Nuclear fusion holds huge promise as a source of clean, abundant energy that could power the world.

Now, fusion researchers at a national laboratory in the US have achieved something physicists have been working towards for decades, a process known as "ignition". This step involves getting more out from fusion reactions than is put in by a .

But just how close are we to producing energy from fusion that can power people's homes? While ignition is only a proof of principle and a first step in a very long process, other developments are also in the works and together they could spark renewed enthusiasm for making fusion a practical reality.

First it's important to recognize that the latest result is indeed a real milestone. The researchers at the National Ignition Facility (NIF) in California fired the world's biggest laser at a capsule filled with , causing it to implode and starting that mimic what happens in the Sun.

The fusion energy released by the implosion was more than that put in by the laser, a massive achievement given that, just a few years ago, the NIF laser could only get out about a thousandth of the energy it put in.

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