Category Archives: energy science

Admiral’s comments on fission hold for fusion 70 years later

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Last month the US Energy Secretary, Jennifer Granholm announced a successful experiment at the Lawrence Livermore National Laboratory in which 192 lasers were used to pump 2.05 mega Joules of energy into a capsule heating its contents to 100 million degrees Centigrade causing fusion of hydrogen nuclei and the release of 3.15 mega Joules of energy.  An apparent gain of 1.1 mega Joules until you take account of the 300 mega Joules consumed by the 192 lasers.  The reaction in the media to this fusion energy experiment and the difficulties associated with building a practical fusion power plant, such as the Spherical Tokamak Energy Production (STEP) project in the UK (see ‘Celebrating engineering success‘ on November 11th, 2022) reminded me of a well-known memorandum penned by Admiral Rickover in 1953.  Rickover was first tasked, as a Captain, to look at atomic power in May 1946 not long after first human-made self-sustaining nuclear chain reaction was initiated in Chicago Pile #1 during an experiment led by Enrico Fermi in 1942.  He went on to become Admiral Rickover who directed the US Navy’s nuclear propulsion programme and the Nautilus, the first nuclear-powered submarine was launched in 1954.  With thanks to a regular reader of this blog who sent me a copy of the memo and apologies to Admiral Rickover, here is his memorandum edited to apply to fusion energy:

Important decisions about the future of fusion energy must frequently be made by people who do not necessarily have an intimate knowledge of the technical aspects of fusion.  These people are, nonetheless, interested in what a fusion power plant will do, how much it will cost, how long it will take to build and how long and how well it will operate.  When they attempt to learn these things, they become aware the confusion existing in the field of fusion energy.  There appears to be unresolved conflict on almost every issue that arises.

I believe that the confusion stems from a failure to distinguish between the academic and the practical.  These apparent conflicts can usually be explained only when the various aspects of the issue are resolved into their academic and practical components. To aid in this resolution, it is possible to define in a general way those characteristics which distinguish one from the other.

An academic fusion reactor almost always has the following basic characteristics: (1) It is simple. (2) It is small.  (3) It is cheap. (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose . (7) The reactor is in the study phase.  It is not being built now.  On the other hand, a practical fusion reactor can be distinguished by the following characteristics: (1) It is being built now.  (2) It is behind schedule. (3) It is requiring an immense amount of development on apparently trivial items. (4) It is very expensive. (5) It takes a long time to build because of the engineering development problems. (6) It is large. (7) It is complicated.

The tools of the academic-reactor designer are a piece of paper and a pencil with an eraser. If a mistake is made, it can always be erased and changed.  If a mistake is made, it can always be erased and changed.  If the practical-reactor designer errs, they wear the mistake around their neck; it cannot be erased.  Everyone can see it. 

The academic-reactor designer is a dilettante.  They have not had to assume any real responsibility in connection with their projects.  They are free to luxuriate in elegant ideas, the practical shortcomings of which can be relegated to the category of ‘mere technical details’.  The practical-reactor designer must live with these same technical details.  Although recalcitrant and awkward, they must be solved and cannot be put off until tomorrow.  Their solutions require people, time and money.

Unfortunately for those who must make far-reaching decisions without the benefit of an intimate knowledge of fusion technology and unfortunately for the interested public, it is much easier to get the academic side of an issue than the practical side. For the large part those involved with academic fusion reactors have more inclination and time to present their ideas in reports and orally to those who will listen.  Since they are innocently unaware of the real and hidden difficulties of their plans, they speak with great facility and confidence.  Those involved with practical fusion reactors, humbled by their experiences, speak less and worry more.

Yet it is incumbent on those in high places to make wise decisions, and it is reasonable and important that the public be correctly informed.  It is consequently incumbent on all of us to state the facts as forth-rightly as possible.  Although it is probably impossible to have fusion technology ideas labelled as ‘practical’ or ‘academic’ by the authors, it is worthwhile both authors and the audience to bear in mind this distinction and to be guided thereby.

Image: The target chamber of LLNL’s National Ignition Facility, where 192 laser beams delivered more than 2 million joules of ultraviolet energy to a tiny fuel pellet to create fusion ignition on Dec. 5, 2022 from https://www.llnl.gov/news/national-ignition-facility-achieves-fusion-ignition

Storm in a computer

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Decorative painting of a stormy seascapeAs part of my undergraduate course on thermodynamics [see ‘Change in focus’ on October 5th, 2022) and in my MOOC on Thermodynamics in Everyday Life [See ‘Engaging learners on-line‘ on May 25th, 2016], I used to ask students to read Chapter 1 ‘The Storm in the Computer’ from Philosophy and Simulation: The Emergence of Synthetic Reason by Manuel Delanda.  It is a mind-stretching read and I recommended that students read it at least twice in order to appreciate its messages.  To support their learning, I provided them with a précis of the chapter that is reproduced below in a slightly modified form.

At the start of the chapter, the simplest emergent properties, such as the temperature and pressure of a body of water in a container, are discussed [see ‘Emergent properties’ on September 16th, 2015].  These properties are described as emergent because they are not the property of a single component of the system, that is individual water molecules but are features of the system as a whole.  They arise from an objective averaging process for the billions of molecules of water in the container.  The discussion is extended to two bodies of water, one hot and one cold brought into contact within one another.  An average temperature will emerge with a redistribution of molecules to create a less ordered state.  The spontaneous flow of energy, as temperature differences cancel themselves, is identified as an important driver or capability, especially when the hot body is continually refreshed by a fire, for instance.  Engineers harness energy gradients or differences and the resultant energy flow to do useful work, for instance in turbines.

However, Delanda does not deviate to discuss how engineers exploit energy gradients.  Instead he identifies the spontaneous flow of molecules, as they self-organise across an energy gradient, as the driver of circulatory flows in the oceans and atmosphere, known as convection cells.  Five to eight convections cells can merge in the atmosphere to form a thunderstorm.  In thunderstorms, when the rising water vapour becomes rain, the phase transition from vapour to liquid releases latent heat or energy that helps sustain the storm system.  At the same time, gradients in electrical charge between the upper and lower sections of the storm generate lightening.

Delanda highlights that emergent properties can be established by elucidating the mechanisms that produce them at one scale and these emergent properties can become the components of a phenomenon at a much larger scale.  This allows scientists and engineers to construct models that take for granted the existence of emergent properties at one scale to explain behaviour at another, which is called ‘mechanism-independence’.  For example, it is unnecessary to model molecular movement to predict heat transfer.  These ideas allow simulations to replicate behaviour at the system level without the need for high-fidelity representations at all scales.  The art of modelling is the ability to decide what changes do, and what changes do not, make a difference, i.e., what to include and exclude.

Source:

Manuel Delanda Philosophy and Simulation: The Emergence of Synthetic Reason, Continuum, London, 2011.

Image: Painting by Sarah Evans owned by the author.

Energy transformations

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I mentioned a couple of weeks ago that I am teaching thermodynamics at the moment [see ‘Conversations about engineering over dinner and a haircut‘ on February 16th, 2022].  I am using a blended approach [see ‘ Blended learning environments‘ on November 14th, 2018] to deliver the module to more than 300 first year undergraduate students with one hour in the lecture theatre each week while the students follow the components of the MOOC I developed some years ago [see ‘Free: Energy! Thermodynamics in Everyday Life‘ on November 11th, 2015, and ‘Engaging learners online‘ on May 25th, 2016].  I have found that first year undergraduates are reluctant to participate in the online discussions that are part of the MOOC and so last year I asked them to discuss each topic in small groups with their academic tutor.  I got some very positive feedback from tutors who had interesting and stimulating discussions with their students.  We are repeating the process again this year.  The first discussion is about energy transformations: noting that energy is always conserved but constantly transformed into different forms, each student is asked to start from an energy state of their choice and to trace the transformations backwards until they can go no further.  In the lecture preceding the discussion with their tutor I provide some examples for starting states, including breakfast cereal, a pole vaulter in mid-jump and a bullet train.  I also describe the series of transformations from the Big Bang to tectonic plate movement: after the initial expansion caused by the Big Bang, the universe cooled sufficiently to allow the formation of sub-atomic particles followed by atoms of hydrogen and some helium and lithium that gravity caused to coalesce into clouds which became the early stars, or solar nebula.  A crust formed on the solar nebula which broke away to form planets.  Our planet has a molten core with temperatures varying from 4,400 to 6000 degrees Celsius, compared to around 5,500 degrees on the surface of the sun.  The temperature variation in the Earth’s core cause thermal currents which drive the movement of tectonic plates and so on [see ‘The hills are shadows, and they flow from form to form, and nothing stands‘, on February 9th, 2022].  Most chains of energy transformation lead backwards to the sun and forwards to dissipation of energy into some unusable form which we might call ‘entropy’ [see ‘Life-time battle‘ on January 30th, 2013].

Conversations about engineering over dinner and a haircut

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For decorative purposes: colour contour map of a face mask produced using fringe projectionRecently, over dinner, someone I had just met asked me what type of engineering I do. I always find this a difficult question to answer because I am sure that they are just being polite and do not want to hear any technical details but I find it hard to give an interesting answer without diving into details. Earlier the same day I had given a lecture on thermodynamics to about 300 undergraduate students so I told my inquisitor about this experience and explained that thermodynamics was the science of energy and its transformation into different forms. Then, I muttered something about being interested in making and using measurements to ensure that computational models of aircraft and nuclear power stations are reliable and the conversation quickly moved on. A week or so earlier, I was having my hair cut when the barber asked me a similar question about what I did and I told him that I was a professor of engineering which led to a conversation about robots. We speculated about whether we would ever lose our jobs to robots and decided that we were both fairly secure against that threat. There is a high degree of creativity in both of our roles – while I always ask for the same haircut, my hair is in a different state every time I visit the barbers’ and I leave looking slightly different every time. I don’t think that I would like the uniformity that a row of robots in the barbers’ shop might produce. And, then there is the conversation during the haircut. A robot would need to pass the Turing test, i.e., to exhibit intelligent behaviour indistinguishable from a human, which no computer has yet achieved or is likely to do so in our lifetime, at least not a cost that would allow them to replace barbers. The same holds for professors – the shift to delivering lectures online during the pandemic might have made some professors worry that their jobs were at risk as recorded lectures replaced live performances; however, student feedback tells us that students have a strong preference for on-campus teaching and the high turnout for my thermodynamics lectures supports that conclusion.

Footnotes:

For a new website I was asked to describe my research interests in about 25 words and used the following: ‘the acquisition of information-rich measurement data and its use to develop digital representations of complex systems in the aerospace, biological and energy sectors’.  Fine for a website but not dinner conversation! 

There have been some attempts to build a robot that cut your hair, for example see this video. 

Image shows a colour contour map describing the shape of a facemask produced using fringe projection which could be used as part of the vision system for a robotic barber.  For more information on fringe projection see: Ortiz, M. H., & Patterson, E. A. (2005). Location and shape measurement using a portable fringe projection system. Experimental mechanics, 45(3), 197-204 or watch this video from the INDUCE project that was active from 1998 to 2001.