Why is fusion power generation still a dream?

Question

When it is naturally occuring in nature (sun, stars, etc)

Answer 1

It is only a dream on earth until we have cracked how to maintain and contain the reaction in such a way that we can extract more energy than we put in to containing and maintaining the fusion in the first place. Needless to say we are trying to build something a tad smaller than the sun and within the constraints of existence on this planet.

Answer 2

Fusion works on the principle that energy can be released by forcing together atomic nuclei rather than by splitting them, as in the case of the fission reactions that drive existing nuclear power stations.

In the core of the Sun, huge gravitational pressure allows this to happen at temperatures of around 10 million degrees Celsius. At the much lower pressure that is possible on Earth, temperatures to produce fusion need to be much higher - above 100 million degrees Celsius.

No materials on Earth could withstand direct contact with such heat. To achieve fusion, therefore, scientists have devised a solution in which a super-heated gas, or plasma, is held and squeezed inside an intense doughnut-shaped magnetic field.

Answer 3

We already have limited contained fusion in the JET and MAST machines.

The next generation ITER is under development as we speak and should crack this problem.

The problem is really an engineer one. We know how thr physics works but keeping the plasma at 100 million degrees without touching the container is trick to say the least. However improvements in computing has allowed us to get the magnetic containment fields to adapt fast enough to make controlled fusion possible, although for JET and MAST, the period of fusion is very limited and we still are getting less energy out then we put in. However, we are now confident it is doable

Visit http://www.iter.org/ for more information

Answer 4

You just answered it: occurs naturaly in stars!
Fusion requires extreme temperatures and pressures that, although we can reproduce, cost much more to produce than the energy collected afterward.
What the scientists are trying to achieve is COLD fusion (fusion at room temperature). An attempt was presented a few years ago, but was proven to be an experimental error.
Pitty!