How can fusion energy be used

Also the neutron energy from fusion is higher than from fission — At present, two main experimental approaches are being studied: magnetic confinement and inertial confinement. The first method uses strong magnetic fields to contain the hot plasma. The second involves compressing a small pellet containing fusion fuel to extremely high densities using strong lasers or particle beams.

In magnetic confinement fusion MCF , hundreds of cubic metres of D-T plasma at a density of less than a milligram per cubic metre are confined by a magnetic field at a few atmospheres pressure and heated to fusion temperature. Magnetic fields are ideal for confining a plasma because the electrical charges on the separated ions and electrons mean that they follow the magnetic field lines.

The aim is to prevent the particles from coming into contact with the reactor walls as this will dissipate their heat and slow them down. The most effective magnetic configuration is toroidal, shaped like a doughnut, in which the magnetic field is curved around to form a closed loop.

For proper confinement, this toroidal field must have superimposed upon it a perpendicular field component a poloidal field. The result is a magnetic field with force lines following spiral helical paths that confine and control the plasma. There are several types of toroidal confinement system, the most important being tokamaks, stellarators and reversed field pinch RFP devices. In a tokamak, the toroidal field is created by a series of coils evenly spaced around the torus-shaped reactor, and the poloidal field is created by a system of horizontal coils outside the toroidal magnet structure.

A strong electric current is induced in the plasma using a central solenoid, and this induced current also contributes to the poloidal field.

In a stellarator, the helical lines of force are produced by a series of coils which may themselves be helical in shape. Unlike tokamaks, stellarators do not require a toroidal current to be induced in the plasma. RFP devices have the same toroidal and poloidal components as a tokamak, but the current flowing through the plasma is much stronger and the direction of the toroidal field within the plasma is reversed. In tokamaks and RFP devices, the current flowing through the plasma also serves to heat it to a temperature of about 10 million degrees Celsius.

Beyond that, additional heating systems are needed to achieve the temperatures necessary for fusion. In stellarators, these heating systems have to supply all the energy needed. The tokamak toroidalnya kamera ee magnetnaya katushka — torus-shaped magnetic chamber was designed in by Soviet physicists Andrei Sakharov and Igor Tamm.

Tokamaks operate within limited parameters outside which sudden losses of energy confinement disruptions can occur, causing major thermal and mechanical stresses to the structure and walls. Nevertheless, it is considered the most promising design, and research is continuing on various tokamaks around the world. Research is also being carried out on several types of stellarator. Lyman Spitzer devised and began work on the first fusion device — a stellarator — at the Princeton Plasma Physics Laboratory in Due to the difficulty in confining plasmas, stellarators fell out of favour until computer modelling techniques allowed accurate geometries to be calculated.

Because stellarators have no toroidal plasma current, plasma stability is increased compared with tokamaks. Since the burning plasma can be more easily controlled and monitored, stellerators have an intrinsic potential for steady-state, continuous operation. The disadvantage is that, due to their more complex shape, stellarators are much more complex than tokamaks to design and build. RFP devices differ from tokamaks mainly in the spatial distribution of the toroidal magnetic field, which changes sign at the edge of the plasma.

The RFX machine in Padua, Italy is used to study the physical problems arising from the spontaneous reorganisation of the magnetic field, which is an intrinsic feature of this configuration. In inertial confinement fusion, which is a newer line of research, laser or ion beams are focused very precisely onto the surface of a target, which is a pellet of D-T fuel, a few millimetres in diameter. This heats the outer layer of the material, which explodes outwards generating an inward-moving compression front or implosion that compresses and heats the inner layers of material.

The core of the fuel may be compressed to one thousand times its liquid density, resulting in conditions where fusion can occur. The energy released then would heat the surrounding fuel, which may also undergo fusion leading to a chain reaction known as ignition as the reaction spreads outwards through the fuel. The time required for these reactions to occur is limited by the inertia of the fuel hence the name , but is less than a microsecond.

So far, most inertial confinement work has involved lasers. Recent work at Osaka University's Institute of Laser Engineering in Japan suggests that ignition may be achieved at lower temperature with a second very intense laser pulse guided through a millimetre-high gold cone into the compressed fuel, and timed to coincide with the peak compression. This technique, known as 'fast ignition', means that fuel compression is separated from hot spot generation with ignition, making the process more practical.

In the UK First Light Fusion based near Oxford is researching inertial fusion energy IFE with a focus on power driver technology using an asymmetric implosion approach. As well as power generation, the company envisages material processing and chemical manufacturing applications. It focuses powerful laser beams into a small target in a few billionths of a second, delivering more than 2 MJ of ultraviolet energy and TW of peak power.

A completely different concept, the 'Z-pinch' or 'zeta pinch' , uses a strong electrical current in a plasma to generate X-rays, which compress a tiny D-T fuel cylinder. Magnetized target fusion MTF , also referred to as magneto-inertial fusion MIF , is a pulsed approach to fusion that combines the compressional heating of inertial confinement fusion with the magnetically reduced thermal transport and magnetically enhanced alpha heating of magnetic confinement fusion.

A range of MTF systems are currently being experimented with, and commonly use a magnetic field to confine a plasma with compressional heating provided by laser, electromagnetic or mechanical liner implosion.

As a result of this combined approach, shorter plasma confinement times are required than for magnetic confinement from ns to 1 ms, depending on the MIF approach , reducing the requirement to stabilize the plasma for long periods.

Conversely, compression can be achieved over timescales longer than those typical for inertial confinement, making it possible to achieve compression through mechanical, magnetic, chemical, or relatively low-powered laser drivers. Due to the reduced demands on confinement time and compression velocities, MTF has been pursued as a lower-cost and simpler approach to investigating these challenges than conventional fusion projects. Fusion can also be combined with fission in what is referred to as hybrid nuclear fusion where the blanket surrounding the core is a subcritical fission reactor.

The fusion reaction acts as a source of neutrons for the surrounding blanket, where these neutrons are captured, resulting in fission reactions taking place. These fission reactions would also produce more neutrons, thereby assisting further fission reactions in the blanket. The concept of hybrid fusion can be compared with an accelerator-driven system ADS , where an accelerator is the source of neutrons for the blanket assembly, rather than nuclear fusion reactions see page on Accelerator-driven Nuclear Energy.

The blanket of a hybrid fusion system can therefore contain the same fuel as an ADS — for example, the abundant element thorium or the long-lived heavy isotopes present in used nuclear fuel from a conventional reactor could be used as fuel. The blanket containing fission fuel in a hybrid fusion system would not require the development of new materials capable of withstanding constant neutron bombardment, whereas such materials would be needed in the blanket of a 'conventional' fusion system.

A further advantage of a hybrid system is that the fusion part would not need to produce as many neutrons as a non-hybrid fusion reactor would in order to generate more power than is consumed — so a commercial-scale fusion reactor in a hybrid system does not need to be as large as a fusion-only reactor. A long-standing quip about fusion points out that, since the s, commercial deployment of fusion power has always been about 40 years away.

While there is some truth in this, many breakthroughs have been made, particularly in recent years, and there are a number of major projects under development that may bring research to the point where fusion power can be commercialised. Much research has also been carried out on stellarators. It is being used to study the best magnetic configuration for plasma confinement. At the Garching site of the Max Planck Institute for Plasma Physics in Germany, research carried out at the Wendelstein 7-AS between and is being progressed at the Wendelstein 7-X, which was built over 19 years at Max Planck Institute's Greifswald site and started up at the end of In the USA, at Princeton Plasma Physics Laboratory, where the first stellarators were built in , construction on the NCSX stellerator was abandoned in due to cost overruns and lack of funding 2.

There have also been significant developments in research into inertial fusion energy IFE. Both are designed to deliver, in a few billionths of a second, nearly two million joules of light energy to targets measuring a few millimeters in size. Between and , the initial designs were drawn up for an International Thermonuclear Experimental Reactor ITER, which also means 'a path' or 'journey' in Latin with the aim of proving that fusion could produce useful energy.

The four parties agreed in to collaborate further on engineering design activities for ITER. Canada and Kazakhstan are also involved through Euratom and Russia, respectively.

The envisaged energy gain is unlikely to be enough for a power plant, but it should demonstrate feasibility. In , the USA rejoined the project and China also announced it would join.

The deal involved major concessions to Japan, which had put forward Rokkasho as a preferred site. India became the seventh member of the ITER consortium at the end of The total cost of the MW ITER comprises about half for the ten-year construction and half for 20 years of operation.

Research is being carried out on suitable materials to minimise decay times as much as possible. A large-scale nuclear accident is not possible in a fusion reactor. The amounts of fuel used in fusion devices are very small about the weight of a postage stamp at any one time. Furthermore, as the fusion process is difficult to start and keep going, there is no risk of a runaway reaction which could lead to a meltdown. Reliable power.

Fusion power plants will be designed to produce a continuous supply of large amounts of electricity. Once established in the market, costs are predicted to be broadly similar to other energy sources. The UK contributes to fusion research in two main ways:. Progress in fusion research. The next steps European fusion research is following a roadmap to achieve power generation around the middle of this century.

Beyond JET, the programme focusses on four main projects:. ITER — a large multinational tokamak that is being built in the south of France. Some of them are working on slightly different magnetic confinement methods, others are pursuing truly innovative—if high-risk—methods that could produce dramatic breakthroughs. All of them are looking for paths to fusion that are simpler and less expensive than ITER. What will come after ITER?

The details are still to be determined, but a number of targets are in sight. If all goes well, the technology from ITER should enable electricity generation from fusion, and member nations are not waiting until the late s to begin planning.

Several follow-on devices that will be even higher performance than ITER are in development. Courtesy: China Institute of Plasma Physics. Its initial phase will demonstrate fusion operation at about MW fusion power, but it will eventually be upgraded to at least 2 GW fusion power and MW net generation. Formal construction of the device is slated to begin in the s, but construction of supporting facilities and key prototype components has already begun at a location in Hefei.

Courtesy: EUROfusion. In the U. Until recently, progress toward fusion energy in the U. Funding for the U. A report from the National Academies of Science in strongly recommended that the U. This plant would likely have net generation of about MW to MW.

The preference for a smaller design reflects the economic realities of electricity generation in the U. The study is expected to be completed later this year. When will we see fusion as a meaningful element of the power mix?

In this, it is worth remembering that practical fission generation was first demonstrated in the s, yet it was not until the mids that commercial nuclear plant construction began on a large scale.

Several of the earliest fission plants were public-private partnerships between utilities and the Atomic Energy Commission. The first U. This does suggest, however, that large-scale commercial fusion energy should not be expected before the s, roughly 20 years after ITER begins DT operations. Much of how a fusion plant would be built and operated does not fit within existing NRC regulations, a fact the NRC itself has recognized.

The fusion industry has begun engaging with the NRC on what such a regulatory approach would look like, but no official rulemaking has begun, nor is it likely to until the technology of fusion power plants is considerably clearer. Both federal and state regulatory environments will need to be adapted for fusion, a process that is likely to be drawn out and subject to extensive litigation.

Though this article has focused on scientific and engineering factors, the ultimate deciding factors will be social and economic. Fusion power plants will be built when investors and public utility commissions begin viewing them as worthwhile investments. Exactly when that point will be reached is difficult to say. It is likely that electricity from the first fusion plants will be expensive compared to other options, though the same was once true about large-scale renewable generation.

Fusion generation is certainly amenable to economies of scale, but the U. The proposed approach of developing a compact fusion pilot plant thus represents a strategic way to develop the technology before scaling up once the investment community has gained confidence in the economics of larger plants.

Another important factor is public acceptance and the degree to which fusion will need to contend with perceptions and misconceptions about fission plants. Both the fusion community and prospective plant owners will need to be proactive in providing effective communication about the technology long before any actual construction begins.

It is worth noting that the likely time frame roughly coincides with the period when many U. In such an environment, the advantages of fusion power could well be economically and socially compelling. Generation III nuclear reactors have not shown much ability to overcome the weaknesses of conventional Gen-II light-water reactor…. View more. Facebook Twitter LinkedIn. Defense Daily subscriber and registered users, please log in here to access the content.

Get a Free Trial Here. Please contact clientservices accessintel. ET , to start a free trial, get pricing information, order a reprint, or post an article link on your website. Jun 1, by Thomas Overton. Water Jun 1, Waste to Energy Jun 1, Workforce Jun 1, Researchers who work on fusion energy are essentially trying to make tiny stars here on Earth.

When two atoms fuse, they lose a bit of their mass, which is released as energy. The E here stands for energy. M is for mass. C is a constant number that is the speed of light in a vacuum. An illustration of the ITER machine, which, if all goes well, will be doing fusion by ITER Organization. Nuclear reactors perform fission , which involves splitting atoms apart. Fusion, by contrast, is when atoms merge together. Fusion converts more mass into energy per reaction than fission does.

The sun weighs about , times more than Earth does. That mass creates powerful gravitational forces that produce extreme pressures. This pressure, combined with temperatures up to 27 million degrees Fahrenheit , gets atoms to fuse together.

We don't have the technology to recreate the Sun's massive pressures, so researchers have to make up for that by getting hydrogen atoms even hotter than the sun does — in the range of hundreds of millions of degrees Fahrenheit. They heat up the atoms using various tools, including particle beams, electromagnetic fields such as microwaves and radio waves, and lasers. The temperatures needed are so hot that the hydrogen fuel becomes a plasma , a state of matter that exists when a gas's atoms split into positively and negatively charged particles.

Stars and lightning are plasma, as is the luminous matter inside neon signs. Researchers have been producing controlled fusion reactions for decades. These days, the big goal that hasn't happened yet is to make a fusion reactor that produces more energy than it takes in.

Plasma, like lightning, is very difficult to control. Cold fusion is the theoretical fusion of atoms at room temperature. No one has ever done cold fusion — although there have been many false claims over the years. Scientists researching fusion energy are more interested in hot fusion, which they have been doing the s — the challenge now is just how to turn it into useful energy. There are many approaches.

Here are the two most worth watching. Researchers often do this in a tokamak , a donut-shaped reactor the weird shape helps keep the plasma in place.

In the s, the European tokamak JET achieved 16 million watts of fusion power for less than a second. On the whole, JET was able to produce 65 percent of the energy that went into the experiment. More recently, an international group is building the world's largest fusion reactor. This is an even bigger tokamak called ITER. The goal of ITER is to produce million watts of power — in the range of a real power plant — for seconds at a time. The researchers also want to produce ten times more energy than is used by the system.

See how tiny that person in blue is compared to this giant fusion reactor? The NIF fires the lasers at a tiny gold can, which vaporizes and gives off x-rays. Those x-rays then hit a spherical pellet of hydrogen fuel that's smaller than a peppercorn. The x-rays heat and compress the fuel, which turns into plasma.