Forgot your password?
typodupeerror
Power Science Technology

Can World's Largest Laser Zap Earth's Energy Woes? 372

Posted by samzenpus
from the what-could-go-wrong dept.
newviewmedia.com writes "Scientists at the Lawrence Livermore National Laboratory plan on using a laser the size of three football fields to set off a nuclear reaction so intense that it will make a star bloom on the surface of the Earth. If they're successful, the scientists hope to solve the global energy crisis by harnessing the energy generated by the mini-star."
This discussion has been archived. No new comments can be posted.

Can World's Largest Laser Zap Earth's Energy Woes?

Comments Filter:
  • bad journalism (Score:5, Informative)

    by QuantumG (50515) * <qg@biodome.org> on Thursday April 29, 2010 @08:01AM (#32028244) Homepage Journal

    The National Ignition Facility is not doing research into energy production. The research they're doing will not have applications in energy production. The hope is that by understanding ignition other nuclear fusion projects will be able to make better progress.. it is completely pure research, as you would expect from a national laboratory.

  • by ShadowRangerRIT (1301549) on Thursday April 29, 2010 @08:09AM (#32028316)
    And for the record, it's been a hell of a lot longer than 20 years that fusion power has been 10 or 20 years away. I think the first promises of that sort appeared around 1950.
  • by Tomsk70 (984457) on Thursday April 29, 2010 @08:30AM (#32028460)

    http://news.bbc.co.uk/1/hi/8485669.stm [bbc.co.uk]

    Slashdot has gone down in my estimations, if the best source they can find is CNN :-(

  • Re:bad journalism (Score:4, Informative)

    by Yvanhoe (564877) on Thursday April 29, 2010 @08:30AM (#32028466) Journal
    From https://lasers.llnl.gov/about/nif/ [llnl.gov]

    The resulting fusion reaction will release many times more energy than the laser energy required to initiate the reaction.
    Experiments conducted on NIF will make significant contributions to national and global security, could lead to practical fusion energy, and will help the nation maintain its leadership in basic science and technology.

    The goal of this kind of experience is geared toward energy production. Granted, this is not a prototype power plant, but one could consider the lasers used there as a prototype for elements of a power plant.

    The summary also is funny in how it understates achievements of fusion research. I remember a physicist saying "The Sun ? Pfah ! Too cold and too inefficient ! If we were to reproduce the conditionss in the sun, we would never get anything that would interest industries !"

  • Re:bad journalism (Score:5, Informative)

    by pedestrian crossing (802349) on Thursday April 29, 2010 @08:35AM (#32028498) Homepage Journal

    I remember a physicist saying "The Sun ? Pfah ! Too cold and too inefficient ! If we were to reproduce the conditionss in the sun, we would never get anything that would interest industries !"

    Indeed. From Wikipedia:

    The energy production per unit time (power) produced by fusion in the core varies with distance from the solar center. At the center of the sun, fusion power is estimated by model to be about 276.5 watts/m3, a power production density which more nearly approximates reptile metabolism than a thermonuclear bomb. Peak power production in the Sun has been compared to the volumetric heats generated in an active compost heap. The tremendous power output of the Sun is not due to its high power per volume, but instead due to its large size.

  • by Dr_Barnowl (709838) on Thursday April 29, 2010 @08:40AM (#32028542)

    Despite it's earlier mention in the thread, I have to take the opportunity to point out that Focus Fusion [focusfusion.org] involves a reactor design that extracts power from the reaction via 2 routes ;

    • Direct induction of current by a stream of helium ions
    • Gamma-voltaic collector

    Both of which are very much more direct than steam generation. I believe the reaction has plenty of waste heat which could be used industrially as well.

  • Units of Measure (Score:3, Informative)

    by halcyon1234 (834388) <halcyon1234@hotmail.com> on Thursday April 29, 2010 @08:47AM (#32028614) Journal

    ...a laser the size of three football fields...

    That tells us nothing without a measurement of density. How many Libraries of Congress worth of energy can those three football fields produce?

  • by Anonymous Coward on Thursday April 29, 2010 @08:49AM (#32028634)

    You need several solar masses to make a supernova. You absolutely can't do it with a terrestial reactor.

  • by ewg (158266) on Thursday April 29, 2010 @08:54AM (#32028694)

    Obligatory link to Edward Teller's article "Can We Harness Nuclear Fusion in the '70s?" in Popular Science magazine, May 1972 edition.

    http://www.popsci.com/archive-viewer?id=VvyLShXydNgC&pg=88 [popsci.com]

  • by da cog (531643) on Thursday April 29, 2010 @08:55AM (#32028708)

    By "mini-star" they just mean a brief fusion reaction that is expected to last for a fraction of a second --- if for no other reason then there is only a limited amount of fuel available to it.

    Also, the way in which many of those involved ultimately intend to use this is not to create a reactor drawing power purely from fusion but rather to create fusion/fission hybrid reactor in which neutrons from the fusion reaction drive fission reactions in nuclear fuel that would not become critical by itself --- i.e., so we can burn things like nuclear waste and thorium. Such a reactor would be intrinsically fail-safe because when fuel pellets stop being dropped into the reactor and ignited by lasers into "mini-stars" (which, again, is something that needs to be done continuously --- several times a second --- since the "mini-stars" burn up all their hydrogen fuel so quickly) then eventually the whole thing shuts down on its own.

    In other words, this is completely unlike the ridiculous and highly implausible fusion reactor featured in Spider-Man 2 which had the magic power to sustain itself by eating everything around it --- which, incidentally, is a power that even our own *actual* sun doesn’t come close to having, since it can only burn its limited supply of hydrogen fuel.

  • by lxs (131946) on Thursday April 29, 2010 @09:03AM (#32028806)

    That's called the Leidenfrost effect [youtube.com].

  • by Dr_Barnowl (709838) on Thursday April 29, 2010 @09:12AM (#32028928)

    This article concentrates on Deuterium-Tritium fusion, and I agree with it in that context.

    Most of the concerns are addressed by the design of a DPF reactor.

    withstand temperatures of millions of degrees for years on end

    That's just FUD, I'm afraid. Even in tokamak reactors, the plasma is kept separate from the reactor vessel. The plasma is at millions of degrees ; the reactor vessel is not. In a DPF reactor, the plasma is a teensy little 12 microns across - even if the contents are running at about a billion Kelvin, they won't heat the reactor vessel to millions of degrees. The reactor is also designed to emit most of it's energy through non-thermal vectors.

    constantly bombarded by high-energy nuclear particles

    True, in a DT reactor. Not so true in a pB reactor - the reaction produces helium and electrons, not neutrons.

    has to make its own nuclear fuel

    This one is the big winner. As they rightly noted, tritium is one of the rarest elements on Earth. A pB reaction uses no tritium, it uses common or garden "normal" hydrogen, and boron, an element that's abundant enough to sell as eyewash.

    no outages, interruptions or mishaps—for decades on end

    When a 1 GW reactor goes offline, yes, you have a shortfall problem. When the proposed 5MW output DPF reactor goes offline for it's routine maintenance (for about 12 hours), you just lean on the others you have running. Lots of small, local, redundant reactors the size of shipping containers make for more reliability than a few whacking great behemoths the size of aircraft carriers. When they cost $300,000 instead of $10,000,000,000, you can afford to pile them high, and sell them cheap.

    must also convert energy from the neutrons into heat that drives a turbine

    The design is intended to use 2 methods of direct energy collection that are not heat engines, a more elegant and efficient solution that places it closer to "power plant" break-even.

    At least they report the purpose of NIF correctly, albeit couched in soft language - it's about "National Security", not energy generation.

  • Re:bad journalism (Score:5, Informative)

    by Anonymous Coward on Thursday April 29, 2010 @09:12AM (#32028932)

    If by "pure research" you mean "nuclear weapons research," then you are absolutely correct. I am a nuclear physicist who has done some work for the NIF project. This is a big make-work project for otherwise the otherwise unemployed nuclear weapons establishment. We don't explode nuclear weapons at the Nevada Test Site anymore, but DOE wants to make sure that we can be confident that our aging stockpile of warheads will continue to operate.

    Part of the project's justification is its potential use as a scientific user facility. A big pulse of 14 MeV neutrons could be valuable for all kinds of nuclear science experiments. But that's a sideshow. Another part of the project's justification is the potential of inertia driven fusion as an energy source. To get a 600 MWe power plant out of NIF, you'd have to implode a capsule something like 10 times per second. That would involve dropping a stream of target pellets into the chamber and having the lasers target them, and hit a falling object simultaneously. Right now, the targets are individually placed at the precise center of the chamber and the lasers are fixed to aim at that point. NIF will fire perhaps twice per day once they get the bugs shaked out, and the laser people convince themselves that the lasers won't destroy themselves each time they are activated.

    Assuming we can overcome those hurdles, then we have the problem of converting a burst of 14 MeV neutrons into usable energy. In a fission reactor, the (charged) fission products carry most of the energy. Being charged, they interact strongly with the fuel. Collisions transfer the energy to the fuel, the fuel heats up, and the flowing water removes the heat from the fuel to make steam and turn a generator. How do you get those uncharged neutrons to deposit their energy in a small volume of material (diffuse heat is useless heat)? Several solution have been proposed, but there are potential problems with each of them.

    Assuming those problems can be fixed, where are you planning to get enough tritium to fuel the thing? NIF's Ignition Campaign is centered around D+T fusion. Tritium is a byproduct of fission reactor operations, but if you need a multi-billion-dollar fission reactor (1,110 MWe) to supply a multi-billion-dollar fusion reactor (600 MWe) with fuel... why not just build two fission reactors and devote the savings to reprocessing or disposing of the spent nuclear fuel?

    In short, Fusion is the power of the Future! (And always will be.)

    To say we're a long way from a viable power plant

  • by Anonymous Coward on Thursday April 29, 2010 @10:26AM (#32030008)

    We're in the 21st century now!

    It was a genetically modified spider.

  • Re:bad journalism (Score:3, Informative)

    by da cog (531643) on Thursday April 29, 2010 @10:32AM (#32030138)
    Indeed, it's not like they've posted information on the fact that they intend to model nuclear weapons in plain sight on the internet as one of their three missions [llnl.gov].
  • Re:bad journalism (Score:3, Informative)

    by Muad'Dave (255648) on Thursday April 29, 2010 @11:13AM (#32030952) Homepage

    ... any viable energy source we have except theoretical fusion processes will run out in less than 100 years time ... 200 years tops for nuclear power ...

    Integral Fast Reactors [wikipedia.org] can extend our nuclear fuel reserves out for 1,000 - 50,000 years [skirsch.com], depending on the estimate, while burning up our current waste.

  • Re:bad journalism (Score:4, Informative)

    by michael_cain (66650) on Thursday April 29, 2010 @11:34AM (#32031332) Journal

    I suspect that plants do not use 100% of available energy reaching the surface of the Earth.

    Correct. Crop plants typically convert 1-2% of the sunlight striking them to biomass. Under optimal conditions, some varieties of sugarcane can convert up to 8%.

    Its not like we'll be coating the surface of the Earth with solar panels within the next 100 years.

    Nor need to. The usual rough figure for PV solar to provide for current US electricity consumption is about 10,000 square miles of Southwestern desert -- a square 100 miles on a side. Of course, you'd also need enormous changes in the national transmission grid, and you'd have to find places to store a bunch of the daytime production for use at night (lots of pumped hydro storage located around the country might work for that).

    I do agree, however, with your concerns about the effect of wide adoption of solar energy on weather patterns.

    I suspect that we can do almost anything we want to a 100-mile square of desert with little or no change on climate or weather except in that immediate area.

  • on average US taxpayers pay $10/month for everything that NASA does.

    Number of US tax payers is about 138 Million [google.com]... NASA Budget is 18.7 $B [nasa.gov](2010). So mathematically the average is closer to $130 per taxpayer...

    $18.700.000.000 / 138.000.000 = $135 per person per year.
    $135 / 12 (months in a year) = $11 per person per month.

  • Re:bad journalism (Score:3, Informative)

    by smellsofbikes (890263) on Thursday April 29, 2010 @12:05PM (#32031930) Journal
    I was reading a book about metabolic biochemistry the other day (thrilling! really!) and the author went through a series of calculations to show that mitochondria produce about four orders of magnitude more power per unit volume than the sun. I guess it's not that weird, though: the sun's predicted to live for 20 billion years, so it can't be burning *that* fast. It just seems surprising.
  • by chris mazuc (8017) on Thursday April 29, 2010 @01:58PM (#32033904)

    As for the topic at hand, like fusion reactors the main problem will be getting MORE energy than you consume.

    Way to go captain obvious.

    Perhaps a smarter move would be to figure out how to harness the star we already have

    Thanks for the laugh. Even with 100% efficient orbital solar stations we would need a few million km^2 of panels just to match current energy usage. That number seemed large to me so I did a little digging and found this image [landartgenerator.org] that details electricity consumption alone. Switching to 100% solar and building a grid capable of redistributing that power from where it is generated to where it is used (nevermind orbital based power stations) would be a megaproject to dwarf every other construction project in history combined.

  • by Anonymous Coward on Thursday April 29, 2010 @03:01PM (#32035016)

    I know you're not seriously suggesting that this could actually end up as a disaster movie scenario, but I'm going to babble about it anyway. This is a tritium/deuterium reaction. Deuterium is rare, and tritium is incredibly rare. There just isn't any chance of any sort of chain reaction with this, so as soon as the fuel is gone, the reaction stops. They know exactly how much fuel is in each pellet, and therefore how much energy will be released and they have the shielding to handle it. All the stuff about about this being a "sun" on earth is just a simplification for the general public. Also known as a lie.

    What is going on here (if they get it to work) is a nothing like what goes on in the sun. Our suns primary fuel is plain old hydrogen, not tritium and deuterium. It's generally expected that the actual ratio of Tritium and Deuterium in the sun to regular hydrogen is minuscule compared to Earth. This is because a tritium/deuterium reaction is much easier to achieve than the standard solar fusion reaction with regular hydrogen, so the suns tritium and deuterium get consumed far, far faster. There probably wouldn't be any in the sun except that the suns environment probably keeps creating new tritium and deuterium which don't last very long. The standard fusion reaction that largely drives the sun is the proton-proton chain reaction (which does briefly involve deuterium as an intermediate step). Producing that on earth is currently considered ridiculous. This is because it requires incredibly high temperatures and pressures and, even in the suns core, it's a rare reaction. As others have pointed out in this discussion, the actual average energy generation of the sun per unit of volume is roughly comparable to a compost heap. It's just that the sun has a huge volume.

    If you're wondering then why the sun is so bright and you can feel its radiated heat while a compost heap far enough away that it looks exactly the same size as the sun doesn't seem to heat you at all and isn't super bright, the answer is simple. Ok, it's actually complex and there's a lot to it that isn't even occurring to me right now, but there's a simple thought experiment that demonstrates at least part of it. It's the sqaure-cube ratio. The area of a cube with sides of length s units is 6s^2 square units. The volume of that same cube is s^3 cube units. So if s is 1, then the area is 6 square units and the volume is 1 cube unit (6/1 ratio), but if the length is 3, then the area is is 54 square units and the volume is 27 cube units (2/1 ratio), and if the length is 6, then the area is 216 square units, and the volume is 216 cube units (1/1 ratio), and if the length is 9 then the area is 486 square units, and the volume is 729 cube units (2/3 ratio), and if the length is 12, then the area is 864 square units, and the volume is 1728 cube units (1/2 ratio), and so on. So, basically, as a cube, or any other three dimensional object (such as a sphere like our sun), grows in volume, its area doesn't keep pace. So, the area of the sun we see is the front for a far greater volume of material. Or, picture a cone shaped compost heap with the blunt end pointing towards you and the pointy end pointing away with the blunt end far enough away from you that it has the same apparent size of the sun. This cone shaped compost heap has a length equal to the radius of the sun and all the heat it is generating is directed towards the blunt end of the cone, at which point it radiates out evenly over the area of the end of the cone. That should be more on the order of what you get from the sun. Actually, I think that, aside from the physical impossibility of the model, I've missed enough things that I've just vaporized you... Thought experiments are hard.

    Anyway, obviously this experiment can't destroy the earth, or even create a massive explosion, or even generate more power than they put into the laser. Still, they do manage to make it sound like the opening to the plot of a disaster movie. I can't help thinking about some of these movie doomsday power g

  • by Sabriel (134364) on Thursday April 29, 2010 @11:47PM (#32040454)

    15,000,000,000,000 W / ~1,300 W/m^2 = ~11,538,461,538 m^2 or ~11,538,461 km^2

    Um... without looking at the rest, do note that 1 km^2 = 1,000,000 m^2. (consider: how many 1x1 metre squares can fit in a 1x1 km square). Your result should thus be ~11,538 km^2.

Old programmers never die, they just become managers.

Working...