FUSION ENERGY: THE ENERGY OF FUTURE





Technology, 23 Dec - 2015 ,

FUSION ENERGY: THE ENERGY OF FUTURE
Credit: ck12.org

Future of Energy is one of the most significant challenge mankind faces today. Despite this challenge, if you randomly pick ten science students, chances are that nine of them would have heard about CERN, the Swiss particle accelerator, but may be none would have heard about ITER, the largest international research endeavor located at Cadarache, Southern France. ITER is much larger than CERN and is one of the biggest scientific collaboration between international community.

ITER (International Thermonuclear Experimental Reactor) is the world’s largest nuclear fusion experiment jointly undertaken by the European Union, China, India, Japan, Russia, South Korea and the United States, aggregating to 35 countries, to explore producing of fusion energy. Nuclear energy is generated by fission by splitting large atoms such as of uranium to produce energy. Fusion is at the other end, where the small atoms of hydrogen are fused together to produce helium and energy.

This is the process, how sun and stars produce energy. At the center of the sun, where temperatures reach 15 million degree Celsius, hydrogen atoms collide at very great speed and fuse. The fusion of light hydrogen atoms produces a heavier element, helium. The mass of the resulting helium atom is not the exact sum of the initial atoms. Some mass is lost and a great amount of energy is gained.

The gravitational forces of stars cannot be recreated on the Earth, necessitating much higher temperatures in the laboratory to compensate. For achieving fusion on earth, scientists have identified the easiest fusion reaction to do is between two hydrogen (H) isotopes deuterium (D) and tritium (T). The DT fusion reaction produces the highest energy gain at the "lowest" temperatures. It requires nonetheless temperatures of 150 million degree Celsius, ten times higher than the hydrogen reaction occurring in the Sun. When these two nuclei, both positively charged, are brought closer together they repel each other being the same sign charge. However when you get them closer and closer the strong force pulls them together. This becomes possible at a very high temperature when nuclei move so rapidly that they overcome repulsion and fuse together. When deuterium and tritium fuse together, for a moment they become helium 5. Helium splits out and a neutron comes out and lots of energy is created.

Tritium is made from the lithium. Lithium and deuterium are plentiful in seawater and in the earth’s crust. The advantage of fusion energy is that it will have virtually unlimited supply, will not produce greenhouse gases and carbon emission, has no radioactive waste and risk of dangerous accidents. The challenge is to create and heat up a gas of hydrogen to a temperature ten times that of the center of the sun. To achieve this a container that doesn’t melt will be required. The method of confining such super hot gas called plasma is with a magnetic device called Tokamak. Tokamaks are donut-shaped devices that uses strong magnetic fields to confine the plasma. The tokamak is designed to harness the energy of fusion. Inside a tokamak, the energy produced through the fusion of atoms  is absorbed as heat in the walls of the vessel. A fusion power plant will use this heat to produce steam and then electricity by way of turbines and generators.

Tokamaks were invented in the 1950s by Soviet physicists Igor Tamm and Andrei Sakharov. Since the 1950s, more than 200 tokamak devices have contributed to the steady progression of research in magnetic confinement fusion. Today, tokamaks in China, Europe, India, Japan, Korea, Russia and the United States with their modifications are conducting scientific programs in furtherance of research in fusion energy. ADITYA (synonym of Sun in Hindi) is the first indigenously designed and fabricated tokamak in India, located at the Institute for Plasma Research in Gujarat and operated since 1989. The Joint European Torus (JET), located at Culham Centre for Fusion Energy in the UK, is the world's largest and most powerful tokamak in operation today and the focal point of the European fusion research.

The ITER Tokamak will be the largest with a plasma volume of 840 cubic meters. Everything about ITER and ITER reactor is big. ITER machine will be 23000 tons and will be heavier than three Eiffel Towers. The material for superconducting magnets would be 100,000 kilometers or stretch around the equator twice. The structure of the ITER central solenoid will be strong to withstand a force of 6000 tons, equivalent to twice the thrust of Space Shuttle at take off. The estimated investment by international community representing half the world’s population is more than $ 16 billion.

ITER is designed to produce 500MW of output power with 50MW of input of power and set the stage for future fusion power plants to be built. Research led by Durham University, in collaboration with the Culham Center for Fusion energy has concluded that a fusion power plant could generate electricity at a similar price to a fission plant. The work on Tokamak at ITER has begun and work is expected to be finished by 2019. However after that getting to a power plant stage and putting electricity on the grid has its own complexity. Some researchers are working on a spherical shape rather than a donut shape of tokamak, which may make tokamak smaller, cheaper and faster. Alternate designs using laser technology are also emerging to join the research on fusion energy. A number of privately funded fusion ventures are coming up each one with different concept. General Fusion, Canada and Tri Alpha Energy, California, USA are leading start ups in the field.

ITER had begun on a political note from the start. In 1985, then US President Ronald Reagan and leader of Soviet Union Mikhail Gorbachev proposed an international facility to develop fusion energy. Easing tensions at the height of the cold war was one of the goals. However lack of political will and lack of funding seems to be the primary reasons for not getting much further on the fusion energy so far. As pointed out, US spent $24.5 billion (more than $150 billion at today’s value) in the lunar mission by 1973 to put man on the moon. Similar political backing and funding would see fusion energy dream realizing much faster for good of the mankind.

Lev Artsimovich, “the father of the tokamak”, once said “fusion will be ready when mankind needs it, maybe a short time before that” Seems that time is approaching very fast.


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