up the heat), and could be altered quite easily (with nothing more than electronic scheduling thermostats).

That’s interesting about heat storage. I guess it makes sense that heat could be stored pretty efficiently. I suppose the main additional cost is the extra capital expense of the storage – I don’t know what the relative size of that expense is.

I would note that I wasn’t talking about V2G, but about something much simpler, which was simply managing the charging of PHEV’s. This would be an easy way to buffer intermittent power generation by renewables.

In areas where A/C demand is the clear culprit for peaks, such as Southern Cal, I too believe that a fairly significant development of solar can occur before storage becomes an issue, as I stated before. However, there are many areas of the country where this is not necessarily the case. For instance, I was surprised to find that Florida’s absolute peak occurs during the winter, not summer, due to backup electric resistance heating that kicks in when it’s too cold for heat pumps. I ran across that interesting fact in one of the DSM reports that can be found at http://www.bpa.gov/Energy/N/Reports/Results_Center.

The “Solar Two” tower in the Mojave had molten salt storage tanks to extend electricity generation after the sun went down. Storage has been studied for both towers and troughs and found to be economically feasible. Solar Tres, the new solar tower being built in Spain will have 16 hours worth of heat storage… enabling it to run 24 hours a day during the summer and with an annual capacity factor of 65%. Some of the solar troughs being built in Spain will also have storage. It’s not THEORETICAL, unlike V2G. The reason some plants, such as Nevada Solar One, decided to not use storage is simply due to the low penetration of solar and the A/C peak in that area. Storage can also be added later if it becomes advantages to do so.

The loses for thermal storage with CSP are not that great. This is because it doesn’t require an extra conversion. Solar Tres, for instance, will heat the molten salt to around 565C. The salt is then either sent to the steam generator directly or stored for later use. The conversion losses are not increased by the storage… unlike any other renewable (wind, wave, PV) storage schemes. The amount of heat lost from the insulated storage tank can be kept to a fairly small amount… significantly less than the other efficiency loss sources in the plant.

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I just ran across another source of info on CSP. At http://www.nrel.gov/csp/troughnet/wkshp_2006.html you can find workshop papers discussing many aspects of solar trough facilities including storage and also the issue of water use. I’ve yet to read through them, but plan to soon.

First, most demand is during the day, and is correlated with or caused by light levels (especially A/C).

2nd, Demand Side Management (DSM) appears to me much more useful, and much cheaper. Don’t forget the demand that primitive DSM moved temporarily to the night in search of cheaper power, which would move back if peak power decreased in cost.

3rd, gas turbines provide a large % of electricity in the South West, including California, and they provide an easy way to match demand with supply.

4th, there are efficiency losses to thermal storage, which reduce it’s value.

5th, I have read that there are no installations of significant size using solar thermal storage – that it is more theoretical than real at this point.

6th, by the time storage is needed, it is highly likely to be available from PHEV’s.

I would estimate that solar electricity will have provide at least 10%, and probably 20% of the kwh’s in a grid before storage begins to be necessary. Even then, only a relatively small % of incremental power would be stored, in order to reduce supply variance and match supply with demand.

On the other hand, I agree that this does not diminish the value of CSP, and that we need diverse forms of supply.

I simply think that decentralized PV is going to grow much faster, due to it’s consumer-side, decentralized nature.

Transporting water has been done for millenia and is a minor challenge, when compared with a change of heart.

Emil M

The two largest planned facilities in the US, Southern Cal Edison and San Diego Electric, are for an initial 800MWp with possible expansion to 1750MWp (though only about 24% capacity factor). These are both using Sterling Solar Dishes. These are not steam based systems so they require only the small amount of water necessary to infrequently clean the mirrored surfaces. The drawback to dish technology compared to solar tower or solar trough is that storage cannot be economically integrated. Of course Southern California’s daytime usage peak matches solar production pretty well, so until solar makes up a march larger percentage of the total mix, storage will probably not be a major issue.

Note from the below source that this is requiring no government subsidy. The attractive thing about CSP is that it’s cost is low enough that, unlike PV, it can compete with conventional sources right now.

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from http://www.businessweek.com/magazine/content/05_37/b3950067_mz018.htm

Why hasn’t Stirling Energy’s technology made more of a splash in the power business? “Our dilemma has always been how to get costs down,” explains Osborn. The dish assemblies now run $250,000 each. But that’s because most have been handcrafted in sporadic lots of one or two units. Building a group of 40 or so would trim the cost to $150,000 each, Osborn estimates. With real mass production, that could drop by 50%.

So when SCE said it wanted to buy more renewable energy, Osborn’s outfit proposed the 500 MW project as the means of moving beyond its chicken-or-egg impasse. Producing that much electricity will require 20,000 dishes, built in a steadily increasing flow over several years. “We’re ramping up now,” says Osborn.

He expects to have 40 dishes in place for a 1 MW facility by the end of next year, followed by 50 MW in 2008. The electricity will be delivered only when the sun is shining, but that’s when the utility’s customers place peak demands on electricity. “Our system is a really good match, providing peak power at times of peak load,” notes Osborn.

The price per kilowatt-hour (kWh) that SCE will pay is confidential and must be approved by the California Public Utilities Commission. But there’s little doubt that the contract will get a thumbs-up, perhaps as soon as next month. One reason: SCE says the price it negotiated is so attractive — “well below the 11.33 cents per kWh” it now pays for peak power — that it won’t seek any subsidies from the state.

Given the logistical, organizational, financial clout the rich countries can muster, I have no doubt the rich can supply all with 100% RES within a decade. What it takes is compassion, translated into vision, political will, courage, boldness.

Even when there are cost not yet taken into account for CSP > when there’s compassion etc, there’s no final block, just a bump in the road ahead.

For small communities and communities far away from easily accesable electricity, all kinds of options are available, which are entirely feasable when Spirit has been allowed to unfold

The 100 book project points in an interesting direction.

Emil M

I am not sure how this cost weighs against the extra cost of storage for PV and CPV (Concentrated PV plants).

I am also not sure, in a time when many people have water shortages, about spending the infrastructure costs of water desalinization on electricity rather than on water for people to drink and irrigate with. Maybe both can be done, which could be great, but I would think that the latter needs to be the bigger priority, especially for developing countries.

I agree with you that the US needs to beef up its grid. My German husband looks at the grid here in L.A. and shakes his head in disbelief. Not sure about, but interested in, the efficiency loss of 5 %. Am very curious to see info on this, if you or anyone gathers it.

Of course, our grid system problems are different from a lot of the world’s, where there is no grid at all. This is a bigger, more costly and cumbersome problem for CSP, as far as it becoming the primary global supplier of electricity any time soon. And a primary reason I remain skeptical about CSP’s usefulness in areas other than a few regions in the world, where it seems poised to work very well.

I’ll deal with water below. A bunch of people have commented on it…