For nuclear fusion, the joke is that it's always 50 years away from reality, so in the context of this discussion (~30 years), fusion isn't even a possibility (Note: Unfortunately the joke's moving to becoming 100 years from reality instead)

~lynn~ : Nuclear fusion has been achieved, and not only uncontrolled nuclear fusion, which is often the example used (hydrogen bombs), but controlled nuclear fusion in many purpose built laboratories worldwide (e.g. JET - a tokamak design, there exist other designs too, one of which was featured in spiderman the movie with the lasers, except that it was quite fake ). The problem is that current fusion experiments use up more energy than they ever release out (well actually no, but they only manage to sustain themselves for only a few seconds, which is so short that it doesn't pay back the energy in heating up the plasma in the first place), and thus the reaction isn't self-sustaining, it quenches itself out once you stop supplying energy into it. The next step is to design a reactor that will produce more energy than is input, giving a sustained reaction, and the extra energy being used to generate power for our use. There is a massive problem with this though:

There is an immense neutron flux bombarding the walls of the tokamak, and no one is really sure how long the reactor's walls can withstand this bombardment. This is mainly a material science problem, finding a way to create a material that will be able to withstand this neutron flux without collapsing in some short timeframe.

ITER is supposed to be the first test fusion reactor that will demonstrate a self sustaining reaction (well a plasma really) for about 10-15 mins iirc, which is much more than what current experiments can do. Unfortunately it's hit into funding snags from the participating governments, and the thing seems to have been delayed to 2026 - that's when the real D-T (deuterium-tritium) plasma fusion will occur, while the earlier opening in 2018 will run experiments, and testing the components of the reactor with hydrogen.

So no, fusion is still very far away from being reality. Perhaps our grandkids, but I'd personally be happy to see fusion plants operating on a large commercial scale globally if it happens within our lifetime.

This post has been edited by bgeh: Oct 15 2009, 06:06 AM

Well it isn't very hard to separate the extremely hot plasma from the walls of the tokamak (note, this is one of the only of the possible designs for a fusion reactor), and actually I doubt whether anything can survive contact with the plasma, which is extremely extremely hot ( >10^8K, or approximately 100 million degrees Celcius), because we can create magnetic fields that will confine all the charged particles in the plasma. As you now can probably see why, neutrons are not charged, and won't be confined by this magnetic field and thus bombard the walls of the reactor. [Well, actually you can use an interpretation of the kinetic energy of the neutrons with temperature, but we disregard that for now]

Also, the idea that fusion will not create any radioactive byproducts isn't exactly true too, for example the walls of the tokamak will probably be highly radioactive after such a bombardment, and will quite likely be highly radioactive for a while too, but of course this is quite negligible compared to the amount of radioactive material produced as a byproduct of current nuclear fission reactors.

This post has been edited by bgeh: Oct 18 2009, 07:33 AM

Denise: The point being, nuclear is indeed a medium term energy source until we can move on to better energy sources, and looks to be the 'greenest' (in terms of carbon emissions) and one of the more viable ones. No one's advocating a full shift to nuclear, but to a more mixed economy, with nuclear being one of the choices explored. Sure nuclear is expensive, but it is looking pretty comparable, if not cheaper than a lot of the 'green tech' that many are pining their hopes on in a post oil/gas/coal future.

Yes you could make weapons from refined uranium, but it's not going to be some terrorist target where the buggers run in grab the fuel rods and run - because the rods themselves will be in bloody boiling salt or some really hot water, and plus it's all radioactive. Heck they could probably scare the heck out of the population if they tried to attack a nuclear plant but they wouldn't be able to extract anything useful or weaponisable in any form. Also, try bombing dams and causing a flood for a terrorist target, washing away the people downstream with little warning at all, if you can't think of one possibility.

Today's nuclear reactors are way safer than in the past, with many of them starting to incorporate passive safety systems where even if operator error causes some screwup, the system is designed such that if the reactor starts going beyond some design limit, the moderator will react in such a way (regulated by temperature) as to reduce or hold the reaction rate from going up further. I agree that the problem of waste is the biggest issue facing nuclear fission today, but research is ongoing on transmutation methods to try to transmute the waste to less radioactive or lower half life materials.

I could go on for a point by point rebuttal, but I'd just like to say finally that while I agree Malaysia is corrupt and everything, we do tend to be competent when it comes to critical things, else you would've heard of Petronas' oil gas rigs going boom in the middle of the sea every 2-3 years or so, which simply doesn't occur

Actually that was the only major project that has come to my mind so far. [I recall other incidents too, the NKVE overpass collapsing during construction, the resort house in Perak or something suddenly collapsing]. So which other major highway is cracking and about to collapse again?

Also, it is likely that most of the work done will be by whoever we partner with to build the nuclear power plant, if it ever commences.

I'm not walking in with some Malaysia Boleh syndrome saying that for the pride of the country, but I'm saying that this is probably one of the better options to be considered if you honestly do want to cut down on carbon emissions, nuclear is going to have to be an option because fusion will not be ready anytime soon, much as everyone likes to use it as a byword, and solar and wind will always have inherent difficulties w.r.t. costs and also the variability problem

Well unless you're willing to pay for the extra cost of solar and wind in your everyday electricity bill, and manage to convince the population that they should also pocket the difference in cost so we can shift to a non-carbon generating power source and yet still avoid nuclear. I wouldn't mind such a thing but well try convincing everybody that the hike in their bills is worth it.

There is already a wall; the tokamak's walls. Also neutrons are quite likely to penetrate very far through most objects. The worry is more of the tokamak's walls not being able to withstand the high flux for a significant time; something that no hypothetical wall can help with.

[Note: I do not know much about a tokamak's construction to be able to say definitively whether a physical wall inside the tokamak itself will be an effective shield; I'd imagine it wouldn't be because it would face the exact same issues of getting bombarded by a high flux of neutrons, and then we'd have to worry about this hypothetical inner wall collapsing instead]

This post has been edited by bgeh: Oct 23 2009, 12:45 AM

Yes but what we're trying to do is buy ourselves some time. Uranium is certainly finite, but it has the added advantage of not being a large carbon emitter, unlike fossil fuels. It's just to buy us more time to do more research in wind/solar/tide/fusion/(some other source) sources of energy, increase their efficiency (for solar), or perhaps do more research into fusion, etc, etc.

They should take over in the medium term/long term, I agree wholeheartedly. But if we are to bridge the gap, and do not want to pump shitloads of CO2 into the atmosphere, nuclear is probably the best like-for-like replacement for our coal/gas/oil power plants, with solar supplementing it (speaking in the context of Malaysia). There is a downside to nuclear though; costs for nuclear are projected to rise by approx 2x, but according to estimates on BBC, that'll still make it cheaper than solar's current prices, plus the added technical advantages outlined above.

http://news.bbc.co.uk/1/hi/technology/8338824.stm

Both ways, the cost of energy is going to have to rise, whether it's nuclear or directly jumping to 'green' alternative energies.

This post has been edited by bgeh: Nov 27 2009, 09:15 PM

Carbon capture isn't as easy as you think; Firstly you need stable geological formations so that the carbon is never suddenly released from some earthquake or something, and also, carbon capture, while being a buzzword, does not have a single large scale implementation yet for power plants. Next, if we find one, we'll have to construct an infrastructure to pipe the CO2 emissions from the power plants to this storage facility, which is somewhat similar, if you think about it, to taking nuclear waste and storing it at the same place, except that we can transport the waste using lorries, instead of having to build pipelines to this storage site; or build multiple storage sites.

Considering how far our power plants are spread around, you can imagine the costs. Sure the tech exists, but being the first few implementers will cost a bloody bomb, and it's also 'short term', to borrow a phrase you're using, since if we do manage to transfer completely to non-carbon sources in 100 years or so, we won't have anyone to sell this carbon capture technology to do. Nuclear on the other hand, already has had plenty of current implementations, and it's just cheaper in general compared to carbon capture, so your point on borrowing money to fund nuclear energy is not really a strong one, because we might have to borrow more instead to retrofit every one of our plants to do so, and even that depends on the geology of the surrounding area.

Note: Clean coal has multiple definitions; in the carbon context it refers to carbon capture, and no one really knows what the cost is yet, because there are no industrial scale power plants operating using carbon capture yet.

And really, 50-100 years is plenty of time for a 'short term technology', considering that coal is itself, in the carbon context, 'short term'.

This post has been edited by bgeh: Nov 28 2009, 10:19 PM