Researchers at the University of Bristol have used graphite, the waste product of nuclear reactors, to develop a man-made diamond which produces electricity when placed in close proximity to a radioactive source. Although these batteries produce only a small amount of current, they offer an incredibly long battery life of thousands of years.
Making Use of Nuclear Waste
Nuclear reactors need graphite blocks to control heat flow and nuclear reactions. When exposed to radioactive uranium rods, the graphite blocks gradually become radioactive, as well. When a nuclear plant gets decommissioned, graphite blocks are one of the main radioactive waste products which need to be handled.
Carbon-14 is the radioactive version of carbon which is found at the surface of graphite blocks. The radiation of this carbon isotope cannot penetrate even a few centimeters of air, but it is not still safe to allow into the environment. The UK currently has almost 95,000 tonnes of radioactive graphite blocks. Researchers believe that, by extracting carbon-14, the majority of the graphite’s radioactive material can be removed. As a result, the cost and danger of storing graphite would be significantly reduced.
Researchers have found a method to reuse these graphite blocks to generate electricity out of the radioactive waste. First, they heat the graphite blocks and turn them into a gas. Then, the radioactive gas is compressed to grow a diamond.
The beta particles emitted by the radioactive material interact with the crystal lattice and throw off electrons.
The result? A radioactive diamond that can generate electricity for thousands of years.
To prove the feasibility of the technique, the research team has designed a prototype nuclear battery using a nickel isotope, nickel-63, as the radioactive source. However, they are planning to use carbon-14 in their future designs.
No Emissions, No Maintenance!
Unlike many conventional methods of producing electricity which rely on moving a magnet inside a coil of wires, the nuclear-powered batteries have no moving parts and the electricity is generated by simply placing the man-made diamond in close proximity to a radioactive source.
To shield the radioactive diamonds and make them safe to handle, a non-radioactive diamond coating is also grown. Dr. Neil Fox from Bristol's School of Chemistry explains that these nuclear batteries have no radioactive threats to the user. He notes that carbon-14 has short-range radiation which can be completely confined within the world’s hardest material: diamond. This non-radioactive diamond coating means that someone in close proximity to a nuclear battery would receive as much radiation as they would sitting next to a banana!
According to Professor Tom Scott of the university's Interface Analysis Centre, the nuclear batteries not only have negligible emissions but they also do not require any maintenance. This fact alone means that nuclear diamonds could be used in areas that are dangerous—or downright impossible—for maintenance workers to reach.
Potential Applications of a Diamond Battery
The bad news is that the produced current is not high enough to power a smartphone. However, the long battery life makes the technology appealing especially for applications where it is not easy or even possible to recharge the battery or replace it with a new one. The longevity of these batteries, which is connected to the half-life of the nuclear waste's radiation, can be crucially important in applications such as designing pacemakers, satellites, spacecraft, and high-altitude drones.
Researchers estimate that nuclear batteries based on carbon-14 will generate above 50% of their maximum power for as long as 5,730 years –– equal to the whole time the human civilization has existed. Hence, with this technology, it would be possible to power interstellar probes long after they lose solar power.
Lithium-Ion, Nuclear Battery, or Another Alternative?
Unfortunately, over the last few years, the battery industry has been cruel to many promising solutions. Researchers in this field need not only to solve many technical problems but also take the technology into the commercial realm. This is not at all easy because even a small battery manufacturer needs to invest nearly $500 million. In fact, according to MIT's Technology Review, one of the main reasons that new battery technologies do not get commercialized is the lack of funding and focus.
Many manufacturers prefer to rely on the incremental improvement of lithium-ion batteries—which has been exceedingly slow, despite some recent, promising research into increased Li-ion capacity—rather than accept the initial huge investment of a new battery which would offer a dramatic improvement over conventional batteries. In October 2015, Lux Research published a report which predicted the lithium-ion battery as the main choice of energy storage for the years ahead.
The nuclear-powered batteries can simultaneously solve a few of today’s serious problems such as nuclear waste disposal, clean electricity generation, and battery life. However, is there a clear path to seeing this technology commercialized? We face some serious questions: Is it economical to convert nuclear wastes into diamond batteries? Or are there only some particular applications that these batteries really lend themselves to?
The details of this technology were discussed at the Cabot Institute's soldout annual lecture––"Ideas to change the world"–– in November.
For more information, check out the University of Bristol's friendly, animated video explaining the technology below: