[Mee-n-Mac]

Originally Posted by ITD

Actually I did notice the vagueness of "Explain this" in your first post and waited until MEE suggested you think it's of a petroleum origin before I commented. {snip}

In regards to the vagueness of the black ring, you probably weren't around when APS (different name, same person) posted in response to this http://www.winnipesaukee.com/forums/...ght=black+ring (scroll to "Questions sharpened" post)

Originally Posted by madrasahs

OK. My boating tour today disclosed a satin black (scratch dull) "bathtub-ring" for miles and miles, including Rattlesnake Island. I was looking for a scientific explanation. (My "working theory" is petroleum-based deposits. I know...DUH)

I guess I should have said APS theorizes not posited.

Originally Posted by ITD

The discussion on alternative sources for energy is interesting also. One statement intrigues me:

Originally Posted by APS

The good news is that the solar promoters have stated that a solar grid measuring 10 miles by 10 miles would provide the US with all of its domestic -- non-transportation -- energy needs. ('Course, that's an immense area to cover with silicon panels).

Originally Posted by ITD

This just doesn't sound right, if it is true someone should be all over it, conspiracy theories aside. {snip}

It doesn't sound right because it isn't right, at least w/o a lot of caveats (like major conservation efforts) applied. Here's a quickie analysis to put some perspective on the number. First lets arrive at a figure for domestic energy use. Last year the US used about 100 Quads (that's 100 quadrillion BTUs) of energy. Of this somewhere between 20 and 30 % is mobile useage so let's be kind and estimate 70 Quads for domestic energy use. Averaging (and this is dangerous as I'll point out later) this use to arrive at an average power production number gives you 3.345 x 10^12 watts (3.345 million million watts). In space where the sun shines 100 % of the time and w/o atmosperic loss you have ~1400 watts per sq meter of energy available and so the minimum area needed to collect the prior power would be ~ 1.69 x 10^9 sq meters or 1670 sq km or 645 sq miles which is an square of 25.4 miles on a side. So we're already exceeding the 10 by 10 mile size but let's continue. You might say OK that's not so bad (25.4 x 25.4) but now bring this number down to Earth. First the Sun doesn't shine as brightly here as in space so at best you get 1000 w/m^2, thus increase the area needed by 1.4 to get the same power production. Second this only happens around noon time with the power falling off to less than 50% at the + and - 4 hr points. Averaged over the course of the day I'll be generous and give you 35% of the max so multiply the area needed again by 2.86 so that the peak production can be increased, stored and later released to meet the average number we're trying to achieve. Now you need to figure in that no PV cell is 100% efficient at converting the energy that falls on it into electricity. Here's where it can get vague as people like to quote all sorts of theoretical and lab vs real world numbers. I'll be generous again and allow a 15% efficiency (7-9 % is more likely for affordable PVs) so multiply yet again by 6.66. Let's forget about how may days of the year the sun shines w/o clouds and how many days the whole array is working w/o downtime and whether dust and dirt further reduce the energy and a raft of other things (like storing and releasing the energy when the Sun isn't shining). You still have to get this hypothetical station on the grid so the DC voltage coming out of the array needs to go through and inverter (like the batteries on a boat) to make AC like you have in your house. Let's give this an 85% efficiency number (multiply again by 1.176) and forgoe considering transmission line and switching losses to distribute our newly found source. What we end up with is an area > 20000 sq miles or > 140 miles on a side. Still not really outrageous but the reason this isn't here now is cost. The cost of such a structure is way off the map and I'm not sure you could make that many PV cells in any reasonable amount of time. Secondly the number above represents an average number and a real issue for the power plants is the peak vs the average demand. Plants are sized with our peak needs in mind more so than our "on average" usage. To handle our peak power demands the array would need to increase yet again in size. Still it makes you wonder if there shouldn't be a big R&D effort for more efficient PV cells (I'd bet there is) and perhaps even more importantly an effort to streamline and reduce the manufacturing costs of such devices. Perhaps the "Quantum dot" research may pay off ??? The technology isn't here yet, not in a form we can pay for (let alone finding the political will to pay for it if the $$s were available). The only way I see to arrive at the aforementioned answer is a major (reduction of >50%), successful conservation effort by the population as a whole (who haven't shown much interest in conservation).

Lastly I'd bet beaucoup $$ there would arise various conservation groups claiming that blocking the sunlight was adversly affecting the flora and fauna underneath the array (probably with some degree of factfulness too). Even in the desert there would be SOS (Save Our Scorpians). I guess they never read Heinlein .... TANSTAAFL.


Lastly I also agree with lg, especially about the "phasing in gradually". I find it's the "jerk" of rapid change that causes so many problems. Give people time to find strategies to adapt and it doesn't hurt so bad. The problem is that this issue doesn't have any really easy, clear, practical answer. Neither party this last election had any real energy policy rather than the usual platitudes. We the people don't know the answer and aren't really asking for one. I think the present "high" prices for gas and oil have a silver lining. If the prices stay "high" for longer than the usual peak, if people begin to believe this is the way of the future, here to stay, perhaps they'll begin to think more about such things.