As our world continues to search for alternative energy sources, researchers are looking to past innovations for power generation potential. Betavoltaic batteries, which harness energy from radioactive decay, were first described by internationally recognized energy expert Paul Rapapport in 1953. Today, this technology is seeing renewed interest thanks to both betavoltaic technology advancements and changes to the devices that could be powered by these “nuclear” batteries.
How do betavoltaic batteries work?
Betavoltaic cells convert the atomic energy stored in a radioactive isotope into electrical energy. The isotope emits electrons, which create electron-hole pairs in a semiconductor. This is quite similar to the photovoltaic effect that occurs within solar cells. Neither betavoltaic nor photovoltaic cells are technically batteries, as they do not store energy. In the case of betavoltaic “batteries,” energy is constantly produced throughout the useful life of the cell.
The History of Betavoltaic Power
In 1953, Paul Rappaport filed a patent application for “radioactive batteries” during his time with RCA’s David Sarnoff Research Laboratories. Rappaport later became widely known for his work with photovoltaic cells and went on to found the Solar Energy Research Institute. The earliest patents to use the phrase “betavoltaic” were filed by City Labs Inc., Donald W Douglas Laboratories, and Medtronic.
Innovation in the space continued through the 1970s, when the Betacel betavoltaic battery was used to power more than 120 pacemakers. The long life (as compared to electrochemical batteries) was seen as a real benefit for implanted devices like the pacemaker. However, as lithium battery technology improved during the same time period, it became the primary method for powering pacemakers due to the radiation and cost concerns surrounding betavoltaic power.
Lithium battery technology is not without limitations. These batteries are prone to overheating, require increasingly costly raw materials, and charge slowly. As technology changes, betavoltaic batteries are experiencing renewed interest. Electronics, including MEMS, are much smaller and require less energy than they did decades ago. Isotope and semiconductor innovations have made betavoltaic cells safer; tritium, an isotope of hydrogen, produces less energy, no radiation, and beta electrons that are easy to block. One organization, which calls itself a nuclear battery company, produces betavoltaic cells that do not require a radiation license. In the decades since Rappaport’s innovation, radioactive isotopes have become common in other everyday items, including exit signs and smoke detectors.
Commercializing Betavoltaic Batteries
Betavoltaic cells have advantages over other battery technologies, including their small size, long life, and resistance to extreme temperatures. These features make the technology ideal for the remote and/or harsh environments often faced in military, space, and medical applications. There are multiple companies innovating in the space for these and other applications, including Medtronic, Elira Inc., City Labs Inc., and SeerStone LLC.
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