Materials that directly convert radiation into electricity could produce a new era of spacecraft and even Earth-based vehicles powered by high-powered nuclear batteries, say US researchers.

Electricity is usually made using nuclear power by heating steam to rotate turbines that generate electricity.

But beginning in the 1960s, the US and Soviet Union used thermoelectric materials that convert heat into electricity to power spacecraft using nuclear fission or decaying radioactive material. The Pioneer missions were among those using the latter, “nuclear battery” approach.

Dispensing with the steam and turbines makes those systems smaller and less complicated. But thermoelectric materials have very low efficiency. Now US researchers say they have developed highly efficient materials that can convert the radiation, not heat, from nuclear materials and reactions into electricity.


Power boost

Liviu Popa-Simil, former Los Alamos National Laboratory nuclear engineer and founder of private research and development company LAVM and Claudiu Muntele, of Alabama A&M University, US, say transforming the energy of radioactive particles into electricity is more effective.

The materials they are testing would extract up to 20 times more power from radioactive decay than thermoelectric materials, they calculate.

Tests of layered tiles of carbon nanotubes packed with gold and surrounded by lithium hydride are under way. Radioactive particles that slam into the gold push out a shower of high-energy electrons. They pass through carbon nanotubes and pass into the lithium hydride from where they move into electrodes, allowing current to flow.

“You load the material with nuclear energy and unload an electric current,” says Popa-Simil.

Space probes

The tiles would be best used to create electricity using a radioactive material, says Popa-Simil, because they could be embedded directly where radiation is greatest. But they could also harvest power directly from a fission reactor’s radiation.

Devices based on the material could be small enough to power anything from interplanetary probes to aircraft and land vehicles, he adds.

“I believe this work is innovative and could have a significant impact on the future of nuclear power,” says David Poston, of the US Department of Energy’s Los Alamos National Laboratory. However perfecting new nuclear technologies requires years of development, he adds.

Popa-Simil agrees, saying it will be at least a decade before final designs of the radiation-to-electricity concept are built.

A paper on the new nuclear power materials was presented on 25 March, at the Materials Research Society Spring Meeting 2008 , San Francisco, California, US.