bechtelplasmafusion



= __ Introduction  __ = Most energy experts agree that, as the world energy consumption continues to grow, fossil fuels, such as oil, coal, and natural gas, will either become too scarce or too polluting to rely upon after the next few decades. If this is true, then there exist only a few alternative sources: solar, wind, geothermal, hydroelectric, biofuel, and nuclear. The alternative that we will focus upon here is type of nuclear reaction known as fusion. This is an entirely different reaction altogether than the typical fission reaction which reactors are already in place using. The biggest differences can be seen in the image below. While fission generates energy from splitting a heavy nucleus into smaller ones, fusion does the opposite and combines two small nuclei into a larger one. To effectively combine two nuclei, one must overcome the enormous repulsive forces of the positively charged protons. The key to this is to heat atoms to extreme temperatures which strip electrons form the nuclei and create an ionized gas known as a plasma. This reaction occurs all of the time in our sun and other stars, but presents significant challenges here on earth. From a physics point of view there are three conditions necessary to achieve controlled fusion: confinement, temperature, and density. Scientists have discovered that the best elements to perform fusion with are tritium and deuterium, to isotopes of hydrogen (shown in the illustration above). Deuterium occurs naturally and tritium can be made within the fusion system from lithium, even though it is not naturally occurring. Deuterium can be distilled from all forms of water and is a widely available, harmless, and virtually inexhaustible resource. The world reserve of lithium is sufficient to supply the world’s fusion electricity needs for well over one thousand years at current rates of consumption. This breeding of tritium can be accomplished by lining the walls of the reactor with lithium. Although this is currently the best option for producing the reaction, there is research being done into the possibility of deuterium-deuterium or other reactions. There are essentially two different methods used by scientists confine a plasma and produce fusion in a laboratory; inertial and magnetic confinement. Inertial confinement basically uses the pressure created by high powered lasers to exert a large amount of force on small collections of material. This is interesting and has many practical applications, but will not be able to meet our energy needs any time soon. Magnetic confinement of plasma offers a much greater potential. Scientists have developed several different geometries for magnetic confinement fusion reactors including the tokamak, spherical torus, and compact stellarator; pictured below. Each of these designs has its own benefits. The most basic type is the tokamak, but the latest scientific discoveries have shown the spherical torus to be the most economical design. We will consider examples of both of these types of reactors later to illustrate the potential and challenges of fusion energy. The fact that particles in a plasma have positive and negative charges allows them to be confined by magnetic fields. These magnetic fields also set up a current in the plasma through induction and increase the energy. There are also several other different techniques used to increase the temperature to meet the huge requirement of the reaction. To initiate the fusion reaction, the plasma must be heated to over 100 million degrees Celsius, which is six times the temperature at the center of the sun. This level of energy is typically attained using radio frequency or microwaves and particle beams. There is research being done into other forms of heating as well. The plasma density requirement also poses challenges to scientists, but this requirement is typically satisfied using the proper inertial confinement and heating systems. More research is being done on this topic to further improve the effectiveness of fusion reactors. Once the fusion reaction begins it has enormous potential for generating large amounts of energy. This reaction converts a very small quantity of matter into a tremendous amount of energy by Einstein’s famous equation. The fusion reaction alone has an energy payback of about 450:1. A great deal of this energy is lost in the reactor, but there are still huge amounts of energy created. Ideally, once the reaction has been obtained, 80% of the energy can be transferred to the walls of the reactor by neutrons produced in the reaction. The remaining 20% of the energy is carried by helium atoms which contribute to the internal heat of the plasma. The ultimate goal of all current fusion research is to use this energy to create what is known as a burning reaction. A burning reaction is one that requires no external energy to maintain the reaction once it has begun. = __ History  __ = Plasma research began in the 1920s and 1930s, but it wasn’t until the 1950s that the first large scale magnetic confinement fusion experiments were started in the US, Britain, and Soviet Union. Magnetic fusion research at Princeton University began in 1951 under the code name Project Matterhorn by professor of Astronomy, Lyman Spitzer. The work being done in these countries was usually an offshoot of their-mononuclear weapon research and was initially classiﬁed. Because of scant progress in each country’s effort and the realization that controlled fusion research was unlikely to be of military value, all three countries declassiﬁed their efforts in 1958 and have cooperated since. In 1961, Project Matterhorn was renamed the Princeton Plasma Physics Laboratory (PPPL) and has since become one of our nation’s current leading research laboratories in the field. In the mid-1960s, the Russians announced breakthrough results with their new torus reactor. During this same period, much of the intellectual foundation was established for the new discipline of plasma science. In the 1970s, uncertainty in long term energy supplies, coupled with the growing environmental movement, combined to create a tremendous amount of enthusiasm for fusion research. For the first time, in 1978, the Princeton Large Torus achieved plasma temperatures above the minimum that would be required for a self-sustaining fusion reaction. Many other tokamaks followed suite with progressively improved performance. Funding for fusion continued to increase through this period until it peaked at $468 million in 1984. In 1986, following the Geneva Superpower Summit, President Reagan and Soviet President Gorbachev discussed the joint design, development, and construction of a magnetic fusion experiment that would, for the first time ever, demonstrate sustained, controlled fusion power. The original agreement was made between these two countries, Japan, and the European Union in 1987, giving birth to the International Thermonuclear Experimental Reactor (ITER). Numerous other breakthroughs were made during the 20th century including the construction of the National Spherical Torus Experiment (NSTX). NSTX began operation in 1999, nine months ahead of schedule. In 2004 record fusion efficiency was achieved with this experiment. In 2005, the process to determine the location of ITER was concluded and in 2007 the ITER Organization was officially established. The first plasma is expected to be created by this reactor in 2018. = __ Who is Involved  __ = Fusion energy truly is a cooperative global objective. Today there are more than 40 countries conducting research in fusion and sharing its vision of satisfying long term energy demands. The climate of cooperation in fusion research has strengthened the development of the underlying science and reduced costs worldwide. The countries involved include those highlighted below. In the US alone there are numerous groups invested in the research and development of fusion energy. One of the most important stakeholders in this is the United States Department of Energy (DOE).The DOE is responsible for discovering long term energy sources to power our country and has funded a large number projects. Other important stakeholders are the research universities and national laboratories who are in charge of developing the scientific and technological advancements necessary to make fusion a viable source of energy. Some of the most prominent are the PPPL, MIT Plasma Fusion Center, Caltech, the University of Wisconsin, and Oak Ridge National Laboratory. Other key actors are the industrial players and fusion collective groups. These included the Fusion Power Associates, the American Physical Society Division of Plasma Physics, General Atomics, and the University Fusion Association. Other stakeholders worth mentioning are those who currently see the negative effects of our current energy sources, which would be eliminated by developing fusion energy. This includes people and other organisms in close proximity to mining and power plant facilities and those effected by global warming. = __ Debates  __ = There are essentially three major debates over plasma fusion. The first is whether or not a self sufficient reaction can even be achieved. Theoretically this is definitely possible and occurs all of the time in the sun, but the big challenge is confinement. Plasma is a chaotic system and not easy to control. Nevertheless, all that is standing in our way is technological advancement, which has shown to be very rapid in fusion development. “Over the past 20 years a 1,000,000 fold increase has been achieved in the overall performance of experimental fusion devices. This record surpasses the often heralded rate of progress in computer chip density and power.” (Fusion Science 2011) This relationship is illustrated in the plot below, which clearly shows exponential technological advancement at a rate faster than that of computing power. This shows that fusion really is a promising source of energy in the future. The second debate is whether or not fusion energy is cost effective. The initial cost of fusion reactors is certainly a large investment, but the cost of fuel is next to nothing and a huge amount of energy can be produced. One quart of fusion fuel, for example, can create the same amount of energy through fusion as burning 6600 tons of coal; thus this reaction is a million times more powerful than a chemical reaction. According to David Ward, a physicist at the UK Atomic Energy Authority who has researched the economics of fusion energy the current estimates of the cost of fusion electricity are between 5 and 10 cents per kilowatt-hour. This is comparable to the cost of energy from fuels which we rely upon heavily today, only without any of the negative externalities. Furthermore, as we continue to advance technology we can build more efficient and cost effective reactors. The third debate is that fusion energy is inherently dangerous because it is a nuclear reaction which creates radioactive waste and a large amount of energy. While it is true that fusion is a nuclear reaction the belief that it is inherently dangerous is nothing more than a misunderstanding. Comparing the process of nuclear energy production by fission and fusion is like comparing apples to oranges. In a fusion reactor there is no chance of a meltdown or serious energy release because as soon as the containment system fails energy from the plasma will be distributed to the walls of the reactor and the reaction will cease. This is why it was realized in the 1950s that nuclear proliferation with fusion was not a possibility. Also, there is little to no radioactive waste produced by the reaction. The only possible sources of radiation are unused tritium emissions and possible radioactive materials created by neutrons interacting with the surface of the containing vessel. The former of these can be minimized well below natural radiation limits by filtering gaseous exhaust and reusing the tritium. The later can be minimized by careful choice and handling of the vessel materials. Either way possible radioactive elements have short half lives, on the order of 10 years. In the 1995 report the President’s Committee of Advisors on Science and Technology states that, “with respect to radioactive waste hazards, those of fusion (based on the most meaningful indices combining volume, radiotoxicity, and longevity) can be expected to be at least 100 times and perhaps 10,000 or more times smaller than those of fission.” = __ Project One: NSTX  __ = The National Spherical Torus Experiment (NSTX) is a cooperative research venture into the effects of plasma confinement by a spherical torus. Theoretically, the spherical torus can maintain a higher plasma density with a weaker magnetic field, thus increasing the economic performance of the reactor. This experiment went online September 1999 producing its first plasma two months ahead of schedule and operating with its full design plasma current of 1 million amperes nine months ahead of schedule. It has since surpassed its design value and attained a plasma current of 1.4 million amperes. This shows the large amount of potential that this research has. This experiment is located at the PPPL test facility in Princeton, New Jersey. This national lab has made many important contributions to the field of plasma physics and is currently one of the leading facilities for research and development. The largest benefit of this project being located here is having the research infrastructure that is already in place. For the 2010 fiscal year, PPPL received $88.3 million in funding for fusion research and currently has 457 employees, including physicists, engineers, technicians, and graduate students. The lab also has the support of the large student and faculty body at Princeton University. Furthermore, the device is located in the former Princeton Large Torus (PLT) test cell and utilizes much of the original equipment. This drastically reduced the cost of the project by about $50 million to a base construction cost of $18.6 million. This cost was not solely covered by the PPPL, but was distributed to the projects other contributors as well. The experiments on NSTX are being conducted by a collaborative research team of physicists and engineers from 30 US laboratories and universities and 28 international institutions from 11 countries. There were not very many significant barriers to the development of this project and the biggest difficulty was developing a better scientific and technological understanding of this new design. Going forward, however, there are large barriers facing the development of a full scale reactor of this type. The biggest of these is acquiring proper funding for the construction of such a project, as will be illustrated in the next example, and testing individual components to ensure they will withstand high plasma temperatures and pressures. These are both important concerns in designing any fusion reactor. All in all, this project has shown to be completely feasible and has made important contributions to our understanding of plasma fusion. Press coverage of the research found at the PPPL can be found at []. = __ Project Two: ITER  __ = The International Thermonuclear Experimental Reactor (ITER) is a project aimed at building the world’s largest and most advanced tokamak fusion reactor. The name ITER also means “the way” in Latin. This project illustrates both the potential and challenges of fusion energy. The goal of ITER is to create the first burning plasma, that is, a plasma which is predominately sustained by the power of its own reaction. ITER will produce 500 million watts of fusion power for a period of at least 400 seconds. This covers the electrical needs for 200,000 average-size homes, assuming 40% efficiency in the conversion of heat to electricity. The heat produced by ITER will be at least 10 times greater than the external power provided to heat the fusion fuel. With this, ITER will provide an essential bridge from previous, small scale experiments, which have produced up to 1 million watts of fusion heat for time periods approaching one second, to a Demonstration Power Plant (Demo) producing 2,500 million watts of fusion heat – the size of modern electrical plants - (1000 million watts of electricity) continuously with a gain of over 25. The Demo project is predicted to be operational around the year 2035. The reason this bridge reactor is important is perform research which will ensure that all of the components function properly with the unprecedented amount of fusion energy which will be produced. This biggest concern is from the neutron flux of the reaction, but without building the full scale reactor and testing, there is no way to be certain what will work. ITER is an international partnership between China, the European Union, India, Japan, Russia, South Korea, and the United States. The site selected for the project is Cadarache, in southeastern France. The decision of where to locate the reactor took several years and primarily came down to the funding for the project. The European Union was prepared to contribute the most to the construction and operation cost and determined that France would be the ideal location. Fusion reactors do not have any strong geographic dependence and could be located in most regions. The only concern is that the reactor needs a large source of water for heat conduction, similar to that of all other power plants. The nearby Canal de Provence will provide this for the reactor, which will only actually use 1% of the water flowing through the canal. The $15-$20 billion dollar cost of the project will be shared by the countries involved, with the host country covering the largest share. The agreement was that the EU would cover 4/11ths, Japan 2/11ths and every other country 1/11th of the total cost each. This is an ambitious project, but it is the next step in attaining a viable fusion energy source. The cost of this venture may be large, but it is a research investment with huge potential paybacks in the near future. News coverage of ITER can be found at []. = __ Conclusion  __ = Plasma fusion scientists face important challenges going forward that will ultimately test the efficacy of this energy source, but if we can manage to overcome these there is enormous potential that can be attained. The major challenges are acquiring funding for research and development of self sufficient fusion reactions and determining the most effective way to generate this energy. Fusion power won’t solve our energy problems in the near future, but it has shown to be one of, if not the best solution in the long run. Fusion can provide us with a w orldwide long-term availability, low-cost energy without virtually any waste production and no possibility of a runaway reaction. This is exactly what we need if we want to continue our modern lifestyles. Renewable energy sources provide numerous benefits as well, but none anywhere near the dense energy per square foot capabilities that fusion reactors do. To make fusion energy viable we need more investment in research and a well educated body of scientists and engineers to lead the way. To help make this a reality, you can encourage your government to invest more in alternative energy research, study hard in school, and help train the scientists and engineers of the next generation! __ Resources: __ Bellan, Paul M. //Fundamentals of Plasma Physics//. Cambridge: Cambridge UP, 2008. Scribd. Web. 3 May 2011. . Chrzanowski, J. H., H. M. Fan, P. J. Heitzenroeder, J. Robinson, M. Ono, and Princeton Plasma Physics Laboratory. //Engineering Overview of the National Spherical Tokamak Experiment//. Rep. Champaign, IL: IEEE, 1995. //IEEE Xplore Digital Library//. Web. 8 May 2011. . Division of Plasma Physics, American Physical Society, Fusion Power Associates, General Atomics, MIT Plasma Fusion Center, Princeton Plasma Physics Laboratory, and University Fusion Association. //Fusion Science: Harnessing the Energy of the Stars//. American Physical Society, 2011. ITER Organization. //ITER - the Way to New Energy//. 2011. Web. 09 May 2011. . Peplow, Mark. "Fusion Power Gets Slammed: But Supporters Say Arguments About Reactor Costs Are Old Hat." //Nature//. //News@nature.com//. Nature Publishing Group, 9 Mar. 2006. Web. 7 May 2011. . U.S. Department of Energy. //Fusion Power//. Princeton, NJ: U.S. Department of Energy, March 2011. U.S. Department of Energy. //ITER and the Promise of Fusion Energy//. Princeton, NJ: U.S. Department of Energy, March 2011. U.S. Department of Energy. //National Spherical Torus Experiment (NSTX)//. Princeton, NJ: U.S. Department of Energy, March 2011. U.S. Department of Energy. //Princeton Plasma Physics Laboratory An Overview//. Princeton, NJ: U.S. Department of Energy, March 2011. Wikipedia. "ITER." Wikipedia, The Free Encyclopedia, 28 Mar. 2011. Web. 7 May 2011. . __ Images: __ [] [] [] [] [] [] [] [] []