Lasers could spark clean nuclear power

An international team of scientists is looking at a new way of creating energy from nuclear fusion, a process that could result in no radioactivity and produce little pollution.

An international team of scientists is looking at a new way of creating energy from nuclear fusion, a process that could result in no radioactivity, produce little pollution and provide a cheap, abundant source of electricity.

The Australian-led team of scientists has used computer models to simulate nuclear fusion without the extreme temperatures currently needed for other fusion methods. Their findings appear in the journal Energy and Environmental Science.

Emeritus Prof. Heinrich Hora of the Department of Theoretical Physics at the University of New South Wales, who is leading the research effort, says the process would rely on a new generation of extremely powerful and very fast lasers now being developed.

"The key is a very carefully controlled extremely short laser pulse essential for ignition. The pulse would ignite a fuel made of ordinary hydrogen and boron-11," said Hora.

"The idea of a hydrogen and boron fusion reaction is interesting because it wouldn't cause neutron production. Neutrons are a problem because they generate radioactivity," he said.

Hora said his team was originally developing computer models using next generation lasers to duplicate the work being done at the new $4-billion US National Ignition Facility at Lawrence Livermore National Laboratory near Oakland, Calif.

Laser pulse

The U.S. scientists are developing what is currently the world's largest laser to ignite highly compressed spheres of deuterium-tritium fuel in a nuclear fusion reaction.

The laser can produce a pulse of a few billionths of a second duration, which produces 500 times more power than all U.S. power stations combined.

Hora's team originally rejected the idea of a hydrogen-boron fuel for their simulations "because the higher temperatures and compression needed made it a hundred thousand times more difficult than the Lawrence Livermore approach, making it just about impossible."

"But when we ran computer simulations using these next generation petawatt (quadrillion watt) strength lasers with a hydrogen-boron fuel, we were shocked to find that it's only 10 times more difficult than deuterium-tritium," he said.

"It makes this all within the reach of current technology in a relatively short time. In fact these types of lasers are already in early testing at Los Alamos National Laboratory," he said.

Hora said the key is to ensure the laser pulse is "extremely clean," lasting no more than a millionth of a millionth of a second.

Fuel advantages

"This allows conversion of optical energy to mechanical energy without heating," he said.

Hora said the hydrogen-boron fuel has a number of advantages over deuterium-tritium.

"It would be largely free of radioactive emissions producing less radiation than that emitted by current power stations that burn coal, which contains trace amounts of uranium," he said.

According to Hora, hydrogen and boron are plentiful and readily accessible, and the waste product of ignition would be clean helium gas.

"The hydrogen-boron fuel would not have to be compressed. This means it needs far less energy to start the ignition," he said.

But Hora warns the study only demonstrates the potential of the new process and much work needs to be done to demonstrate it in practice.