Nuclear energy was first used commercially to generate electricity in the 1950s. As the world woke up to the harmful effects of burning fossil fuels in the next two decades, nuclear power gained more traction.
Now, there are more than 400 nuclear plants across the world, meeting almost 10% of the world’s energy needs. Even after witnessing two mammoth-scale disasters in Chernobyl and Fukushima, nuclear power continues to be popular for its low carbon emissions. It stands only next to hydroelectric power among the largest low-carbon clean energy sources.
Being a low-carbon clean energy source is one thing but the more relevant question in today’s energy scene is whether nuclear energy is renewable or not. The world and the scientific community, in particular, are divided on the answer.
This article takes a look at the various definitions and arguments on the topic and comes up with an answer to the question “Is nuclear energy renewable or nonrenewable?”.
Let’s begin by understanding the real meaning of the terms “renewable” and “nonrenewable”. Then move on to how nuclear plants generate electricity.
What is renewable energy?
A renewable energy source is one that gets constantly refilled or replenished as it is used up. At no point in time, there will be a shortage of supply. The best examples of renewable energy are solar and wind energies.
As long as the sun is shining and the sunlight reaches the surface of the earth, providing us with heat and light, we have unlimited and inexhaustible access to both solar power and wind energy. It doesn’t matter how much of the available sunlight and wind we are using to generate electricity.
Without any effort or action from us, the amount of sunlight and wind remains the same. In other words, these energy sources renew on their own. And so they are called renewable energy.
Though the term “renewable energy” is a recently coined one, the concept itself is as old as the solar system.
What is nonrenewable energy?
An energy source that doesn’t renew or replenish and may get exhausted is termed nonrenewable. As we use it up to meet our energy needs including generating electricity, its supply gets depleted and we will ultimately run out of it.
If the time to renew or replenish is too long, again, the energy source is considered nonrenewable. For example, fossil fuels, oil, natural gas, and coal. They take millions of years and exact climatic conditions to form. The coal, oil, and natural gas deposits we are using up presently formed millions of years ago when the earth underwent a unique set of circumstances.
Whether the same events will repeat is highly doubtful. Without them how long will it take for the formation of coal and oil remains to be seen. Moreover, our consumption rate is too high for a chance for replenishment. All this makes fossil fuels nonrenewable.
When the rate at which an energy source is getting used up is far too quickly than it is getting replenished, it is as good as not being replenished. Hence such energy sources are deemed to be nonrenewable.
Now that we understand the terms renewable and nonrenewable, let’s examine the great debate on the renewability of nuclear energy.
What is nuclear energy?
The most common method of electricity generation is by using steam to turn the turbine of the generator. The generator converts the mechanical energy of the turbine into electrical energy. In a coal-powered thermal power plant, water is turned into steam by burning coal. The heat energy needed for this can be derived from other energy sources as well.
In nuclear power plants, this heat energy comes from nuclear fission. That is the splitting of an atom to form smaller atoms. As each atom splits, vast amounts of heat energy are released. This process of nuclear fission needs to be continuous to generate a constant supply of heat energy needed to produce steam to turn turbines.
The nuclear chain reaction is not a common occurrence for all elements we have discovered so far. Nuclear fuels need to be fissile to sustain a nuclear chain reaction. This happens only with radioactive metals Plutonium-239 and Uranium-235.
More on nuclear fuels
Both plutonium and uranium are radioactive elements present on the surface of the earth. More than one isotope of each of these elements is mined, though only Plutonium-239 and Uranium-235 are fissile. This means only these specific isotopes of these elements can be used as nuclear fuel.
Before these two elements can be used as nuclear fuel, they need to undergo the enrichment process. During this process, isotopes are separated using lasers and the concentration of the nuclear fissile isotope is increased. The laser also excites the molecules using a process called photoexcitation. In this process, the laser adds energy to the electrons of a particular isotope, thereby altering its properties and helping them break free.
Plutonium-239 is not commonly used in nuclear plants as fabrication of plutonium is more expensive. As plutonium is more radioactive, it necessitates more safeguards, increasing the expenditure. Moreover, the extraction of plutonium from nuclear fuel for reuse is again a costly process. Also, there are serious concerns about its safety, security, and environmental implications.
On the other hand, uranium is ideal as nuclear fuel as it undergoes spontaneous nuclear fission at a slow rate. This means that most of the nuclear power plants operating worldwide use enriched Uranium-235 as the fuel.
Uranium is found in nature in three isotopes – Uranium-238, Uranium-235, and Uranium-234. Uranium-238 is the heaviest and most abundant among the three. However, it doesn’t undergo fission and hence cannot be used as nuclear fuel. The same is true for uranium-234 as well. Only uranium-235 qualifies as nuclear fuel.
Is Nuclear Energy Renewable or nonrenewable?
The question about the renewability of nuclear power needs to be considered on two levels – the process and the nuclear fuel.
Nuclear fission is a continuous process. In this, the uranium-235 atom, enriched by bombarding it with neutrons, splits into two, releasing heat energy and neutrons. When these neutrons bombard other atoms, the process is repeated, generating more heat energy and releasing more neutrons.
So, going by the definition of renewability, nuclear fission is a renewable process. However the same cannot be said about nuclear fuel. That is uranium-235.
Uranium is found on earth’s crust and this naturally-occurring uranium is only mildly radioactive. Most of it is uranium-238, which is not fissile enough to be used as nuclear fuel. Uranium-235 forms only 0.7% of the naturally-occurring uranium.
And like any other mineral deposit on the earth, uranium deposit is also finite, unlike wind or solar energies. To make it renewable, nuclear fuel should be able to replenish itself or be available for an indefinite period.
The known deposits of uranium-235 are limited and the current technology used for the extraction of uranium doesn’t help much. This makes nuclear power nonrenewable even when the process is renewable.
Another argument for its consideration as nonrenewable energy is the coal-fueled power used in the extraction and refinement of uranium. Even if we find abundant deposits of uranium, we would still need to rely on fossil fuels for their extraction, processing, storage, and transportation. This makes nuclear energy nonrenewable.
The rate at which we are using up the uranium deposits also affects its renewability debate. If we use nuclear energy faster than we can replenish it or if the process generates harmful nuclear reactor waste or the enrichment process of uranium generates greenhouse gasses like carbon dioxide, it would not be correct to call nuclear energy renewable.
Other arguments against nuclear energy
Another major reason for the opposition to nuclear power is the harmful nuclear reactor waste generated by nuclear plants. This will continue to remain radioactive and thereby harmful to humans for thousands of years. They need to be kept in safe storage until they are not radioactive anymore.
When radioactive material is not handled responsibly and disposed of properly, it can cause serious harm to human beings, animals, and the environment. It can cause severe burns and serious diseases like cancer, bone decay, blood diseases, and radiation poisoning.
To prevent such events, the radioactive waste is stored in water-filled containers to keep it cool and avert contact. The disposal of radioactive waste is a controversial issue across the world.
Another bone of contention about nuclear energy is the access to nuclear fuel. Uranium deposits are found only in a small region of the entire world. The rest of the world has to import it. This takes away energy independence for most of the world’s countries, including the United States.
What does the future hold for nuclear energy?
Despite all the arguments against nuclear energy, even the staunchest of its distractors do not deny its low carbon emissions. Today, when we are grappling with the aftereffects of global warming and climate change brought on by fossil fuels, nuclear energy finds many takers. It is considered the lesser of the evils.
However, to help it replace fossil fuels, the availability of uranium-235 is the major stumbling block. Supporters of nuclear energy argue that newer deposits of uranium and newer technology for uranium extraction will come up. Already there is a proposal to extract uranium from seawater.
Another solution proposed is the use of thorium, a radioactive metal found in soil, water, and almost all plants. Or find a safer way to use plutonium. Small modular reactors, molten salt reactors, and fast reactors are all aimed at more efficient use of nuclear fuel and lesser and safer nuclear reactor waste.
Nuclear energy comes saddled with numerous advantages and disadvantages. However, we at present are not in a position to discard it completely because of the immediate threat posed by fossil fuels. None of the renewable energy sources are developed or established enough to take on fossil fuels. Intermittent availability and limited capacity are the main drawbacks.
Until that time when we can develop renewable energy capacity to meet the energy demands and overcome their limitations, we may have to continue our dependence on nuclear power. Renewable or nonrenewable, we can take comfort in the fact that it is clean energy with low carbon emissions.
You may also want to take a look at our guide on 10 disadvantages of nuclear energy for more information.