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301 comments on Dr Deffeyes defines a date

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AlanfromBigEasy on February 16, 2006 - 10:05am Permalink | Subthread | Parent | Comments top
In the district heating and cooling schemes that I know of, chilled & heated water can only be pumped a few miles (like 2 or so).

Solar power is a low value use of land, so they are likely to be located "in the middle of nowhere".  The demand for chilled water will likely be limited to the support staff.

Perhaps the bed of the Salt River in Phoenix could be covered with raised mirrors, but aesthetics and glare into offices would prevent this.  Not at the airport, glare into pilots eyes.

OTOH, storing hot oil till the sun sets and temperatures decline may well be worth doing.  Increase the natural gas supplemental heating (only 2% on NV 1, vs. 25% before) to offset any cooling but get greater thermodynamic efficiency.

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Engineer-Poet on February 16, 2006 - 6:43pm Permalink | Subthread | Parent | Comments top
You misunderstand.  Solar power may be a low-valued use, but roofs are low-value territory.  So's the air over parking lots.

Solar power is more valuable at the point of use than far away (avoids all the expense and losses of the transmission system); if the roof of the 7-11 sports a mirror array which powers the whole thing and the waste heat air-conditions it too, you've effectively gone off-grid while the sun is shining.  Have another unit or two to shade the parking lot, and you could supply excess power to charge the cars coming and going.

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AlanfromBigEasy on February 16, 2006 - 9:56pm Permalink | Subthread | Parent | Comments top
I see difficulties in the economics of scaling down to "7-11 size" and anything less than "Regional Shopping Mall" size.

Rooftops are NOT so cheap.  Additional structure to support solar load (weight).  Elevating them above parking lot has some additional costs as well (like elevating above river bed).

Also, great care must be taken to not break the watertightness of a roof, and any reroofing has to be done under/around solar collectors and their supports.

Still, I good see a 200 acre array mounted over some of the parking lots in Phoenix.  Concrete around each post to prevent accident knocking down pole and spilling 750 C oil everywhere !  Capital cost of lost parking spaces due to poles & guards is a high value loss and probably kills idea unless parking becomes "surplus".

Perhaps 0.5% of Phoenix load that way.

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Engineer-Poet on February 17, 2006 - 3:31pm Permalink | Subthread | Parent | Comments top
The tech to do a 7-11 size unit is already in the California desert; it's the 37-foot diameter solar Stirling dishes.  They require a post to mount them, but you could incorporate that into a corner of the building and make it do double duty.

It might be cheaper to do it with heliostats feeding a fixed collector.  If so, the result would not look all that much different from a filling station with roofed pump islands.

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301 comments on Dr Deffeyes defines a date

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