EE0111

FUTURE IS FUSION AS A SUSTAINABLE NON - CONVENTIONAL ENERGY SOURCE

1 Ms.B.SRIVIDYA 2 Ms.S.SOUJANYA

Abstract: World population growth and the rising standard of living in developing countries increase

strain on the energy supply and the impact of energy consumption. We cannot rely on fossil fuels indefinitely. Firstly, supplies of oil, coal and gas are finite and will eventually run down. Secondly, the greenhouse gases produced through the burning of fossil fuels are a major driver of climate change, scientists believe. The challenge ahead is to supply an increased worldwide demand, while restricting carbon emissions and conserving the dwindling supply of fossil fuels

A long-term solution to overcome the present energy demand is FUSION RESEARCH; constructional inventions made on this process will energize the whole world more than needs. Nuclear fusion offers perhaps the best potential for a solution to the world’s energy needs, and now is the time for renewed focus on the remaining scientific challenges that must be overcome before a viable fusion power station can be built.

This paper deals with the fusion processes, reactor design and getting power from reactor plant, that can be the major energy source for future and how it can alter the face of the world with its own way of advancement. Keywords:

Fusion Research, Fossil fuels, Plasma, Greenhouse gases.

Conclusion:

In few decades, controlled nuclear fusion has been promised as safe, green alternative to fossil fuels, environmentally acceptable energy alternative for the future; enabling the production of vast amounts of energy from abundant sources. Actually, the international controlled fusion research programme is sound and healthy, and has achieved significant progress (International Fusion Research Council 2005), but the road to the reactor is more difficult than originally envisioned.

1. III/ IV B.Tech 2. III/ IV B.Tech D.V.R College of Engg and Tech D.V.R College of Engg and Tech vidya242@gmail.com .

www.jntuworld.com

GROWING NEEDS FOR ENERGY: Energy is required to sustain and improve the quality of life. Primitive man requires energy in the form of food, which he got by eating animals, plants. He used his own muscles to help him convert energy into useful work. In course of time he begins to use the wind energy for sailing ships or driving wind mills and the waterfalls to turn water wheels. So far, he was using only renewable sources of energy. The industrial revolution brought about far-reaching changes. Man began to use new sources of energy like coal, oil & natural gas. With the discovery of electricity and development of central power station based on hydro/fossil fuels, the harnessing of energy for comforts and economic well being, heralded a new era. The Second World War brought a new source of energy, nuclear energy with its stunning success in the energy arena. The future demands for energy are likely to increase, both an account of increase in population and standard of living in various parts of the globe. The world population increasing at a rate of 25, while the energy consumption rate is increasing at 5% per year. The world energy consumption is rather unevenly divided among the nations.

PRIMARY ENERGY CONSUPTION IN WORLD IN 2000

PETROLIUM

NATURAL GAS

COAL

HYDRO POWER

NUCLEARENERGY

COURTESY:-Conservation commission of the world energy conference, Guildford (UK) (Year 2000).

WHY FUSION

SUSTAINABLE.

ECO FRIENDLY

NO CONTRIBUTION TO GLOBAL WARMING IN ANY FORM.

ABUNDANT FUELS.

NO LONG LIVED RADIOACTIVE PARTICLES.

131974

310 252 58 58 611251

3825

176

5500

11374

52124368

6015

805

0

2000

4000

6000

8000

10000

12000

JAPAN

INDIA

USSRUSA UK

FRANCE

GERMANY

CHINA

COUNTRIES

ENER

GY

PER

CA

PITA

,PO

PULA

TIO

N

www.jntuworld.com

CONTROLLABLE

GIGANTIC ENRGY SOURCE FOR ALL FUTURE NEEDS.

UNINTERRUPTED POWER SUPPLY (THEY WORK INDEPENDENT OF THE WEATHER,

UNLIKE WIND AND SOLAR POWER).

EFFICIENT CONVERSION OF MASS TO ENERGY.

WASTES AS INERT GAS.

RENEWABLE WHAT IS FUSION?

A form of nuclear reaction in which, two light atomic nuclei fuse together to form heavier ones. The fusion process releases a large amount of energy, which is the energy source of the sun and the stars.

For two nuclei to fuse, a substantial energy barrier must be overcome before fusion can occur. At large distances two naked nuclei repel one another because of the repulsive electrostatic force between their positively charged protons. There must have enough kinetic energy to overcome the force of electric repulsion that keeps them apart. This we can achieve by applying thermo nuclear temperatures /velocities. If two nuclei can be brought close enough together, however, the electrostatic repulsion can be overcome by the nuclear force which is stronger at close distances.

The element hydrogen has the lowest atomic number, since the nuclei of its three isotopes all carry a single positive charge. Hence hydrogen isotopes, which also have the lightest nuclei, should be particularly suitable for the production of energy by the fusion of two light nuclei to form a heavier nucleus. Two isotopes of Hydrogen, Deuterium and Tritium nuclei are accelerated towards each other at thermonuclear temperatures/velocities. They combine to create an unstable Helium-5 nucleus, but which is highly unstable, decays into He-4 nucleus, a neutron and both with ejection of

www.jntuworld.com

high energies 1H2+1H3 2He5

2He5 2He4 (3.5MeV) + n (14.1MeV)

MECHANISM FOR ENERGY PRODUCTION

Different light elements can be used for fusion. The reaction which requires the lowest temperature and confinement product is that between deuterium and tritium. In this process a helium atom and neutron with high energies are ejected.

By surrounding the plasma with highly effective walls, the neutron kinetic energy is converted to heat during slowing down. The heat is taken away from the plant by a coolant, which is used to run turbines, lead to production of electric power.

www.jntuworld.com

An ideal model of fusion reactor.

TECHNICAL ISSUES: Need enough particles to fuse: n•

Need to keep the plasma together long enough for fusion reactions to occur: τ

Need enough energy for the particles to fuse: T

So the product n τT must be large enough to sustain fusion events at a sufficient level to produce

net power.

www.jntuworld.com

REQUIREMENTS A) FUEL. Prime fuels used in a fusion reactor are Deuterium, Tritium.

DEUTERIUM, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen. Deuterium thus accounts for approximately 0.015% of all naturally occurring hydrogen in the oceans on Earth, very little deuterium in the interior of the (Sun), since thermonuclear reactions destroy it.

The deuterium fuel is abundant in water (30 g/m3) and can be extracted by electrolysis. Lake Geneva alone, for instance, contains enough deuterium to supply all the primary energy needed by our planet for several thousand years.

www.jntuworld.com

TRITIUM does not occur naturally and will be bred from Lithium within the machine. Therefore, once the reaction is established, even though it occurs between Deuterium and Tritium, the external fuels required are Deuterium and Lithium.Consequently, the deuterium-tritium fuel cycle requires the breeding of tritium from lithium using one of the following reactions:

n + 6Li → T + 4He

n + 7Li → T + 4He + n

B) PRODUCTION OF PLASMA

Plasma is typically super heated ionized gas simply as an electrically neutral medium of positive and negative particle. "Ionized" refers to presence of one or more free electrons, which is not bound to an atom or molecule. The free electric charges make the plasma electrically conductive so that it responds strongly to electromagnetic fields. Charged particles must be close enough together that each particle influences many nearby charged particles, rather than just interacting with the closest particle.

High temperature means high average ion velocity. The fastest ions in head-on collisions produce fused nuclei.

Fusion reactor plasma must fulfill the following basic two conditions

(i) The product of the plasma density and the confinement time of the plasma thermal energy must be at least of the order 10^20 m-3 s and

(ii) The plasma temperature must be at least 100 million K.

Operations to make plasma

In an operating fusion reactor, part of the energy generated will serve to maintain the plasma temperature as fresh deuterium and tritium are introduced. However, in the startup of a reactor, either initially or after a temporary shutdown, the plasma will have to be heated to some low temperatures than desired. Insufficient fusion energy is produced to maintain the plasma temperature.

Ohmic Heating Since the plasma is an electrical conductor, it is possible to heat the plasma by passing a current through it; in fact, and the current that generates the poloidal field also heats the plasma. This is called ohmic (or resistive) heating. The heat generated depends on the resistance of the plasma and the current. But as the temperature of heated plasma rises, the resistance decreases and the ohmic heating becomes less effective. It appears that the maximum plasma temperature attainable by ohmic heating is 20-30 million degrees Celsius. To obtain still higher temperatures, additional heating methods must be used.

www.jntuworld.com

Neutral-Beam Injection Neutral-beam injection involves the introduction of high-energy (neutral) atoms into the ohmically heated, magnetically confined plasma. The atoms are immediately ionized and are trapped by the magnetic field. The high-energy ions then transfer part of their energy to the plasma particles in repeated collisions, thus increasing the plasma temperature. Radio-frequency heating In radio-frequency heating, high-frequency waves are generated by oscillators outside the reactor plant, have a particular frequency , their energy can be transferred to the charged particles in the plasma, which in turn collide with other plasma particles, thus increasing the temperature of the bulk plasma.

TECHNOLOGICAL & ECONOMICAL HURDLES

Designing the plants to retain temperatures equivalent or greater than that at Sun’s core.

Production of thermonuclear temperatures to heat the plasma, and manufacture of super conducting magnets.

Developing fusion technology including superconducting magnets and advanced materials, especially low-activation first-wall materials. Advancing plasma and fusion science and engineering in pursuit of national science and technology goals.

It is far from clear whether nuclear fusion will be economically competitive with other forms of power. The low estimates for fusion appear to be competitive with but not drastically lower than other alternatives.

BENEFITS

No chain reaction is involved and the reaction is thermally self-limiting. The reaction can never run out of hand.

EFFICIENCY IN CONVERTING MASS INTO ENERGY:

To generate 1000 MW in one day requires 9000 tons of coal and generates 30,000 tons of CO2 (plus other noxious gases, e.g., SO2 and NO2). To generate the same amount of energy from fusion requires about 2.5 pounds of D + T and makes 2 pounds of He.

NO ATMOSPHERIC POLLUTION:

www.jntuworld.com

The fusion reaction produces helium which is an inert gas. Fusion produces no greenhouse gas emissions. Fusion power plants will not generate gases such as carbon dioxide that cause global warming and climate change, or other gases that have damaging effects on the environment.

LOW-COST, ABUNDANT FUELS:

First of all, fusion is an almost limitless fuel supply. The basic fuels are distributed widely around the globe. Deuterium is abundant and can be extracted easily from sea water. Lithium, from which tritium can be produced, is a readily available light metal in the Earth’s crust.

NO LONG-LIVED RADIOACTIVE WASTE:

Only metal parts close to the fusion plasma will become radioactive. Any radioactive waste generated will be small in volume and the radioactivity will decay over several decades with the possibility of reuse after about 100 years.

AN INHERENTLY SAFE SYSTEM:

A “melt-down” cannot occur! Fusion reactors are passively safe. Even the worst conceivable accident would not require evacuation of the surrounding population because always required amount of fuel is supplied for second to sec unlike in fission where a large fuel is supplied at a time.

REAL SCENARIO

The Joint European Torus (JET), the world’s largest fusion device, has already achieved energy break-even. JET has made great advances, but is unable, and indeed was never designed to produce a blueprint for an energy-producing reactor. This is why the next generation machine, ITER, which should see its first plasma around 2015, is necessary.

ITER’s experimental programme will lead to a design for an energy-producing reactor within the coming decades.

ITER will be the final step of scientific validation on the road to a technically viable reactor. If successful, it will be followed by an energy-producing demonstrator that will allow the technology for large-scale energy production to be put through its paces before a prototype of fusion reactor can show its economic competitiveness. The need for ITER, a machine integrating the science and technology of fusion energy production, is undisputed.

www.jntuworld.com

BIBLIOGRAPHY

“Non conventional sources of energy” by G.D.Rai. Proceedings of International Conference on New Millennium “Alternate Energy

Solutions for Sustainable Development “Jan17-19, 2003, P.S.G & SESI. R. W. Bussard, "Fusion as Electric Propulsion," Journal of Propulsion and Power, v

6. "Nucleus", Encyclopedia Britannica,” nuclear reactor”, Wikipedia. Wilson P. and Fischer U.: “Analysis and Implementation of a Monte Carlo High

Energy Neutron. Source for IFMIF,” Proc. 19th Symposium on Fusion Technology,

www.jntuworld.com