When you've got equipment that is 40% efficient in solar/electric conversion, then when several tens of millions of dollars later you come up with a design that is 99% efficient, then is it precisely only two and one half times more productive than the 40% model, and neither one is going to remotely approach "saving the earth."

Solar flux (energy) per square meter at the surface of the earth is strictly limited. Nothing will "increase" it, and nothing will make it useful at night.

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Stirling engines (super-efficient heat engines) driving generators would provide useful AC power with controllable and readily transmittable wattage. Stirling engines may turn out to be more efficient and cheaper than photo-voltaic cells besides being way cheaper because they can operate from heat/light collecting mirrors that use the entire solar spectrum instead of the restricted solar spectrum of PV cells. In short they can theoretically generate more energy per square meter than a PV system.

Solar electric has a long way to go. But the sooner it is recognized as necessarily a minor accessory and NOT a replacement for serious POWER, the more funding will be saved for development of full-scale full-time alternative power solutions.

Nuclear (fission, then fusion) of course is the obvious ideal choice for compact, reliable, and cost effective.

We have yet a lot to learn, but hey, the century is young!

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But Jeffrey, have you ever given serious thought on how to tap that wave power? A few watts would be easy, but megawatts would be something else, and storms would be a fatal flaw.

Tides can be tapped by standard hydroelectric generators working in both directions. But no greenies would sit still for that no way, no how. Even I would put the quash to a tidal power plant.

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Hey Roger, Peter V thinks there is no future in solar energy, so maybe you should just retire now. After all, anyone that makes 7 out of 8 posts must be right.

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None of this is new folks.

Focusing more light onto solar cells and/or a turbine isn't new. Focusing enough sunlight on anything will burn through steel has been known for years.

He's just jumping on the grant wagon for governmnent $$$$.

Hope his mind is more organized than his office.

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ps: you can do any of this stuff this guy did in your backyard and you sure as shoot don't need a phd.

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Thanks Tom Beal for a very engaging article about one of Tucson's great thinkers.

Regrettably, some posters above make Roger Angel look more deserving of the resources and attention he's getting, not less as they intend.

Angel's chief aim here appears to be to generate abundant energy without producing and releasing CO2, which is thought to be driving climate change.

Is he using smoke and mirrors to do it? No, just the mirrors. I don't see an issue. The process won't release CO2. The high efficiency means relatively low loss of heat from the system. A process that doesn't generate CO2, but loses heat to the atmosphere, doesn't solve our climate problem.

As Angel states clearly, he's leaving storage and transmission to others. Which is fair enough, although of course it could delay or stop application of Angel's technology. But we won't know that until we try, will we?

Angel has a 'can do' attitude. A few of our posters above, a 'can't do' attitude. I know which attitude I prefer to be driving our research.

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Steve #16, I think Peter must work for the nuclear industry, because his solution is always more nuclear reactors.

Of course, he would rather grace us with his brilliance on these forums, than particpate in an academic peer-reviewed environment. I don't think Roger Angel would give Peter the time of day. But here on these forums, Peter can post all the quasi-intellectual pessimism he wants.

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Dominion Resources has been using a double lake power storage facility for a few years in southwest Virginia. Water is pumped up to a higher lake during low demand, then passed through turbines to the lower lake during periods of higher demand. This tech nique allows greater utilization of existing generating capacity and delays the need for new power plants.

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Great story, and Roger Angel is a terrific asset to UA and Tucson and Arizona.

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Peter V.-You & Mr. Angel need to get together. With your combined knowledge of solor power & all of the science behind it, you guys could come up with a do-able solution. I'm sincere about this!

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Now now, folks let's keep in mind the issue of "energy" has been politicized by people who are largely clueless. The best way to alleviate that situation is to debate it openly.

Roger Angel, who I have known professionally since his arrival on campus is a truly brilliant guy with a refreshingly practical approach in his mirror design work.

Many of us, scientists and engineers in the astronomy biz, had known in the sixties that a spinning disk of liquid takes on a parabolic shape, and parabolic shapes make the best mirrors. My line of thought had been to use ice, plaster, or plastic, for cheap marginally effective mirrors; but I had dismissed it as "impractical" because of inevitable micro-vibrations that would make for a very poor reflective surface. My field is computer control systems and electro-optics, not optics, so my interest at the time was only peripheral.

Roger in his mirror lab had access to the best large-scale equipment known to man along with a thorough knowledge of glass. He put it together with some brilliant mechanical engineering to solve the vibration problem, but it was a long time coming.

Presently with the engineering problem solved thanks to Roger's effort and his great team at UA, bigger and still bigger mirrors are now cost effective.

Mirrors are of course the best concentrators of solar flux, so they are key components of any high-temperature solar energy device.

Photovoltaic panels don't need mirrors because they are large area, low-temperature radiance/electric convereters. Their disadvantage is cost, "clutter," maintenance, and short life.

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...if you've been in Arizona, read the ADS newspaper, or spent the last several years on this website, then you are well aware of Pete V's background.

LOL! I don't think I've ever read a sentence with more logical fallacies packed into such a small space. Thanks for the laugh! I don't mean that in a mean way, your comment really did make me laugh out loud! Lets just say that it is possible to be in Arizona, read the comments on ADS a couple of times a week, and to have noticed Peter V.'s comments, without knowing who he is.

I assume that my assumptions about him were correct. Would you enlighten me? Is he a scientist/engineer?

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Looks like Peter V. answered for himself while I was composing my post (I remembered that it was time to water my squash plot in the middle of my response).

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Response to Jack M's "preconceived notions" is to point out that the concept of Mankind-caused climate change has been totally discredited by Science in the historical past, but it has been reanimated with a new political spin during recent decades, although the old superstitious aspect of it remains potent -- the GUILT of Mankind for daring to use the earth by living on it.

In the old days the guilt-ridden dupes of priests would be willing to sacrifice their first-born (see Abraham and Isaac in O.T. and piles of child bones in Phoenician temple sites).

So since AGW is a reborn formerly discredited concept the burden of its PROOF is entirely on the shoulders of its proponents, not on its detractors.

It is not up to disbelievers to disprove whatever nonsense catches the public fancy. The priests of the new religion must make a convincing case with demonstrable proof that is "falsifiable."

In other words, just one experiment to the contrary would blow the whole proposition. THAT has now happened several times, but the AGW thing retains a zombie existence.

Now let's get back to the questions of electric power.

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Sunbeams and Breezes are indeed "free" and they are worth every penny of that, you see.

In other words to turn them to good use, other than bringing comfort and life to the earth's surface, requires a very expensive human artifice -- solar power converters and wind turbines.

The fundamental difficulty with any artifice is the dissipated nature of sunbeams and breezes. They are weak everywhere, so they require concentration by means of something large, nay VERY large, so as to interrupt and suck up enough total energy to be interesting.

"Large and Larger" means clutter. Clutter is anathema to engineers because it implies inefficiency which indeed is the case with attempts to harness sunbeams and breeze.

Inefficiency means waste; and waste is EXPENSIVE.

That is a summary of my fundamental objections to solar and aeolian power.

You can refute it by showing me some kind of solar or wind power that is actually auditor-verified CHEAPER AND MORE RELIABLE than fuel, hydro, or nuclear power in a real and significant commercial application.

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As for clutter in one's office, it is an indicator of high level intellectual work.

Administrative work on the other hand is at its highest level in a well-organized office.

The issue is clouded by the fact that some incompetent people have cluttered offices from sheer laziness; or on the contrary, incompetent people man cleverly cover their deficiencies by keeping a well-organized totally sterile office.

I think that familiar picture of Roger's office is a three-dimensional shadow of his ten-dimensional mind's thought processes.

It is possible for creative people to think in way more than three dimensions, but paper and equipment necessarily is restricted to three dimensional space, so a certain degree of pile-up is typical.

It may look like chaos to the untrained eye, but WOE to the janitor or wife who so much as touches one stray sheet of it.

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I have to agree with the clutter thing - both ends of it. The new energy production has to be simplified.

I can't imagine one source of energy replacing fossil fuels - we'll need solar, wind, hydro, geothermal all to cover the weakness of each.

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If everyone in Tucson who is over weight were put on exercise bikes hooked up to generators Tucson could be the energy capital of the world.

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"Peak oil" is a flawed concept for several reasons. Here are one good reason:

Since the state of the oil-seeking art is still being improved along with the oil-extracting art, it is premature to make any intelligent estimate of the existence of, or the time of a peak in source or supply of oil.

It is reasonable to suppose that oil will ultimately increase in price after what may be a long period of glut that is yet unfinished.

As the long-term oil price increases over a span of MANY decades, the funding for alternatives will NATURALLY increase without any government interference being necessary.

In the meantime domestic gas MUST be exploited because nowadays we are just blowing it off in flares whenever we can't find a way to store it, ship it, or pipe it.

AMERICAN natural gas needs way more public attention if a putative passion for "freedom from foreign oil" has any validity.

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Angel is a veritable genius, let him do his thing, he's certainly produced amazing results to this point.

Solar and other alternative forms of energy have always been expensive, they are viable now only because of the price and the availability of oil. When there are no other options, you will be burning your furniture.

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Solar is NOT being "driven by the price of oil" 43. That is a liberal lie accepted by credulous true believers. Oil is still cheap, and it is likely to stay cheap for a few decades to come.

The ONLY reason for solar power to exist in its present impractical manifestations is artificial top-down economics that will collapse with the whim of a next election like a multi-billion dollar house of cards.

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A damper to Ed's enthusiasm 44 for ALL ideas might be to suggest the Laws of Thermodynamics cannot be repealed or declared unconstitutional, nor can they be held null and void by governmental or religious authority.

Ideas that defy the Laws of Thermodynamics are not worth the Internet bandwidth.

Where Public Education has failed, intellectual weeds will thrive. Weeds are clutter on the intellectual landscape.

So Ed 44 may actually be referring to ideas from humble origins that have been heretofore ignored that DO respect the Laws of Thermodynamics in extremely clever ways either advertently or inadvertently. Those might be world winners.

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The problem with solar is there is no good way to store the energy (with one exception, which I'll get to). Pumping water up hill during the day (to a lake or whatever) and letting it run downhill during the night through a turbine sounds attractive. But it won't work. There is a law of thermodynamics which tells us this. That law says you will never recover enough energy during the downhill trip as you expended on the uphill trip. It is a net-loss game. You can do it, and it will store energy for you, but you will pay for your net loss because you pay for the energy difference. The other portable with using water is it doesn't have enough heat capacity or potential energy in it. Per unit volume you can't use it efficiently do much work.

Batteries will work for about a few KW or so, enough to about power a house. But they are expensive, and need to be maintained and replaced. They are not practical for the MW or GW installations required for a city, and even for a house they are not really cost effective.

There is one storage method which is being used and it seems to work. It is expensive though. That is where you focus the suns heat and melt some salt. You need about 4000F to do it, but folks like Dr. Angel know how to get there. Then you pump the hot melted salt deep into the ground, where it is insulated by the earth. At night you pump it back up and use it to make steam, which can drive your turbines. There is a large installation in France which does it this way and it works. Expensive, but it works.

The second problem is transmission and conversion. Solar power comes as DC and the grid uses AC. If you are going to send your DC solar power any distance (more than about 100 km) you want it to go DC, so Dr. Angel is correct about national DC transmission lines. But you need to convert it to AC once it gets where it is going. This is not cheap to do. There is bunch of infrastructure that goes along with it. You need to be grounded on both ends. This is not simple on the MW or GW scale. The Pacific DC Intertie which is a DC transmission line running from Oregon to LA (and provides about 50% of LA's power) is an example. The ground on the Portland end is a circular trench 2 miles in diameter filled with electrodes and powdered carbon. On the LA end there is a similar circle of electrodes buried in the sea floor about 40 miles off the coast from LA. These kinds of things are horribly expensive to build and expensive to maintain.

Solar can be made to work, as long as we're willing to pay for it. Right now solar costs about 7X than a coal-fired plant. Even the most optimistic projections say we can never bring it below about 3X – 4X coal fired. There are two problems. One are those pesky laws of thermodynamics. We can't change those. The second problem is on the collection end. Collectors are cheap, and we know how to do that. It's the infrastructure that goes along with it that sets the price. Make your collectors twice as efficient as they are today and you won't dent costs a cent.

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How about that weather we are having?

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Marcus--

The French solar salt installation runs at about 3400F at the "business end." You need to have your salt at about 1050F because commercial power turbines require their steam to be at 1025F and 1625 PSI. It is possible to generate electricity from lower temperature salt. A few installations use salt at 700F, but they are 1/3 as efficient as the 1050F ones. Some research installations have generated electricity from salt as cool as 400F, but they play some tricks to get there. They compress their salt beds to about 4X atmospheric pressure, so you have to pay for the cost of running those compressors. Obviously, you can't do this on a large scale, and you can certainly not do it in underground storage.

The US has one solar salt installation, which is Solar One up in the Mojave desert. We got bored of that one, and converted it to Solar Two. It worked really well for a while. Then we sold it. Strangely, it became a telescope. It really did. It had bunches of mirrors which could be pointed up at the sky at night. It is now CACTUS, which stands for Converted Atmospheric Cherenkov Telescope Using Solar-2.

We are now building Solar Tres. The thing people don't really realize is how inefficient these solar plants are. Solar Tres will be absolutely state of the art, using molten salt. It will generate about 15 MW of electricity, and take up a huge portion of the desert. It can power 40,000 homes. A drop in the bucket.

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Moving and storing liquids at 4,000F will surely run into horrendous energy losses by conduction, convection, and radiation no matter how clever their insulation may be. I wonder if these designs are run through rigorous energy audits before they are signed off.

Of course the input energy, sunlight, is free and expendable. But the equipment is exotic and expensive so what will happen on the bottom line? subsidy?

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