If someone asks me what the primary source of energy is here on planet earth. My prompt reply without thinking would be Sun, yes our star Sun. We use car, bus, electric trams for transportation, fuel for burners, computers for computation likewise and we all power these machines with fossils energy, heat energy, electrical energy, mechanical energy likewise. We can convert one form of energy into the other. But from where do we get the energy? We have Fossils fuel in the form of higher hydrocarbons, hydro energy in the form of potential head of water, wind energy in the form of air current, geothermal energy from earth, oceanic energy from wave velocity, nuclear energy from atom, thermal energy from sun rays likewise. Have your ever thought what originated these energy sources? Fossils fuels we obtain from conversion of organic matter or hydrocarbons under pressure in the earth, hydro energy from flow of river, wind energy from differential atmospheric pressures, geothermal energy from heat inside the earth, oceanic waves from tidal forces, nuclear energy from the existence of elements. Existence of hydrocarbons, flow of water, flow of air, heat inside earth, oceanic tidal waves, existence of elements all are accrued to the sun. It is the sun which create hydrocarbons from photosynthesis by sunlight, flow of water from evaporation resulting into rain by sun rays, atmospheric pressure diifrence due to uneven heating at two places, heat inside earth by earth separation from sun, oceanic tidal waves due gravity of earth created by sun. There is a beautiful dynamic balance maintained between incoming heat from the sun and outgoing heat to the space and if this balance is upset, it may lead to Ice Age or Fire Age on earth. Surprisingly, we are not sure whether the earth’s temperature is changing downward or upward. But it is certain an upset in this dynamic balance will result in catastrophe.

But today the world is facing severe energy deficit. Our sustenance depends upon our basic needs of food, clothing and shelter. All these primary needs can only be met when we have energy to produce agricultural commodities, run factories, extract building materials and do other allied activities essential for human survival. If we want to lead a comfortable life, we need further energy.

Today, the European Union imports more than 50% of its energy, mostly in the form of oil and gas, from outside the Union. Many of the regions of the world that supply our energy are geographically remote and some may be politically unstable. With current trends, it is predicted that by 2030 the EU will depend on imported energy for 70% of its total needs. Over the next 50 years, the global demand for energy may double in some developing countries.

Eighty two percent of Europeans acknowledge that the way they consume and produce energy has a negative impact on climate. At the same time, 50% perceive climate change as one the most serious problems our world faces and call for immediate action. Therefore it is urgent that alternate source of clean energy may be found out.

Sun as has been stated, is the main source of energy here on the earth. I am not considering that energy contributed by nuclear fission of heavy elements since these elements owe their existence not to sun but Supernovae explosions. Can’t we generate energy as the sun generates by making a miniature sun here on earth which can supplement our energy needs. After all what is there in the sun that generates energy and can we not replicate it here on the earth? It is a known fact that the sun is a vast and enormous ball of hydrogen which is being fused to helium under high pressure and temperature. Temperature at the core of the sun is six million degrees centigrade.



Surface Area Of Earth (Image Courtesy Google)

We also have sufficient hydrogen on the earth, 70 percent of the earth surface is covered with water. A molecule of water contains 11 percent hydrogen. For fusing hydrogen, our worry would be to achieve this high temperature in the range of hundred millions degree centigrade. Such reactions involve nuclei of hydrogen atoms which fuse with one another and form helium. Such reactions are called nuclear fusion and liberate tremendous amount of energy.

But when a nucleus under certain favourable conditions breaks, it also liberates huge energy equal to mass difference of the reactants from the products. In such nuclear fission reactions, smaller atomic elements are produced from higher ones. Since such nuclear fission also liberate energy equal to mass difference multiplied by velocity of light squared. And velocity of light is 30000000000 cm per second, therefore, its square would even be more huge, the energy thus given out from such reactions is extremely large.

But why can’t we resort to nuclear fission which does not necessitate huge temperature and pressure for its reaction to take place? It is submitted that we have plants based on nuclear fission with adequate safeguards. Even then adequate is not always adequate in case of accident and natural calamities. Inherently, nuclear fission reactions involve emission of alpha, beta, gamma rays or all these rays together. However hard one attempts, danger of leakage of these emissions can not be ruled out. Alpha rays are in fact energetic nuclei of hydrogen atoms, beta rays energetic moving electrons and gamma rays high energy neutral particles or photons. These rays are invisible but fatal. In addition to emission of these rays, elements of lower atomic number are also ejected and these radio active elements go on emitting fatal radiations for years together depending upon their half life period. Half life period is that period which is taken by the radio active element for its decay to half of its original mass. The half life time of some radio active elements is hundreds of years and that means radio active emission will prevail hundred of years making the area unfit for habitation.

Nuclear fission power plants due to natural calamities or otherwise suffered leakages of radio active emissions and also elements. On March 11, 2011, a major earthquake struck off the coast of Japan, producing a massive tsunami. As of August 2011, the tsunami alone was estimated to have killed over 15,000 people, with another approximately 4,600 missing. The tsunami also swamped the Fukushima 1 nuclear power plant complex on Japan’s eastern coast, which had three of its six reactors operational when the earthquake occurred. Within a matter of days, the three originally operational reactors were in full meltdown, and fire had swept through a fourth (previously-idle) reactor. Radiation spewed from some of the crippled reactors, prompting the evacuation of many tens of thousands of people who were living within 12.5 miles (20 kilometres) of the Fukushima 1 plant.

Besides loss of human lives, there were also, of course, huge economic costs. The financial costs of the Fukushima nuclear disaster alone were enormous. Estimates publicized in June 2011 concerning costs stemming from the nuclear catastrophe ranged from a low of $71 billion to a high of $250 billion.

In November 2011, for instance, instruments at Fukushima detected radioactive xenon leaking from one of the damaged reactors, indicating that nuclear fission was still occurring within the reactor, although probably at a low level. A survey of radioactive contamination issued in November 2011 indicated that 10 percent of Japan was contaminated with low levels of radioactive cesium (Cs). The radioactive contamination consists of the isotopes 134 Cs and 137 Cs, with half-lives of approximately 2 and 30 years, respectively. This means it will take about 30 years for half of the radioactive 137 Cs to disintegrate. Learning lessons from these disasters, most countries abandoned their pending projects of power from nuclear fission.

It is, therefore, our requirement that nuclear reactions should be clean, secure and energy-full. Therefore we will have to resort to nuclear fusion which is taking place in the sun. We will have to make a miniature sun. We have sufficient hydrogen along with its isotope deuterium. We need isotope tritium for facilitating nucleus fusion. An Isotope of an element is that which has lower or higher number of neutrons than required in its nucleus. Another interesting characteristic of isotopes is that these exhibit same chemical properties as those of parent atom meaning thereby that isotopes of Hydrogen will have same chemical properties as those of hydrogen. That means atomic structure wise these isotopes differ from parent atom but chemically these are same.

Hydrogen has a proton in its nucleus and also has a lone electron moving around in orbit. If hydrogen atom has an additional neutron in its nucleus or two additional neutrons in its nucleus, then these are called isotope deuterium and tritium or simply deuterium and tritium respectively. It is estimated that one litre of water contains .033 gm of deuterium. Tritium is generated from the nuclear fusion reaction and is also supplemented from element lithium. The element lithium is also plentiful in nature. The lithium which is being used in your laptop battery, would be sufficient to produce energy equivalent to 40 tonnes of coal.

There are two types of nuclear fusion reactions, one from deuterium, deuterium and the other from deuterium, tritium.

Deuterium, Deuterium Fusion reaction is given below.

Deuterium + Deuterium —————–> Isotope of He + n + 3.27 MeV

Deuterium, Tritium Fusion reactions are given below.

Deuterium + Deuterium ————–> Tritium + H + 4.03 MeV

Deuterium + Tritium ———–> He + n + 17.59 MeV

Tritium is also generated from He as given in the reaction below.

Li + n —————–> He + Tritium + 4.8 MeV

where symbols n is neutron, MeV is mega electron volt, (electron volt is a unit of energy), He helium, Li lithium.



Nuclear Fusion Reaction Between Deutarium And Tritium (Image Courtesy Google)L

It is reiterated here that energy liberated in these reactions is mass difference between reactants and products multiplied by the velocity of light c squared and is huge. It is clear from above reactions that we get neutron as byproduct and this neutron is again utilised for conversion to tritium.

It is submitted that neutron is not radioactive and is thus innocuous. Second byproduct is tritium which is radioactive but its half life time is only ten to twelve years which is small. Further, tritium is also utilised as fuel for fusion. Therefore, energy liberated from fusion is clean, controlled and without the hazards of radioactivity.

As already stated, for fusion reaction to take place the temperature must be hundred million degree centigrade. Such a huge temperature will burn the container of reactor to ashes. Therefore, we need such a vessel which can withstand such huge temperature and pressure but even Titanium can not withstand such temperature.

The detonation of the first thermonuclear bomb, codenamed “Mike,” took place on November 1, 1952, on the Eniwetok atoll, a small coral island in the Pacific Ocean. The U.S.-built bomb consisted of a cylinder 20 feet (6 meters) tall and 6 feet, 8 inches (2 meters) in diameter, weighing 164,000 pounds (61,212 kilograms). Even the bomb’s designers were amazed by its explosive force. Its fireball was 3 miles (4.8 kilometres) wide. Within 90 seconds, the mushroom cloud had risen 57,000 feet (over 17,000 meters) into the air. Eventually, after five minutes, the cloud reached a height of 135,000 feet (over 41,000 meters), with a “stem” 8 miles (13 kilometres) across.

People on ships 100 miles (161 kilometres) away saw the flash. The explosion completely destroyed the island of Elugelab, carving out an underwater crater that was 6,240 feet (1,902 meters) wide and 164 feet (50 meters) deep and lifting 80 million tons of soil into the air. A bomb of this type would devastate any city on Earth.Thereafter the then USSR also tested fusion bomb in August 1953. In such fusion bomb, isotopes of hydrogen are subjected to at least fifteen million degree temperature with the help of nuclear fission bomb placed at the centre of the fuel. Such fusion bombs are uncontrolled unclear fusion reactions which result into uncontrolled vast devastation.

But we are considering controlled fusion. Before I proceed further, I explain the necessity of millions of degree temperature for nuclear fusion. I submit that like all atoms, isotopes of hydrogen have also election moving around the nucleus. When an isotope comes in close proximity of the other, the electrostatic force repels them and their nuclei never come so close as to fuse with one another. But when temperature is raised, thermal energy is supplied to the electrons which free themselves from the nuclear attraction. In such a situation, the electrons after being ejected from nucleus move freely and so move positively charged nuclei. It thus becomes a soup of free moving electrons and nuclei. Such a state of matter is called plasma which consists of free moving electrons and ions. Free motions of these charged particles (electrons and ions) constitute electric field and electric field is always associated with magnetic field. Thus at this high temperature plasma exhibits magnetic field. It is therefore apparent that we can control plasma by applying external magnetic field over it.

In order to accomplish this, the plasma is surrounded by magnetic field toroidal and poloidal generated by the magnets placed around the torus shaped tube which contains the isotopes deuterium and tritium of hydrogen. These isotopes are fully separated from the walls of the tube by the repulsion of the magnetic fields. The solenoid coil at its centre acts as primary winding and the fuel isotopes as secondary windings. The isotopes of hydrogen gets heated by the current flowing in it due to its ohmic resistance to that stage where electrons are ejected out of nuclei and the electrons and nuclei move freely and nuclei fuse forming helium and liberating neutrons. Nuclear reactions as already discussed take place and energy in the form of heat is liberated from fusion reactions. This toroidal magnetic field repels the magnetic field created by moving charges in the plasma and plasma is contained inside.This is called toroidal magnetic confinement. Such a reactor is called Tokamak a Russian name for torus shape.



A Section Of Tokamak (Image Courtesy Google)

But such a confinement is also not free from the defect that when moving electrons and nuclei drifts from each other, they constitute electric field. To avoid such current, upper and lower part of plasma is connected to magnetic lines of force and separated charges is short circuited along these field lines. To avoid magnetic field generated from the moving charges, poloidal magnetic field is also applied. It is submitted that in spite of application of magnetic field, plasma still leaks out, this decreases the temperature in the reactor and decelerate the reaction. In addition, this also reduces the residence time for completion of reaction which further reduces the efficiency. A minimum time of one second is essential for best result for nuclear fusion reaction. The efficiency of reaction is assessed by Lawson Criterion which is product of fuel or isotopes density and residence time. For optimum results, it is essential that product of plasma density and residence time be maximised.

In toroidal magnetic confinement, plasma moves but an arrangement can be made where the fuel is used in the form of dense pellets which are kept stationary. These pellets are then bombarded intermittently by high energy photons or with laser gun which impart energy to fuel raising its temperature to the stage where the isotopes implode and fuse. Such an arrangement is called inertial Confinement System. Here there is no necessity of creation of plasma or its confinement or maintaining temperature.

However both systems of fusion as discussed above, are not efficient due to presence of impurities in fuel. Impurities lower the temperature of reactants which in turn retard the reaction rate. Thus more the impurities, lower the temperature and lower the fusion. Further, change in particle density from 1023 p/cubic metre, Confinement time less than 1 second and temperature less than 100 million degree centigrade decrease the efficiency of fusion reaction. Plagued with these difficulties, no fusion reactor has been successful so far. Regarding achievement of temperature as high as 100 million degree centigrade, secondary coil heating as already discussed proves insufficient, it is therefore supplemented with radio frequency heating to maintain the temperature.

Seven partners countries China, India, Japan, South Korea, Russia, the United States, and the European Union has agreed to construct an advanced tokamak fusion reactor called the International Thermonuclear Experimental Reactor ITER at Cadarache, north of Marseille, France. This reactor will produce 10 times more power than that is fed into it. If all goes as planned, a 50-megawatt input of electrical power into the ITER fusion reactor will result in an output of 500 megawatts of power. The purpose of this experimental reactor is to show the world that clean, adequate and cheap power is available for alleviating global poverty.

How then can we transport the energy which is 1000 times more than what we generate from nuclear fission? I submit that energy generated from fusion reaction is mainly heat energy. This heat energy then can be used in boiler for producing steam to run turbine to generate electric energy. This electric energy can then be transmitted through transmission* lines to far away places for its utilisation. I want to bring this fact to the notice of my learned readers that the electrical energy generated at an instant will have to be consumed immediately because first it is alternating in nature and can not be stored in a battery. Second, if we want to store it by rectifying it to direct current, we need heavy rectifiers and heavy storage batteries. Unluckily, such storage and rectification at the cost of power loss are not yet available except in emergent cases. Further such high energy storage batteries are also not in existence. Therefore when we need less power, we will have to shut down the generator and when we need extra power, the generators kept running freely, will have to be connected to the load.

What are the bottlenecks in obtaining energy from fusion? There still exists technical problems of leakage of particles from hot plasma, impurities in fuel, difficulties in achieving the huge temperature, retention of this temperature for period more than one second likewise. Though consistent efforts are being made yet commissioning of ITER is not in sight.

A report published in the month of June, 2016, broke the news of further delay upto the year 2025. That too not for production but for generation of plasma. French Physicist Bernard Bigot, former head of France’s Alternative Energies and Atomic Energy Commission, was brought in as ITER director-general in 2015 to shake up the organization and draft a credible schedule. Independent assessments of ITER, however, question whether the 2025 target can be met for the first experiment using “burning” fusion fuel – a mixture of deuterium and tritium (D–T) – will have to wait until 2032.

Earlier this year, it was revealed that ITER managers were pushing for the five-year delay and had asked for an additional cash injection of €4.6bn. While the delay has been granted, the project’s seven partners – China, the EU, India, Japan, Russia, South Korea and the US – have announced they are unlikely to raise the additional finances. This means that completion of the project could slip even further beyond 2025, a worry that was expressed earlier this year in a report from the US Department of Energy (DOE) entitled “US Participation in the ITER Project”.

A day which is “tomorrow of tomorrow—–” never comes. In fact it expresses that tomorrow which is infinitely away. Never ending delays prompted those connected with the progress of ITER to say, “Fusion is the energy of the future and will ever remain the energy of future.” I pray, the subscribers to this saying may prove wrong. I hope USA which has always stood for the countries in trouble and also projects in trouble, may come forward with funds.

It reminds me of nineteen sixties when India’s agriculture produce was insufficient to feed its population. Great Prime Minister Lal Bahadur Shastri advised Indians to observe weekly fast on Monday to tide over that difficult situation. It was ‘Great’ America that came to India’s rescue by providing wheat under PL 480 Programme. PL 480 or Public Law 480 also known as “Food for Peace” is a funding avenue by which US food can be used for Overseas Aid. With these positive thoughts in my mind, I hope Department of Energy (DOE) of USA will fund this experimental fusion reactor in larger global interest and “Secure, abundant, cheap energy will be available to help feed all.”

I opened this article by introducing the role of the Sun in providing us ever pervading energy which humans are striving to generate here on the planet earth. I often think, our existence is attributed to the Sun. Even Hindu religion has primordial ‘Gayatri Mantra’ which is dedicated to Lord Sun. It makes mention in Rig Veda. It is recited as

“om bhūr bhuvaḥ svaḥ

tát savitúr váreṇ(i)yaṃ

bhárgo devásya dhīmahi

dhíyo yó naḥ prachodayāt”

– Rigveda

Its meaning is given here below.

“Let us meditate on that excellent glory of the divine vivifying Sun,

May he enlighten our understandings.”

— Translated by Monier Monier-Williams

Huge and massive sun creates huge gravitational compression at its core and that produces temperature in the range of millions of degree centigrade. This huge temperature and pressure convert hydrogen to plasma which facilitates nuclear fusion emitting huge energy for our survival. What is confining plasma in the sun? It is the huge gravitational pressure and temperature at its centre. What regulates the temperature there? It is the balance between thermal energy and gravitational energy. Whenever there is an increase in gravitational pressure due to perturbation, the temperature rises and with that expansion in volume of the sun occurs. This expansion reduces the temperature and gravitational compression.This annuls the effect of perturbation in gravitational compression and the temperature. In this way, the temperature, pressure are maintained and the fusion reactions continue unhindered.

Coming back to fusion reaction at ITER, I submit most of the journey has been completed, the last legs will also be overcome. The day is not far away when our dream of secure, abundant, clean and cheap energy from nuclear fusion will come true.

End.

N B Transmission* lines: If learned readers are interested in knowing how the power is transmitted and what are power losses, they may further read my article “Can Power Tariff Be Reduced To Half,” at https://narinderkw.wordpress.com/2016/09/10/can-power-tariff-be-reduced-to-half/

Writer is an Electronics and Electrical Communication Engineering graduate and was earlier Scientist, then Instrument Maintenance Engineer, then Civil Servant in Indian Administrative Service (IAS). After retirement, he writes short stories and also on subjects, Astronomy, Mathematics, Yoga, Humanity etc



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