Brown.Eric.spring.wiki.2011

__**Nuclear Fusion**__

__Energy and Water, a Global Concern__ Planet Earth is currently at a cross roads in history. Two major problems face humanity at the beginning of this decade: global climate change, and a sustainable water supply for the populations of the planet. Whether or not one actually believes in climate change is a matter of personal opinion. But the statistics linking greenhouse gas emissions to a global rise in temperature are convincing. The following pictures, taken for the United States EPA Climate Change Slideshow, show the link between increased gas emissions, and the rising global temperature. This rise in temperature could have disastrous affects on human populations if left unchecked. Billions could be displaced along heavily populated coastal regions by rising sea levels as a result of polar ice caps melting. The world's bread baskets, currently rich with fertile lands, could become unable to support the Earth's populations. The burning of fossil fuels, leading to an overall rise in the Earth's temperatures can no longer sustain the human race as a viable energy option. []

__Fossil Fuels: The Driving Force__ In the past fifty years or so global demand for energy has soared. In just 2010 alone, global demand power jumped 5%. More than 80% of this energy is generated from fossil fuel burning sources. Oil, coal, and natural gas are the three primary fuels burned by the energy industries. As seen in the following equation for the combustion of hydro-carbons, each of these fuels results in CO 2 released into the atmosphere, contributing to global climate change.

[]

This carbon dioxide creates a greenhouse effect, trapping in heat from the sun's warmth and gradually warming the Earth's temperatures over many years. Left unchecked, this simple chemical formula has the potential the change the planet into something very different than what we know today.

__Options: What Can and Must be Done?__ The major concern in relation to these two issues is that an easy way to fix one will result in a worsening of the other. Water desalination is easy, but requires much energy. Currently, nearly all of that energy would have to come from fossil fuel burning sources, worsening the climate change issue. So what can be done? What is needed is a source of energy that is accessible, clean, and powerful. Nuclear fusion could be the answer to the world's cry for energy. Global emission from non-clean energy sources has increased exponentially since the dawn of the twentieth century. The greenhouse gases released by these fuels are the driving forces behind global climate change. []

Some sources believe that to reverse the global rise in temperatures, nothing less than a 75% reduction in greenhouse gas emissions is necessary over the never 50 years. To do this, the human race needs to harness clean and renewable energy sources. Most clean energy sources have their drawbacks. Wind, hydro, solar, and geo-thermic power stations can only be built where conditions are suitable, and produce relatively small amount of energy for their size. But nuclear fusion has none of these drawbacks. It requires but the technology required to operate it, and the small amount of fuel to cause the reaction. To reverse the trends it has started, man kind needs to invest in the technology of nuclear fusion.

__Nuclear Fusion: Harnessing the Power of the Sun__ The idea of nuclear fusion is simple. Take two light atoms and smash them together under extremely high temperatures (whereas the fission of two atoms heavier than iron produces energy, the __fusion__ of two lighter atoms produces energy). The result is a single heavier atom and the release of vast amount of thermal energy (the difference between the masses of the stating molecules and the final resulting molecule becomes energy in the form of light and heat). Like most power stations now, this heat from the reaction will be used to convert water into steam. The steam can then be used to do work on a steam turbine attached to an electrical generator, producing electricity.

Most modern scientists agree that the most promising fuel is the D-T Fuel Cycle (Deuterium and Tritium). Both isotopes of the hydrogen atom (Deuterium 2 H and Tritium 3 H) are found in nature, however tritium is found in near negligible amounts, and therefore requires a reaction with lithium to be created. The large ratio of mass between these two isotopes, with deuterium at 2 amu, and tritium at 3 amu, make hydrogen a favorable element for a fusion reaction. [|ttp://www.atomicarchive.com/Fusion/Images/fusion.jpg]

A fusion reactor may be of two types: inertial or magnetic confinement. In an inertial confinement reactor, multiple laser heat the fuel to the point where the molecules can overcome their repulsive bonds, and fuse together to for a single, heavier element. In a magnetic confinement reactor uses magnetic and electrical fields to perform the same task. Both require energy to operate, but release far more energy than they consume once the reaction is initiated. The following images represent the basic workings of these two designs (inertial confinement left, magnetic right). []

The following is a video produced by The Institute for Plasma Physics that describes the inner workings of a nuclear reaction, and the potential it will play in the future of this planet.

media type="youtube" key="vDAZsPkTkMM" height="349" width="560" align="center"

__Greenhouse Gases: Prevalence?__ One of the major advantages to a world powered by nuclear fusion would be the negligence of all fossil fuel burning for power producing purposes. A fusion reactor uses only hydrogen as a reactant, and creates only tiny amount of helium as a product. This can been seen in the following stoichiometric equation.

2 H+ 3 H + Heat 4 He + Heat

__Water Desalination: How Can Fusion Help?__ In the modern world, the biggest problem contributed to the desalination of sea water is the energy required to separate the water for the non desirable waste. Currently, around 80% of that energy would come from sources utilizing fossil fuels, contributing the problem of global climate change.

Modern science tells us that the most efficient ways to desalinate sea water is through distillation, or through reverse osmosis. Both of these processes are straight forward, but energy intensive. On average, it requires 0.75 kW Hr of energy to desalinate one cubic meter of water. In July of 2010, Joint European Torous caused a reaction in magnetic confinement that produced more than 10 MW (1 MW = 1,000 kW) sustained for about 0.5 seconds. Assuming a reaction could be sustained, and utilizing the figures above, one can calculate that a single fusion reactor could desalinate more than 13,000 cubic meters of water an hour (around 350,000 gallons). This means that if one fusion reactor could be run for a 24 hour period with a sustained reaction, and all the produced energy was used to desalinate sea water, about 8.4 million gallons of fresh water could be produced in one day.

(Reverse Osmosis) [] The average American uses between 80-100 gallons of water per day. Assuming maximum water consumption, a single fusion reactor could produced enough fresh water every day for 84,000 people.

__Fusion Power: The Answer to the World's Needs__ Fusion power has a lot going for it. It has the ability to answer the world's demands for both clean energy, and clean water. As it uses no fossil fuels in its reaction, a fusion power reactor would not contribute to the global rise in temperature. The only product released from a fusion reactor is helium, a gas harmless to the environment around it.Fusion power also has the advantage of producing little to no nuclear waste. Unlike modern fission plants which create waste taking thousands of year to degrade, certain types of fusion have to advantage of producing no nuclear waste, while others produce little. []

A second advantage of the fuel used for fusion is its abundance on this planet. According to International Thermonuclear Experimental Reactor group, the needed reserves of fuel found in the ocean are enough to power the entire planet for the next 60 million years (assuming no increase in power usage). Lithium, required to create the hydrogen isotopes necessary for the fusion reaction, can be found both ashore and in the sea. The ITER states that there is enough of this resource ashore to create 3,000 years worth of fuel, while there is enough in the seas to create an additional 65 million years worth. This amount of available fuel is a far cry from the few decade of oil left to the people of the world.

Finally, unlike nuclear fission, nuclear offers the world zero potential for a catastrophic disaster. Being a precise instrument, a fusion reactor requires finely controlled temperature, pressure, and magnetic fields to operate. If the reactor were to become damaged, it would offset these balances, and the fusion reaction would not longer be sustainable. Whereas a fission reactor may produce heat energy for days after its shut down, a fusion reactor would stop producing heat within minutes. This negates the potential for a meltdown scenario that the world has seen in the past.

__Criticism: Is Fusion a Viable Option?__ Fusion may have a lot going for it. It is clean, sustainable for millions of years, and has a risk that is a fraction of modern fission reactors. But not everyone sees these benefits as the savior of humanity, and most believe that fusion has a long way to go before it can become a viable power source. Since the early 1950's scientists around the world have been working to transform fusion into a viable energy source. The growth and advancement in technology has been slow at best. Even more than 60 years later, researchers have struggles to perform a sustained reaction. To date, the longest reaction has been performed by JET (Joint European Tours) and lasted only around five seconds, a far cry from the sustained reaction that would be required to turn a fusion reactor into the power we will need in the coming years. []

In addition to the slow progress made in the field of nuclear fusion, critics may also cite lack of fusion to solve a large portion of our clear energy problem, automobiles. Fusion technology does not show any potential to power the ever growing car industry. The technology required to operate a nuclear reactor could never be used to power a modern automobile (at least according to modern engineers). Therefore fusion cannot be considered the save all for the problem of global climate change.

Thirdly, many countries do not have the technology or the resources to operate a plant as complex as a fusion reactor. The most power and affluent nations in the world have worked for the past 60 plus years with the result of a five second fusion reaction. Most countries around the world would not have the resources to build, maintain, and operate a plant of the capabilities that many researchers hope to achieve. Many of these countries are the same nations that will someday be in dire need of a way to produce fresh water. Without the options of a clean, sustainable energy source like fusion, they will more than likely but forced to turn to fuels such as oil of gas.

Finally, critics of fusion power may cite its relation to nuclear chemistry and the possible effects this could have on the environment. Although the products of a fusion reactions have no radioactive properties in themselves, parts of the possible fuel may be highly radioactive. According to most modern researchers, the most promising fuel cycle for a fusion reaction is the Deuterium-Tritium cycle. Although there may be enough raw material to power the planet for millions of years with these fuels, they do not come without draw backs. The hydrogen isotope tritium is highly radioactive. This radioactivity, much like the fuel in modern fuel plants, could have the potential to cause damage to those it came in contact with, as well as the environment surrounding it. It would require special handling and care. In addition to the fuel itself, the process of a fusion reaction would cause the inner pieces of a reactor to become severely radioactive (again much like a modern fission reactor). The difference between a modern fission reactor, and a fusion reactor is that the half life of the radioactivity within a fusion reactor would be about half of that within a fission reactor (within 300 years it would have the same radioactivity as coal ash).

__The Modern Energy Supply: Where are the Fusion Reactors?__ In the modern world fusion power generates 0% of the energy used around the world. There is not a single full time functioning reactor on the planet. This is because of the simple fact that researchers have yet to create a sustainable fusion reaction. To date, the longest reaction is the 5 second reaction performed by JET (Joint European Torus) in July, 2010. Though a powerful reaction, it would need to be sustained for an extender period of time for it to become a viable energy source. Researchers around the world are working towards a sustainable fusion reaction, but there is still much work to be done. It is impossible to know when, or even if, the world will see its first fusion reactor for commercial use.

[] __The Future: What Do We Need for a Fusion Powered World?__ One may ask we in the past 60 years researchers have yet to crack the science behind nuclear fusion and its applications to the commercial world. After all, fusion was weaponized as the Hydrogen bomb in 1955 when the Soviet Union detonated the world's first thermonuclear weapon. One may also remember the short time it took for weaponized nuclear fission to make its way into the commercial world as a power source (less than a decade after the first nuclear weapons tests). [] (The fusion powered Tsar Bomba, a 50 mega-ton thermonuclear weapon detonated by the USSR in 1961. It is the most powerful weapon even utilized by humanity to date)

This is not a simple question to answer. The only answer that can be given for sure, is that fusion research needs more time and funding to grow parallel to the worlds growing energy demands. It is impossible to predict when fusion power may be available to the average citizen, but research has come a long way since it began 60 years ago. One can only hope that the break researchers have been waiting for is on the near horizon.

__The World: How Can Fusion Help?__ As can been seen, the world will face many problem in the coming decades. Humans will face an ever growing shortage of water, fossil fuels will run out in the next few decades, global temperature will continue to rise if clean energy cannot be utilized. The good news is that all of these problems. The bad news is that for the moment, bettering one will worsen the other. With current technology, switching to clean, renewable energy will mean less greenhouse gas emissions, but will also mean less available power, meaning less power to make fresh water. Inversely, we have the ability to create plentiful amounts of fresh water, but doing so will use huge amounts of fossil fuel, depleting reserves, and adding to an ever growing climate change problem.

So how can fusion help?

Fusion has the advantage of being able to attack the two main problems facing humanity. It is a clean, practically renewable (65million years worth of fuel) energy source that has the potential to create vast amounts of useable energy. If mankind can harness this energy to power the world, climate change and lack of water will no longer be of concern. Fusion utilizes no fossil fuels, and therefore will not contribute to the greenhouse effect. The energy provided by fusion plants could be used for energy intensive activities that power a clean, sustainable, healthy world. Energy from fusion could desalinate water for the regions of the planet short on available resources. Fusion power could be used to isolate hydrogen molecules, thus powering fuel cells and negating the need for the internal combustion engine. It could replace the modern nuclear fission plants around the world, cutting off the non stop flow of nuclear waste resulting from years of fission (along with the inability to be weaponized, the radioactive material that results from fusion has a a half life that is a fraction of the the fuel used in a fission reaction). Fusion has the ability to change the world as we know it. One may only hope that it can change our world before it is too late.

__Works Cited__

[] [] [] []