Order from us for quality, customized work in due time of your choice.
Abstract
Nuclear batteries harvest energy from radioactive specks and supply power to microelectromechanical systems (MEMS). The potential of nuclear batteries for longer shelf-life and higher energy density, when compared with other modes of energy storage, makes them an attractive alternative to investigate. The performance of the nuclear battery is a function of the radioisotope(s), radiation transport properties, and energy conversion transducers. The energy conversion mechanisms vary significantly between different nuclear battery types, where the radioisotope thermoelectric generator, or RTG, is typically considered a performance standard for all nuclear battery types. The energy conversion efficiency of a non-thermal-type nuclear battery requires that the two governing scale lengths of the system, the range of ionizing radiation and the size of the transducer, be will well-matched. Natural mismatches between these two properties have been the limiting factor in the energy conversion efficiency of small-scale nuclear batteries. Power density is also a critical performance factor and is determined by the interface of the radioisotope to the transducer. Solid radioisotopes are typically coated on the transducer, forcing the cell power density to scale with the surface area (limiting power density). Methods that embed isotopes within the transducer allow the power density to scale with cell volume (maximizing power density). Other issues that are examined include the limitations of shelf-life due to radiation damages in the transducers and the supply of radioisotopes to sustain a commercial enterprise.
Introduction
A burgeoning need exists today for small, compact, reliable, lightweight, and self-contained rugged power supplies to provide electrical power in such applications as electric automobiles, homes, industrial, agricultural, recreational, remote monitoring systems, spacecraft, and deep-sea probes. Radar, advanced communication satellites, and especially high-technology weapon platforms will require much larger power sources than today’s power systems can deliver. For very high-power applications, nuclear reactors appear to be the answer. However, for the intermediate power range, 10 to 100 kilowatts (kW), the nuclear reactor presents formidable technical problems.
Because of the short and unpredictable lifespan of chemical batteries, however, regular replacements would be required to keep these devices humming. Also, enough chemical fuel to provide 100 kW for any significant period of time would be too heavy and bulky for practical use. Fuel cells and solar cells require little maintenance, and the latter need plenty of suns.
Thus the demand to exploit radioactive energy has become inevitably high. Several methods have been developed for the conversion of radioactive energy released during the decay of natural radioactive elements into electrical energy. A grapefruit-sized radioisotope thermo-electric generator that utilized heat produced from alpha particles emitted as plutonium-238 decay was developed during the early 1950s.
Since then nuclear has taken significant consideration in the energy source of the future. Also, with the advancement of technology, the requirement for lasting energy sources has increased to a great extent. The solution to the long-term energy source is, of course, nuclear batteries with a life span measured in decades and the potential to be nearly 200 times more efficient than the currently used ordinary batteries. These incredibly long-lasting batteries are still in the theoretical and developmental stage of existence, but they promise to provide clean, safe, almost endless energy.
Unlike conventional nuclear power generating devices, these power cells do not rely on a nuclear reaction or chemical process and do not produce radioactive waste products. Nuclear battery technology is geared to applications where power is needed in inaccessible places or under extreme conditions.
What are nuclear power batteries?
The terms atomic battery, nuclear battery, tritium battery, and radioisotope generator are used to describe a device that uses energy from the decay of a radioactive isotope to generate electricity. Like nuclear reactors, they generate electricity from atomic energy but differ in that they do not use a chain reaction. Compared to other batteries they are very costly, but have an extremely long life and high energy density, so they are mainly used as power sources for equipment that must operate unattended for long periods of time, such as spacecraft, pacemakers, underwater systems, and automated scientific stations in remote parts of the world.
Nuclear battery technology began in 1913 when Henry Moseley first demonstrated the beta cell. The field received considerable in-depth research attention for applications requiring long-life power sources for space needs during the 50s and 60s. In 1954 RCA researched a small atomic battery for small radio receivers and hearing aids. After RCA development, over the years many types and methods have been developed. The scientific principles are well known, but modern nano-scale technology and new wide-bandgap semiconductors have created new devices and interesting material properties not previously available.
Batteries using the energy of radioisotope decay to provide long-lived power (10-20 years) are being developed internationally. Conversion techniques can be grouped into two types: thermal and non-thermal. The thermal converters (whose output power is a function of a temperature differential) include thermoelectric and thermionic generators. The non-thermal converters (whose output power is not a function of a temperature difference) extract a fraction of the incident energy as it is being degraded into heat rather than using thermal energy to run electrons in a cycle. Atomic batteries usually have an efficiency of 0.1-5%. High-efficiency betavoltaics has 6-8%.
Types of Nuclear Batteries
Nuclear Batteries are mainly classified into two main categories:-
Thermal converters
Thermal converters are devices that convert heat energy to electrical energy i.e. whose output power is a function of a temperature deferential. Thermal converters are also classified into four types.
Thermionic Converter
- Radioisotope Thermoelectric generator
- Thermo Photovoltaic Cells
- Alkali Metal Thermal to Electric Converter
Non Thermal converters
Non Thermal converters extract a fraction of the nuclear energy as it is being degraded into heat. Their outputs are not functions of temperature differences as the thermoelectric and thermionic converters. Non Thermal generators can be grouped into five classes.
- Direct Charging Generators
- Betavoltaics
- Alphavoltaics
- Optoelectric
- Reciprocating Electromechanically Atomic Batteries
Fuel considerations
The major criterions considered in the selection of fuels are:
- Avoidance of gamma in the decay chain
- Half-life
- Particle range
- Watch out for (alpha, n) reactions any radioisotope in the form of a solid that gives off alpha or beta particles can be utilized in the nuclear battery. The first cell constructed (that melted the wire components) employed the most powerful source known, radium-226, as the energy source. However, radium-226 gives rise through decay to the daughter product bismuth-214, which gives off strong gamma radiation that requires shielding for safety. This adds a weight penalty in mobile applications.
Radium-226 is a naturally occurring isotope that is formed very slowly by the decay of uranium-238. Radium-226 in equilibrium is present at about 1 gram per 3 million grams of uranium in the earth’s crust. Uranium mill wastes are readily available sources of radium-226 in very abundant quantities. Uranium mill wastes contain far more energy in the radium-226 than is represented by the fission energy derived from the produced uranium.
Strontium-90 gives off no gamma radiation so it does not necessitate the use of thick lead shielding for safety. strontium-90 does not exist in nature, but it is one of the several radioactive waste products resulting from nuclear fission. The utilizable energy from strontium-90 substantially exceeds the energy derived from nuclear fission which gave rise to this isotope.
Once the present stores of nuclear wastes have been mined, the future supplies of strontium-90 will depend on the amount of nuclear electricity generated hence strontium-90 decay may ultimately become a premium fuel for such special uses as for perpetually powered wheelchairs and portable computers. Plutonium-238 dioxide is used for space applications.
Advantages
The most important feat of nuclear cells is the life span they offer, a minimum of 10 years! This is whopping when considering that it provides nonstop electric energy for the seconds spanning these 101ong years, which may simply mean that we keep our laptop or any handheld devices switched on for 10 years nonstop. Contrary to fears associated with conventional batteries nuclear cells offer reliable electricity, without any drop in the yield or potential during its entire operational period. Thus the longevity and reliability coupled together would suffice the small factored energy needs for at least a couple of decades.
The largest concern about nuclear batteries comes from the fact that it involves the use of radioactive materials. This means throughout the process of making a nuclear battery to final disposal, all radiation protection standards must be met. Balancing the safety measures such as shielding and regulation while still keeping the size and power advantages will determine the economic feasibility of nuclear batteries. Safeties with respect to the containers are also adequately taken care of as the battery cases are hermetically sealed. Thus the risk of safety hazards involving radioactive material stands reduced.
As the energy associated with fissile material is several times higher than conventional sources, the cells are comparatively much lighter and thus facilitate high energy densities to be achieved. Similarly, the efficiency of such cells is much higher simply because of radioactive materials in little waste generation. Thus substituting the future energy needs with nuclear cells and replacing the already existing ones with these, the world can be seen transformed by reducing the greenhouse effects and associated risks. This should come as a handy savior for almost all developed and developing nations. Moreover the nuclear produced therein are substances that don’t occur naturally. For example, strontium does not exist in nature but it is one of the several radioactive waste products resulting from nuclear fission.
Drawbacks
First and foremost, as is the case with most breathtaking technologies, the high initial cost of production involved is a drawback but as the product goes operational and gets into bulk production, the price is sure to drop. The size of nuclear batteries for certain specific applications may cause problems, but can be done away with as time goes by. For example, the size of the Xcell used for laptop batteries is much more than the conventional battery used in laptops.
Though radioactive materials sport high efficiency, the conversion methodologies used presently are not much of any wonder and at best match conventional energy sources. However, laboratory results have yielded much higher efficiencies, but are yet to be released into the alpha stage.
A minor blow may come in the way of existing regional and country-specific laws regarding the use and disposal of radioactive materials. As these are not unique worldwide and are subject to political horrors and ideology prevalent in the country. The introduction legally requires these to be scrapped or amended. It can be however hoped that, given the revolutionary importance of this substance, things would come in favor gradually.
Above all, to gain social acceptance, new technology must be beneficial and demonstrate enough trouble-free operation that people begin to see it as a ‘normal’ phenomenon. Nuclear energy began to lose this status following a series of major accidents in its formative years. Acceptance accorded to nuclear power should be trust-based rather than technology-based. In other words, acceptance might be related to public trust in the organizations and individuals utilizing the technology as opposed to based on the understanding of the available evidence regarding the technology.
Applications
- Space Applications
- Medical Applications
- Mobile devices
- Automobiles
- Military Applications
- Underwater sea probes and Sea Sensors
Conclusion
The world of tomorrow that science fiction dreams of and technology manifests might be a very small one. It would reason that small devices would need small batteries to power them. The use of power as heat and electricity from radioisotopes will continue to be indispensable. As technology grows, the need for more power and more heat will undoubtedly grow along with it.
Clearly, the current research on nuclear batteries shows promise for future applications for sure. With the implementation of this new technology credibility and feasibility of the device will be heightened. The principal concern about nuclear batteries comes from the fact that it involves the use of radioactive materials. This means throughout the process of making a nuclear battery to final disposal, all radiation protection standards must be met. The economic feasibility of nuclear batteries will be determined by their applications and advantages. With several features being added to this little wonder and other parallel laboratory works going on, nuclear cells are going to be the next best thing ever invented in human history.
References
- Power from radioisotopes,’ USAEC, Division of Technical Information # Powerstream.com
- Powerpaper.com
- Technologyreview.com
- Wilcipedia.com/atomic_battery
Order from us for quality, customized work in due time of your choice.