Physics Today: Batteries can power anything from small sensors to large systems. University of Missouri researchers are developing a nuclear energy source that is smaller, lighter and more efficient.
"To provide enough power, we need certain methods with high energy density," said Jae Kwon, assistant professor of electrical and computer engineering at MU. The radioisotope battery can provide power density that is six orders of magnitude higher than chemical batteries.
Kwon and his research team have been working on building a small nuclear battery, currently the size and thickness of a penny, intended to power various micro/nanoelectromechanical systems. Although nuclear batteries can pose concerns, they are safe are already powering a variety of devices, such as pace-makers, space satellites and underwater systems.
Kwon's innovation is not only in the battery's size, but also in its semiconductor. Kwons battery uses a liquid semiconductor rather than a solid semiconductor.
The critical part of using a radioactive battery is that when you harvest the energy, part of the radiation energy can damage the lattice structure of the solid semiconductor, said Kwon. By using a liquid semiconductor, we believe we can minimize that problem.
Kwon has been collaborating with J. David Robertson, chemistry professor and associate director of the MU Research Reactor, and is working to build and test the battery at the facility.
In the future, they hope to increase the battery's power, shrink its size and try with various other materials. Kwon said that the battery could be thinner than the thickness of human hair.
Nuclear batteries in general may find use in deep space manned craft propulsion systems.
For one, the use of nuclear batteries as highly modular, highly replacable units can be of benefit in powering ion or electron rocket engines.
An energy density of 6 orders of magnitude greater than chemical systems is nothing to sneeze at. One can imagine an outbound space craft with a mass of about 300 metric tons perhaps carrying 100 metric tons of batteries wherein the space craft could undertake several journeys if not many journeys to the outer reaches of our solar system, and then back to Earth again, before the highly modular batteries would need replacing. The mass specific power output of such batteries will need improving in order to enable timely exiting and egress of manned space craft from the inner solar system.
As for small nuclear batteries, they can be of use in powering so-called micro-sattelites which have a mass in the range of one kilogram to perhaps 10 kilograms.
I cannot think of a better use for radio-isotopes than to power manned space craft and sattelites via incorporation into nuclear batteries.
In a sense, nuclear batteries for space systems already exist in the form of radiothermal generators that have seen service on some of our deep solar system probes. However, a true nuclear battery that is as modular and replacible as a Duracell D size battery would be a big improvement.
In an era when we are starting to see the limits of chemical combustion rocket technology for manned space flight applications beyond Earth and Lunar orbit, perhaps the folks at NASA could stand to study the practicality of cost effective and safe nuclear batteries to power future deep space manned vessels.