One of the ways in which we can generate a tremendous amount of energy is through nuclear reactions. Nuclear power plants use a nuclear reaction to heat water into steam, which in turns spin turbines that generate electricity.
The United States generates more nuclear energy than any other country in the world, and almost 20% of the total energy requirement of the US is met through nuclear energy.
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There are two types of nuclear reactions by which we can generate energy – nuclear fission and nuclear fusion.
Many believe that both nuclear fission and nuclear fusion are used in nuclear power plants to generate energy. However, we only use nuclear fission, even when we know that nuclear fusion is a much better alternative in terms of fuel availability and energy production.
So, why are we dependent on the more hazardous option of nuclear fission? Let’s discuss.
Before we get into the specifics of fission and fusion, you need to understand the difference between the two.
Nuclear Fission: The process of generating heat by splitting heavy atoms. The splitting of atoms is achieved by hitting the heavy atom with high-speed particles, usually neutrons.
Nuclear Fusion: The process of generating heat by joining two lightweight atoms to form a heavier atom.
The nuclear generators that we have today use nuclear fission to generate heat. A nuclear fission reactor uses ceramic Uranium Oxide pellets for its cores.
The Uranium atoms are then split by bombarding it with neutrons. The split results in a tremendous amount of heat, releasing more neutrons in the process.
These new neutrons then hit other Uranium atoms, which keeps on generating more heat and neutrons. This is called a chain reaction and we control the rate of reaction using moderators like graphite or water.
A coolant is circulated to absorb the heat and prevent the reactor from getting too hot. This is the heat that turns the coolant (water) to steam and then to useful energy.
The thermal output is very large for the Uranium pellets that we use in nuclear reactors, making the reactor economical in a sense. Just 20 grams of uranium fuel can make as much energy as 400 kilograms of coal.
Just eight Uranium pellets can power a house for a year.
When we compare nuclear energy with other forms of fossil fuels in regards to producing heat, nuclear energy comes out to be far cleaner since no CO2 is produced.
Even though we use nuclear fission for our power, it is actually more polluting and hazardous to work with when compared to nuclear fusion. Our sun burns bright and hot from the energy that is produced from nuclear fusion.
In theory, nuclear fusion can be driven by the unification of two light atoms, and we have the perfect candidates for the process as Tritium and Deuterium. The advantage of using nuclear fusion is that unlike Uranium, we have an abundance of Tritium and Deuterium as they are the isotopes of Hydrogen.
The resultant nuclear waste is less radioactive than we get from nuclear fission. There is also zero possibility of any meltdown happening, which makes nuclear fusion much safer to work with when compared with fission.
With nuclear fusion showing great potential than fission, why aren’t we using it? The answer is that the conditions for facilitating nuclear fusion are arduous to recreate.
We have discussed that the sun works on nuclear fusion, and this is because the temperature and pressure at the sun’s core are far greater than what we can recreate in nuclear reactors. If we were to replicate such settings, we need to bring the reactor temperature up to 6 times the temperature at the sun’s core, which equates to about 100 million degrees Celsius.
The sun can facilitate fusion with just 15 million degrees Celsius because of its high pressure sustained within its core.
The immense energy requirement is owed to the fact that nuclear fusion brings together two positive atoms to fuse. Since like charges repel, we need to give the atoms tremendous amounts of energy.
However, scientists have been trying to crack the code on how to facilitate fusion reaction on earth.
The attempt at creating such a setting was first made possible through an Apparatus called Tokamak. This is a donut-shaped chamber which uses electricity to charge the gas within the tube.
When the gas gets large amounts of charge, it changes the state to Plasma.
Since the chamber is in a state of vacuum before the gas is pumped in, the scientists are able to mimic the high pressure and raise the temperature even further to sustain a fusion reaction. However, to keep the reaction going, we need a ton of electricity and a chamber that can hold the plasma for some time without melting all the parts.
The highest that we have got with containing high-temperature plasma is 102 seconds, made possible by the EAST Reactor located in China.
Scientists often joke that fusion energy has been 20 years away for the last six decades.
Now, this doesn’t mean that we are giving up on the dream of a much cleaner and safer energy. Instead, 35 nations have come together, pooling in resources of $25 billion to create the largest research project ever in history called ITER (International Thermonuclear Experimental Reactor).
The goal of the project is to create sustainable fusion energy by 2035. The ITER is basically a powerful version of the Tokamak reactor which can sustain plasma for more than an hour, enough to power 50,000 households.
ITER is now under construction in Saint-Paul-lez-Durance, southern France.
Last year, a group of researchers from the Princeton Plasma Physics Laboratory was successful in stabilizing the plasma in fusion reactors, in order to prevent fluctuations in temperatures and densities. This breakthrough will help in preventing nuclear reactions from halting.
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We are also seeing the rise of many startups who want to bring fusion energy operational before 2035. One such example is Commonwealth Fusion Systems, a company planning to have a working fusion reactor by 2025.
It is safe to say that progress is certainly being made in regards to fusion technologies. It is not certainly within arm’s length, but surely it’s fruition is going to be well worth the wait.