Why is nuclear fusion not curently used as an energy source on earth?

Answer 1

We do not currently have the technical knowledge to produce controlled fusion reactors on a scale large enough to produce power. Right now, the only two viable uses of fusion are in the Sun, and in hydrogen bombs, but the latter is an uncontrolled reaction, not suited for use in a power plant.

The problem is that, in order to produce a fusion reaction, you need extremely high temperatures and pressures. That's easy for the Sun to do, because of its enormous mass and gravity, but on Earth it is a problem.

Once you have that fusion reaction going, then you need a way to contain it. Unfortunately, there is nothing that can hold the plasma needed for the fusion reaction, because it will burn through anything.

Since plasma is a charged stream, we can use magnetic fields to bottle it, so to speak, but in order to produce a strong enough magnetic field, we often need to use super-conducting magnets, which means very, very cold temperatures.

The conflict is that we need to maintain pressure and ultra high temperature in close proximity to super-cold temperatures. We just have not been able to accomplish that other than in very, very tiny experiments, with monstrously large machines.

Work is ongoing in various labs to attempt this, but I am going to guess that, without the benefit of some stupendous discovery, we are at least 50 or 100 years away from being able to sustain a controlled fusion reaction in a size sufficient to generate commercial power.

Answer 2

Hydrogen and Helium ions plasma need to be moving at extreme speeds and at extreme temperatures. So it needs to be controlled very carefully or else a fusion reactor would melt. Also, it is too hard and dangerous to sustain that temperature in present reactors so it would not be reliable and energy companies will lose money because starting the reactor takes too much energy.

Answer 3

The answer is that it is very difficult to make it work. Various teams in different countries have tried, I believe the best result so far is the JET (Joint European Torus) which has produced a fusion reaction but it only lasted less than 1 second. A further torus type installation is planned called ITER. In the USA there is a laser device being set up to try to produce fusion in a small pellet of fuel. Apart from such experiments, which would only demonstrate feasibility in any case, nobody yet has worked out a practical design to harness the power output. The fission reactor is simple in comparison. Hopefully fusion will become practicable sometime, but it is certainly at least 50 years away. See links below

Answer 4

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Answer 5

It has turned out to be quite difficult to achieve this, and so far no practical way has been found - at least, not practical enough for commercial use. Basically, a temperature of perhaps a hundred million degrees has to be maintained for at least a few seconds, at a considerable pressure.

Answer 6

We have as yet been unable to sustain a stable fusion reaction long enough for this to work.