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

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."

Comments

bad journalism

[QuantumG]

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.

Re:bad journalism

[pedestrian crossing]

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.

Re:bad journalism

[Anonymous Coward]

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

Re:Fusion power dream

[Dr_Barnowl]

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.