Is Renewable Energy Fusion Wikipedia

Fusion energy is a form of renewable power that is generated by the same process that powers the sun and stars. It works by fusing together light atomic nuclei, such as hydrogen isotopes deuterium and tritium, to form heavier elements and release energy (1). The key advantage of fusion power is that its fuel supply is virtually limitless and the process does not emit greenhouse gases or long-lived radioactive waste. Due to these benefits, fusion energy has the potential to provide safe, sustainable, and low carbon energy far into the future.

Fusion reactions occur when atomic nuclei are subjected to extreme heat and pressure, causing them to move very fast and overcome their electrostatic repulsion. This allows the nuclei to get close enough for the strong nuclear force to take over and fuse them together into a new heavier nucleus. The mass defect between the lighter nuclei and the heavier product nucleus is converted into kinetic energy, following Einstein’s famous formula E=mc2. Inside the core of the sun, gravitational pressure creates ideal conditions for fusion. On Earth, we use powerful magnetic fields to contain and compress a plasma of fusion fuel to over 100 million degrees Celsius, hotter than the core of the sun (2).

If harnessed at scale, fusion energy could provide a sustainable solution for rising global energy demand. A key advantage is the abundance of fuel sources like deuterium which can be distilled from seawater. Fusion power plants would also produce no long-lived radioactive waste. While significant research remains, fusion technology has advanced rapidly and could be viable for commercial power generation within the next few decades.

History of Fusion Research

The concept of nuclear fusion first emerged in the 1920s, when British astrophysicist Arthur Eddington proposed that stars generate energy from fusing hydrogen into helium. This built on earlier work by physicists like Albert Einstein, who theorized that mass and energy are equivalent as described by his famous equation E=mc2.

A major breakthrough came in 1932 when British scientists Mark Oliphant, Paul Hartek, and Ernest Rutherford achieved the first artificial fusion reaction by bombarding deuterium with deuterons. This demonstrated that nuclear fusion reactions were possible to replicate on Earth.¹

In the 1950s and 60s, research intensified with experimental fusion reactors like the ZETA reactor in the UK and the Soviet Tokamak-1. These achieved fusion reactions for brief moments but encountered major difficulties in sustaining the reactions.² The tokamak design later became the basis for more advanced fusion reactors.

Major government research programs were also initiated during this period, with increased funding and urgency around harnessing fusion as a clean energy source. This resulted in new facilities like the Joint European Torus and progress toward the ITER experimental reactor, which began construction in 2007.

While significant hurdles remain, decades of research and innovation have brought the dream of fusion power steadily closer to reality. With the latest reactor designs and supercomputing capabilities, scientists are optimistic that the first electricity-generating fusion plant could become operational within the next 15-20 years.

How Fusion Reactors Work

Fusion reactions occur when two light atomic nuclei collide at extremely high speeds and fuse together to form a heavier nucleus. This releases a tremendous amount of energy in accordance with Einstein’s famous equation E=mc2 (where E is energy, m is mass, and c is the speed of light). For fusion to occur, the nuclei must overcome the electrostatic repulsion between their positive charges and get close enough together for the short-range strong nuclear force to bind them together. This requires temperatures of hundreds of millions of degrees Celsius, hot enough to ionize the gas and create a plasma. The most practical fusion reaction uses deuterium and tritium isotopes of hydrogen, which fuse together to form helium and release a neutron. This DT reaction occurs at “lower” temperatures of 100-300 million degrees Celsius.

To achieve fusion conditions, the plasma must be confined and insulated from its surroundings. Magnetic and inertial confinement are the main approaches. Magnetic confinement uses strong magnetic fields to contain the plasma. Devices like tokamaks, stellarators, and magnetic mirrors maintain the plasma equilibrium while it is heated to fusion temperatures. Inertial confinement compresses a pellet of fusion fuel extremely rapidly using focused laser or particle beams. The resulting implosion creates a brief fusion burn before the plasma disassembles.

Once fusion reactions begin, the high-energy neutrons released can trigger further fusions, creating a self-sustaining chain reaction. The energy released as radiation and kinetic energy of the neutrons is captured to produce electricity. However, the plasma must be confined long enough at suitable density and temperature to provide a net energy gain. Reaching this breakeven point has been the central challenge of fusion research for decades.

Sources:

https://www.iaea.org/newscenter/news/nuclear-fusion-basics

Major Fusion Reactor Designs

There are several different approaches to designing a fusion reactor with the promise of producing net energy gain for generating electricity. Here are three of the leading contenders:

Tokamak

The tokamak is currently the most advanced and studied fusion reactor design. Tokamaks use magnetic fields to confine a hot plasma in a donut-shaped chamber. The Joint European Torus (JET) tokamak in the UK set the record for fusion energy output in 1997, producing 16 MW for one second while consuming 24 MW¹. Major experiments are now underway to demonstrate a sustained fusion reaction with net energy gain in tokamaks, including ITER in France and the Chinese Fusion Engineering Test Reactor (CFETR). However, tokamaks face challenges with plasma disruptions and the complexities of maintaining precise magnetic field symmetry.

Stellarator

Stellarators use twisted, 3D-shaped magnetic coils instead of a symmetrical donut design to achieve magnetic confinement of the plasma. This removes the risk of disruptions, but stellarators are more complex to design and build. The largest stellarator, Wendelstein 7-X in Germany, successfully contained a hydrogen plasma for up to 30 minutes and reached temperatures over 100 million degrees Celsius². However, stellarators have not yet demonstrated net energy gain. More research is needed to scale up stellarators and improve plasma confinement.

Inertial Confinement

Inertial confinement fusion (ICF) uses lasers or particle beams to rapidly compress and heat a small pellet of fuel to reach fusion conditions. Lawrence Livermore National Laboratory’s National Ignition Facility uses 192 high-powered lasers to heat and compress a BB-sized pellet, but so far has not reached net energy gain³. ICF requires precise, highly controlled rapid implosion of the fuel capsule. While some private companies are pursuing ICF, technical challenges remain around efficiently compressing targets while minimizing energy losses.

Challenges in Harnessing Fusion

There are four main challenges that researchers have faced in developing fusion power:

Extreme Heat

The plasma inside a fusion reactor can reach temperatures over 100 million degrees Celsius ^{(IAEA, 2021)}. This is hotter than the core of the sun. These extreme temperatures put immense stress on reactor materials and components. Developing materials that can withstand the heat and neutron bombardment inside a fusion reactor for decades remains an ongoing engineering challenge ^{(GAO, 2023)}.

Plasma Instability

The plasma used for fusion reactions must be confined using strong magnetic fields. However, the plasma is prone to turbulence and instabilities that allow heat and particles to leak out. Controlling and stabilizing the plasma long enough to sustain fusion reactions is difficult ^{(Knowable Magazine, 2023)}.

Energy Balance

Fusion reactions require a large initial energy input to heat the plasma. The energy generated from the fusion reactions must exceed this input to achieve net energy gain. So far, no fusion device has successfully produced more energy than required to initiate the reactions.

Tritium Supply

The primary fusion reaction combines deuterium and tritium, two isotopes of hydrogen. While deuterium can be readily extracted from seawater, tritium is rare on Earth. Fusion power plants may need to breed their own tritium fuel from lithium, which brings additional engineering challenges.

Current Fusion Research Projects

There are several major fusion research projects currently underway around the world. The largest and most advanced is the ITER project, located in southern France. ITER is an international collaboration involving 35 countries to build the world’s largest experimental tokamak fusion reactor. Construction began in 2010 and is expected to be completed by 2025. The goal of ITER is to achieve a sustained fusion reaction that produces 10 times more energy than required to initiate the reaction, an important milestone on the path to fusion power.

Another major fusion experiment is the National Ignition Facility (NIF) located at Lawrence Livermore National Laboratory in California. Unlike ITER which uses magnetic confinement, NIF aims to achieve fusion through inertial confinement using high-powered lasers. NIF conducts fusion experiments to study weapons physics, but the long-term hope is the research will enable fusion energy production.

The Joint European Torus (JET) tokamak in England held the fusion energy record for a plasma pulse, generating 59 megajoules of energy over 2 seconds in 1997. JET is now being upgraded with the ITER Test Blanket Module program to test tritium breeding modules that could be used in future fusion power plants.

Germany’s Wendelstein 7-X (W7-X) stellarator, which began operation in 2015, is an experimental fusion device testing an alternate magnetic confinement design. W7-X set a new record for plasma duration, sustaining a hydrogen plasma for 30 minutes in 2020. Research on stellarators like W7-X aims to advance fusion reactor design.

Fusion Technology Spinoffs

While harnessing fusion energy for commercial power generation remains an ongoing goal, the research and development efforts have already led to numerous technological spinoffs in other fields. As noted by ITER, the quest for fusion has advanced the fields of superconductivity, plasma physics, electromagnets, materials science, and vacuum technology.

Specifically, the development of strong superconducting magnets for plasma confinement has benefited medical applications like MRI scanners. Fusion research has also driven advances in high-performance computing for plasma modeling and diagnostic systems for precise plasma measurements. The extremely high vacuums needed for fusion experiments have led to improved vacuum technologies and sealants across industries.

According to an OSTI report, the requirements for plasma exhaust control and management have advanced materials engineering and technologies for handling intense heat loads. Fusion programs have also developed remote handling systems for work in radiation intense environments. Such robotic maintenance technologies have applications in nuclear power, defense, and even space exploration.

Overall, the mission to harness fusion power has created numerous spinoff technologies, materials, and knowledge that benefit society in areas far beyond energy generation. The pioneering work done in fusion science will continue enabling progress in complementary fields.

Fusion Reactors for Power Generation

While fusion power generation remains decades away, researchers are making steady progress toward building the first fusion reactors capable of generating net energy gain. Current experimental reactors like ITER are not designed to produce electricity, but rather to demonstrate the feasibility of fusion energy. The next generation of demonstration reactors in the 2030s-2040s will aim to actually generate hundreds of megawatts of power. But it likely won’t be until at least the 2050s that multi-gigawatt fusion power plants could start coming online.

According to experts, fusion is unlikely to make more than a minor contribution to the world’s electricity supply before 2060-2070 [1]. The major hurdle is scaling up reactor designs while also increasing plasma confinement performance and net energy gain over break-even. But if these engineering challenges can be overcome, fusion could represent a major leap in clean energy production with abundant fuel and no long-lived radioactive waste.

The potential for fusion to provide copious, safe, carbon-free energy makes it well worth the decades of research still required. In the second half of this century and beyond, fusion power plants could start supplanting traditional nuclear fission and fossil fuel plants to become a primary source of electricity worldwide. This would dramatically reduce greenhouse gas emissions and provide energy security for centuries to come.

Safety and Environmental Impact

Fusion energy has significant safety and environmental advantages over nuclear fission. Unlike fission reactors, fusion reactions do not produce high-level radioactive waste or emit greenhouse gases. The primary waste product of fusion is helium, an inert gas. While fusion reactors do produce some low-level radioactive waste from neutron activation of the reactor structure, the amount is orders of magnitude less than fission and the radioactivity decays to safe levels within decades rather than millennia [1].

Furthermore, a fusion reactor cannot undergo meltdown or cause an uncontrolled release of radiation. Fusion requires precise conditions to occur and halts immediately if those parameters are disrupted. This gives fusion an inherent level of safety not present in fission [2]. Fusion reactions also do not produce long-lived radioactive isotopes that require secure, long-term storage. Overall, fusion offers the possibility of abundant carbon-free energy without the concerns over nuclear proliferation or catastrophic accidents associated with fission reactors.

The Future of Fusion

While significant scientific and engineering challenges remain, many experts are optimistic that fusion power can be realized in the coming decades. With continued advancement in superconducting magnets, plasma confinement techniques, and materials science, the goal of a net energy producing fusion reaction is in sight according to a recent article by the MIT Plasma Science and Fusion Center.

The next major milestone will be the completion of ITER, an international fusion experiment under construction in France that is designed to be the first fusion device to produce net energy output. While not a power plant, insights from ITER along with progress in smaller experiments will pave the way for commercial fusion facilities. When fusion is realized, it has the potential to provide vast, sustainable, safe, and carbon-free energy alongside renewable sources like solar and wind. Fusion would complement other clean energy technologies, operating continuously to provide baseload power.

Overall, many experts project commercial fusion power plants could be online within the next few decades. While significant challenges remain, the fundamental physics has been proven and the engineering know-how is advancing steadily thanks to increased investment and global cooperation in fusion research. If this progress continues, fusion promises to be a revolutionary technology that could provide abundant clean energy far into the future.