During the summer since 2018, the hobby drone has launched a small package near the mouth of Stromboli, a volcano off the coast of Sicily that has erupted almost constantly over the last century. As one of the most active volcanoes on the planet, Stromboli is a source of fascination for geologists, but collecting data near the moving hole is fraught with danger. Thus, a team of researchers from the University of Bristol built a robot volcanologist and used a drone to take him to the top of the volcano, where he passively watched every quake and quiver until it was inevitably destroyed by an eruption. The robot was a softball-sized sensor pod powered by microdoses of nuclear energy from a radioactive battery the size of a square of chocolate. 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 are just the beginning. Over the past few years, Scott and a small group of collaborators have been developing a fictional version of the dragon egg nuclear battery that can last for thousands of years without ever being charged or replaced. Unlike batteries in most modern electronics, which generate electricity from chemical reactions, the Bristol battery collects particles spit out of radioactive diamonds that can be made from reformed nuclear waste.
Earlier this month, Scott and his associate, a Bristol chemist named Neil Fox, set up a company called Arkenlight to commercialize 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. As Scott and the Arkenlight team refine their design, they will create a pilot plant for their mass production. The company plans to launch its first commercial nuclear batteries by 2024 ̵
Conventional chemical or “galvanic” batteries, such as the lithium-ion cells in a smartphone or the alkaline batteries in the remote control, are great for draining a lot of energy in a short time. The lithium-ion battery can only run for a few hours without recharging, and in a few years it will lose a significant part of its charging capacity. By comparison, nuclear batteries or betavoltaic cells have been involved in producing small amounts of energy for a long time. They don’t release enough juice to power a smartphone, but depending on the nuclear material they use, they can provide a stable drip for small devices for millennia.
“Can we power an electric vehicle?” The answer is no, says Morgan Boardman, CEO of Arkenlight. To power something that is energy hungry, he says, means that “the mass of the battery would be significantly greater than the mass of the vehicle.” Instead, the company is considering applications where it is impossible or impractical to change a battery regularly, such as sensors in remote or hazardous locations in nuclear waste repositories or satellites. Boardman also sees applications that are closer to home, such as using the company’s nuclear batteries for pacemakers or wearables. It envisions a future in which people save their batteries and change devices, not the other way around. “You’ll replace the fire alarm long before you replace the battery,” says Boardman.
Not surprisingly, many people may not like the idea of having something radioactive somewhere near them. But the health risks of betavoltaics are comparable to the health risks of exit signs that use a radioactive material called tritium to achieve their red glow. Unlike gamma rays or other more dangerous types of radiation, beta particles can be stopped in their tracks with just a few millimeters of shielding. “Usually, the battery wall alone is enough to stop emissions,” said Lance Hubbard, a materials scientist at the Pacific National Laboratory who is not affiliated with Arkenlight. “The inside is not radioactive at all and that makes them very safe for humans.” And, he added, when the nuclear battery runs out, it disintegrates to a stable state, which means there is no remnant of nuclear waste.