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Molten Salt-Based Solar Power Plant

Posted by ryuzaki0 on from the would-you-like-fries-with-that dept.

rcastro0 writes "Hamilton Sundstrand, a division of United Technologies, announced today that it will start to commercialize a new type of solar power plant. A new company called SolarReserve will be created to provide heat-resistant pumps and other equipment, as well as the expertise in handling and storing salt that has been heated to more than 1,050 degrees Fahrenheit. According to venture capitalist Vinod Khosla 'Three percent of the land area of Morocco could support all of the electricity for Western Europe.' Molten Salt storage is already used in Nevada's Solar One power plant. Is this the post-hydrocarbon world finally knocking?"

31 of 478 comments (clear)

  1. Pretty light on detail by AshtangiMan · · Score: 4, Informative

    Don't current adsorption chillers use solar heat/ molten salt? A pretty week summary but perhaps someone out there knows how this works . . .

    1. Re:Pretty light on detail by jcaldwel · · Score: 5, Informative

      I'm with you, I wanted more info. I found a page with a little more technical information about how this works: http://www-stud.fht-esslingen.de/projects/alt_energy/sol_thermal/powertower.html

    2. Re:Pretty light on detail by modecx · · Score: 5, Informative

      Metals can be a great conductor alright, but most aren't all that great at storing heat, especially compared to water, which has every metal beat to a margin greater than 5:1. At any rate, you misunderstand the purpose of the molten salt. It's there to move heat alright, but not entirely through heat conduction. Heat conduction is far too slow a process be used in a multi megawatt power plant. The molten salt is there because it's pumpable, so that it can quickly gather up a bunch of energy from the reflectors, and just as quickly dump it through conduction when the heat is used to make steam. Water is king, in terms of storing heat, unfortunately it turns to gas at a relatively low temperature. Fortunately, it can be stored under pressure, unfortunately the pressure goes up very much at very high temperatures, which makes containing it more expensive, more dangerous and generally harder to do.

      Heat engines also require a big temperature gradient to do work at high efficiency, which makes using steam directly a harder proposal. Molten salt is well understood in used as a coolant in some types of nuclear reactors, and it works well for this purpose, and that's why it's used.

      --
      Constitutional rights may be respected, repealed, or modified; but they must never be ignored.
    3. Re:Pretty light on detail by falconwolf · · Score: 3, Informative

      The molten salt is there because it's pumpable, so that it can quickly gather up a bunch of energy from the reflectors, and just as quickly dump it through conduction when the heat is used to make steam. Water is king, in terms of storing heat, unfortunately it turns to gas at a relatively low temperature.

      However in cases like the Nevada Solar One power plant, it's oil that is circulated through tubes and is heated. Then the heated oil goes through a heat exchanger where the heat is transfered to water which spins the turbines. Only if the heat can't be used right away will the heat be transfered to the salt, which stores the heat for later use.

      Falcon
      --
      Should there be a Law?
    4. Re:Pretty light on detail by ibbey · · Score: 4, Informative
      I suspect that this is the difference between this latest invention and the the current tech, though it's certainly not clear from the article. The January '08 issue of Scientific American covers this topic, and they say that one of the breakthroughs needed for molten salt solar is to be able to directly use the molten salt as the transfer fluid. The article doesn't go into a lot of detail on this topic, but here's the quote:

      Engineers are also investigating how to us molten salt itself as the heat-transfer fluid, reducing heat losses as well as capital costs. Salt is corrosive, however, so more resilient piping systems are needed.
      The article is available online, and I highly recommend anyone interested in solar check it out. They outline a plan that could provide 69% of the countries electricity & 35% of it's total energy from solar by 2050.
    5. Re:Pretty light on detail by Mark_MF-WN · · Score: 4, Informative

      The larger the plant gets, the more inefficient it gets.
      Actually, this the exact opposite of reality. Larger plants are vastly more efficient. Otherwise, all of the world's power would be provided by trillions of 500 milliwatt plants rather than thousands of 500 megawatt plants.

      Think about it -- these plants have to store heat; heat is proportional to mass, which scales as cube of diameter. Meanwhile, they lose heat at a rate that is proportional to surface area, which scales as the square of diameter. You need only the most basic math skills to see that this results in VASTLY better efficiency at larger sizes.

      But, no, I'm sure you're much smarter than... you know... the actual engineers and physicists who designed this plant. Or the people who built any of the nuclear plants that pump liquid salt to transfer heat. Those silly people, they've probably never even HEARD of using oil to store heat!

      Solar panels and cells are expensive to produce, and the process uses tremendous amounts of energy. After all, it requires producing perfectly pure silicon, not a trivial task. And a huge amount of waste is produced in the process.

      That's not to dismiss solar cells -- but we need to explore every avenue. And at the large scales where power plants become commercially viable, heat engines rule. Coal and gas-fired reactors, as well as nuclear plants, they're all just big heat engines. Heat engines have over two centuries of engineering research and development behind them. And Semiconductors just can't be produced in large enough quantities cheaply enough (yet).

  2. SciAm article by snaildarter · · Score: 2, Informative

    Yes, hot salty, um, fluid is real solution to the world's energy problems. There is an excellent article in Scientific American about it in the latest issue.

    http://www.sciam.com/article.cfm?id=a-solar-grand-plan

    Unfortunately, it will take massive investments to make this stuff really viable. Fortunately, some European governments are stepping up with real money. Unfortunately, America hasn't for about a decade.

    --
    Japanese scientist: Technically, sir, tomatoes are fags. Military scientist: He means fruits.
  3. Article reads like a business deal. by Kuukai · · Score: 5, Informative

    If you're more interested in the technology, try looking at this. It doesn't work "like a hydroelectric plant." (spinning a turbine doesn't = "hydroelectric") It simply uses an array of mirrors to aim sunlight at salt and heat it. The molten salt can then be used to steam water and turn a turbine, or saved for later.

    --
    Sendou Wave Kick!!
  4. Still limited by Carnot efficiency by compumike · · Score: 3, Informative

    Any system that does a thermal -> mechanical conversion is limited by the Carnot efficiency. This system would be limited by the temperatures of the hot side (sun's heating of the salt, balanced with losses from the pipes) and the cold side (presumably atmosphere or a cold river). In contrast, a solar cell directly rectifies electromagnetic field energy (light), so it doesn't obey the Carnot limit. That's why for a system like the one in this article, there's a need to push the operating hot-side temperature up as much as possible.

    --
    Educational microcontroller kits for the digital generation.

    1. Re:Still limited by Carnot efficiency by GameMaster · · Score: 2, Informative

      That will only matter if we actually manage to develop, and mass produce, photovoltaic cells that reach anywhere near the efficiency of traditional heat engine generator facilities at a reasonable price per watt over the life of the panel. Much like the fuel cell, we've had the photovoltaic technology for a very long time and have yet to produce any truly efficient products that weren't extremely high priced specialty items for things like satellites and such. It would be great if we manage to come out with an economical device, but past experience suggests that we shouldn't hold our breath for a major breakthrough anymore than we should for other similar technology such as fuel cells, fusion power, or Artificial Intelligence (all of which are perpetually X years away from becoming practical and X never seems to shrink).

      --

      Rules of Conduct:
      #1 - The DM is always right.
      #2 - If the DM is wrong, see rule #1
    2. Re:Still limited by Carnot efficiency by Rei · · Score: 5, Informative

      Huh? Have you compared what people were paying for solar cells back in the 70s to what they are now? And even today's prices are inflated by manufacturing shortages (the market isn't stable). If manufacturing actually met demand, we'd be paying about $3/W today, not $4.80/W. And this ignores CIGS production like NanoSolar's that's just now coming online. NanoSolar claims $1/W would still be profitable for them. The other CIGS manufacturers also (quite reasonably) anticipate very low production costs. Sure, indium is rare (about as common as silver), but you only need a tiny amount of it.

      As for the necessity of high efficiency, it's not neccessary. Even if just a small fraction of the world's urban area was paved with inefficient solar cells, it'd still power the world. I don't care to repeat this calculation yet again (I do it about once a month it seems), but look up China's total urban area (just China's) and do the math with 10% efficient cells (less than NanoSolar's) at, say, 20% coverage and an average 100W/m^2, then compare that to the entire world's electricity demand.

      As for what potential efficiency we're capable of, it's actually looking up. But not for CIGS -- for more conventional semiconductor cells, which aren't likely to be cheap enough to panel the world. We're up to a staggering 42.8% now (Honsberg and Barnett) -- and the record keeps growing at a rather surprising clip. And there's more potential for that number to keep growing up to 60-70% or so. There are three technologies pushing this -- the ability to get multiple electrons out of a single photon, the use of integrated beam splitters so that different parts of the cell can be optmized to specific parts of the solar spectrum, and the use of phosphor coatings that can be excited to release photons in a desired energy range. These technologies may not end up running our grid, but they'll be running our satellites, our malibu lights, our self-illuminated highway signs, and so forth.

      Back to the initial topic: Just to drive home the point as to how much photovoltaic prices have been dropping, let's put in some historical price points (in non-inflation-adjusted dollars):

      1956: Bell solar cell: $300/W .
      Early 1970s: Bergman's improvements lowers the price from then $100/W to $20/W

      Specifically (in 1994 dollars):
      1976: ~$51
      1977: ~$38
      1978: ~$27
      1979: ~$21
      1980: ~$18
      1981: ~$15
      1982: ~$14
      1983: ~$11
      1984: ~$11
      1985: ~$10
      1986: ~$9
      1987: ~$8
      1988: ~$8
      1989: ~$8
      1990: ~$8
      1991: ~$7
      1992: ~$7
      1993: ~$6
      1994: ~$6

      In non-inflation-adjusted dollars, solar prices were at a minimum in the early '00s (~4$/W, if I recall correctly), and rose up until this summer due to supply shortages, when they started to go down again. And with the CIGS companies, the prices can be expected to go down a lot over the next several years. Anyways, I really don't see how anyone can look at the numbers and act like solar hasn't been advancing by leaps and bounds since it was first turned from a laboratory curiosity into a commercial product in the '50s.

      --
      Next to my desk we have an Ire Extinguisher. Our boss is really assertive, so we like the idea of having it.
  5. Re:I know this is somewhat OT by MBCook · · Score: 2, Informative

    There WAS a liquid sodium reactor in the US. The seals in the cooling system seals started to fail leading to severe consequences. See Wikipeida.

    --
    Comment forecast: Bits of genius surrounded by a sea of mediocrity.
  6. Nothing new here. See Solar Two Mojave by John+Sokol · · Score: 3, Informative

    I will just dump a mess of links from an old E-mail I did on this some time ago. It's all good stuff, Solar two in Mojave was also molten salt based. I knew someone who bought it after it failed and got to explore it before it was partly dismantled.

    ---------

    Solar two was a flat mirror array.

    Search google image search with
                "solar two" Mojave

    http://maps.google.com/maps?f=q&hl=en&geocode=&q=yermo,+ca&ie=UTF8&ll=34.871919,-116.83416&spn=0.005915,0.010042&t=h&z=17&om=1

    Take the link above and zoom out, just below and to the right is a Parabolic glass mirrors plant

    http://en.wikipedia.org/wiki/Solar_Two

    http://www.powerfromthesun.net/Chapter10/Chapter10new.htm

    http://en.wikipedia.org/wiki/Image:Solar_Two_2003.jpg

    http://en.wikipedia.org/wiki/Image:Solar_Two_Heliostat.jpg

    http://theothersolar.com/?m=200702

    http://www.commondreams.org/headlines06/1101-10.htm

    http://www.global-greenhouse-warming.com/solar-central-power-towers.html

    http://www.ldeo.columbia.edu/edu/dees/U4735/projections/pitman/solar.elec.jpg

    http://fixedreference.org/2006-Wikipedia-CD-Selection/wp/s/Solar_power.htm
    (search for "Solar two")

    http://www.reia-nm.org/HTML_Docs/Solar_Thermal_Electrical.html

    http://greatgreengadgets.com/gadgets/category/solar/

    http://www.answers.com/topic/solar-thermal-energy

    http://blogs.business2.com/greenwombat/2006/week44/index.html

    Excellent page on many technologies - Sorry it's in Spanish.
          http://g3nergy.blogspot.com/2006_11_01_archive.html
          Search for "Australia to Build 154 MW Solar Energy Plant"
          This one is identical in design to the one in the Mojave Dessert here.

    http://ludb.clui.org/ex/i/CA4965/ Abandoned Solar Power Plant

    --
    I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso
  7. Re:I know this is somewhat OT by BlueParrot · · Score: 3, Informative

    To which he replied "This is what happens when sodium gets wet," and he threw a chunk of sodium into some water.


    Care to guess what happens when 300 C warm and radioactive water goes from 15 mega pascal to neutral pressure within a fraction of a second after a coolant pipe bursts? No matter if it is sodium or water primary coolant leaking is a Bad Thing (tm) , and sodium has the advantage that you don't have to keep it under pressure, thus reducing the chance of a leak greatly.

    In addition sodium is practically non-corrosive to steal, while boric-acid spiked water at 300 C is quite agressive. Sodium also has a much better heat conductivity than water, so the reactor won't melt down if the primary cooling pumps fail ( natural convection of the coolant is enough to cool the spent fuel once the chain reaction has stopped, as it will do due to thermal expansion of the fuel rods ).

    Having said this, my favourite candidate for coolant is molten-lead. Like sodium you don't have to pressurise it, it doesn't react with water or air, it won't boil even if you overheat teh ractor so much that the steel melts, and it is an excellent radiation shield against gamma-radiation. Main issue is corrosion, but 20+ years of research has produced alloys that are very stable in molten lead, so you could expect comercial plants using it within a deacde or two.
  8. Re:Danger Will Robinson! by MachineShedFred · · Score: 2, Informative

    While I'm sure your post was in joking fashion, Rocketdyne was the company who made the five F-1 motors in the first stage of the Saturn V.

    I know, I know... why ruin jokes with facts! Why, indeed - I'm an ass. That's why!

    --
    Slashdot still doesnâ(TM)t support Unicode after it was added to the HTML standard in 1997.
  9. O&M Expense by sphealey · · Score: 2, Informative

    Molten salt heat exchange technology isn't new, and has been tried in various forms of electric generating plant for at least 25 years to my memory (and probably a lot longer - they tried a lot of odd stuff in the 1920s and 1950s). The think to keep an eye on is projected operating and maintenance expenses over the long term. Molten salt is nasty stuff and does a lot of damage to everything it touches. Major components such as pumps have to be considered replacement rather than repair items for example. So the O&M cost projections are critical.

    sPh

  10. salt - water heat exchanger: tricky by smellsofbikes · · Score: 4, Informative

    Here is a shorter, and in my opinion, more informative summary. They're heating up sodium chloride salt, then using that to produce steam from water, which drives turbines. That's nice, because molten salt is fairly nasty stuff to work with.
    Anything has its chemical activity rise exponentially with temperature (the Arrhenius equation) so as things get hotter, they get more chemically aggressive. Molten glass will dissolve bricks and mortar. Molten sodium and chlorine ions are even nastier -- a sodium ion is a very small object, only a little larger than hydrogen -- and can diffuse into metals, weakening them and creating leaks.

    --
    Nostalgia's not what it used to be.
    1. Re:salt - water heat exchanger: tricky by smellsofbikes · · Score: 2, Informative

      They're using the sodium chloride as a thermal reservoir -- heating it and relying on its high temperature to make up for its so-so specific heat. Water's specific heat isn't much different, but it's difficult to contain as steam. So they heat up the salt -- or anything else -- and let it gradually cool down, extracting heat from it by vaporizing water and reclaiming the energy through turbines. That way they can produce power all night off the heat saved during the day.
      It's not a bad idea if they have a good insulated container for the molten salt. It introduces a lot of waste because of the cumulative inefficiency of heat transfer between the different systems, but it allows a system based on this to provide more reliable energy -- energy that's closer to being on-demand, rather than just when the sun is shining strongly enough.

      --
      Nostalgia's not what it used to be.
  11. Re:I know this is somewhat OT by Rob+Riggs · · Score: 5, Informative
    You admit that it's somewhat OT, but did you also know it's mostly BS?

    Two competing concepts for cooling nuclear submarine reactors were available, cooling by pressurized water and by liquid metal. Rickover wanted to try both of them, so he arranged with Westinghouse in 1949 to investigate the pressurized water approach, and with General Electric in 1950 to pursue a liquid sodium approach.

    Rickover's faith in nuclear submarines was vindicated in January 1955, when the USS Nautilus reported that it was underway entirely with nuclear power. The Nautilus employed the pressurized water method of reactor cooling. The Navy's second nuclear submarine, USS Seawolf, was powered by a reactor using liquid sodium.
    http://www.u-s-history.com/pages/h1857.html
    --
    the growth in cynicism and rebellion has not been without cause
  12. Re:Nuclear's the future. by soul_well · · Score: 2, Informative
    Not so. Solar is closer to meeting our needs than you may realize. Nanosolar has been in the news recently for producing its first runs of third generation solar panels. These are essentially printable sheets of foil that are cheap and easy to produce.

    The NYT quotes Nansolar's founder and CEO Martin Roscheisen saying, "With a $1-per-watt panel, it is possible to build $2-per-watt systems." That $2-per-watt figure comes from the Energy Department, the cost of building a new coal plant.

    source

    The future is here, and it isn't nuclear.

  13. Several liquid metal cooled reactors, actually by mbessey · · Score: 2, Informative

    The first US nuclear power reactor (EBR-1) was a liquid-metal cooled breeder reactor, as was the Fermi 1 reactor near Detroit, Michigan. The Fermi reactor had a minor meltdown accident in 1963. Overall, the safety record of liquid-metal reactors hasn't been particularly impressive, at least in the power-generation arena.

  14. Re:A few notes and questions by sholden · · Score: 5, Informative

    1. Solar cells are made from silicon, which carried in trucks and hence not carbon neutral. Every power source is not carbon neutral since it has manufactured components that were transported at some point. Of course once you have plentiful power from the nuke plants you might change that...

    2. It'd be mighty expensive but you could just mix it back with the non-uranium rock you dug out and put it back where you found it... A lot of that waste also isn't waste, it's fissionable material that politically isn't used (because doing so gives you plutonium easily used in weapons).

    3. In 20 years we'd run out if we just used uranium in nuke plants for all our electricity. Again allow breeding to plutonium and it turns into 2000 years...

    4. The top 5 known recoverable uranium holders are: Australia, Khazakhstan, Canada, USA, South Africa - they make up about 2/3rds of the total. From a Western world perspective, that's a much nicer set then the oil top 5: Saudi Arabia, Canada, Iran, Iraq, Kuwait...

  15. Re:Nuclear's the future. by jcaldwel · · Score: 4, Informative

    While I would love to believe some form of solar power would meet the world's needs, it simply isn't feasible with current technology.

    Much of the argument against solar is one of economics, but a company called Nanosolar has recently produced solar panels making energy more cheaply than coal. "Current Technology" is a moving target.

  16. Re:Nuclear is not the future.. by AJWM · · Score: 4, Informative

    so you need a lot of high quality ore to get fuel in an expensive and energy intensive process (eg. heat a heavy metal all the way to a gas and centrifuge it).

    Um, no. You only need to do that if you're planning on building bombs. (And anyway, gas centrifuges don't heat the uranium to a gas but chemically convert it to uranium hexafluoride before centrifuging.)

    There are plenty of reactor designs that run on unenriched uranium, including most of the nuclear power plants in Canada (CANDU) and places to where Canada has sold reactors.

    --
    -- Alastair
  17. Re:Nuclear is not the future.. by AJWM · · Score: 2, Informative

    and requires the heavier isotope

    Oh, and actually it's the lighter isotope (235 vs 238) that's the one of interest.

    --
    -- Alastair
  18. Re:A few notes and questions by Rei · · Score: 2, Informative

    Where are you going to get the power to charge the batteries in 10 minutes?

    Wow, there are still people out there asking this question? It's really, really simple. There are three ways to charge.

    1) Slow charge overnight. Anyone can do this without any specialized hardware.
    2) Fast charge at gas station. Truck stops already have a lot of power going to them, as do many gas stations, and few would hestitate to upgrade their wiring if it adds another revenue stream.
    3) Fast charge anywhere using a fast charger. The same batteries used in your vehicle can charge your vehicle. They slow charge from the wall, and when you plug in, they charge your vehicle. While it's an extra purchase cost, it also provides further advantages: A) automatic grid power load balancing (a favorite of power companies), and B) home backup power

    Even if the battery technology was here today, the power distribution infrastructure isn't, and isn't on its way either.

    Yes it is, and yes it is (and why don't people look this up first?) Let's do the math: the average car goes something around 40 miles a day. EVs are typically 120-200Wh/mi, so that's 4.8-8kWh/day. Let's go with the high end, 8. That's 240kWh a month. At 10 cents per kilowatt hour, that's $24 a month. Compare that to your monthly power bill, and notice something? Your existing power usage almost certainly dwarfs that which would be used by an EV, especially in the summer (midday during the summer most accurately reflects our generation baseline). Even if you merely use 20% less power at night during the day (as opposed to the more typical usage of several times less power at night than during the day), that right there is enough to charge your vehicle.

    Even if this *wasn't* the case, it's much easier to build power generation and transmission infrastructure than it is to replace aging oil infrastructure and develop new fields, so it's a rather dumb argument to make to begin with.

    You didn't even discuss range, yet claimed that it will remain insufficient without any evidence to counter what I wrote. No surprise there.

    --
    Next to my desk we have an Ire Extinguisher. Our boss is really assertive, so we like the idea of having it.
  19. Re:sun renewable? by Urkki · · Score: 2, Informative

    No she was not right. A renewable resource is one that we humans can currently cause to be renewed through our own actions. For example when we harvest plants we can plant new ones in their place. Wind, hydro, and solar power all come from the sun. And just where do you think the energy for the plant to grow (form organic molecules for structure and energy storage) comes from?

    There is no *real* renewable energy, laws of ethropy make that an impossible thing. A perpetual motion machine is impossible (as far as we know). That's why "renewable energy" means something else, basically an energy source that is not permanently depleted by us humans using it.

    It's a bit of a definition issue really. For example there is some controversy wether peat should be considered renewable or non-renewable, as it takes hundreds or thousands of years for a peat swamp to accumulate. Still, if you count all the peat accumulated over a year, you can harvest an awful lot of it without taking more than is accumulated back.

    So the teacher was right, but apparently she was unable to explain or understand the conecpt properly, which isn't very good either.
  20. Re:sun renewable? by Urkki · · Score: 2, Informative

    The energy for the plants comes from light of course, but it doesn't have to come from the sun. Any light source emitting the appropriate wavelength(s) will do. Resource have other uses then energy such as lumber, paper, thread, drugs, etc. If we ever figure out controlled sustainable fusion we'll no longer be dependent on the sun as our primary energy source. I also didn't say that renewable resources were infinite, I merely said that we currently have the ability to replace those that we use which is something we can do for coal and oil but not for the sun. I'm not sure I understand what you are trying to say...

    Synthesized oil or coal are not energy sources, they are ways to store energy. Energy for the synthetication must come from some actual energy source. Fossil oil and coal are energy sources for humans, but they are non-renewable because more of them will not appear from anywhere (not in human time-scales anyway), and they get less and less as we use them. And even though the energy for the fossil fuels came from the Sun, we are harvesting it from the fossil fuel, so the fossil fuel is considered to be the energy source for us (and same with wind power etc), even if it is originally the Sun's energy (which is originally energy from the Big Bang, which got it's energy from nobody-really-knows-where).

    Also, plants grown with other than sun light aren't energy sources. Then the energy source is whatever is used to power the artifical lights for growing them.

    Fusion energy will not be renewable either, because the more we use it, the less of it there is left. There's just so much of it (except usable reserves of the "ultimate fusion fuel", Helium-3, may be limited within our solar system) that we won't run out.

    Sun's enegy output is the only known renewable origin of energy in our solar system, because it doesn't matter if we use it or not, there won't be any more or any less of it left, no matter how much solar energy we collect. Also, any energy source that uses the Sun's energy and grows/accumulates back in human time-scales, is considered renewable, such as wind or naturally (without non-renewable fossil fuel based fertilizers) grown biomass. They "come back" quite fast, and if we use it at most at that rate, we will never run out.
  21. Re:Nuclear is not the future.. by Anonymous Coward · · Score: 1, Informative

    You've got it backwards. Wind and solar can't provide capacity for peaks. Well, solar sort of can since a lot of industrial activity goes on during the day, but in general solar and wind can't be turned on by the flip of a switch to match a peak in usage. Something that can take care of those peaks is hydroelectric. That's how the supply is regulated on for example the Scandinavian grid, where only the hydro plants have their output regulated by the frequency on the grid. All other power plants are used in an on/off way, outputting as much as they can whenever they are in operation.

    Some people think that wind has no place on the grid since it will fail to provide any power in the statistically impossible scenario where the wind isn't blowing anywhere in for example all of Europe. But that's of course a crackpot argument. If you build wind generators all over a continent you will have power all the time. Not getting enough power? Just build more generators, and on windy days you use the excess power to make hydrogen for cars and other off-grid energy using devices. While the variations in power output of solar/wind/tidal plants is a distinctly non-trivial problem, the pieces of the puzzle are known and the problem is certainly solvable.

  22. Correcting misunderstandings in parent post by Eivind+Eklund · · Score: 2, Informative
    We can deal with the production of power in the day and consumption at night by using power storage. This can presently be done at about 80% efficiency, through the use of water storage (you pump water up into a reservoir when you have surplus power, and release it when you need to draw power).

    The difference in consumer voltage between Europe, Japan and the US is a non-issue - we transport electricity at a much higher voltage, and then transform it down close to the point of use. The same isn't quite true for frequency - it is synced at 50/60Hz in the grid - but there are production facilities in operation that produce it at a different frequency and convert it to the grid frequency using a frequency changer. You can read more about in Wikipedia's utility frequency article.

    The main problem with interconnecting the continents is the power loss associated with long distance transmission. As far as I understand, this makes interconnection impractical at the moment - local storage (as in the reservoirs described above) being more economical. Superconductors may some day change this.

    Eivind.

    --
    Doubting the existence of evolution is like doubting the existence of China: It just shows that you're uninformed.
  23. Re:Nuclear is not the future.. by Phanatic1a · · Score: 2, Informative
    The French, who have come the farthest in reprocessing, are finding out it's not as simple to reprocess as many would have you believe. IEEE's magazine "Spectrum" has a good article on this: "Nuclear Wasteland"

    That article doesn't support what you claim.

    The French experience clearly does show that reprocessing need not be the dangerous mess that other countries, including the United States, have made of it [see photo, "Blue Glow of Success"]. The U.S. military used reprocessing for several decades to separate plutonium from spent fuels, providing fissionable material for bombs. The result was widespread contamination--which has been in some cases irremediable--in the central Washington desert and the South Carolina coastal plain.

    France, in contrast, now reprocesses well over 1000 metric tons of spent fuel every year without incident at the La Hague chemical complex, at the head of Normandy's wind-blasted Cotentin peninsula. La Hague receives all the spent fuel rods from France's 59 reactors. The sprawling facility, operated by the state-controlled nuclear giant Areva, has racked up a good, if not unblemished, environmental record.

    [...]

    Nevertheless, although it may be safe to proceed with reprocessing, France's experience suggests that reprocessing as done now is not ready to catalyze a full-blown nuclear renaissance. The problem in a nutshell is that without breeder reactors, which can break down the most long-lived elements in nuclear waste, reprocessing comes nowhere near achieving Finck's 100-fold reduction in that waste.


    It's not the reprocessing that's the problem, it's the lack of economical breeders. More research into things like the IFR is most definitely called for.