As a digital technology expert, I am fascinated by the transformative potential of new technologies. One of the most tantalizing and elusive of these is nuclear fusion – the process that powers stars like our sun. For decades, fusion has been touted as the ultimate solution to humanity‘s energy problems – a virtually unlimited and greenhouse gas-free source of power. But despite billions of dollars invested and countless promises made, fusion reactors capable of producing electricity remain perpetually on the horizon, seemingly always a few decades away. In this article, I will take a deep dive into the science, technology, and economics of fusion power and assess whether it is truly the dawn of a new energy age or a shimmering mirage that will never be reached.
Fusion vs. Fission
First, let‘s clarify what fusion is and how it differs from the nuclear fission reactions used in present-day nuclear power plants. In fission, heavy atomic nuclei like uranium-235 are split apart, releasing energy. In fusion, light atoms are fused together into heavier elements, also releasing energy in the process. The main fusion reaction being pursued for power generation is:
D + T → 4He + n + 17.6 MeV
A deuterium nucleus (D) and a tritium nucleus (T) fuse to form a helium nucleus (He) and a neutron (n), releasing 17.6 mega-electron volts (MeV) of energy. Deuterium is an isotope of hydrogen with one proton and one neutron, while tritium has one proton and two neutrons.
Fusion has several advantages over fission:
- Abundant fuel: Deuterium can be extracted from seawater, enough to last millions of years. Tritium is rare but can be bred from lithium, which is abundant.
- No meltdown risk: Fusion reactions are difficult to sustain and any malfunction causes rapid cooling and shutdown.
- Less radioactive waste: Fusion mainly produces helium, although some reactor components are activated and need disposition.
- No greenhouse gas emissions: Fusion does not release carbon dioxide or methane.
The key disadvantage is that fusion is much harder to achieve than fission. This is because the nuclei are both positively charged and repel each other. To get them close enough to fuse, they must be heated to tremendous temperatures, on the order of 100 million degrees Celsius. At that point, the fuel atoms become a plasma – a state of matter where electrons are separated from nuclei. The challenge is to confine and control this extremely hot plasma long enough for fusion reactions to occur and produce net energy.
Magnetic Confinement Fusion
The leading approach to fusion is magnetic confinement. Powerful magnetic fields are used to contain the plasma and keep it away from the reactor walls. The most promising magnetic confinement device is the tokamak, a donut-shaped chamber surrounded by complex arrangements of electromagnetic coils.
First developed in the Soviet Union in the 1960s, tokamaks have been the workhorse of fusion research for decades. The world‘s largest tokamak, ITER, is currently under construction in France. ITER is designed to produce 500 MW of fusion power from 50 MW of heating power, achieving a fusion gain factor Q of 10. However, this is still a research reactor not designed to capture usable energy.
Other notable tokamaks and their fusion performance:
| Tokamak | Location | Year | Fusion power | Gain factor (Q) |
|---|---|---|---|---|
| JET | UK | 1997 | 16 MW | 0.67 |
| TFTR | US | 1993 | 10.7 MW | 0.27 |
| JT-60 | Japan | 1998 | 8.1 MW | 1.25 |
| EAST | China | 2021 | 10 MW | 0.33 |
| KSTAR | South Korea | 2020 | 3.2 MW | 0.27 |
Magnetic confinement fusion must overcome several technical challenges to be viable for power generation:
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Plasma instabilities: The plasma is prone to instabilities that can rapidly degrade confinement. Suppressing these instabilities through control of plasma shape and profiles is an active area of research.
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Heat exhaust: Even with good confinement, some heat and particles escape the magnetic fields and strike the reactor walls. Managing these heat loads and preventing undue component damage is a major challenge.
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Superconducting magnets: The magnetic fields needed for confinement are so strong that they can only be produced by superconducting electromagnets. These are expensive, tricky to manufacture, and require constant cryogenic cooling to function.
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Tritium breeding: Tritium is rare and must be produced by bombarding lithium with neutrons in a breeding blanket surrounding the reactor. Efficiently extracting this bred tritium and minimizing tritium losses is another engineering challenge.
Inertial Confinement Fusion
An alternative approach to fusion is inertial confinement. Rather than steady magnetic fields, inertial confinement uses rapid energy pulses from lasers or ion beams to compress and heat a fuel capsule to fusion conditions. The capsule‘s own inertia provides a brief period of confinement.
The world‘s most energetic laser, the National Ignition Facility (NIF) at Lawrence Livermore National Lab, is an inertial confinement device. In August 2021, NIF achieved a major milestone by producing 1.35 MJ of fusion energy from 1.9 MJ of laser energy, a gain factor of 0.71. This is the closest any fusion experiment has come to scientific breakeven, where fusion power out equals power in.
However, NIF was built mainly for nuclear weapons research and is not suitable as a basis for power plants. Practical inertial fusion power would require gains of 100 or more and repetition rates of several shots per second. Most inertial fusion research is now focused on alternative drivers like heavy ion beams and pulsed power machines.
Fusion Startups
In recent years, there has been a surge of private investment in fusion startups. According to the Fusion Industry Association, over 30 companies are now pursuing fusion, with over $4 billion in cumulative funding. These startups are developing a wide range of novel reactor designs.
Some of the most prominent fusion startups:
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Commonwealth Fusion Systems (US): Developing high-field superconducting tokamaks in collaboration with MIT. Aims to demonstrate net energy gain by 2025.
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General Fusion (Canada): Pursuing magnetized target fusion, which compresses plasma with pistons and heats it with particle beams. Plans to operate a demonstration power plant in the early 2030s.
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TAE Technologies (US): Developing a beam-driven field-reversed configuration reactor. Has raised over $1 billion in funding. Claims it can commercialize fusion by the late 2020s.
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Tokamak Energy (UK): Building spherical tokamaks with high-temperature superconducting magnets. Aims to demonstrate grid-ready fusion power by 2030.
The optimistic timelines put forth by some of these startups are viewed with skepticism by many fusion scientists. The Fusion Electricity: A roadmap to the realisation of fusion energy report by the European fusion research consortium EUROfusion projects a demonstration fusion power plant DEMO operating by 2051, and commercial power plants coming online by 2061 at the earliest.
Economics of Fusion Power
The economics of fusion power are highly uncertain, given that no fusion power plants have been built. Advocates argue that fusion‘s advantages – abundant fuel, no greenhouse gas emissions, and intrinsic safety – mean it will ultimately be cheaper than fossil fuels or renewables. However, the upfront capital costs and technological risks are substantial.
A 2018 study by the Energy Options Network estimates an LCOE (levelized cost of electricity) for fusion of around $65/MWh, which would be competitive with current power sources. However, this assumes that the construction costs and performance of commercial fusion plants are close to what is projected. Any delays or cost overruns – which have been common in fusion projects – would significantly increase the LCOE.
Initial fusion power plants will likely be more expensive until economies of scale and learning effects drive down costs. They may require some form of government support or carbon pricing to be competitive at first. Unique aspects of fusion like tritium handling will also add regulatory and waste management costs compared to other clean energy sources.
Applications and Implications
If fusion does succeed as a power source, it could have far-reaching implications beyond the electricity sector. Fusion could be used to produce high-temperature heat for industrial processes, desalinate water, recycle waste and power spacecraft.
In the computing realm, the complex modeling and simulation needed for fusion research is already pushing the boundaries of high-performance computing. Exascale supercomputers like Frontier will allow unprecedented plasma physics calculations. The massive data streams produced by fusion reactors could drive advances in AI and machine learning for control and optimization.
As an energy-dense power source with low environmental footprint, fusion could also revolutionize space exploration. Compact fusion reactors could provide power and propulsion for long-duration spaceflight and bases on the Moon, Mars and beyond. Fusion-powered rockets could greatly reduce travel times in the inner solar system. Of course, the engineering challenges of space-rated fusion are even greater than on Earth.
More speculatively, the ability to replicate stellar power in reactors could inspire a sense of awe and change our cosmic perspective. Harnessing the primal forces that forged the elements and built the universe may prove to be a turning point in humanity‘s relationship with the natural world, for good or for ill. As Carl Sagan famously said, "We are made of star stuff" – will we have the wisdom to wield the power of the stars?
Conclusion
Nuclear fusion is one of the grandest and most difficult scientific and engineering challenges ever undertaken. The promise of clean, abundant, and safe energy is tantalizing, but the road to fusion has been long and filled with obstacles. While significant progress has been made, practical fusion power plants are still likely decades away at the earliest.
Major scientific facilities like ITER and NIF will be critical to advancing fusion science, but it will probably take a concerted international effort on the scale of the Manhattan Project or Apollo Program to ultimately bring fusion to the grid. Innovative ideas from fusion startups could potentially accelerate that timeline, but their lofty claims should be viewed cautiously until validated by scientific results.
Even if fusion does succeed, it is not a panacea. Fission, renewables, and storage will also be essential in decarbonizing the world energy system on the timescales needed to mitigate climate change. And no technology can substitute for social and political changes toward sustainability and equity.
As a computer scientist, I am awed by the scope and difficulty of the fusion challenge. It is one of the most computationally demanding and data-intensive domains of science. Modeling the staggering complexity of plasma physics and finding paths to fusion amid vast parameter spaces will require the most powerful supercomputers and advanced AI tools we can build.
Fusion may be the most consequential technology of the 21st century, or it may be a chimera forever just out of reach. But in the effort to grasp this elusive star, we will learn more about the universe and ourselves. The pursuit of fusion is the pursuit of knowledge – and that is always worthwhile. In the words of physicist Lev Artsimovich, "Fusion will be ready when society needs it." Let us work to create a society wise enough to use such a profound gift.
