China-Developed Photovoltaic
Nuclear Battery could Run for Centuries: Scientists
·
In-built
energy converter works like a solar panel to capture alpha rays and convert them
first into light and then electricity
·
High
decay energy of alpha-radioisotopes – between four and six mega electron volts (MeV)
– offers the potential to far outstrip beta-radioisotope devices
Chinese
scientists say they have developed a nuclear-powered battery with a photovoltaic
cell that could generate electricity for hundreds of years, at an overall efficiency
thousands of times higher than its closest rivals.
According
to a paper published in the peer-reviewed journal Nature, the researchers were looking
for a way to harness alpha rays released by decaying radioactive isotopes, in a
field where most advances have focused on beta radiation.
The
increasing demand for clean energy solutions and small, long-lasting alternative
power sources have sparked broad research interest in nuclear batteries but alpha-radioisotopes
are considered the most likely contenders for a micronuclear battery.
This
is because the high decay energy of alpha-radioisotopes – between four and six mega
electron volts (MeV) – offers the potential to far outstrip beta-radioisotope devices,
whose decay energies reach several tens of kiloelectron volts (keV) at best.
However,
with their extremely short penetration in solids, alpha particles lose substantial
energy through the self-absorption effect.
“This
self-absorption significantly reduces the actual output power of tested alpha-radioisotope
micronuclear batteries to levels far below theoretical expectations,” said the study’s
lead author Wang Shuao from Soochow University.
Wang
– whose achievements include significant advances in the treatment of nuclear waste
and waste water, as well as emergency response protocols for accidents – has spent
years focused on China’s strategic needs for sustainable nuclear development and
safety.
Now,
along with a team of researchers from the Northwest Institute of Nuclear Technology
and Xiangtan University, Wang has designed a nuclear battery that has an inbuilt
layer that works like a solar panel to optimally use alpha radiation.
The
team incorporated an “inbuilt energy converter” – a polymer layer surrounding the
isotopes that transmits the energy released during radiation by converting it into
light and then electricity, just like a photovoltaic cell.
Using
only 11 micro curie of the synthetic radioactive chemical
243Am, the assembly produced visible radioluminescence from the alpha ray emitted
by the isotope’s decay, according to the paper.
Further
experiments determined that the power output of the luminescence was 11.88 nanowatts,
with a decay-to-light energy conversion efficiency reaching an impressive 3.43 per
cent, the paper said.
The
Chinese researchers said their device – a type of photovoltaic nuclear battery –
converts radioactivity into electrical energy, has an extraordinarily long lifespan,
and performs independently of temperature variations.
According
to the paper, the experimental battery boasts a total power conversion efficiency
of 0.889 per cent and produces 139 microwatts per curie.
The
researchers said the design was rigorously validated through experimental and theoretical
tests which showed an 8,000-fold enhancement in energy conversion efficiency compared
to conventional battery architectures.
According
to the paper, the energy converter is exceptionally stable, with performance parameters
nearly unchanged over 200 hours of continuous operation. Given that the half-life
of 243Am spans several centuries, the battery may have an equal lifespan, it said.
China’s
Science and Technology Daily newspaper hailed the achievement as “one of the significant
breakthroughs in the nuclear battery field in recent decades”.
The
breakthrough not only addresses major strategic needs in China’s nuclear safety
and sustainable nuclear development, but also offers a new approach to the resource
utilisation of nuclear waste, the newspaper said.
The
extremely long half-lives and high-energy alpha decay of some isotopes manifests
as the long-term radiotoxicity of nuclear waste. But as an energy source, they offer
the advantages of a long lifespan and high energy, according to the article.
“This
achievement, as one of the significant breakthroughs in the nuclear battery field
in recent decades, opens new directions for the utilisation of actinide nuclides
outside the nuclear fuel cycle,” the newspaper report said.