Energy generation via nuclear fusion has several advantages. Nuclear fusion power or nuclear fusion energy is cleaner than fossil fuels or hydrocarbons, more sustainable and reliable than renewable energy sources like solar power and wind power, and less risky than nuclear fission power. It has the potential to advance further civilizations and even solve pressing socioeconomic problems. However, despite these benefits, nuclear fusion remains difficult to achieve due to practical reasons, thus damping hopes for nuclear fusion energy.
The Prevailing Challenges in Energy Generation Via Nuclear Fusion: Why is Nuclear Fusion Difficult to Achieve?
Nuclear fusion is a reaction in which two light atomic nuclei combine to form a single heavier one. This specifically happens when two light nuclei come close enough and produce a strong nuclear force that overcomes the electrical repulsion between protons. The process results in the release of a huge amount of energy. For example, the formation of a helium nucleus from two hydrogen nuclei produces about 6 million volts of energy.
The aforementioned is the same process that powers the sun and other stars. Energy generation via nuclear fusion aims to replicate how these stars produce energy. However, while the process seems straightforward, it is difficult to achieve in a manner that is practical or economical. It is important to note that scientists have replicated nuclear fusion in a controlled environment but the energy input far surpasses the energy output.
1. High Temperature and High Pressure Requirements For Producing Self-Sustaining Fusion and Meaningful Fusion Energy
Achieving and maintaining required high temperatures and high pressures are one of the central challenges in nuclear fusion energy. High temperatures give atoms enough kinetic energy needed to overcome the repulsive force between their positively charged nuclei while high pressures are needed to confine these atoms and prevent them from escaping.
High temperatures also turn matter into plasma while high pressure keeps it confined under this state. Take note that plasma is a state of matter in which atoms are stripped of their electrons and leave them as free-moving positively charged ions. This is the only state of matter that can achieve the high temperatures and pressures required for fusion reactions to occur.
Nevertheless, based on the aforementioned, the higher the temperature, the faster the atoms move, and the higher the pressure, the more denser these atoms become, thus increasing their likelihood to collide and fuse. High temperatures and high pressures support the needed environment for nuclear fusion reaction to take place.
The required temperatures and pressures for energy production via nuclear fusion differ across different types of fusion being pursued or the type of fuel being used. The first-generation fusion system called deuterium-tritium fusion requires around 100 million degrees Celsius and a variable pressure requirement dependent on the method used.
It is also important to factor in the energy confinement time or the measure of how long a plasma can retain its heat and density for a significant amount of energy to be released. A nuclear reactor must simultaneously achieve and maintain the needed heat, density, and energy confinement time. This represents the Lawson criterion of self-sustaining fusion.
Scientists have used different methods to control high temperatures and pressures for nuclear fusion. These include using magnetic fields, powerful lasers, and ion beams. Take note that achieving and maintaining the required temperatures and pressures using available methods remain impractical because of the large energy requirement.
2. Minimizing Energy Input and Maximizing Maximum Energy Output For Achieving an Economical Energy-Positive Result
Another reason why nuclear fusion energy is difficult to achieve is that current experiments based on current capabilities have repeatedly demonstrated that a particular nuclear fusion reaction consumes more energy than it produces. Remember that achieving and maintaining the required temperatures and pressures require a huge amount of energy.
The Tokamak Fusion Test Reactor in New Jersey produced 11 megawatts of fusion power from 40 megawatts of input power in 1994. The Joint European Torus in the United Kingdom broke the record for the highest sustained energy pulse ever created in February 2022. The experiment generated 1.8 megajoules of fusion energy from 24 megajoules of input power.
Researchers at the National Ignition Facility in the U.S. announced on 13 December 2022 that they had achieved a net energy gain from a fusion reaction. The experiment produced bout 3.15 MJ of energy while consuming 2.05 MJ of input. The drawback is that the lasers used consumed 322 MJ of grid energy in the relevant conversion process.
Another group of researchers working on the International Thermonuclear Experimental Reactor in France has an ambitious goal of achieving net energy gain by producing 500 million watts of fusion power from 50 million watts of input power for at least 400 seconds. The fact remains that nuclear fusion reaction is still energy-intensive.
Then there is also the Lawson criterion. This figure of merit in nuclear fusion research compares the rate of energy being generated by fusion reactions within the fusion fuel to the rate of energy losses to the environment. To be specific, in order to generate usable energy via nuclear fusion, a system would have to produce more energy than it loses.
3. Excessive Costs and Technical Requirements of Running Experiments and Maintaining Feasible and Practical Facilities
Costs represent another challenge in nuclear fusion energy. These costs come from various sources. One of which is the cost of building and running facilities. The Joint European Torus has an estimated cost of around USD 1.9 billion. The Korea Superconducting Tokamak Advanced Research is the least expensive at around USD 300 million.
The more expensive ones include the National Ignition Facility or NIF in the U.S. which costs around USD 5 billion and the International Thermonuclear Experimental Reactor or ITER in France which costs around USD 18 billion. ITER is an ongoing project that aims to develop the first fusion reactor that can produce more energy than it consumes.
It is important to underscore the fact that the costs of the aforementioned facilities are mounting due to ongoing research. Nuclear fusion experiments are expensive due to a number of factors. These include the costs of acquiring and maintaining specialized equipment and the costs coming from expending huge amounts of energy in each experiment.
The energy requirement is an important cost and a significant factor that impedes practical nuclear fusion energy. Take note that current experiments are small-scale and operate in short durations. The capabilities of existing facilities would incur higher and uneconomical costs for larger-scale and longer-lasting nuclear fusion reactions.
It is also worth mentioning that the entire nuclear fusion capabilities of the world remain under the research and development phase. Researchers and institutions are still in the process of discovering, developing or inventing, and testing relevant technologies and processes that would make energy generation via nuclear fusion both feasible and practical.
Nuclear fusion energy also struggles with producing the required fuel. Deuterium can be extracted from saltwater but tritium is scarce. Facilities need to produce tritium by using neutrons from the fusion reaction to convert lithium into tritium. Dealing with radiation and waste is also another technical requirement. These are added complex and expensive processes.