World's Largest Solar Array to use Stirling Engine

An anonymous reader writes "Stirling engines are not a neglected or forgotten technology after all, according to a story at PESN. With 20 years of in-the-field fine-tuning, Stirling Energy Systems is now ready to go big -- real big. They signed a purchase agreement Tuesday with Southern California Edison (SEC), to install a 20,000 dish array that will cover 4,500 acres and will be capable of generating 500 megawatts of electricity -- more than all other U.S. solar projects combined -- making this the largest solar installation in the world. Each collector has a 37-foot-diameter array of mirrors to focus the sun's rays on the Stirling engine, which turns the heat into rotational torque for electricity generation. According to a spokesperson for SCE, this purchase will be in their commercial interest, requiring no subsidy in order to compete, implying that the efficiencies of the technology will give them an edge in the market."

Comments

Good

[RandUser]

I'm glad to see alternative energy sources being developed, I just wish public opinion would change faster so we can get some more nuclear plants as well.

Re:Good

[magarity]

As long as they're pebble bed reactors, I'm all for it. The hugemongous three mile island style are white elephants in comparison.

Re:Good

[MyLongNickName]

If gas hits $3/gallon, and stays there for a year, the American public will accept anything. While I cringe when I have to buy gas, I hope the price keeps going up. Maybe then, we will have the economic incentive to kick the oil habit.

Re:Good

[norwoodites]

Let see, it is about $5/gallon in the UK and the US is complaining about $3/gallon wtf. This is just under estimate too because I am converting from £ to $ and liters to gallons.

Re:Good

[Rei]

Yeah. Because everyone wants a nuclear reactor that combines the wonderful properties of graphite (see "The graphite fire" subsection) as a moderator, with water (graphite generates explosive hydrogen with high temperature steam) often in the primary or secondary cooling loop (helium is the primary coolant), with safety features such as no containment structure (this list is just a start - there's many times more that didn't make the list)

Yes, PBMRs have a negative void coefficient (reaction slows as temperature increases); big deal, so does almost every reactor build in the west in the past three decades. Yes, helium is the primary coolant; that doesn't help when there's a jam or corrosion that leads to a rupture, in which case water and/or air enters the chamber (a much hotter chamber than PWRs) - and yes, this has already happened. Containment structures have saved our collective arses from the unexpected too many times to be omitted.

PBMR proponents talk about safety, but they're really about reactor cost. They're hardly the only innovative reactor design out there, but they're apparently the only one that your average slashdotter knows about. There are thorium breeders, reactors that run on unenriched fuel, and designs like my favorite, BREST - a lead-bismuth breeder which can cool itself with natural convection, uses the ground as shielding, has the fuel naturally encased in lead, and unlike most breeders, uses no liquid sodium.

As an aside, we really should move to safe breeder designs, either thorium or uranium based.
U-235 is only 0.7% of natural uranium, and natural uranium isn't incredibly plentiful in deposits concentrated enough to justify mining (I read once that known deposits would supply the world at current power consumption for only a few hundred years). It's a shame that most U-238 goes to waste (yes, some is used in things like armor, bullets, and weights, but we produce far more of it than is used for such tasks)

Re:Good

[Ironsides]

I'm not sure why the lack of interest in pebble beds, but I'm guessing they need some political pressure...

As I understand it, the pebble bed nuclear reactors make it really hard to re-enrich the uranium after usage. This is a bad idea as re-enriched uranium can be reused and produces less radioactive waste in the long run. All we have to do to solve the reenrichment problem and a large part of our nuclear waste is to build a fast breeder reactor and start recycling the used material.

This was the original plan when nuclear power plants were first developed. President Carter used execuitive order to ban fast breeder reactors back in the 70's, so it wouldn't take much to undo that ban.

Re:Good

[Danger Stevens]

But the big argument against all-electric (also called gas-optional) cars is that the electricity has to come from *somewhere* and coal plants aren't much better than combustion engines.

If the grid runs off clean and safe nuclear, cars can run of batteries.

Re:Good

[Rei]

1. There is a big debate over the graphite's role in Chernobyl. The Soviets who put out the fire were insistant that the graphite was burning - they even had debates over how to put out the burning graphite without encouraging faster burning or secondary reactions. Nuclear professionals in America are insistant that nuclear grade graphite only erodes - that it doesn't burn - and lab tests of fresh graphite hold this out. Even simple erosion of radioisotope-laden graphite would be awful, of course (especially in this case where the graphite is in direct contact with the nuclear reactants and daughter products), but it's hard to deny the Soviet field reports. In all likelyhood, fresh nuclear-grade graphite doesn't burn well, but after it is bombarded by high energy radiation and corrosive chemicals for long periods, it does.

2. There *Is* water in the system of most PBMR designs. As I stated, helium is the primary coolant; however, some use water as a secondary coolant in the core (such as China's design), and even some designs that don't use it in the core have a secondary loop in which water is pyrolized into hydrogen and oxygen.

3. "seven layers of containment". Um, yeah right. There's only one pressure-tight containment level in PBMRs. The graphite isn't pressure tight - it's just a coating, and one that gets highly contaminated in the process. The reactor vessel and associated helium loop and pellet recycling are pressure tight. Unlike most nuclear reactors, the reactor building is not a positive pressure structure.

4. "Without the helium moderator the chain reaction stops". This is called "a negative void coefficient", and it's nothing remotely new. Three mile island had a negative void coefficent too. The problem is that the reactor core, even if *all* reaction were to cease, still has a huge amount of heat inside of it, and this residual heat is what poses the threat. By the way, helium is not a moderator - graphite is. You'll note that in demonstrations, the only thing that they demonstrate is shutting down the helium coolant - they never violate the integrity of the pressure vessel. This is because oxygen (and even potentially water or steam) can get in, and this can have very serious consequences. And, without a containment structure...

5. "Gas moderated reactors are a means to make Thorium breeders" - Once again, the term is "gas cooled", not "gas moderated". Do you even know what a moderator is?

Re:Good

[Squalish]

I've been convinced after doing some research that the likelyhood of the geiger counter becoming a whole lot more active very quickly is greater in the struggle over the last few oil fields than it is from waste plutonium.

Re:Good

[richie2000]

Frankly, I've always thought that Carter's moves on energy were irrational and borderline cookoo given that he and I attended the same nuclear power training several decades appart.

Maybe you never had the misfortune of having to clean up after a nuclear accident? And maybe he had access to a lot more information about these accidents than you or I ever will? I dunno, that's why I asked if anyone knew why he banned breeders. Apparently, it was an attempt to hinder proliferation of weapons-grade plutonium, a subject I suspect never came up in your nuke power training...

Cite source for clean-up as the Navy had not yet had one accident by the time he was discharged. To this day, we are still waiting for a screw up.

I never said it was a Navy screwup. Non-Navy screw ups galore.

December 12, 1952 - The first serious nuclear disaster occurred at the NRX reactor in Chalk River, Canada. A massive power excursion destroyed the core, resulting in a partial meltdown. A series of hydrogen gas explosions threw a four-ton gasholder dome four feet (1.2 m) into the air, where it jammed in the superstructure. Thousands of curies (several terabecquerels) of fission products were released into the atmosphere, and a million US gallons (3,800 m) of radioactively contaminated water was pumped out of the basement into shallow trenches not far from the Ottawa River. The core was buried. Jimmy Carter, then a nuclear engineer in the US Navy, was among the cleanup crew.

Say "no" to Solar

[Anonymous Coward]

While the solar panel industry would like you to believe Solar Power to be "eco friendly", unlike most "alternative energy" technologies, Solar energy is not a renewable resource. We have a limited amount of sunlight and increased use of commercial solar power would mean less to be used elsewhere, potentially creating an ecological disaster if this happened on a large enough scale. The solar industry likes to throw around statistics about how the entire U.S. could entirely move over to solar power if we created such-and-such amount of solar panels, but what they don't mention is if we did this we would completely exhaust our supply of solar energy by 2150.

Use of solar power should be avoided at all costs. Help promote renewable energy sources instead.

http://nosolar.net/

Re:Say "no" to Solar

[Vombatus]

We have a limited amount of sunlight

But, if you save some of that daylight http://it.slashdot.org/article.pl?sid=05/07/20/195 7200&tid=103&tid=185&tid=218, you would have more to use.

Re:4500 acres?

[uberdave]

Counting or not counting the uranium mines, heavy water refineries, and spent fuel storage facilities?

space power on earth!

[J05H]

Sterling engines are pretty cool. They have one huge advantage over silicon solar power: much much less pollution in production. Photovoltaics are basically large chips, they use the same nasty chemicals and lots of electricity. Sterling engines are just machines, and very scalable apparently.

Funny that one solar-dynamic powerplant will double the solar power being utilized.

One of the Sterling engine makers has a deep-space powercell that combines a sterling converter and a big hunk of plutonium oxide. Man, I wish I could get one for the basement...

Josh

4500 Acres Sounds Like a Lot

[yrogerg]

but for the record: 4500 acres is only 7 square miles.

It sounds a lot smaller when you put it that way.

OK, so what's the catch?

[Bryan Ischo]

I know some knowledgeable Slashdot reader can help me here. What I want to know is, what is the drawback to such a power system? It sounds like it generates quite a bit of power, and looks like a completely clean source. Are these things super expensive to build? Is it really hard to keep these things lined up with the sun to produce optimal power?

There is the issue of not being able to produce any power at night. But intelligent use of battery stores along with some supplemental traditional powered generators might take care of that, especially since power draw from the grid is (I'm guessing) much less at night.

So - what's the catch? Why aren't fields of these things going up like crazy?

Re:OK, so what's the catch?

[aktzin]

Wikipedia to the rescue:

http://en.wikipedia.org/wiki/Stirling_engine#Probl ems_with_Stirling_engines

Pseudoscience?

[rdwald]

Stirling engines seem legitimate enough, but the linked site describing them seems somewhat crack-potish. They promote cold fusion and zero point energy, as well as a number of "alternative energy sources" I've never even heard of. There's also a page trying to disprove the Peak Oil theory, which should be real popular with the Slashdot crowd. Anyway, I sometimes wish that /. nerds had a greater understanding of the pure sciences, rather than just software engineering. Oh well.

Re:Not surprising

[inode_buddha]

I've seen people take the old 6-foot TV dishes and mirrorize them, either with silver paint or glueing a zillion tiny glass mirors onto them. Mother Earth News did a project like that back in the 1970's IIRC. The heat near the focal point was in the thousands of degrees F and powered a small energy-efficient home.

Re:Stirling engines

[apa666]

The only drawback is they lose some of their stealthyness due to the giant solar reflector beaming sunlight down the periscope.

Re:Environmental loop...

[syphax]

OK, here are some notes on this:

1. It's not like you are covering 4500 acres (that's 7 sq. miles) with solid concrete. The actual footprint of these dishes is fairly small; the main impact will be the amount of sunlight hitting the ground. judging from the area, this may not be such bad thing. Shade for the desert tortoises and the like.

2. It's reasonably scalable. Using SGS's numbers, and being conservative, let's say these things can crank out 400 kWh/m2 per annum. At 2004 US electrical consumption of roughly 1.2 trillion kWh (source: EIA), you're talking about needing ~30 billion sq. m. of collectors, which is about 12,000 square miles, to supply 100% of current electrical needs. You could fit that in about 5% of Texas- not an insignificant amount of land, but doable (you don't have to have all the collectors in one place, and you can probably install them on under-utilized land- say, parking lots- just jack up the collectors a few feet to provide SUV clearance).

So although I'm sure some people will get bent out of shape, I don't see the land area requirements as a big deal. If these things are truly economically competitive, as the article suggests, watch out.

Re:Stirling engines

[aktzin]

The nice folks at Kockums (a division of ThyssenKrupp Marine Systems in Sweden) set up this web page in English with a cutaway view and diagram:

http://www.kockums.se/Submarines/aipstirling.html

A couple of good reasons...

[Goonie]

I can't find the reference, but part of the problem is that the US nuclear regulatory regime is designed around the assumption of monolithic, large light-water reactors. The idea of a modular system where you can add another reactor module quickly doesn't fit in with the approval process, removing one of the biggest advantages.

Secondly, US companies aren't developing PBMR designs; South African and Chinese ones are. Funnily enough, the subsidies for nuclear R&D and deployment currently floating around Washington are aimed at the American nuclear power industry, not its foriegn competitors.

Mind you, if Westinghouse's cost estimates on its new AP-1000 power plant design turn out to be it's going to be pretty competitively priced anyway. Pebble beds aren't the be-all and end-all. One concern is whether there'll be enough helium available to run them...

Cheap Parabolic Dishes (in a relativesense)

[Redge]

A company in Australia is developing this type of technology for self-contained power generation in remote locations (and 3rd world countries/natural disaster areas). They are using a parabolic dish made from mirror polished bands of stainless steel. Stainless steel (while expensive) stands up to bad weather much better than glass mirrors - and by making the dish with bands (with gaps in between them) you reduce the effect that wind had on the dish.

They are making a dish that isn't affected by wind (except for wind that flattens buildings) doesn't get damaged by hail (unless it's bigger than a cricket ball) and is only 5% less efficient than the same size mirror dish. They don't have a website worth mentioning - but they are developing all this in conjunction with the CSIRO - so you may find something here (CSIRO) http://www.csiro.gov.au/ about it all. Look for Sterling engine power generation. The CSIRO did publish something recently in a subscription only publication about this.

In case you were wondering how I know - my brother works for the small electronics firm that came up with the parabolic dish idea. They have also come up with a sun tracking mechanism that costs $15 to manufacture.

Pity a 5KW generation system costs $25000 all up - but they expect it to last for 25 years or more.

All dollar figures here are Australian Pesos.

Oh yeah - they get around the "How do you generate electricity at night without sunlight light" issue, by using the dish to heat up 300KG (or so) of salt and graphite - which then acts as a heat battery. Apparently they can run the Stirling engine for 3 days or so after the Salt Cell gets to about 900 degrees centigrade.

The standard anti-nuclear answer. How smart!

[Draveed]

The reactors at Chernobyl are not the same design of any reactors built in the US. So there's no point in bringing it up unless you just want to scare people.

And the fears over Three Mile Island are just plain ignorance. It was a minor incident that didn't hurt anyone. Don't believe me? Too bad. The Pennsylvania court system does. After years of litigation, the courts ruled there isn't enough evidence anyone was harmed by the accident to support even going to trial.

My favorite quote is, "The court has searched the record for any and all evidence which construed in a light most favorable to Plaintiffs creates a genuine issue of material fact warranting submission of their claims to a jury. This effort has been in vain."
Here's a link to the ruling - Click Me