In summer of 2018, an amateur drone dropped a small package near the lip of Stromboli, a volcano off the coast of Sicily that has erupted almost constantly for a century. As one of the most active volcanoes on the planet, Stromboli is a source of fascination for geologists, but collecting data near the rotating vent is perilous. So a team of researchers from the University of Bristol built a volcanologist robot and used a drone to transport it to the top of the volcano where it could passively monitor every earthquake and quake until it was inevitably destroyed. by a rash. The robot was a sensor the size of a soft ball powered by microdoses of nuclear energy from a radioactive battery the size of a square of chocolate. The researchers called their creation a dragon egg.
Dragon eggs can help scientists study violent natural processes in unprecedented detail, but for Tom Scott, a materials scientist in Bristol, volcanoes were just the beginning. Over the past few years, Scott and a small group of collaborators have developed an improved version of the Dragon Egg nuclear battery that can last for thousands of years without ever being charged or replaced. Unlike the batteries of most modern electronic devices, which generate electricity from chemical reactions, the Bristol battery collects particles spewed out by radioactive diamonds that can be made from reformed nuclear waste.
Earlier this month, Scott and his collaborator, a chemist in Bristol named Neil Fox, started a company called Arkenlight to market their nuclear diamond battery. Although the nail-sized battery is still in the prototyping phase, it is already showing improvements in efficiency and power density compared to existing nuclear batteries. Once Scott and the Arkenlight team have refined their design, they will set up a pilot plant to mass produce them. The company predicts that its first commercial nuclear batteries will hit the market by 2024 – don’t expect to find them in your laptop.
Conventional chemical or “galvanic” batteries, such as lithium-ion cells in a smartphone or alkaline batteries in a remote control, are great for providing a lot of energy for a short period of time. A lithium-ion battery can only run for a few hours without recharging, and after a few years it will have lost a substantial fraction of its charging capacity. Nuclear batteries or betavoltaic cells, by comparison, aim to produce very small amounts of energy for a long time. They don’t make enough juice to power a smartphone, but depending on the nuclear material they use, they can deliver a steady drop of electricity to small devices for millennia.
“Can we power an electric vehicle? The answer is no, ”says Morgan Broadman, CEO of Arkenlight. To power something that consumes a lot of energy, he says, that means “the mass of the battery would be significantly greater than the mass of the vehicle.” Instead, the company is investigating applications where it is impossible or impractical to regularly change a battery, such as sensors in remote or dangerous locations in nuclear waste repositories or on satellites. Broadman is also seeing applications closer to home, such as using the company’s nuclear batteries for pacemakers or portable devices. He envisions a future in which people keep their batteries and replace their devices, rather than the other way around. “You’ll replace the fire alarm long before you replace the battery,” says Broadman.
Unsurprisingly, perhaps, many people don’t like the idea of having something radioactive nearby. But the health risk from betavoltaics is comparable to the health risk from exit signs, which use a radioactive material called tritium to achieve their characteristic red glow. Unlike gamma rays or other more dangerous types of radiation, beta particles can be stopped in their path by just a few millimeters of shielding. “Usually, only the battery wall is enough to stop emissions,” says Lance Hubbard, a materials scientist at the Pacific Northwest National Laboratory who is not affiliated with Arkenlight. “The interior is hardly radioactive at all, which makes it very safe for people.” And, he adds, when the nuclear battery runs out of power, it decays to a steady state, which means there is no nuclear waste.