A PRECIOUS breakthrough perhaps? Researchers say they can use nuclear waste to make a diamond battery that could power satellites and pacemakers.
A team from the University of Bristol in the UK has demonstrated it can produce a diamond battery from radioactive nickel-43, and its attention is now focussed on optimising the processes to use radioactive carbon-14 instead. The advantage of using carbon-14 lies in the fact that it is generated in graphite blocks used to moderate reactions in nuclear power plants. The development could therefore help clean up nuclear waste.
Materials researcher Tom Scott explains: “There are no moving parts involved, no emissions generated and no maintenance required, just direct electricity generation. By encapsulating radioactive material inside diamonds, we turn a long-term problem of nuclear waste into a nuclear-powered battery and a long-term supply of clean energy.”
Chemist Neil Fox told The Chemical Engineer that the UK has built up stockpiles of some 95,000 t of graphite blocks, 15% of which is carbon-14. He explained that the process of recovering the carbon-14, which is concentrated on the outside of the graphite blocks, involves heating it up using the Sabatier process to produce a carbon-14-methane feedstock, which is then used to make the radioactive diamond.
“We make synthetic diamonds in thin films or free-standing membranes using chemical vapour deposition. That requires a feedstock gas mixture which is 98% hydrogen and the rest is the carbon feedstock,” Fox said. “The process involves working at sub-atmospheric pressures. We use a plasma-assisted chemical vapour deposition and that allows us to speed up the growth rate significantly.”
This radioactive diamond is then surrounded by a layer of non-radioactive diamond, which in turn is surrounded by a semi-conducting diamond material.
“We have an impurity in there to make it a semiconductor, and that gives us the structure we need to harvest the electrons,” Fox said. “It’s analogous to a diamond solar cell but it is using beta radiation rather than sunlight to generate the electron hole pairs.”
These surrounding layers absorb the vast majority of the radiation, meaning the device emits less radiation than a banana.
The resulting battery is low power compared to a standard alkaline AA battery but it would last for a very long time. Given the half life of carbon 14, any battery made from it would take 5,730 years to reach 50% power.
Scott added: “We envision these batteries to be used in situations where it is not feasible to charge or replace conventional batteries. Obvious applications would be in low-power electrical devices where long life of the energy source is needed, such as pacemakers, satellites, high-altitude drones or even spacecraft.”
“There are so many possible uses that we’re asking the public to come up with suggestions of how they would utilise this technology by using #diamondbattery.”
The team’s attention has turned to optimising the processes for scaleup, including separating carbon-14 from carbon-12 and carbon-13. Fox said the team has a number of research proposals in progress.
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