You are the most uninformed poster I have ran across in all the websites and forums I visit for these many years and even back unto the days of BBs. Back even unto Compuserve. Back even to chiseled stone tablets passed around the campfires.Back I am sure to grunt language yelled from the trees. Back before Adam could speak and Eve lifted her loincloth, there must have been someone like Hothgor (perhaps serpentinelike) telling a pack of lies and BS.  

Your ignorance and communication skills are a waste of human flesh.

You post balderdash and try to pretend its a fount of knowledge when its just your lame efforts at googling.

I think I'll just go down there and SPREAD MY LEAVES and collect me some power.

BTW, I'm so glad to hear you're not preparing.

Let's try some numbers instead, WRT "Enough light energy falls on the American south west to provide all the energy the world needs."

World energy consumption - at least that which is accounted for - around 10-12TW. Sunlight at surface 1050 W/square meter. Area about 10000-12000 square kilometers. So my crude ballpark-o-meter says, yes, the proposition is "theoretically" true.

Of course, it's fairly simplistic theory. That area is for high noon, facing directly on, with 100% areal coverage, and no clouds or haze anywhere in sight. So if I'm going to trust my life to this thing, I need to recalibrate my  ballpark-o-meter.

It's not always high noon, so multiply the area by pi over two or about 1.57. (We aren't going to be building 10000 square km of complicated, expensive, moving structures anytime soon. Not in anything but some nightmare.) And night eventually comes (see The Dying Night by Isaac Asimov), so multiply by 2. And sometimes it's cloudy or hazy even in the desert, and collector surfaces gather dust and mineral deposits. So multiply by 2 again. And we don't really get 100% efficiency out of any known large-scale system (and precious few lab systems either for that matter.) Let's be really super optimistic, and also ignore conversion-transmission-conversion losses, and call it 40% - for the outdoor system - not just the lab version of the individual solar cells or other elements. So multiply by another 2.5. And the days are short in the winter, and sunlight gets weak near dawn and dusk, and surfaces will reflect more away at shallow angles, so multiply by another 1.3 (SWAG).

So we multiply the area by 20. We need 200000-240000 square km of collector surface.

Now, the Southwest is not on the equator, and it's sometimes winter, so multiply the land area by the secant of the sum of some reasonable latitude and the earth-axis tilt of 23 degrees, yielding, say, 1.4. And we don't want our fiendishly expensive collectors shadowing each other too much when it's not high noon, and the environmentalists won't let us have 100% areal coverage anyhow. So multiply the land area by another 2, except that's almost certainly too low and should probably be closer to 4. So we need somewhere on the order of 700000-1000000 square km of land, rooftops, and whatever.

At the very minimum, this is a monumental project involving technology that does not quite exist yet, and given that scope, deadlines are growing short. It probably can't be done at all without substantially disempowering NIMBYs and BANANAs, so it may prove impossible under "democracy". Of course it's not really going to be concentrated in one spot - the European concept of a huge project in the Sahara connected  up with an undersea cable or three is a highly vulnerable epitome of geopolitical and strategic stupidity - but most spots will have more bad weather and less sun in winter than the US southwest. In addition, many rooftops and such in many inhabited areas are shadowed by trees for much or all of the year, an inconvenience to which our southern Californian contributors often seem utterly oblivious.

BTW, yeah, I know. There are efficiency gains to be had, Engineer-Poet wrote about that the other day. On the other hand, population is still exploding, as are economic expectations in poor countries. So at this level of analysis, I'm saying that's roughly a wash over the next few decades. At best.

P.S. one other dose of reality - even if there were thousands of energy-harvesting and/or energy-producing methods, it's highly likely that less than a dozen will account for nearly all of the net production.