A California facility which opens today hopes to create conditions similar to those found in a star, using the world’s most powerful laser beam. But despite the possible ecological benefits, there are claims the project has only received ongoing funding because of its military potential.

The National Ignition Facility, housed at the Livermore National Laboratory, has a purpose that’s considerably more simple to explain than to carry out. Using mirrors to amplify the light, 192 lasers are fired at a container of hydrogen fuel approximately the size of an eraser.

If all goes to plan, the atoms in the hydrogen fuse together. The mass of each fused hydrogen atom is slightly lower than that of the two single atoms which came together and the difference is released as thermonuclear energy. According to the Economist, the power produced at the moment of fusion could reach 500 trillion watts – or 3,000 times the combined electricity use of the world’s population.

Much of the promotion for the project has involved the potential for producing fusion energy, a type of power which, on paper at least, would be relatively sustainable without damaging the environment. There’s not immediate prospect of that being possible, however. It could be years before the setup even achieves the first step, ignition (the point at which the energy produced by the fusion is more then the energy needed to provoke the fusion).

There are also astrophysics uses for the project. Scientists will be able to replace the hydrogen with the different materials thought to make up particular stars or planets and then see what actually happens when they explode.

However, the main use of the $4 billion venture is for nuclear testing. At the moment, full-blown testing of nuclear weapons is outlawed by an international agreement and the US relies on either partial test or computer simulations. The National Ignition Facility would allow genuine practical testing of different weapon set-ups – though on such a tiny scale that it wouldn’t violate the test ban or cause the damage that results from testing a full-sized weapon.