Using such a long time for trying to get it work sounds like a wrong approach to me.

Our star, the Sun, has been producing energy by the process of nuclear fusion for billions of years and supplying to all planets around it for about 5 billions years. Instead of trying to do on our planet employing complex methodologies, our R&D should have been to must find ways to convert solar energy in an economical way. Inventions of the steam engine using coal and gasoline engines using oil have side tracked the issue of developing technologies for effective use of solar energy. Work on these direction is being done seriously only now !!

First of all: are we talking about inertial confinement fusion (ICF) or about fusion energy in general?

If we just talk about ICF, I would say it is not very practical for energy production, because the technical processes involved are quite complicated, first of all the refuelling is troublesome (but that doesn't mean that we can learn a lot of fundamental science from it).

If we talk about fusion in general there are several issues to be adressed:

1) Just because it is no easy task, we should stop try to achieve it? - that sounds not like a thing a ambitioned scientist or engineer would say (keep in mind that fusion is the most efficient method of energy production which nature hase to offer, as far as we know).

2) @ S. V. G. Menon: The worldwide yearly budget that is spent for R & D of fusion technology is neglible compared to the fundings for solar, wind, etc... Thus your argument is not really valid (in fact the energy production should be a mixture of all possible ways which are non-polluting).

3) @ Henk Smid: An observed net power output is also quite remarkable given the fact that the fusion reactors that we have now are not optimized for power output - they are all scientific reactors which means that they are for studying the scientific concepts of fusion and not for producint power. The first reactor which is supposed to deliver more power than it consumes is the ITER reactor - currently built in France.

The most promising fusion concepts are the TOKAMAK and the stellerator, but to my personal opinion it could be also a hybrid of those two which will make fusion available for the common energy markets.

@Henk Smid: On this I'd like to quote Kurt Goedel: "I would rather be an optimist and a fool than a pessimist and right." :)

but honestly, yes, I think it is possible, just because I think that if nature can do it and if we can understand it, we also can do it (it will be, however, quite hard to achieve, as I wrote before).

You have to keep in mind, what I also stated before: none of the existing fusion reactors was designed to have a net energy output, so it is not astonishing that no real power production was achieved. The current reactors were built to gain the knowledge of what is needed to constract a functional power plant and it is a big difference if you make up a "laboratory" device or something that you want to use in a "production" process. The requirements are totally different.

yes it can be done..we have come a long way we should not think about it when are getting positive results recently.

@Johannes Gruenwald: I would like to add to your comment, yes we don´t have any fusion reactors which produce energy output, but it doesn´t mean that we are not going to have them, the complications can be solved(finally it is an engineering challenge) definitely there will be solution. I don´t know much about inertial confinement, even my knowledge is limited to magnetic confinement. But we should try in all possible ways to generate fusion power, let the time decide. We don´t know when something is going to turn up.

@S. V. G. Menon: Atleast what i believe is solar can be solution for energy demand but only fractionally. In a bigger picture you have to see that fusion can solve the major problem in future, after all we have done it for 50 years why can´t we do it few more years, as I said that let the time decide which one is the best.

Inertial fusion has the drawback that needs a lot of maintenance, as much than perhaps wiil not be profitable bcause the megawatts-hour cost must maintain under coal plants cost, but it will be the future because renewable do not work all the day, sun energy is low in winter and it is needed a lot of energy in so energy hungry world.

The main advantages of inertial fusion are:

1. It works as could be seen in thermonuclear bombs tests

2. It is a lot easier to heat up the plasma, accordingly Stefan-Boltzman law a plasma at 15 keV radiates a lot of energy (1 m2 radiates the same than the whole sun), so it is bettes as long as the plasma area is very small and the ignition time very short compared with magnetic fusion machines

3. It exists 2 machines that reached breakeven using inertial

I wrote a paper speaking about this fact that can be downloaded from my profile or here.

Plasma Temperature and Radiation in Tokamak, ICF, HIF and Pulsotron

Data Plasma Temperature and Radiation in Tokamak, ICF, HIF and Pulsotron

Yes, ICF alone has issues, particularly with the Lawson criteria.  I would not fund ICF alone, based on several published studies in this area.

Is not the second megawatt fusion electrical plant scheduled to come on line next year?  So, a broader answer is possible, that ICF combined with other methods are currently able to supply electricity.

ITER and other large/huge, in progress, attempts will eventually replace these smaller fusion reactors, I hope.  I used the word replace, instead of supplement, as ITER will produce so much greater wattage, at lower cost, I hope.  The smaller fusion reactors will remain in service, as ITER size reactors will have scheduled shutdowns, and the required electricity must come from somewhere.