Every second, the sun produces more energy than the earth uses in years. It is not surprising then that researchers have long dreamed of harnessing the enormous potential of solar energy. What’s happening 150 million kilometers away from us? Answer: Fusion.
Small atomic nuclei fuse together to form larger ones, and heat is created in the process. More specifically, two hydrogen nuclei fuse together to form the hydrogen isotope deuterium. The new atom can then merge with another hydrogen atom to form a light isotope of helium.
After that, two helium atoms naturally form into two protons. When the final product is compared with the four protons that were joined, 0.7 percent of the original weight has ‘disappeared’ and was converted to energy.
The total binding energy of the resulting helium is much lower than those in the original four protons, and each such chain reaction releases 26.73 mega electron volts of energy, to be more specific.
All of this is explained in Einstein’s famous formula E=MC2, which describes how matter and energy are equivalent. Mass is energy.
Initially, fusion was explored for military purposes.
Classic nuclear weapons were built on the principle of fission – where heavy atoms decay into smaller elements and release energy. Add an element of fusion, and efficiency of the weapon could be significantly improved.
A fission-based nuclear weapon will not be able to use more than a small fraction of its fuel before the bomb blasts itself and the process stops. With deuterium, a high enough temperature for fusion can be initiated. The neutrons emitted in the process speeds up the original fission process, and the effectiveness of the weapon increases significantly.
Taming the potential for peaceful purposes
Unlike fission, which gave us nuclear power, it has proved difficult to harness the enormous potential of fusion. Although it’s been almost 60 years since the first human-initiated fusion reactions on Earth, we have not yet managed to understand the process well enough to be able to extract energy in a controlled manner.
As early as 1946, two English researchers patented a type of fusion reactor. Their concept was to run the current through the plasma, creating a magnetic field that pushed the plasma inwards, which in turn created a powerful magnetic field with additional force inwards, and so on in a nuclear reaction that was supposed to generate high enough temperatures so fusion could occur.
The process was difficult to control and unstable, so alternative routes were explored. The latest in a series of large-scale experiments is ITER, a test facility with a so-called Tokamak reactor currently being built in France. The United States, China, Europe, Russia, Japan, India and South Korea are supporting the project. No previous fusion experiments have managed to extract more energy than is required in the process. ITER is designed to give ten times as much energy as is needed to drive the process.
ITER’s construction is time consuming, and energy production is not expected to go online until 2026.
Is fusion the solution to future energy problems? Or is it an unattainable dream? We do not know. But we do know that the potential is enormous, and that we enjoy the fruits of fusion every day.
The article was published in September 2011