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Fusion EnergyPower for future generations

With an increasing world popu-lation and a growing econo-my, the demand for energy is

certain to grow. To bring the standard ofliving of the world population up to west-ern standards by the year 2100 will re-quire up to five times as much energy aswe use today. New solutions will be re-quired for providing an answer to boththe energy demand and the emissionproblems associated with our presentenergy system. Fusion energy, the ener-gy source of the sun and the stars, hasseen remarkable progress over the lastdecades, and is now ready to move outof the laboratory.

Background

Energy supply must be geared to ensur-ing the uninterrupted physical availabil-

ity of energy products, at a price that isaffordable for all consumers, while re-specting environmental concerns andlooking towards sustainable develop-ment. Environmental concerns have high-lighted the weaknesses of present ener-gy sources. Sustained economic growthand the increasing use of energy servic-es are contributing to the increase ingreenhouse gas emissions. Climatechange is a major challenge and a long-term battle for the international commu-nity.

Apart from climate change mitigation,another important issue is the need feltby many countries to generate their en-ergy independent of foreign fuel supply.A recent green paper of the EuropeanCommission points out that Europe im-ports about 50% of its energy, and that

this fraction will increase to 70% in thenext twenty years, unless action is tak-en. The uneven distribution of energysources around the world holds greatpotential for international conflict. Recentinternational tensions have again high-lighted the importance of this energy-security issue.

The need for new non-polluting and sus-tainable forms of energy to reduce theenergy dependency of developed coun-tries and to contribute to climate changeminimisation is therefore becoming ur-gent. To meet this challenge, all energyoptions have to be considered that cancontribute to an optimised future energymix. Fusion, which would be particularlysuited for the centralised supply of base-load electricity, appears as one of the mostattractive long-term energy options be-cause of the widespread and abundantdistribution at low cost of its fuel sup-plies and because of its favourable safe-ty and environmental features. Fusionenergy would ideally complement inter-mittent renewable energy sources in thefuture energy mix.

In a fusion reactor, light atoms (isotopesof hydrogen) fuse together and release avery large amount of energy. The fusionprocess takes place at an extremely hightemperature of 150 million degrees Celsi-us. At this temperature, matter forms aplasma, a hot gas of charged particles.The energy released in the fusion reac-tion is used to generate electricity.

Fusion research started some decadesago, but only at the end of the 1960s didmajor scientific events, such as the useof ‘tokamak’ machines for the confine-ment of hot plasmas, enhance the levelof knowledge sufficiently to put fusionon the path towards a future energysource. The fuels of a fusion reactor are

Plasma image from the START experiment at UKAEA, Culham.

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widely distributed around the world,cheaply available, and inexhaustible.

The long-term objective of fusion pro-grammes in the international communityis the creation of prototype plants forpower stations to meet the needs of so-ciety: operational safety, environmentalcompatibility, economic viability. Duringthe last years, very important results havebeen achieved, confirming that fusionshould now be considered as a credibleenergy option having the potential forclean, large-scale power generation.

Safety and Environmental Issues

The safety and environmental aspects ofpossible future fusion power stationshave been assessed in many and exten-sive studies, all of which have confirmedthe attractive characteristics of fusionpower. The operation of fusion powerstations will make no adverse contribu-

tion to global climate change as no green-house gases are produced.

There is no possibility of uncontrolledpower runaway since inherent physicalprocesses limit power excursions of thefusion plasma. Moreover, the plasma ves-sel of a fusion reactor will only containenough fuel for a relatively short burn-ing time – less than a minute. The fusionprocess can therefore be stopped with-out problem and with no consequences.Even in the case of a total loss of activecooling, melting of the reactor structuresis excluded due to the low density of de-cay heat of the materials present in thereactor. Even in the worst possible in-plant driven accident scenario, the riskto the general public would be below thelevel at which evacuation of the areaaournd the power plant is required.

The fusion fuel cycle does not involveany input of radioactive material and

there is no radioactive waste associatedwith spent fuel. Radioactivity is presentin the intermediate fuel, tritium, but thereis no radioactive fuel cycle outside thepower station as the tritium is made in-side the plant. Fusion power stations willnot make use of uranium, plutonium orother fissile materials; none of the mate-rials required are subject to the non-pro-liferation treaties, so the presence of il-licit fertile or fissile materials could beeasily detected.

The radiotoxicity of the activated struc-tural materials generated by a fusion re-actor during its lifetime will only last forapproximately one hundred years, afterwhich the activity is comparable to thatof the ash from coal power stations. Af-ter this cooling-down period almost allthe materials in a fusion power stationcould be disposed of as non-activewaste, recycled, or given shallow-landdisposal. Therefore, fusion waste would

A look inside the Joint European Torus (JET), the largest fusion experiment in the world. JET is located in Culham, GB.

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JET has produced significant fusionpower in deuterium/tritium plasmas (upto 16 MW) in the short pulses character-istic of existing experimental devices.‘Break-even’ conditions, where the fusionoutput power equals the external inputpower required to heat the plasma, havealmost been reached. Moreover, JET hasdemonstrated that fusion devices can beoperated safely with tritium fuel and thatradioactive structures can be mainte-nanced and modified using remote han-dling techniques.

Thanks to the success of JET and otherexperiments, the world fusion communi-ty is ready to take the “Next Step” of con-structing a larger device, which will pro-duce plasmas under reactor conditionsof high power gain and provide a reliablebasis for proceeding to a demonstrationreactor, capable of producing electricity.This project, under the name of ITER, isa collaboration between EU, Japan, Rus-sia, Canada, China and the USA. ITERwill produce ten times more power thanis needed as input.not constitute a permanent burden for

future generations.

Progress in Fusion Research

There has been great scientific and tech-nological progress in developing fusionover the last decade. The figure aboveshows the progress of the so-called ‘tri-ple product’, a figure-of-merit whichmeasures the performance of a fusionplasma. The triple product has seen anincrease of a factor of 100.000 in the lastthirty years, and another factor of 6 isneeded to arrive at the level required fora power plant. In the figure, the progressis compared to that of computer chips.

The central research facility of the Euro-pean Fusion Programme is the Joint Eu-ropean Torus (JET), in Culham, Great Brit-tain. The focusing of significant Europe-an fusion research funding on JET hasmade it the pre-eminent fusion facility inthe world and allowed Europe to takemajor strides in fusion research. JET iscomplemented by a number of special-ized smaller devices run by more than 20individual member states. JET was ap-proved in 1974, began operations in 1983,and met its planned operational goals onschedule in 1990. Since then, a new sci-

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Moore's Law: number of transistors

doubles every 2 years

Fusion: figure-of-merit (the 'triple product')

doubles every 1.8 years

Target ITER

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The progress of fusion research through the years measured by the triple product,which is an indication of the performance of a fusion plasma. For comparison, thedevelopment of computer chips is indicated.

An artist’s impression of the Joint European Torus, JET

entific programme has started, and JETnow serves as a research facility hostinga large number of international researchefforts.

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The current ITER design is a cost-effec-tive tokamak, which allows the study ofburning plasmas under physics condi-tions which can be extrapolated to a re-actor and in which important reactor tech-nologies will be integrated. The ITERparticipants now have to approve theconstruction of the machine and selectthe site where this international projectshould come to life. A decision about howto proceed with ITER is expected in thecourse of 2003.

In parallel to the realisation of ITER, theFusion Programme will need to come withfurther technology developments in or-der to build a commercial electricity-pro-ducing reactor. Technological progressis required in several areas, especially inthe development of plasma-facing mate-rials sustaining high heat loads and oflow activation structural materials.

Economics of Fusion Electricity

To be a viable commercial option, fusionmust be competitive with other mid-21st

century electricity-generation technolo-gies. As in nuclear fission, the invest-

ment cost dominates in assessing thecost of electricity (equivalent to more than70%). The cost of fuel would represent anegligible percentage. Many studieshave been conducted within the frame-work of the fusion programme to evalu-ate electricity costs for fusion and com-pare them with those of other advancedor renewable energy sources.

Comparing the projected costs of elec-tricity from energy sources producingsteady power, the projected fusion costsare roughly comparable to those fromclean (pollution abated) coal plants andabout fifty percent larger than those fromfission. The projected fusion costs arealso comparable to the projected costsof electricity from typical renewables1. Incomparison to renewables, fusion has theadvantage of being able to provide con-tinous base load electricity, without ad-ditional cost for storage.

The direct costs of electricity generationdo not include costs such as those asso-ciated with environmental damage or ad-verse impacts upon health. In the case ofsome present sources of electricity, these

“external” costs are substantial. Appre-ciation of the importance of external costshas become widespread in recent years.Studies show that fusion, along withwind, belongs in the class of low externalcost sources1.

For comparison: the external costs of elec-tricity from present European coal-firedplants are high, twenty times greater thanthe estimated external costs of fusionelectricity. About one half of the estimat-ed external costs of the coal-fired stationsis attributed to climate change.

Fusion in the Future Energy Mix

In the future, fusion will be part of anenergy system in which several energysources complement each other. The ev-olution of the energy mix is investigatedusing energy scenario’s, which describethe use and production of energy for acertain period in the future. These sce-nario’s can be modeled on a computer.

In studies using this approach, fusionpower was incorporated into existingeconomic modelling of energy scenariosfor Europe2, up to the end of this centu-ry. The most important constraints ap-plied in these studies were on carbon di-oxide production. The important con-straints applied to fusion were assumedlimits to the speed with which it could bedeployed.

These studies show, broadly, that fusioncould bring a contribution of at leasttwenty percent of the electricity supplyby the end of this century, mainly con-strained by the assumed rate at which itcould be deployed. However, fusionwould capture little or none of the marketif there were no environmental con-straints or little economic development.Since the environmentally-constrainedscenarios were constructed to have min-imal cost, satisfying the demand withoutfusion would be more expensive: thesums involved are huge, dwarfing thecosts of fusion development.

Fusion is currently not considered animmediately helpful CO2-mitigation tech-nology, because it will not be economi-cally available in the coming decades. In-termediate solutions, like the substitutionof coal by natural gas and CO2-seques-

The ‘next step’ fusion experiment: ITER

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tration could, however, help to reduce thegreenhouse gas emissions in the shortand medium term and fusion could thenbe available when a replacement of thesetechnologies is necessary because of theexhaustion of resources and issues ofenergy security.

With these long-term prospects in mind,it is clear that public funding is still need-ed for further fusion energy development.Since the relevant industries are orient-ed towards short-term profit, their earlyparticipation in fusion funding cannot beexpected. However, industry will readilybenefit from spin-off emerging from pio-neering projects such as the large scalesuperconducting coils required for a fu-sion reactor.

A Roadmap to Fusion Energy

In a report to the EU Council Presidencypublished mid 2001, a group of independ-ent experts chaired by David King (ChiefScientific Advisor to UK Prime MinisterTony Blair) advocate a fast track ap-proach towards the development of com-mercial fusion energy. The fast track road-map consists of two generations of de-vices, first the ‘next step’ ITER, and sec-ond a prototype power plant DEMO/PROTO. This development should becombined with the parallel testing of ap-propriate plasma-facing materials. Thesecond device should demonstrate the

technical feasibility, potential reliabilityof operation and economic attractivenessof fusion energy, and should serve as acredible prototype for a commercial powerplant. DEMO/PROTO could achieve netelectricity production about 35 years af-ter the decision to construct ITER, afterwhich commercial deployment of fusionenergy could start.

Whether the fast track roadmap can befollowed strongly depends on politicalwill. If the development steps that areperformed in parallel in the fast track sce-nario are instead performed sequentially,the time to net electricity production willbe extended to about fifty years. The fasttrack scenario could substantially reducethe total amount of funding to reach thelong-term objective, but this does requireincreased short-term funding.

The fast-track timescale has found reso-nance outside of Europe as well: follow-ing a request by the Department of Ener-gy of the USA, the American FESAC ad-visory committee published a report Jan-uary this year, detailing the requirementsfor achieving fusion-powered electricityto the grid in 35 years.

A Need for Fusion?

The upward trend in future energy de-mands is a reality that needs to be faced.Emission of greenhouse gasses affect-

ing the climate, the adverse health effectscaused by the present energy system,and the energy-security issue all demandradical changes in the way we produceour energy. We need a full range of safeand environmentally-friendly energy op-tions applicable to the near-term, medi-um-term and long-term.

With its inherent environmental and safe-ty advantages fusion should be seen asan important element in any global strat-egy designed to allow sustainable eco-nomic growth. As fusion is particularlysuited for base load electricity produc-tion, it is the ideal complement of otherrenewable sources in the future energymix. Fusion technology, brought to frui-tion, will be an asset of the utmost valueto give to our descendants.

Notes1) G. Borelli et al., Socio-Economic Researchon Fusion, Summary of EU Research 1997-2000, EFDA–RE–RE-1, July 2001.2) P. Lako, J.R. Ybema, and A.J. Seebregts,Long-term Scenarios and the Role of FusionPower, ECN-C-98-095, Petten, February1999.

ContactProf. N.J. Lopes Cardozo, FOM-institutefor plasma physics, P.O. Box 1207, 3430BE Nieuwegein, The Netherlands, Tel.+31 (0)30 6096999, Fax: +31 (0)30 6031204,email: cardozo@rijnh.nl.

On the Internetwww.efda.org: Starting point for theEuropean Fusion Programwww.iter.org: The ‘next step’ fusionexperiment ITERwww.jet.efda.org: The largest fusionexperiment in the world, JET in Cul-ham, GBwww.fusion.org.uk: General informa-tion on fusion

Inside the TEXTOR tokamak, located in Jülich, Germany

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FOM - Institute forPlasma Physics Rijnhuizen