Cassandra has moved. Ugo Bardi publishes now on a new site called "The Seneca Effect."

Sunday, April 29, 2018

Nuclear Fusion: is it still worth investing on it in an age of cheap renewable energy?

A review by Giuseppe Cima of the situation with nuclear fusion. The matter is complex, but Cima identifies the crucial point: even assuming that nuclear fusion were to work as expected, it would be more expensive than the presently available renewable technologies. Consider also that it will take decades before we can have fusion reactors able to produce commercially available energy (if ever). How much better and cheaper will renewables be by that time? Considering that fusion is not a "clean" technology, as sometimes claimed, it doesn't seem to have any realistic chance to be useful for something, now or in the future. So, why are we still spending money and resources on this technology? One more example of the human blind faith in technology and its miracles (U.B.)

ITER TOKAMAK, looking carefully, at the bottom right circled in red, a human in a yellow jacket. The probable size of a magnetic confinement fusion reactor is huge and it's at the core of most of its problems.

My view on nuclear fusion, in a nutshell

 by Giuseppe Cima

Nowadays few businesses would invest in conventional nuclear power stations. In the US, subsidies of 100% or more fail to attract private investments for a nuclear fission power station, the classic form of nuclear energy. So, the perspectives for a revival of nuclear are not rosy.

But there exists another form of nuclear energy, thermonuclear fusion, the one that powers the stars. Fusion, the sticking together of light nuclei such as hydrogen, is a nuclear reaction distinct from fission, where heavy atoms, such as uranium, break apart. Fusion energy research has been pursued since the WWII years in national labs and universities all over the world. Despite all efforts, though, so far it has not provided a clear indication of being feasible. What are the current perspectives of this form of energy?

Fusion technologies

There are two ways to burn hot nuclear fusion fuel: make it react very quickly before the burning gas flies away, the way an H bomb works, or use a magnetic field to insulate the plasma from the reactor walls. The bomb method can be replicated in a series of micro-explosions in the lab, but the rate has to be high enough to produce relevant electric power and this poses huge unsolved problems. A giant laser fusion experiment in the US, the National Ignition Facility, has demonstrated how difficult and expensive is to produce a micro-explosion once a day. Imagine doing that hundreds of times per second for years. Even with a budget provided by the military for weapon development, laser fusion is far away from pointing to a credible commercial reactor.

Therefore, from the inception of fusion energy research, most efforts have been devoted to magnetic confinement of steady state hot plasmas. After 70 years of trying, almost everybody in the field has concentrated on one favorite scheme which goes under the name of TOKAMAK, a Russian invention. The tests performed so far indicate that the minimum size of a potential reactor core will be large, the size of a large building. ITER, a TOKAMAK presently under construction in France to demonstrate the feasibility of fusion, is of this size but, apart from the size, it is so expensive that its construction is requiring the financial contribution of all developed nations on earth.

The doughnut-shaped ITER reactor core is 30 meter in diameter, 20 m high. It is an extremely complex device, much more sophisticated than an equivalently powerful nuclear fission reactor and roughly 10 times the volume. Its core weights more than 30 thousand ton, just the floor of ITER uses 200 thousand cubic meters of concrete.

Size is the most obvious drawback of nuclear fusion: the large size makes it impossible to mass produce these reactors. This factor gives a considerable advantage to the competition, made of comparatively small generators: gas turbines of 50-100 MW, efficient windmills of a few MW, photovoltaic solar panels of less than 1 kW. These generators can be transported by truck and the speed of their industrial development has been inversely proportional to the power of an individual module. The cost of electricity for photovoltaics and wind originates mainly from the cost of capital invested in the generator and its ancillary equipment, just as it's the case for Deuterium-Deuterium fusion where the fuel is nearly free. Natural gas power stations burn inexpensive fuel and have the lowest generator capital cost of all, but are CO2 polluters, nowadays a serious drawback.

We must specify that the fuel for fusion reactors is nearly free only in the case of the Deuterium-Deuterium fusion. The current idea, instead, is to use the easier reaction of Deuterium with Tritium, the latter being another radioactive isotope of Hydrogen. It is a very rare isotope that can be bred in the same TOKAMAK which is burning it, but not in sufficient quantity to keep these reactions going. This is another issue of ITER-like reactors, for the time being swept under the rug.

Because of its large size and complexity, it's very hard to imagine that a TOKAMAK fusion reactor could be less expensive than a conventional fission reactor and detailed present-day estimates put the cost of the kWh to more than 12 ¢, just for the capital cost, and before knowing all the details of a working reactor.

Instead, electricity commercialized from unsubsidized photovoltaic and wind generators is presently sold at prices between 2 and 7 ¢/kWh, depending on location, and there is room for more savings. These sources are intermittent, fusion is not, but for a renewable-dominated electrical production, the additional cost of energy storage would entail a fraction of the cost of energy production. This is a purely economic consideration: renewables are already less expensive than fusion energy.

There is a second very relevant drawback linked to the large size of the fusion reactor: its development time. ITER will experiment with real fusion fuel not earlier than 2035 and will realistically carry on the experiments in the following 10 years. It implies that this experimental phase, not a prototype reactor since ITER will be incapable of producing energy, will have taken roughly 50 years.

To make a dent in the world electricity production one should implement thousands of 1 GW size reactors. How long of an experimentation phase should one consider to reach this goal from when ITER will have answered the initial round of questions? Maybe 100 years, i.e. a couple of experimental phases.

To summarize, on top of a plethora of unresolved, even unknown, design issues of technical nature, magnetic fusion poses problems linked to the huge size of the TOKAMAK reactor core: a large kWh cost and a very long development time. For the ones sensitive to the "cleanliness" of fusion I also have to mention that ITER at the end of its life will present a bill of around 30,000 tons of heavily radioactive waste without having produced a single kWh. Magnetic fusion is not clean: its fuel and the products of the reactions may be modestly radioactive, but the machinery itself is not.

Why the reactor has to be large

Why a magnetic fusion reactor has to be big, physically very large? Thermonuclear fuel has been proven to burn in the H bomb, but it can burn also non-explosively, think of the sun. For any fuel to burn in steady state, the energy released in the volume of the burning matter equals the energy escaping from it, heat produced equals heat lost, the energy balance equation. The rate at which energy is produced grows in proportion to the density of the fuel, the number of atomic nuclei per unit volume. The reactor power density increases with the density of the reacting particles.

The plasma in a reactor is a gas of atomic constituents roughly in thermal equilibrium, its kinetic energy content is characterized by a pressure. If the TOKAMAK plasma has to be contained by a magnetic field, the field pressure has to be substantially higher than the plasma pressure. The magnetic pressure produced by the external superconducting magnets at the plasma location is limited at present to less than 200 atmospheres by the mechanical strength of the magnets. Improvements are foreseeable on the magnets front and they would be helpful, but the magnet materials are themselves subject to the laws of nature of solids: these improvements will be marginal.

Like in an ordinary gas, the plasma pressure is proportional to particle temperature and density. The fusion temperature has to be in the region of hundreds of millions of deg C hence, because of the magnetic pressure limit, the particle density turns out to be pretty low, a million times less than the molecular density of the air we breathe. The result is a low power density.

On the other side of the reactor power balance equation, the energy lost by the plasma is dictated by plasma turbulent motions and the size of the device. Turbulence has been experimentally demonstrated to be present at a significant level in all magnetically confined plasmas of thermonuclear interest, just like with water in a canal.

The analogy is close, for a given incline the water flow in a canal is constrained by an irreducible turbulent drag, with negligible dependence on the canal construction details. This is the case also for energy confinement in a thermonuclear plasma, it's dominated by unavoidable turbulent fluid motions. But a reacting core large enough to reach power breakeven always exists because its volume (energy production) to surface (losses) increases with its size, a purely geometric consideration. The sun, even without a magnetic field, is certainly large enough for breakeven.

These are the reasons why the tokamak reactor has to be very large. The size required to maintain the large core temperature needed for the plasma to fuse. This is the main factor making nuclear fusion expensive and very hard.

Bottom line

As things stand, present-day renewable technologies are considerably less expensive than a potential nuclear fusion reactor - even assuming it would work as expected. My work in fusion coincided with the Reagan electric sector deregulation when something similar happened between natural gas and coal-fired power stations. The development of large aviation jet engines made possible efficient, inexpensive, factory produced, electricity generators which proved to be impossible to beat and coal power plant investors went bankrupt to allow for the American industry to take advantage of the newer, less expensive, technology. It was then too early for the wind and photovoltaic revolution but now they are here to make nuclear fusion obsolete before it has been proven to work.

The author

Giuseppe Cima has been employed in various capacities by fusion research labs and Universities in Europe and the US for most of his professional career: Euratom Culham UK, ENEA Frascati and CNR Milan, the Fusion Research Center at UT Austin. He published more than 70 peer-reviewed papers in this field, mostly about EM waves for plasma diagnostic and heating, magnetic configurations, turbulence measurements. After losing faith in a deconstructionist approach to fusion, he started an industrial automation company in Texas. He is at present retired in Venice, Italy, where he struggles to protect the environment, conserve energy and teach technology and science.


  1. If the heat from a fusion powerplant is extracted via a Rankine cycle conversion it can only be removed at temperatures of about 700 C, as used in a modern supercritical steam turbine. Concentrating solar power (CSP) plants can already easily reach these temperatures. Higher temperatures cannot be used due to the limitations of turbine and boiler metallurgy. Since land area is not a major issue for a stationary power plant, there is no real penalty for the large heliostat arrays of CSP needed to gather the diffuse energy of the sun at the earth's surface.

    All these facts mean that fusion plants are a huge waste of money. The capital needed to contain the fantastic temperatures required for fusion far exceeds that required for a CSP plant, which can already produce temperatures as high as anyone can use. I wonder that anyone ever thought a fusion plant was a good idea. It's like buying a flamethrower to use as a hand warmer; thermal overkill.

    1. The energy/temperature of the tokamak reactor neutrons is in principle appealingly high to efficiently convert to usable electricity, a virtually infinite temperature energy source ( in the Johnson - Nyquist sense) but nobody would know how to do it, so the present fusion tokamak scheme makes use of conventional steam turbines. Considering all other technical unresolved issues of fusion this is a minor drawback common to most energy converters.

  2. Fusion has sense on some areas. In deep space, far from the sun, nuclear energy (fusion or fission) is needed.
    But on Earth, renewable require huge surface areas. We are yet very far from saturation, so places where there is not other use, it's ok to use renewable, but we could free more surface if we have fusion power.
    Another point it's food. Food require surface, but indoor allow us to create a lot more food. But that model won't work if the energy to make food come from renewable, as we will change food space by energy space.
    With fusion+indoor plants we could extend our food supplies by large, only limited by the heat excess. Not as greenhouse, but pure heat production cause by this nuclear power.
    Even if our population were flat (what it's desirable), indoor gardening could allow to free space to take back as wild areas.

    1. For the entire energy need (for model case) it will be necessary in middle Europe to cover 10% of built up area only.
      For the wind following reflection: for approx. 1 GW (350 turbines,3 MW) wind park is needed about 450 km2 area, but the consumed and disturbed land for one turbine is about 120 m2 (basement and road), for entire wind turbines therefore less than 0,01%. The rest, also 99,99% can be used for forestry, pasture or agriculture or stay under natural conditions

  3. Ugo,

    Thank you for posting signor Cima's article. It's absolutely essential reading on fusion reactors for non-professionals like me. (I have BA degree in Art History).

  4. In Science Fiction tales, the alien fusion reactors are the secondary power supply of small space ships, those stuffs are fast veichles to travel inside the solar system, but they haven't enought energy, and no smart equipments for long interstellar voyages. If you want to travel from Earth to other far stars, for sure you need a starship cruiser because it has got a annihilation reactor for antimatter and lots more of smart equipments too.

    Everybody knows that Ezezel is an alien, he lives inside the alien base in Mars, he usually tells stories about the small space ships technology and to power on a small space ship engine, the first step to do, it is to start up a fission nuclear reactor because it always initializes the fusion reactor, so when the fusion reactor becomes self sustained only, then the fusion reactor starts to feed all space ship systems, and space engines too.

    For sure, everybody knows that for interstellar cruiser class the fusion reactor is only the second step, because it initializes the annihilation reactor so it's antimatter only who provides enought energy for reaching a large fraction of light velocity (something in between from 0.50c until 0.997c, for sure speed it depends of the starship cruiser class). The very best of interstellar cruisers are the big Theosalis class: it's for sure a big UFO disk up to 30mt of diameter, perfect round with a perfect ellipse profile, it has got 2 nuclear reactors, 2 fusion reactors, 1 annihilation reactor, and for storing antimatter a big magnetic tank, inertial dampers, lots of computers, suspended animation cells for the crew, and a very powerful armaments (lots of foo fighters, strong laser and X-rays/Gamma Rays guns, EMP and kinetic cannons and lots more). For sure the most important thing of the interstellar cruiser class space ship is their big plasma coat, it is magnetic contained outside the ship, it protects the crew from outside radiations and small meteorites during the long time voyage into space.

    Sometimes some small space ships with fusion reactor have a plasma coat too, but it's thinner.

    Ok folks, after this short funny story of science fiction, it seems to me that it emerges a couple of things:

  5. 1st bad point: if french tokamak project runs and it is energy efficient as alien fusion reactors do, then for sure what's good for the goose is good for the gander; in future tokamak will provide power for feeding power smart grid, so cities and trains and metros, desalination plants, will run at zero CO2 emissions. Tokamak project will remplace during time the large fraction of nuclear fission reactors in the world. Ist and may be IInd world may converge to fusion power plants. May be, also subs and big containers ships could have tokamak power too in the distant future?. But airplane can't fly with nuclear or fusion reactors, and there's not enough litium on earth for feeding batteries for electric power cars, as mankind did with metal tank for storing fuel and feeding engines.

    Yes, for sure tokamak stuffs are expensive: quite expensive, lots more expensive than a fission nuclear power plant and it will need long time to build one. Long time of construction process means a lots of money to invest in. Nations will need also investiments for mitigating climate damages too, and if you put too money in one thing, you will run out resources for another or viceversa.

    2nd good point: on the moon there is a lot of He-3 and those stuffs are natural resouces, they are quite useful for fusion reactors, so in the future mankind will have to pick up some He-3 from moon, to feed future fusion reactors. Alien does it for long time, so mankind can do too. Those high tech stuffs will be available in the Ist world, may be in IInd world too, but for sure those kind of stuffs are not for IIIrd world, and in 2050 there will be 2.5BILLION of people in Africa knocking at the bord of northest Africa in front of Mediterraneann sea, and it will be lots of problems in Asia where in 2050 there will be up to 5BILLION people.

    3rd bad point: tokamak project doesn't solve the issue of nuclear wastes of old nuclear fission power plants, for example Plutonium-244 remains radioactive for 80 million years. Think about that: 80 million years, it seems to me it is a lot of time for the mankind scale, don't you?!.

    4st point, last but not least: thermodynamics don't care of tokamak project, and this is a serious problem.

    Sea level will rise +1.5mt for the end of 2050, +3mt for the end 2100, +7mt from 2100 lots more in the future.

    Polo nord ice free is a real thing for 2030 (this event will be an important tipping point also for AMOC-THC and for the world climate)

    CO2 is still rising and for sure a level of 402PPM means +4C of climate change increasing.

    Methane hydrates are melting in

    There's no evidence of a concrete geoengenering technologies for gas serra emissions.

    So at the end of the day, if tokamak project runs and it is more energy efficient then an old fission nuclear power plant, we can imagine the tokamak porject will remplace very slowly only the fraction of the nuclear fission percentage of future energy mix needed for mankind in 2050. This means, fossil fuels will still remain in use in many different forms, in the future, and this is not a good thing.

  6. Our civilised industrial/commercial existence can be summed up in six words:
    explosive force converted into rotary motion

    Bear that simple reality in mind when thinking of ''cheap unlimited electricity''

    Like any other energy source, electricity is useless until it is put to work--ie you have to use it to make things move---just as oil is useless until it is burned/converted so that energy can be released from it

    irrespective of source---the notion of ''cheap electricity'' keeps going round and round---as if unlimited electricity is going to solve our looming problems---if we achieved endless cheap electricity, we still have to make to machines to utilise that electricity.

    Cheap electricity will not "MAKE" a lightbulb, or insulate wire, or extract food from the earth -or most of the million other things that fossil fuel slaves do for us.

    And all those people in poverty in Africa and Asia up to 2050 will be demanding the ''good things'' of the civilised west, but by then the oil that provided them will be gone

    All we will be able to offer will be ''cheap electricity''...meaning their standard of living (and ours) will plunge even lower than it is now.

    best of luck with that deal

    1. Norman,

      I generally agree with your analyses of our predicament, but I think you missed something here. With enough cheap electricity we can indeed do just about anything, including making oil out of carbon sucked out of the atmosphere (together with some hydrogen from water).

      With unlimited clean energy fresh water can be extracted from the sea, all food could be grown in skyscrapers, ore concentrations would make no difference-just add more energy to the extraction process, and just about any current terrestrial resource problem can be solved.

      Of course, unlimited very cheap energy is unlikely; capital costs come with every technology and it will be hard to beat the low cost of drilling small holes in the ground and pumping out oil by the millions of barrels a day, but should we ever discover the equivalent of those Star Trek dilithium crystals, a lot of changes could happen rapidly. Energy makes everything happen; with enough of it almost anything is possible.

  7. Dear Prof, the Science Technology and Society Studies (STS) literature shows that the success of certain technologies does not depend on their efficiency, sustainability or convenience but on their alignment with specific societal interests. Nuclear Fusion is compatible with an authoritative form of capitalism. The same that sustains nuclear fission plants. It's not about cheaper renewable energy, it's about what kind of society a certain technology enables and what futures it disables. I love this blog, but I think your arguments would be much sharper if you consider this power-related aspects of technological development. STS literature is full of good insights

  8. Può anche darsi che, dal buco nero del progetto ITER studiato per succhiare menti e risorse, scaturisca qualcosa di buono per la società, ma se così fosse sarà solo per caso e per errore. Basta immaginare dove saremmo ora se si fosse investito queste risorse sulle rinnovabili, ma anche una piccola parte delle armi per difendere e sostenere il petroldollaro. Ciao

    1. My negative observations concern the sole scientifically legitimate, presently investigated, line of research in fusion. I am not advocating to cancel all research in fusion, I think that academic, mostly theoretical, research would still be a sensible thing to finance. What's not is the construction of hugely expensive pieces of electromechanical equipment (ITER is the largest single "science" experiment in the world by cost) bound to slow down the progress of new, still unknown, ideas rather than advancing the very long term prospect of the exploitation of fusion power.

  9. Question for the writer: is this a scam?

    1. There are scams among private initiatives in this field, I’ll write about them soon in this blog in detail. The short answer about the scammers is that it depends on whom you are talking about, in the same organization there are people who know, people who don’t and people who are not sure of how things work even if all have a vested interest in the enterprise.

  10. Quick question for Dr Cima: is there any chance at all that fusion could be used to directly produce electricity? (Nuclear to date has been a matter of vast steam kettles to spin turbines. Fast breeders (remember them?) required torrential liquid sodium metal to shift the heat from the dense core!)

    This post triggered a memory from a decade ago when discussion of energy futures seemed immediately relevant (spike in the price of oil). I had a conversation with an 'eminent' biologist (FRS) whose research bent was toward biotech. He saw fusion research as a necessary fail-safe to avoid inadequate substitutes for fossil fuel and what he called 'lifeboat technologies'. I would agree with him about the likely inadequacy of substitutes if BAU is the aim. His belief in fusion however seems fantasy.

    I note co-incidentally that while some look forward to ‘electrification’ of society and while for example in the UK the proportion of ‘renewables’ in power generation has increased from 10% to 23% since 2012, this increase has been accompanied by a steady year-by-year decline in total use of electricity. Six years is too soon to see a trend, but ... increasingly, 'Waiting for Breakthrough' seems like an exercise in breath-holding.


    1. In principle yes, TAE out of Irvine aims to do that for example. They lightly say that reaction charged products will produce electricity through a not better identified reverse cyclotron effect.
      Their scheme is based on a very marginally exoenergetic reaction, the p-B11 reaction, fission rather than fusion, the proton splits the boron nucleus into alphas.
      Maybe their mysterious reverse cyclotron works but the more essential energy producing scheme seems very unlikely to end well. Their real aim is at listing with NASDAQ and run.

    2. Thanks for that pep. I just looked up TAE on Wikipedia; founded 1998; private funding.
      Quotes: “As of 2014, TAE is said to have more than 150 employees and raised over $150 million,] far more than any other private fusion power research company or the vast majority of federally-funded [US] government laboratory and university fusion programs”
      “As of July 2017, the company reported that it had raised more than $500 million in backing.[7] In November 2017, the company was admitted to a United States Department of Energy's Innovative and Novel Computational Impact on Theory and Experiment program…
      “Main financing has come from Goldman Sachs and venture capitalists such as Microsoft co-founder Paul Allen's Vulcan Inc., Rockefeller's Venrock, Richard Kramlich's New Enterprise Associates, the Government of Russia, through the joint-stock company Rusnano, invested in Tri Alpha Energy in October 2012, and Anatoly Chubais, Rusnano CEO, became a board member.

      Hmm… interesting line-up… same as my old FRS contact who seems to have pinned his faith on ‘technology’, much as did T. Blair PM when challenged about future energy problems in UK.

    3. Phil, TAE from the technical point of view seems to me to be among the least likely to obtain anything useful. They picked the hardest reaction of all, only a factor of 10 or so energy gain where you have to stuff all inefficiencies of the process to get something out. Plus lots of other details which are hard to explain here but are very substantial.
      The main one is that the process they are counting on is too rare compared to others in their energy range.
      Proton-Boron colliding beam fusion reactor - Vernon Wong, B. N. Breizman, and J. W. Van Dam, University of Texas at Austin
      They have been around for twenty years now with no progress to show, they have changed their reactor model substantially over the years and they are now repurposing the company towards cancer treatment
      They were thinking of making gigawatts and now they find out they are making microwatts?
      It feels like propaganda to keep the investors happy.
      Piketty is right, too much money in the wrong hands.
      I am waiting for Michel Moritz to write another article on this favorite theme of his:
      "The subprime ‘unicorns’ that do not look a billion dollars" - FT oct16 2015

  11. The United States is the only large economy that has consistently reduced its Carbon Intensity for the last seven years, in spite of withdrawing from the Paris accords. All the other countries talk a good line, but keep increasing their CO2 emissions. How is this possible?

    The main reason is, as Dr. Cima mentions in his "Bottom Line", that coal is rapidly being replaced by natural gas for electricity generation. The Shale-Gas revolution has changed everything, driven by the technologies of horizontal drilling and fracking (totally misunderstood by most people), and is delivering a real solution independent of political posturing.

    Natural gas is essentially Methane (CH4) which is 80% Hydrogen and the cleanest-burning fuel available. People worldwide use it to cook their food. It's the closest thing to a "Hydrogen Economy" we will likely ever get. When used in the most advanced dual-cycle co-generation systems (gas-turbine followed by steam turbine using waste heat from the gas-turbine) is now achieving commercial energy efficiencies greater than 60% with more improvements possible. This technology will be essential in a world of more wind and solar generation as base-load power for night-time and no-wind conditions.

    Battery storage on a massive scale is unlikely for the next 40 - 50 years because of the cost and scarcity of raw materials, without a super breakthrough in the electro-chemistry. Remember that we burn millions of tons of hydrocarbons daily, and a battery releases energy by oxidizing (essentially "burning") an alkali metal like Lithium, and then recharges by chemically reducing the metal again. Thus, a large battery capable of storing one days-worth of electricity would weigh tens of millions of tons!!!

    Best regards,

    Paul Sinclair

    1. Is methane better? Really not!
      Although it is claimed that the energy use of methane is far more favorable from the climatic point of view than coal, its climatic effect is on the contrary higher. A study of Robert W. Howart of Cornell University, a study of Robert H. W. Howart of Cornell University, has been releasing 3.6-9.9% of methane into the atmosphere, and with other effects (aerosols), methane obtained by HF is 20% more harmful to climate than coal-fired power plants.
      It has been found that over the first 20 years, the greenhouse effect of methane is much stronger to capture 84 to 87 times more heat than carbon dioxide, and in the first 100 years, the impact of 34 to 36 will be stronger than that due to the corresponding amount of CO2. Even relatively small leaks have a great impact on the climate.

  12. Molecular weight of methane is 16, 4 from hydrogen, 12 from carbon -- that's 25% hydrogen, not 80%.
    Better than other hydrocarbons for CO2 emission, but not by a lot....

    1. 80% of the atoms in CH4 are hydrogen, but as you point out only 25% of the molecular weight. More important than either, for equal weights, CH4 produces 52% more energy than just carbon when they are oxidized. That's because even though hydrogen is very light (just 1/12th the weight of carbon), it's per atom combustion enthalpy is 73% that of carbon.

  13. Wind and photovoltaic should certainly be used when appropriate, but I do not think they will fulfill the energy demand on the large scale, because they are very diluted and require large extensions, with a high impact on the environment. Nuclear energy has an unbeatable advantage over any other source. Due to the conversion of mass into energy, it is very concentrated. A standard nuclear power station produces as much power as 100 km2 of solar panels or 5000 wind mills, whose impact on the landscape one can easily imagine. Therefore, if we do not like nuclear fission, we’d better work for developing nuclear fusion and make it work, although timescales are in the order of a few decades. It could have been faster if more resources and less politics had been put into it. Still, it remains the ultimate solution for the energy needs of the growing population and for preserving our planet. In the mean time, we need to do our best with available CO2 free technologies.

    1. Dear Paola, thank you for your comments.
      The experience of fission teaches you how things work in the real world: fission produces less radioactive waste, costs less than a foreseeable fusion reactor and works! but only countries with nuclear weapons still invest in fission reactors. Most of the world doesn’t, while renewables now account for a third of the electricity production in many countries.
      My criticism towards fusion covers the ITER line (among the serious contenders).
      The tokamak line is not a few decades from applications, it’s a century away and in europe is the single most financed technological initiative (it’s not science, no hope for a generic scientific fallout from fusion,
      I think researchers should go back to the drawing board and rethink from scratch.
      New ideas could pop up which are viable but the tokamak line is a fraud. There is no fuel to fuel it, it’s a bigger deal to recycle than an equivalent fission reactor, just to mention two obvious drawbacks. It’s not me saying it, it’s a whole country of scientists, see for example what the guy in chief of the us operations was saying in 2012., .
      I think that 20 year old statements by Sessler, LBNL, e Stix, PPPL, about unresolved ITER issues are still perfectly valid: “the negative impact on future research that would rebound from a mechanical or physics failure in this single device.” and that “the step is too large and the overall concept, for all its attractiveness, is both premature and overambitious with respect to current knowledge.”
      It’s difficult to be objective from the inside.
      The fusion community in Italy for example is so intellectually compromised that nobody seems to object to the recent fusion initiatives of our main state energy companies, ENEL and ENI, fallen pray to obvious scams.



Ugo Bardi is a member of the Club of Rome, faculty member of the University of Florence, and the author of "Extracted" (Chelsea Green 2014), "The Seneca Effect" (Springer 2017), and Before the Collapse (Springer 2019)