In the summer of 2018, a drone dropped a small package near the Stromboli crater. The Stromboli volcano, located off the coast of Sicily, has been erupting almost continuously for the past century. As one of the most active volcanoes on Earth, it has long fascinated geologists, but collecting data near its churning crater can be extremely dangerous. So a team of researchers from the University of Bristol built a "volcano detection robot" and used a drone to transport it to the top of the volcano, where it could passively monitor every quake and tremor of the volcano until it Until it is inevitably destroyed by an eruption. The robot is a softball-sized sensor capsule powered by a microdose of nuclear energy from a radioactive battery the size of a chocolate square. The researchers call their creation "dragon eggs."
The Dragon Egg robot can help scientists study this violent natural process in unprecedented detail, but for Tom Scott, a materials scientist at the University of Bristol, For us, volcano detection is just the beginning. Over the past few years, Professor Scott and a small group of collaborators have been developing an upgraded version of Dragon Egg's nuclear energy battery that could last for thousands of years without ever needing to be recharged or charged. replace. Unlike the batteries in most modern electronics, which produce electricity through chemical reactions, the battery studied by the University of Bristol collects particles ejected from radioactive diamonds, which can be made from engineered nuclear waste.
Earlier this month, Scott and his collaborator Neil Fox, a chemist at the University of Bristol, founded a company called Arkenlight. company, which aims to commercialize their nuclear diamond batteries. While the fingernail-sized battery is still in the prototype stage, it has already shown improvements in efficiency and power density compared to existing nuclear batteries. Once Scott and his team at Arkenlight have perfected their design, they will set up a pilot facility for mass production. The company plans to have the first commercial nuclear batteries on the market by 2024—just don't expect to find them in your own laptops.
Traditional chemical batteries or "primary cells", such as the lithium-ion batteries in smartphones or the alkaline batteries in remote controls, can release large amounts of power in a short period of time. Lithium-ion batteries can only last a few hours without charging, and after a few years of use, their recharging capabilities will decrease significantly. In contrast, nuclear or betavoltaic batteries (a type of battery that converts radioactive beta radiation into electrical current) are batteries that can continuously produce tiny amounts of electricity for long periods of time. The amount of electricity they emit is not enough to power a smartphone, but based on the nuclear material they use, they can provide stable power output for small devices for thousands of years.
"So, can we use nuclear batteries to power electric vehicles? The answer is - no." Morgan Boardman, CEO of Arkenlight, said that it is necessary to power such an energy-consuming thing power supply, which means "the 'mass' of the battery will need to be significantly greater than the 'mass' of the vehicle." Instead, the company is looking to expand into applications where regular battery replacement is nearly impossible or impossible, such as sensors in nuclear waste repositories or satellites in remote or dangerous locations. Boardman also sees applications closer to home, such as using the company's nuclear batteries in pacemakers or wearable devices. He envisions a future where people keep batteries and replace devices, rather than the current situation of frequently swapping out batteries on the same device. "You're going to replace several fire alarms before you ever replace the batteries because the batteries have outlived the equipment," says Boardman.
Not surprisingly, most people would definitely resist nuclear batteries because they believe they would produce radioactive material and be hazardous to their health. But judging from the health risk report of the Betavoltaic battery, it is comparable to the health risks of the "exit mark", which uses a radioactive material called "tritium" to achieve Its signature red fluorescence. Unlike gamma rays or other more dangerous types of radiation, beta particles only need a few millimeters of shielding to stop them in their tracks. "Usually just the walls of the battery are enough to stop any leakage," said Lance Hubbard, a materials scientist at Pacific Northwest National Laboratory. "This leaves the nuclear battery with virtually no radioactive material inside, which makes it very safe for people to use." " And, he added, when a nuclear battery runs out of power, it decays to a steady state, meaning there is no nuclear waste left inside it.
The first betavoltaic batteries have been around since the 1970s, but until recently, no one had access to them. They were originally used in pacemakers, where a defective power pack could mean the difference between life and death, until they were eventually replaced by cheaper lithium-ion alternatives. Today, the popularity of low-power electronic products heralds a new era for nuclear batteries. "It's a great power source option for very small power devices -- we're talking about microwatts or even picowatts here." Hubbard believes: "The Internet of Things is driving these energy sources "
A typical betavoltaic battery consists of thin, foil-like layers of radioactive material sandwiched between semiconductors. Its power generation principle is: when the nuclear material decays naturally, it emits high-energy electrons or positrons called beta particles, which disperse the electrons in the semiconductor material, thereby generating electric current. In this sense, a nuclear battery is similar to a solar panel, except that its semiconductor absorbs beta particles instead of photons.
Like solar panels, nuclear batteries have a strict energy limit. Their power density decreases as the source is farther from the semiconductor. Therefore, if the thickness of the battery layer exceeds a few microns, the power of the battery will drop drastically. Additionally, beta particles are fired randomly in all directions, which means that only a small fraction of the particles will actually hit the semiconductor, and only a fraction of those will be converted into electricity. As for how much radiation a nuclear battery can convert into electricity, Hubbard said: "At this stage, an efficiency of about 7% is the most advanced."
This is Arkenlight's "Betalight" "Voltamp battery, integrated with a sensor package. Unlike carbon-14 batteries, "Betalight" is a traditional "sandwich" nuclear battery made of tritium.
This is far from the theoretical maximum efficiency of nuclear batteries (about 37%). But that's where a radioactive isotope called carbon-14 can help. Carbon-14 is best known for its role in radiocarbon dating, which allows archaeologists to estimate the age of ancient artifacts, but it can also power nuclear batteries, as it can act as both a radioactive source and semiconductor. It also has a half-life of 5,700 years, which means that carbon-14 nuclear batteries could in principle power electronic devices for longer than humans have had written language.
Scott and his colleagues grew artificial "carbon-14" diamonds by injecting methane into hydrogen plasma in a special reactor. When the gas is ionized, the methane decomposes, and the carbon-14 collects on the substrate in the reactor and begins growing in a diamond lattice. However, Scott and his colleagues used this radioactive diamond in a traditional "sandwich" cell configuration, in which the nuclear source and semiconductor are discrete layers.
Moreover, they have applied for a patent for injecting carbon-14 directly into laboratory equipment to grow diamonds. The diamonds produced by this method are similar to the diamonds in our daily rings. The result is a crystalline diamond with a seamless structure that minimizes the distance beta particles can travel and maximizes the efficiency of nuclear batteries.
"Until now, the radioactive source has been separated from the diode that receives the radioactive source and converts it into electricity." Boardman said: "This is a breakthrough development ."
"Carbon-14" is formed naturally when cosmic rays strike nitrogen atoms in the atmosphere, but it is also produced as a byproduct in the graphite blocks that contain the control rods of nuclear reactors. These lumps will eventually become nuclear waste, and Boardman says there are nearly 100,000 tonnes of this irradiated graphite in the UK alone. The UK Atomic Energy Agency recently recovered tritium, another radioactive isotope used in nuclear batteries, from 35 tons of irradiated graphite blocks, and the Arkenlight team is working with the agency to develop a similar process to recover carbon-14 from graphite blocks.
If Arkenlight succeeds, it will provide an almost inexhaustible supply of raw materials for manufacturing nuclear batteries. The British AEA estimates that less than 100 pounds (approximately 45.36kg) of carbon-14 is enough to make millions of nuclear batteries. Additionally, by removing radioactive carbon-14 from the graphite block, it will be downgraded from high-level to low-level waste, making it easier to handle and safer for long-term storage.
At present, Arkenlight has not used modified nuclear waste to create a betavoltaic battery (Betavoltaic battery). Boardman said that before it is ready to be put into use, the company’s nuclear diamond battery is in It still needs several years of improvements in the lab. But the technology has already attracted interest from the space and nuclear industries. Boardman went on to say that Arkenlight recently received a contract from the European Space Agency to develop diamond batteries for what he calls "satellite RFID tags," which emit weak radio signals. , predicting continued identification of satellites for thousands of years. However, their vision does not stop at nuclear batteries. Arkenlight is also developing a gammavoltaic battery that can absorb gamma rays emitted by nuclear waste repositories and use them to generate electricity.
Arkenlight's prototype gammavoltaic battery, which will convert gamma rays from nuclear waste repositories into electricity.
Arkenlight is not the only company working on nuclear batteries. U.S. companies like City Lab and Widetronix have been developing commercial betavoltaic batteries for decades. These companies focus on more traditional layered nuclear batteries, and they use tritium rather than carbon-14 diamond as their nuclear power source. Michael Spencer, an electrical engineer at Cornell University and co-founder of Widetronix, said radioactive materials must be chosen with their application in mind. For example, carbon-14 emits fewer beta particles than tritium but has a half-life 500 times longer. This is indeed an advantage if you need something to last forever, but it also means that a carbon-14 nuclear battery would have to be much larger than a tritium battery to provide the same amount of power. "The choice of isotope brings a lot of trade-offs," Spencer said.
If nuclear batteries were once a fringe technology, they appear poised to enter mainstream energy. We don’t necessarily need—or want—all of our electronics to last thousands of years. But when we do that, we're going to have a battery that's always going to be running... maybe the next generation, and the next, and the next, and the next.
Written by: GolevkaTech