Solar tower in Spain

May 3, 2007 7:15 AM

Solar Tower (text and video). "The rays of sunlight reflected by a field of 600 huge mirrors are so intense they illuminate the water vapour and dust hanging in the air."
posted by stbalbach (61 comments total)

For comparison, the 11 megawatts generated while the sun is shining, a single nuclear power plan generates on average 1000 megawatts 24x7. But:

The vision is of the sun-blessed lands of the Mediterranean - even the Sahara desert - being carpeted with systems like this with the power cabled to the drizzlier lands of northern Europe.

posted by stbalbach at 7:18 AM on May 3, 2007

Don't look at it, Marion!
posted by cog_nate at 7:21 AM on May 3, 2007 [3 favorites]

Is it true that this power is three times more expensive than power from conventional sources? Yes...

I'd like to see the following codified into international law: All comparisons of clean vs fossil energy must attach to the latter the price of removing the same quantity of CO₂ from the air. It would also be a good idea to add, what is it now, $5 billion/month in Iraq.

I thought this was going to be one of those passive solar tower deals, where it's basically a hugeass greenhouse that heats air which then rises up the tower to drive a wind turbine. This system seems to require a lot more engineering and maintenance (solar tracking and whatnot). How do they compare wattage-wise?
posted by DU at 7:23 AM on May 3, 2007

I thought this was going to be one of those passive solar tower deals, where it's basically a hugeass greenhouse that heats air which then rises up the tower to drive a wind turbine. This system seems to require a lot more engineering and maintenance (solar tracking and whatnot). How do they compare wattage-wise?

DU: From what I've read those things are gigantic. Much larger then anything built by people in the past. In comparison, this thing is about 40 stories tall. I imagine its a bit cheaper.

This is a pretty standard Concentrating collector with a steam engine.
posted by delmoi at 7:34 AM on May 3, 2007

Whoa.
posted by lostburner at 7:49 AM on May 3, 2007

That thing looks awesome. The article suggests that it will be able to throttle up to much greater production than its current 11 MW:
But ultimately, the entire plant should generate as much power as is used by the 600,000 people of Seville. Current production is said to be enough to power 8000 homes. This one tower will be able to achieve at least a ten-fold increase in output? Or are additional towers going up on the site? Anybody know?
posted by Mister_A at 7:57 AM on May 3, 2007

There was something similar to this in a recent issue of Pop Sci but it was, if I recall, much larger but functioned on the same principle. I think the design could be installed in an agricultural location with some spinoff bennies like water condensation watering the crops.

I love ideas like this.
posted by fenriq at 7:58 AM on May 3, 2007

Here in Albuquerque at Sandia National Labs and Kirtland AFB is the National Solar Thermal Test Facility which has been in operation since 1978 and has contributed to a great deal of research in this field. Here's a couple of WikiPedia articles on Solar Thermal Energy and Solar Power Towers. And here's a site called Pointfocus, a clearinghouse for solar power using lenses and mirrors. For the hell of it, here's Sandia's page on all their alternative energy research.
posted by Ethereal Bligh at 8:06 AM on May 3, 2007

I have no idea how effective this thing is, but as art it's superb. I want to go see it immediately.
posted by Artw at 8:08 AM on May 3, 2007

Oh, I see that buried in NSTTF's site there's a FAQ on this installation and technology. It's not very comprehensive, but it does have some interesting information.
posted by Ethereal Bligh at 8:11 AM on May 3, 2007

I'd like to see the following codified into international law: All comparisons of clean vs fossil energy must attach to the latter the price of removing the same quantity of CO2 from the air. It would also be a good idea to add, what is it now, $5 billion/month in Iraq.

No kidding. In the area of energy particularly people have too long taken the perspective that if someone else is paying for it (e.g. dead Iraqis, the children of tomorrow, all life on earth, whatever), it's free.
posted by Mr. President Dr. Steve Elvis America at 8:30 AM on May 3, 2007 [1 favorite]

This one tower will be able to achieve at least a ten-fold increase in output? Or are additional towers going up on the site?

Doesn't totally answer your question, but the article does mention that there is currently one mirror field, but another (larger) field is being constructed.
posted by pardonyou? at 8:39 AM on May 3, 2007

I'm guessing this lovely photo of converging solar death-rays illustrates some sort of test.
posted by Western Infidels at 8:49 AM on May 3, 2007

I'd never heard of this sort of solar power, I thought the only workable technique was using photovoltaic cells.

Neat technology.
posted by aerotive at 8:53 AM on May 3, 2007

A couple of decades ago, one of the tricky aspects of making a system like this work was getting all those mirrors aligned and tracking the sun during the course of the day.

Today, the computers used to do the job are so mundane, such old hat, they aren't even mentioned in the article or the video.

That says something profound about the pace of progress in the computer field, or our apathy about the solar power field, or both.
posted by Western Infidels at 9:03 AM on May 3, 2007 [1 favorite]

wow.
posted by nickyskye at 9:06 AM on May 3, 2007

...one of the tricky aspects of making a system like this work was getting all those mirrors aligned and tracking the sun during the course of the day...

This problem can be made tricky if you overthink it. But really, pointing at the sun is a simple problem of causing a shadow to disappear. Put an upright stick among some photocells. If the shadow causes one cell to go dim, tip the opposite direction. Pointing at a known offset from the sun is a simple matter of mounting your sensor at an angle.

Granted, each mirror will drift a little and then correct, but a) the resolution can be made as fine as you want and b) if the target is large enough that doesn't matter.
posted by DU at 9:12 AM on May 3, 2007

What never gets mentioned, but I'd always be interested in seeing, is what does the price turn out towards being over time?

Oil becomes more expensive as it becomes harder to retrieve, nuclear power has costs for maintainance, waste storage, and security, etc. I have no idea about coal other than coal miners pay with their lives and dams devastate fish runs.

As mentioned above, it's really the same logic between buying fair trade vs. sweatshop- it's probably more expensive on your end, but who's not paying with blood on the end you don't see?
posted by yeloson at 9:22 AM on May 3, 2007

See also: Project STACEE, a thermal research station that's part of Sandic Labs' National Solar Thermal Test Facility in New Mexico.
posted by Smart Dalek at 9:30 AM on May 3, 2007

"Sandia." Heh.
posted by Smart Dalek at 9:31 AM on May 3, 2007

Great technology. If we combined this kind of tech with the same amount of effort on energy efficiency and reducing our usage overall we could probably manage never to invade anyone else for oil ever again.
posted by imperium at 9:32 AM on May 3, 2007 [1 favorite]

Keeping the mirrors clean seems to be the biggest challenge.
posted by stbalbach at 9:33 AM on May 3, 2007

Good stuff. Thanks, stbalbach.
posted by weapons-grade pandemonium at 9:46 AM on May 3, 2007

I'd love one of those in town center to power the downtown businesses. It would be a convenient landmark, plus we could worship it!
posted by The Deej at 9:47 AM on May 3, 2007

I would totally worship that thing. Say, wouldn't it work better if it were a giant black slab? [/Arthur C. Clarke]
posted by Mister_A at 9:59 AM on May 3, 2007

there's also this thing (solar one/two/tres) that's been around for quite a while...
posted by joeblough at 10:05 AM on May 3, 2007

DU: ...really, pointing at the sun is a simple problem of causing a shadow to disappear. Put an upright stick among some photocells. If the shadow causes one cell to go dim, tip the opposite direction. Pointing at a known offset from the sun is a simple matter of mounting your sensor at an angle.

Well, we can't all be PhysicsGenius.

My (admittedly limited) professional experience in industrial control systems leads me to believe that nothing like that is ever remotely as simple as you'd imagine at first.

Clouds during part of the day could leave mirrors stranded many degrees from the sun, for example. Dirt, bird poop, and spiderwebs interfering with each of 1,000 sun-tracking shadow-boxes would make for a huge maintenance headache. One centralized, sophisticated sun-tracking box sounds good - but would require a computer to figure out individual mirror positions and a network on which to distribute those results. Plant operators are likely to demand feedback on actual mirror positions, too, so the system can notify them when they're not pointing where they should be, for whatever reason, etc. etc.
posted by Western Infidels at 10:27 AM on May 3, 2007

Cost is the first big problem with photovoltaic solar, though it may be a temporary one. According to The Economist:

"Decades of research have improved the efficiency of silicon-based solar cells from 6% to an average of 15% today, whereas improvements in manufacturing have reduced the price of modules from about $200 per watt in the 1950s to $2.70 in 2004. Within three to eight years, many in the industry expect the price of solar power to be cost-competitive with electricity from the grid."

Full article (subscription required)
posted by sindark at 10:32 AM on May 3, 2007

Didn't the Mythbusters already do this??? Oh wait, they used theirs for EVIL!!!
posted by afx114 at 10:33 AM on May 3, 2007

nothing like that is ever remotely as simple as you'd imagine at first

Good point, but I'm pretty sure systems similar to the one I described have been in actual use. In particular, in the early 20th century there was a guy (can't remember his name, but he started out in Philadelphia) that had a commercial grade system that basically used this idea. You don't even really need any electronics--just the photocell, a motor and some wiring.
posted by DU at 10:34 AM on May 3, 2007

Nevada Solar One 64MW solar thermal project outside of Boulder City, NV. Came online last month.
posted by SirOmega at 10:48 AM on May 3, 2007

This thing is beautiful. Nobody will ever want it in their backyard. I was shocked when I heard people calling wind turbines "eyesores." People have no sense of aesthetic. But then again, I'm a mechanical engineer and have a certain fondness for quiet, efficient, streamlined things.
posted by SBMike at 10:57 AM on May 3, 2007

Am I a bad person for wanting to see the reporter burst into flames at the top of the tower?
posted by OverlappingElvis at 11:24 AM on May 3, 2007

It would be really neat if they could figure out a way to incorporate this kind of thing into city planning; You could stick one of these collectors in the center of town and use rooftops and mirrored buildings around it to provide it light.

Useful and cyberpunk.
posted by quin at 11:30 AM on May 3, 2007

I was out at a farm in Phoenixville, PA the other day. From the hillside I stood on, I had a gorgeous view of farmland, rolling hills, and -- the Limerick Nuclear Power Plant. Two large cooling towers that look like Central Casting's idea of nuclear power plant cooling towers should look like exhaled fluffy white clouds of vapor. The nuclear power plant is not the eyesore that a coal-fired plant might be, but all the same it is disquieting because those two iconic towers carry a lot of psychic baggage. What I'm saying is, I would love to have something like that in my backyard, especially considering the alternatives.
posted by Mister_A at 11:52 AM on May 3, 2007

I just read this story from 2005 about Bill Gross and a mini one of these called the SunFlower. He came up with a neat way of controlling all the mirrors with just one motor by placing them on bearings in some sort of curve (or something like that) anyway his points the beam at a photovoltaic.

His company which the article mentioned was about to go IPO is now public, SPWR and has just announced a 4.8MW project in Spain as well. Cool stuff.
posted by zeoslap at 11:57 AM on May 3, 2007

I was interested in the EnviroMission solar chimney. However, it looks as though the project has stalled out. Bummer.
posted by Mr_Zero at 11:58 AM on May 3, 2007

I was interested in the EnviroMission solar chimney. However, it looks as though the project has stalled out. Bummer.

Yeah, I was hopeful about that one too, but it doesn't look like it's going to happen.
posted by homunculus at 12:05 PM on May 3, 2007

This new idea looks promising. Thanks for the link, stbalbach.
posted by homunculus at 12:06 PM on May 3, 2007

The Enviromission chimmney pilot only produced 60 kW max, 30 kW average according to this video, an order of magnitude less than this newer one (11 MW)
posted by jacobsee at 12:18 PM on May 3, 2007

Keeping the mirrors clean seems to be the biggest challenge.
Been reading your Platform Sutra again, stbalbach?
Top link!
posted by Abiezer at 1:33 PM on May 3, 2007 [1 favorite]

All well and good. Now what do we do for electricity at midnight?

The big problem with this is the motors that move the mirrors. If you have a huge number of those, then statistically speaking a certain number of them will fail per month and have to be replaced, part of the ongoing cost of keeping a plant like this working.

The US uses electricity at an average rate of about 400 gigawatts. (Peak usage is much higher.) It would take 36,000 11MW plants like this to power the US... during the day. Which leaves the problem of electric power at midnight unsolved. Or on cloudy days.
posted by Steven C. Den Beste at 1:33 PM on May 3, 2007

I wonder how much energy they consumed to build it.
posted by moonbiter at 1:40 PM on May 3, 2007

It gets a lot more plausible if you make some kind of drive for energy efficiency at the same time though.

(There should be some kind of renewable energy FAQ I can point people to when they pull the "what happens if it isn't sunny/windy/tidey" type questions)
posted by Artw at 1:44 PM on May 3, 2007

“All well and good. Now what do we do for electricity at midnight?”

Did you ask that ironically, or did you not read any of the links?

Oh, wait:

“Which leaves the problem of electric power at midnight unsolved. Or on cloudy days.”

You didn't read the links.
posted by Ethereal Bligh at 1:49 PM on May 3, 2007

SCDB: Come on man, electricity use is at it's peak during the day. Can't you imagine how supplementing the existing grid with this to reduce reliance on radioactive waste producing coal plants might be a good thing? Might save large quantities of fossil fuels? Why are you so personally addicted to oil and coal? Use your imagination. I know you can do it.

Use these in the desert.
Turbines in windy areas.
Geothermal where practical.
Tidal forces on the coasts.
Nuclear where necessary and for high use areas.

There is no magic bullet, you use everything you have.
posted by IronLizard at 1:51 PM on May 3, 2007

I dunno, I kinda prefer the trough-concentrator style. If you use the Mojave Desert, 1000 acres = 350MW. But it definitely doesn't have the same visual impact as the solar tower approach.
posted by aramaic at 2:09 PM on May 3, 2007

electricity use is at it's peak during the day

Um, no, not always.
posted by Steven C. Den Beste at 2:35 PM on May 3, 2007

Holy shit, people don't use air conditioning in NY in January?
posted by Artw at 2:38 PM on May 3, 2007

Haha, good one scdb. You're absolutely right. The New Year party is wayyyy too important to consider such silly things as clean, renewable energy.
posted by IronLizard at 3:10 PM on May 3, 2007

The US uses electricity at an average rate of about 400 gigawatts. (Peak usage is much higher.) It would take 36,000 11MW plants like this to power the US... during the day. Which leaves the problem of electric power at midnight unsolved. Or on cloudy days.

Steven, don't you realize that mixing solar power and straw men could cause a fire?

It's really fortunate that we didn't start using coal, oil, or nuclear energy until we ironed out all possible objections. We could have flooded Bangladesh or something ridiculous like that. Whew!

This is like the guy who invented the water mill being told, well, it's nice, but you can only use it where there's water. Don't you have anything better?

In any case, this is not something presently proposed for the US, and I certainly haven't heard anyone propose that this could or should replace all power generation in the US, so it's just a really, really, really dumb example. If we're being nice.

In any case, this sort of alternative energy is something to be judged on qualities such as how close it approaches zero emissions, availability of unproductive land, average daily sunlight, and so forth.

Which leaves the problem of electric power at midnight unsolved.

They use passive heat storage, so they can actually generate power 24/7. It's ultimately supposed to generate 32MW, not the current 11MW, and is part of a complex that will be developed over several years that will eventually produce 300MW. And it's in Spain, where overall energy costs are higher than in the US, so the cost differential even for a pilot project is not as daunting.
posted by dhartung at 3:25 PM on May 3, 2007

I just want photovoltaic for my home, with maybe a nice wind turbine if I get a big plot of land away from the whiners. And a thorium reactor.
posted by adipocere at 5:06 PM on May 3, 2007

Which leaves the problem of electric power at midnight unsolved.
posted by Brian B. at 6:30 PM on May 3, 2007

I have no idea how effective this thing is, but as art it's superb. I want to go see it immediately.

Let's hope artw and fellow admirers lives near enough to Seville they can cycle or walk otherwise 'saving the environment' this way is all going to be a little counter-productive isn't it ?
posted by southof40 at 11:19 PM on May 3, 2007

I have a thousand or so square feet of flat rooftop that I'd love to use for solar collection.

Some day...
posted by five fresh fish at 11:21 PM on May 3, 2007

MetaFilter: You didn't read the links.
posted by homunculus at 11:46 PM on May 3, 2007

Every time I see a solar plant story, I am reminded that engineers didn't take enough biology classes. Evolution has brought us an amazing diversity of life on this planet that directly converts solar energy into biomass. Why is it we think we can design a more efficient solar energy collector than a leaf? Biomass has the advantage of having been engineered by evolution to work the best of all systems, is so diversified it exists to optimal performance in all climates, is often beautiful, is renewable, and traps carbon while releasing oxygen.

So, it still seems to me that a more likely source of energy from the sun is biomass. The trick is releasing the energy in a carbon neutral way. Burning is generally the way we release the energy of the chemical bonds, and when you burn you release CO2 - but when you regrow the biomass, you retrap it too. Then the issue is trying to retrap as much as you release, which is a concern....but it is not true that humans must be entirely carbon neutral. We must reduce our impact quite a lot, but not to the point of zero emissions.

Also, this new solar tower plant very pretty, but ultimately only one very small chunk of the energy problem could be resolved with something like this. For one thing, it seems a little odd to think one could put these all over African desert to power Europe (not to mention that, hmmm, someone in Africa might want the power). Aside from the massive loss of efficiency in such long transmission wires and the political issues, I don't see much about the environmental consequences of covering acre upon acre of desert with these things.
posted by Muddler at 2:32 AM on May 4, 2007

At night, we will release the 50 MW kites.
posted by NekulturnY at 3:44 AM on May 4, 2007

Your favorite operating emissions free power generation scheme sucks.

It sucks because it doesn't work 24 hours of the day, 365 days a year. Therefore we should stick with the polluting sources for all 24 hours of all 365 days of the year. No reason to incrementally improve, because if we can't do it all right now, there is no point in doing anything.

Or maybe I'm just the type of poster who has to come in to every thread to assert my intelligence, even if the opposite result is being accomplished.
posted by zhivota at 9:08 AM on May 4, 2007

Biomass has the advantage of having been engineered by evolution to work the best of all systems

Incorrect. Evolution is toward the good enough.

Look at your knees. Terrible design. But good enough.

Likewise, chlorophyll. Good, but not necessarily best.
posted by five fresh fish at 6:56 PM on May 4, 2007

“Evolution is toward the good enough.”

Yeah—and not just “good enough”, but “good enough for reproduction”. Evolution will result in many systems that we're not currently clever enough to surpass. Others we can. And those we currently can't, we probably will sooner or later. Most of our design constraints and goals will be different from what the selection pressures pushed an evolved system toward.

That said, the truth is that we're not currently that clever. Evolution has “solved” a lot of problems far better than we are able at present.

A really good book on biophysics and related engineering is Steven Vogel's “Life's Devices”.
posted by Ethereal Bligh at 9:59 PM on May 4, 2007