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Electric aircraft? It’s happening, in a small way

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the Ampaire 337

I no longer write on my solutionsok blog, as it’s just easier for a lazy person like me to maintain the one site, but as a result I’ve not been writing so much about solutions per se, so I’ll try to a bit more of that. The always entertaining and informative Fully Charged show on YouTube provides plenty of material about new developments in renewable energy, especially re transport, and in a recent episode, host Robert Llewelyn had a bit to say about electric planes, which I’d like to follow up on.

Everyone knows that plane travel has been on the up and up haha for decades, and you may have heard that these planes use up a lot of fossil fuel and produce lots of nasty emissions. According to the Australian government’s Department of Infrastructure and Many Other Things (DIMOT – don’t look it up) Australia’a civil aviation sector contributed 22 million tonnes of CO2-equivalent emissions in 2016. That’s of course a meaningless number but safe to say it’s dwarfed by the emissions of the major aviation countries. I assume the term ‘C02-equivalent’ means other greenhouse gases converted into equivalent-impacting amounts of CO2. For aircraft this includes water vapour, hydrocarbons, carbon monoxide, nitrogen oxides, lead and other atmosphere-affecting nasties. More innovative and less polluting engine designs have failed to halt the steady rise of emissions due to increased air travel worldwide, and there’s no end in sight. It’s really the only emissions sector for which there is no obvious solution – unlike other sectors which are largely blocked by vested interests.

So, while few people at present see electric aircraft as the big fix, enterprising engineers are making steady improvements and trying for major breakthroughs with an eye to the hopefully not-too-distant future. Just a couple of days ago, as reported on the nicely-named Good News Network, the largest-ever hybrid-electric aircraft (it looks rather small), the Ampaire 337, took flight from Camarillo airport in California (of course). The normally twin-engine plane was retrofitted with an electric motor working in concert with the remaining fuel engine to create a ‘parallel hybrid’, which significantly reduces emissions. After this successful test run, there will be multiple weekly flights over the next few months, and then, if all goes well, commercial short-haul flights are planned for Hawaii.

Of course, here in Australia, where electric cars are seen by power-brokers as some kind of futuristic horror set to destroy our way of life, there’s no obvious appetite for even wierder flying things, but our time will come – or perhaps we should all give up and invade western Europe or California. Meanwhile, Fully Charged are saying ‘there’s no shortage of aircraft companies around the world [including Rolls Royce] developing electric aircraft’, as well as converting light aircraft to electric (the Ampaire 337 mentioned above is actually a converted Cessna 337). A Canadian airline, Harbour Air, is converting 3 dozen seaplanes to electric motors, with first passengers flights expected by late 2021. These will only be capable of short flights in the region of British Columbia – range, which is connected to battery weight, being perhaps the biggest problem for electric aircraft to overcome. Again according to Fully Charged, there are over 100 electric aircraft development programs going on worldwide at present, and we should see some results in terms of short-haul flights in five years. Perfect for Europe, but also not out of the question for Adelaide to Melbourne or Port Lincoln, Canberra to Sydney and so on. Norway has a plan to use electric aircraft for all its domestic passenger flights in the not-too-distant future.

A name dropped on Fully Charged, Roei Ganzarski, seems worth following up. He says ‘By 2025, 1000 miles in an electric plane is going to be easily done. I’m not saying 5000 miles, but 1000 miles, easily.’ Ganzarski is currently the CEO of magniX, an ‘electric propulsion technology company’, based in Seattle. His company made the motors for the Ampaire 337, I think.

It should be pointed out that UAVs (unmanned – or unpersonned? – aerial vehicles), aka drones, are small electric aircraft, so the principle of electric flight is well established. It’s also worth noting that electricity doesn’t have to come from batteries, though they’re the most likely way forward. Solar cells, for example, can directly convert sunlight into electricity, and in 2015/16, using two alternating pilots, Solar Impulse 2 became the first fixed-wing, piloted, solar-powered aircraft to circumnavigate the globe. Fuel cells, particularly using hydrogen, are another option.

At the moment, though, hybrid power is all the go, and the focus is on light aircraft and short-haul flight. General aviation is still a long way off because, according to this Wikipedia article, ‘the specific energy of electricity storage is still 2% of aviation fuel’. As to what that means, I have very little idea, but this steal from a Vox piece on the topic helps to clarify:

The key limitation for aircraft is the energy density of its fuel: When space and weight are at a premium, you want to cram as much energy into as small a space as possible. Right now, some of the best lithium-ion batteries have a specific energy of 250 watt-hours per kilogram, which has already proved viable in cars. But to compete on air routes up to 600 nautical miles in a Boeing 737- or Airbus A320-size airliner, Schäfer estimated that a battery would need to have a specific energy of 800 watt-hours per kilogram. Jet fuel, by comparison, has a specific energy of 11,890 watt-hours per kilogram.

So, specific energy is essentially related to energy density, and I know that getting batteries to be as energy-dense as possible is the holy grail of researchers. So, until that ten-fold or 100-fold improvement in energy density is achieved by the battery of batteriologists beavering away at the big plane problem, we should at least push for light aircraft and short-haul flights to go completely electric asap. Ausgov, do us proud.

Written by stewart henderson

June 12, 2019 at 9:47 am

towards James Clerk Maxwell 3 – Benjamin Franklin and Coulomb’s Law

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Coulomb’s law – attraction and repulsion

Canto: So we’ve been looking at electricity and magnetism historically, as researchers, scientists, thinkers, experimenters and so on have managed to piece these processes together and combine them into the one thing, electromagnetism, culminating in J C Maxwell’s equations…

Jacinta: Or going beyond those equations into the implications. But of course we’re novices regarding the science and maths of it all, so we should recommend that real students of this stuff should go to the Khan academy lectures, or Matt Anderson’s lectures for the real expert low-down. As will we. But we need to point out, if only to ourselves, that what we’re trying to get our heads around is really fundamental stuff about existence. Light, which is obviously fundamental to our existence, is an electromagnetic wave. So, think magnetism, think electricity, and think light.

Canto: Right, so we’re going back to the eighteenth century, and whatever happens after Hauksbee and Polinière.

Jacinta: Well, scientists – or shall we say physical scientists, the predecessors of modern physicists – were much influenced throughout the eighteenth century by Newton, in particular his inverse square law of gravity:

F=G{\frac {m_{1}m_{2}}{r^{2}}}\

Newton saw gravity as a force (F), and formulated the theory that this force acted between any two objects (m1 and m2 – indicating their masses) in a direct line between their respective centres of mass (r being the length of that line, or the distance between those centres of mass). This force is directly proportional to the product of the two masses and inversely proportional to the distance. As to G, the gravitational constant, that’s something I don’t get, as yet. Anyway, the success of Newton’s theory, especially the central insight that a force diminishes, in a precise way, with distance, affected the thinking of a number of early physical scientists. Could a similar theory, or law (they didn’t think in terms of theory then) apply to electrical forces? Among those who suspected as much were the mathematician Daniel Bernoulli, who made major contributions to fluid dynamics and probability, and Alessandro Volta, who worked on electrical capacitance and storage, the earliest batteries.

Canto: And Joseph Priestley actually proposed an inverse square law for electricity, but didn’t work out the details. Franz Aepinus and Benjamin Franklin were also important 18th century figures in trying to nut out how this force worked. All of this post-Newtonian activity was putting physical science on a more rigorous and mathematical footing. But before we get to Coulomb and his law, what was a Leyden Jar?

Jacinta: Leyden jars were the first capacitors. They were made of glass. This takes us back to the days of Matthias Bose earlier in the 18th century, and even back to Hauksbee. Bose, a professor of natural philosophy at the University of Wittenberg, worked with and improved Hauksbee’s revolving glass-globe machine to experiment with static electricity. He added a metal ‘prime conductor’ which accumulated a higher level of static charge, and gave spectacular public demonstrations of the sparks he created, using them to set alcohol alight and to create ‘beatification’ effects on a woman wearing a metal helmet. All great japes, but it promoted interest in electricity on the continent. The trick with alcohol inspired another experimenter, Jurgen von Kleist, to invent his Leyden jar, named for Kleist’s university. It was a glass container filled with alcohol (or water) into which was suspended a metal rod or wire, connected to a prime conductor. The fluid collected a great deal of electric charge, which turned out to be very shocking to anyone who touched the metal rod. Later Leyden jars used metal foil instead of liquid. These early capacitors could store many thousands of volts of electricity.

Canto: At this time, in the mid-eighteenth century, nobody was thinking much about a use for electricity, though I suppose the powerful shocks experienced by the tinkerers with Leyden jars might’ve been light-bulb moments, so to speak.

Jacinta: Well, take Ben Franklin. He wasn’t of course the first to notice that electrostatic sparks were like lightning, but he was possibly the first to conduct experiments to prove the connection. And of course he knew the power of lightning, how it could burn down houses. Franklin invented the lightning rod – his proudest invention – to minimise this damage.

Canto: They’re made of metal aren’t they? How do they work? How did Franklin know they would work?

Jacinta: Although the details weren’t well understood, it was known in Franklin’s time that some materials, particularly metals (copper and aluminium are among the best), were conductors of electricity, while others, such as glass, were insulators. He speculated that a pointed metal rod, fixed on top of buildings, would provide a focal point for the electrical charge in the clouds. As he wrote: “The electrical fire would, I think, be drawn out of a cloud silently, before it could come near enough to strike….” He also had at least an inkling of what we now call ‘grounding’, as per this quote about the design, which should use “upright Rods of Iron, made sharp as a Needle and gilt to prevent Rusting, and from the Foot of those Rods a Wire down the outside of the Building into the Ground”. He was also, apparently the inventor of the terms negative and positive for different kinds of charge.

Canto: There are different kinds of charge? I didn’t know that.

Jacinta: Well you know of course that a molecule is positively charged if it has more protons than electrons, and vice versa for negative charge, but this molecular understanding came much later. In the eighteenth century electricity was generally considered in terms of the flow of a fluid. Franklin posited that objects with an excess of fluid (though he called it ‘electrical fire’) were positively charged, and those with a deficit were negatively charged. And those terms have stuck.

Canto: As have other other electrical terms first used by Franklin, such as battery, conductor, charge and discharge.

Jacinta: So let’s move on to Charles-Augustin De Coulomb (1736-1806), who was of course one of many scientists and engineers of the late eighteenth century who were progressing our understanding and application of electricity, but the most important one in leading to the theories of Maxwell. Coulomb was both brilliant and rich, at least initially, so that he was afforded the best education available, particularly in mathematics…

Canto: Let me write down Coulomb’s Law before you go on, because of its interesting similarity to Newton’s inverse-square gravity law. It even has one of those mysterious ‘constants’:

{\displaystyle F=k_{e}{\frac {q_{1}q_{2}}{r^{2}}},}

where F is the electrostatic force, the qs are particular magnitudes of charges, and r is the distance between those charges.

Jacinta: Yes, the Coulomb constant, ke, or k, is a constant of proportionality, as is the gravitational constant. Hopefully we’ll get to that. Coulomb had a varied, peripatetic existence, including a period of wise retirement to his country estate during the French revolution. Much of his work involved applied engineering and mechanics, but in the 1780s he wrote a number of breakthrough papers, including three ‘reports on electricity and magnetism’. He was interested in the effect that distance might have on electrostatic force or charge, but it’s interesting that these papers placed electricity and magnetism together. His experiments led him to conclude that an inverse square law applied to both.

Canto: I imagine that these constants required a lot of experimentation and calculation to work out?

Jacinta: This is where I really get lost, but I don’t think Coulomb worked out the constant of proportionality, he simply found by experimentation that there was a general law, which he more or less stated as follows:

The magnitude of the electrostatic force of attraction or repulsion between two point charges is directly proportional to the product of the magnitudes of charges and inversely proportional to the square of the distance between them.
The force is along the straight line joining them. If the two charges have the same sign, the electrostatic force between them is repulsive; if they have different signs, the force between them is attractive.

It seems the constants of proportionality are just about units of measurement, which of course were different in the days of Coulomb and Newton. So it’s just about measuring stuff in modern SI units using these laws. It’s about conventions used in everyday engineering, basically. I think.

Canto: Equations like these have scalar and vector forms. What does that mean?

Jacinta: Basically, vector quantities have both magnitude and direction, while scalar quantities have magnitude only. The usual example is speed v velocity. Velocity has magnitude and direction, speed only has magnitude. Or more generally, a scalar quantity has only one ‘dimension’ or feature to it in an equation – say, mass, or temperature. A vector quantity has more than one.

Canto: So are we ready to tackle Maxwell now?

Jacinta: Hell, no. We have a long way to go, with names like Gauss, Cavendish and Faraday to hopefully help us along the path to semi-enlightenment. And I think we need to pursue a few of these excellent online courses before we go much further.

References

Khan academy physics (160 lectures)

Matt Anderson physics (191 lectures)

https://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation

https://www.britannica.com/technology/Leyden-jar

http://www.americaslibrary.gov/aa/franklinb/aa_franklinb_electric_1.html

http://www.revolutionary-war-and-beyond.com/benjamin-franklin-and-electricity-letters.html

https://en.wikipedia.org/wiki/Coulomb_constant

https://www.britannica.com/biography/Charles-Augustin-de-Coulomb

https://www.britannica.com/science/Coulombs-law

https://en.wikipedia.org/wiki/Coulomb%27s_law

Written by stewart henderson

May 18, 2019 at 6:04 pm

Towards James Clerk Maxwell 2 – Francis Hauksbee’s experiments

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an electrostatic generator – one of Hauksbee’s many ingenious experimental devices

Canto: So we’ve witnessed electricity since we’ve had the wit to witness, in lightning. And through our attempts to understand and harness those scary bursts of energy we’ve transformed our world.

Jacinta: We’ve written about lightning before, but the info we presented there was accumulated over centuries. Now we’re going to travel back to the early years of the Royal Society in England, the early 1700s, a mere 300 years ago, to reflect on the first experiments with electricity – remembering that there was no electric power and light in those days, that gods were in the air and much was mysterious.

Canto: Electricity from the start was much sexier, and scarier, than magnetism – lightning very very frightning was the most obvious physical manifestation, and its power was easily recognised. It could kill at a stroke, while magnetism seemed all about metals getting stuck together, and needles pointing north. Interesting, but hardly earth-shattering.

Jacinta: Lightning was all about gigantic sparks shattering the sky, and the ancients, who spent so much of their time in darkness, must have seen other, less impressive and dangerous sparks, the sparks of static electricity, and wondered.

Canto: In the recent BBC documentary The story of electricity, narrator Jim Al-Khalili begins by describing Francis Hauksbee‘s experiments with static electricity and electroluminescence in the early 1700s, which dazzled visitors to the Royal Society. These were the first properly documented experiments with the mysterious force, and a collection of his papers describing these experiments was widely read by the 18th century cognoscenti – including Joe Priestley and Ben Franklin. He employed the newly-invented air pump (simply a pump for pushing out air, as in a common bike pump), popularised in England by Robert Hooke some decades before. Hauksbee made his own improvements, enabling the pump to create a vacuum.

Jacinta: Yes Hauksbee was a more interesting figure than The story of electricity presents. He didn’t ‘lose interest’ but worked on his experiments and reflected on them until his final illness in 1713 – and I’m thinking that illness, since he was only in his late forties – may have been due to mercury poisoning. Hauksbee was ‘lower class’ so few details of his life are documented. However, in these experiments he wasn’t thinking so much of electricity as of ‘attractive forces’. Also as an experimenter who must always have seen himself as an underling (in his book he mentions his ‘want of a learned education’), he doubtless felt obliged to follow the guidance of his Royal Society ‘master’, Newton, which took him into different fields of research….

Canto: The term ‘electricity’ was possibly not in common use then? You’re right, though, about Hauksbee, who rose from obscurity to become a member of the Royal Society, probably under the auspices of Newton. In late 1705, as a result of some spectacular effects displayed to the Society he became intrigued by ‘mercurial phosphorus’. The fact that mercury, in a vacuum, glowed when shaken, had already been noted by Jean Picard, a 17th century French astronomer, and the Swiss mathematician Johann Bernoulli.

Jacinta: And this has to do with electricity?

Canto: We shall see. Hauksbee wanted to work out the conditions under which this mercurial light was produced. He found that the more air in the container, the weaker the light. Also the light’s intensity depended on the movement of the mercury. He concluded that the friction of the mercury against the glass was the major cause. But was it only mercury that had this property, and was it only glass that brought it out? He experimented with other materials, finding a means of rubbing them together in a section of his air pump, Amber rubbed with wool produced a light, brightened in the absence of air. By contrast metal on flint only produced sparks when air was present. Remember, oxygen wasn’t known about at the time. In late 1705 Hauksbee presented one of his most spectacular experiments for the Society. Ingenious instrument-maker that he was, he created a glass globe, from which air could be pumped in and out, on a rotating spindle. The spinning globe came into contact with woollen cloth, and the contact created a weird purple light inside the evacuated globe, which reduced as air was let in. It was a fantastic mystery.

Jacinta: I’m hoping you can solve it.

Canto: Great expectations indeed. He experimented further, and found that when he pressed his own hands against a spinning evacuated globe, the same bright purple glow was produced, which again faded when air was let in to the globe.

Jacinta: Okay, what Hauksbee was exploring in these experiments are what we now call triboelectric effects. I remember playing around with this in schooldays by rubbing a plastic pen along the sleeve of my jersey and watching the fibres stand on end as the pen passed, and hearing the prickling sound of static electricity. The pen was then capable of lifting scraps of paper from the desk, for a time. But I didn’t see any purple lights and I’m not sure how the presence or absence of air relates to it all.

Canto: Yes, triboelectricity is about the exchange of electric charge between different materials – the build-up and discharge of electrical energy. It seems that some materials have a more or less positive charge and some have a more or less negative or opposite charge (because positive and negative are really arbitrary terms, the key point is their relation to each other), and we know that like charges repel and opposite charges attract.

Jacinta: You’ve brought up the word ‘charge’ here, and I’m wondering if that’s just an arbitrary word too – like degree of positive charge just means degree of being repulsed by its opposite, negative charge. In other words, different materials are attracted to or repulsed by each other to varying degrees under various conditions, and that degree or ‘amount’ of attraction or repulsion is referred to as ‘charge’. So ‘charge’ is a relational term…

Canto: Ummm. Maybe. In any case, if you take these different materials down to the atomic level, and I’m not sure how you take plastic and wool down to that level – I mean I know plastic is a petrochemical product, but wool, which I’ve just looked up, has a very complex chemistry – but the fact that the plastic pen, after some rubbing, pulls the fibres of your woollen sleeve towards it is because there’s an attractive force operating between opposite charges. In fact there’s a movement of electrons between the materials, from the wool to the plastic. This electron transfer leaves those woollen fibres with a net positive charge, which is attracted to the now negatively charged plastic due to the electron flow. I think.

Jacinta: Mmm. None of this was understood in the early eighteenth century, obviously. But before we go back there, we’ll stay with this concept of charge, which is nowadays calculated as a fundamental or base unit, based on the electron or its opposite, charge-wise, the proton. These elementary particles have the same but opposite charge, though they’re very different in mass (something which seems suspect to me). Anyway, taking things on trust, a unit of charge is ‘defined’ in standard macro terms as a coulomb, named for the 18th century French physicist Charles-Augustin de Coulomb. One coulomb equals approximately 6.24 x 1018 protons (or electrons). We’ll come back to this later, no doubt. Returning to Hauksbee’s experiments, he soon realised that it was the glass, not the mercury inside it, that was the agent of electrical effects. His experiments with glass globes were written down in great detail, a boon to later researchers.

Canto: Interestingly, I’ve discovered that, more or less exactly at the same time, one Pierre Polinière was conducting and presenting experiments on electroluminescence in Paris:

A closer examination of these experiments reveals not only that Polinière had personally presented them before the French Academy of Sciences, but that Polinière and Hauksbee, starting from a common interest in the ‘mercurial phosphor’, had conducted similar investigations and had in fact simultaneously announced their independent discoveries of the luminescence of evacuated glass containers.

Pierre Polinière, Francis Hauksbee and electroluminescence: a case of simultaneous discovery.
David Corson, 1968.

Jacinta: So we might finish by trying to explain our current understanding of electroluminescence (EL) and its applications. It’s a sort of combo of electricity and light, as you can imagine, or electrons and photons on the level of particles. For example, semiconductors emit light when subjected to a strong electric field or current….

Canto: Is that the basis of LED lighting?

Jacinta: Absolutely. Electrons in the semiconductor material recombine with electron holes, emitting energy in the form of photons. So it has taken us three centuries to really effectively harness the electroluminescent effects demonstrated by Hauksbee in the early days of the Royal Society.

Canto: What are electron holes? I’m thinking not ‘holes in electrons’ but holes left by electrons as they’re displaced in an electric current?

Jacinta: Yes, or almost. It’s like the lack of an electron where you might expect an electron to be. These holes where you might expect an electrically charged particle (an electron) to be, act like positively charged particles – a positron, say – and move through a lattice like an electron does. We could get into very complicated electronics here, if we had the wherewithal, but these holes are examples of quasiparticles, which mostly exist within solids. Fluid movement within solids (not apparently a contradiction in terms) is extremely complicated. Who would’ve thunk it? This movement of electrons and protons within solids is ‘regulated’ by Coulomb’s Law. Remember him? We’ll be getting to that law very soon, as it’s essential to the field of electromagnetism. And that’s our topic don’t forget.

towards James Clerk Maxwell: 1 – a bit about magnetism

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the terrell, or model globe, with which Gilbert conducted experiments

Canto: So what do you know about magnetism?

Jacinta: Well not a lot but I’m hoping to learn a lot. Some metals – but perhaps it’s only iron – appear to be attracted by other metals – or other bits of iron – so that they’re pulled together and are hard to pull apart, depending on the strength of the magnetism, which is apparently some kind of force. And I believe it’s related to electricity.

Canto: We shall learn more together. All this enquiry stems from a perhaps vague interest in James Clerk Maxwell, who famously connected electricity and magnetism in an equation, or a series of equations, or laws, with a great deal of mathematical sophistication, which I don’t have. Maxwell is hardly a household name in the way that Newton and Einstein are, but he’s undoubtedly revered among mathematical physicists. My own interest is twofold – I’d like to understand more about physics and maths in general, and – I’m Scottish, sort of. That is, I was born there and grew up among Scottish customs, though I’ve lived in Australia since I was five, and I always like to say that I haven’t a nationalist cell in my body. I’ve never waved a flag or sung any of those naff national anthems, and I have dual British/Australian citizenship only as a matter of convenience – and I suppose the more nations I could become a citizen of, the more convenient it would be. And yet. I’ve always felt ‘something extra’ in noting the Scottish contribution to the sciences and the life of the mind. James Hutton, Charles Lyell, James Watt, Adam Ferguson, David Hume and Adam Smith are names I’ve learned with a glimmer of unwonted or irrational pride over the years, though my knowledge of their achievements is in some cases very limited. And that limitation is perhaps most extreme in the case of Maxwell.

Jacinta: So we’ll get back to him later. There are good, easily available videos on all matters scientific these days, so I’ve looked at a few on magnetism, and have learned a few things. Magnetism apparently occurs when the atoms in a block of material are all aligned in the same direction, because atoms themselves are like tiny magnets, they’re polarised with a north and south pole, which I think has something to do with ionisation, maybe. Most materials have their atoms aligned in an infinity of orientations, with a net effect of no magnetism. Don’t quote me on that. The Earth itself is a gigantic magnet with a north and south pole. If it wasn’t, then the solar wind, which is a plasma of charged particles, would strip away the ozone that protects us from UV radiation. Because that field is sucked in at the poles, we see that plasma in the northern and southern latitudes, e.g. the northern lights. We now know that magnetism is essential to our existence – light itself is just a form of electromagnetic radiation (I think). But what we first learned about this stuff was pretty meagre. There were these rocks called lodestones, actually iron ore (magnetite), which attracted iron objects – swords and other tools of the iron age. What was this invisible force? It was named magnetism, after the region of Magnesia in what’s now modern Greece, where presumably lots of these lodestones were to be found. Early discoveries about magnetism showed that it could be useful in navigation…

Canto: But that wasn’t too early – there’s something of a gap between the discussions in Aristotle and Hippocrates and the 12th century realisation that a magnetic needle could be used for navigation. At least in Europe. The Chinese were well ahead in that regard. But I should stop here and say that if we’re going to arrive at Maxwell, it’s going to be a long, though undoubtedly fascinating road, with a few detours, and sometimes we might move ahead and turn back, and we’ll meet many brilliant characters along the way. And, who knows, we may never even arrive at Maxwell, and of course we shouldn’t assume that Maxwell is at the summit of all this.

Jacinta: So the first extant treatise on magnets was the Epistola de Magnete, by Petrus Peregrinus, aka Pete the Pilgrim, in 1269. It was described as a letter but it contained 13 chapters of weighty reading. The first 10 chapters apparently describe the laws of magnetism, a clear indication that such laws were already known. He describes magnetic induction, how magnetism can be induced in a piece of iron, such as a needle, by a lodestone. He writes about polarity, being the first to use the term ‘pole’ in this way – in writing at least. He noted that like poles repel and unlike poles attract, and he wrote of a south pole and a north pole. That’s to say, one end of a needle points north when given its head – for example when suspended in water. He also describes the ‘dry’ pivoted compass, which was clearly well in use by that time.

Canto: What he didn’t know was why a needle points north – actually magnetic north, which isn’t the same as the north pole – but close enough for most navigational purposes. He didn’t know that the Earth was a magnet.

Jacinta: On compass needles, there’s a neat essay online on how compasses are made. I’m not sure about how GPS is making compasses obsolete these days, but it’s a bit of a shame if it’s true…

Canto: So the next name, apart from the others, to associate with work on magnets was William Gilbert, who published De Magnete in 1600. This gathered together previous knowledge on the subject along with his own experimental work. One of the important things he noted, taken from the 1581 work The Newe Attractive, by Robert Norman, was magnetic inclination or dip, probably first noted by the Bavarian engineer and mathematician Georg Hartmann in the mid sixteenth century. This dip from the horizontal, either upward (steepest at the south pole) or downward (north pole) is a result of the Earth’s magnetic field, which doesn’t run parallel to the surface. Inspired by Norman’s work, Gilbert conducted experiments with a model Earth he made, concluding that the Earth was a magnet, and that its core, or centre, was made of iron…

Jacinta: Just how did he he work that out? Did he think that a bar magnet passed through the centre of the Earth from north to south pole?

Canto: I don’t think so, it’s probably more like he thought of Earth as a gigantic spherical lodestone with iron at its centre. It’s understandable that he would infer iron to be inside the Earth to make it magnetic, but he was the first to give a geocentric cause for the behaviour of compass needles – others had thought the attractive force was celestial. Interestingly, Gilbert was also a Copernican, in that he thought it absurd that the stars, which he believed to be vastly distant, revolved around the Earth. So he argued that the Earth turned, a view that got Galileo into so much trouble a few decades later.

Jacinta: Useful to be a Protestant in those times. Thank Dog for Henry VIII.

Canto: He also took an interest in what was later called electricity, though he didn’t consider it connected to magnetism. He built a versorium, the first electroscope, used to detect static electric charge. It was simply a metallic needle pivoted on a pedestal, like a compass needle but not magnetised. The needle would move towards a statically charged object, such as rubbed amber. In fact, Gilbert’s experiments strove to prove that static electricity was distinct from magnetism, which was an important development in early modern science.

Jacinta: I suppose we’re going to learn exactly what ‘static’ electricity is and how it fits in the over-all picture?

Canto: We shall try, though I shudder to think about what we’re embarking on here.

Jacinta: And I shudder to think about what cannot possibly be avoided – mathematics.

Canto: Well, yes, as we enter the 17th century, we’ll be encountering some great mathematical developments – with figures like Descartes, Pascal, Fermat, Liebniz and Newton all adding their weighty contributions to Galileo’s claim that nature is a book written in the language of mathematics.

Jacinta: Shit, I’m having a hard enough time trying to understand this stuff in English.

Canto: Hopefully it’ll be a great and rewarding adventure, and on the way we’ll learn about Coulomb’s inverse-square law, which is central to electrostatics. Meanwhile, it seems not much was added to our understanding of magnetism for a couple of hundred years, until Hans Ørsted’s more or less accidental discovery in 1819 that an electric current could create a magnetic field, by noting that a compass needle moved when placed near an electrified wire. Alessandro Volta had invented the voltaic pile, or battery, twenty years earlier, leading to a pile of electrical experiments in subsequent years.

Jacinta: But we’ll have to go back to the eighteenth century or beyond to trace developments in electricity before Ørsted’s finding brought the two fields together. And maybe we’ll look at the mathematics of
Charles-Augustin de Coulomb and others in the process. Let’s face it, we can’t progress towards Maxwell without doing so.

Canto: Tragic but true.

Written by stewart henderson

March 31, 2019 at 1:37 pm

technomagic – the tellingbone

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weirdly wired – the first telephone

The telephone remains the acme of electrical marvels. No other thing does so much with so little energy. No other thing is more enswathed in the unknown.

Herbert Casson ‘The history of the telephone”, 1910. Quoted in “The Information”, J Gleick

I recently had a conversation with someone of my generation about the technology of our childhoods, and how magical they seemed to us. So let me start with the motor car, or auto-mobile. Our first family car was a Hillman Minx, which was bought in maybe 1964 or so, not too long after we arrived in Australia. The model probably dated from the early or mid-fifties – we certainly weren’t wealthy enough to buy a brand new car. But that didn’t make it any less magical. How was it that you could turn a key and bring an engine to life, and with a bit of footwork and handiwork get the beast to move backward and forward and get its engine to putter or roar? I hadn’t the foggiest.

Next in the mid-sixties came the television box, fired by electrickery. Somehow, due to wires and signals, we could see a more or less fuzzy image of grey figures from faraway, giving us news of Britain and the World Cup, and shows from the USA like Hopalong Cassidy and the Cisco Kid, all made from faraway – even one day from the moon – for our entertainment and enlightenment. Wires and signals, I mean, WTF?

Next we became the first people in the street to have our own tellingbone (or that’s what we proudly told ourselves, actually we had no idea). So people would ring us from the other side of town and then talk to us as if they were standing right next to us!! It was crazy-making, yet people seemed generally to remain as sane as they had been. I would lie in bed trying to work it out. So someone would dial a number, and more or less instantaneously a ringing sound would come out of the phone miles and miles away, and a person there would pick up this bone-shaped piece of plastic with holes in it, and they would talk into one end and listen through the other end, and they could hear this person on the ‘end of the line’ miles away far better than they could hear someone else talking in the next room, all thanks, we were informed, to those wires and signals again.

So, forward to adulthood. One of the most informative books I’ve read in recent years is titled, appropriately enough, The Information, by James Gleick. It’s a history of information processing and communication from tribal drumming to the latest algorithms, and inter alia it tells the story of how the telephone became one of the most rapidly universalised forms of information transfer in human history in the period 1870-1900, approximately. And of course it didn’t come into existence out of nowhere. It replaced the telegraph, the first electrical telecommunications system, itself only a few decades old. Previous to this there were many experiments and developments in the field by the likes of Alessandro Volta, Johann Schweigger and Pavel Schilling. Studying electricity and its potential was the hottest of scientific activities throughout the 19th century, especially the first half.

The telegraph, though, was a transmission-reception system run by experts, making it very unlike the telephone. Gleick puts it thus:

The telegraph demanded literacy; the telephone embraced orality. A message sent by telegraph had first to be written, encoded and tapped out by a trained intermediary. To employ the telephone, one just talked. A child could use it.

Nevertheless the system of poles and wires, the harnessing of electricity, and the concepts of signal and noise (both abstract and exasperatingly practical) had all been dealt with to varying degrees of success well before the telephone came along.

So now let’s get into the basic mechanics. When we talk into a phone we produce patterned sound waves, a form of mechanical energy. Behind the phone’s mouthpiece is a diaphragm of thin metal. It vibrates at various speeds according to the patterned waves striking it. The diaphragm is attached to a microphone, which in the early phones consisted simply of carbon grains in a container attached to an electric current, which were compressed to varying degrees in response to the waves vibrating the diaphragm, modulating the current. That current flows through copper wires to a box outside your home which connects with other wires and cables in a huge telecommunications system.

Of course the miracle to us, or to me, is how a sound wave signal, moving presumably more or less at the speed of sound, and distinctive for every human (not to mention dogs, birds etc), can be converted to an electrical signal, moving presumably at some substantial fraction of the speed of light, then at the end of its journey be converted back to a mechanical signal with such perfect fidelity that you can hear the unmistakeable tones of your grandmother at the other end of the line in real time. The use of terms such as analogue and digitising don’t quite work for me, especially when combined with the word ‘simply’, which is often used. In any case, the process is commonplace enough, and has been used in radio, in recorded music and so forth.

It all bears some relation to the work of the greatest physical theorist of the 19th century, James Clerk Maxwell, who recognised and provided precise relationships between electrical impulses, magnetism and light, bringing the new and future technologies together, to be amplitude-modified by engineers who needed to understand the technicalities of input, output, feedback, multiplexing, and signal preservation. But as the possibilities of the new technology expanded, so did technological expertise, and switchboards and networks became increasingly complex. They eventually required a numbering system to keep track of users and connections, and telephone directories were born, only to grow in size and number, costing acres of forestry, until in the 21st century they didn’t. I won’t go into the development of mobile and smartphones here, those little black boxes of mystery which I might one day try to peer inside, but I think I’ve had enough armchair demystifying of the technomagical for one day.

Yet something I didn’t think of as a child was that the telephone was no more technomagical than just speaking and listening to the person beside you. To speak, to make words and sentences out of sounds, first requires a sound-maker (a voice-box, to employ a criminally simplistic term), then a complex set of sound-shapers (the tongue, the soft and hard palates, the teeth and lips) into those words and sentences. Once they leave the speaker’s lips they make waves in the air – complex and variable waves which carry to the hearer’s tympanum, stimulating nerves to send electrical impulses to the auditory cortex. This thinking to speaking to listening to comprehending process is so mundane to us as to breed indifference, but no AI process comes close to matching it.

References

The information, James Gleick, 2011

https://electronics.howstuffworks.com/telephone1.htm

https://www.antiquetelephonehistory.com/telworks.php

https://www.thoughtco.com/how-a-telephone-works-1992551

Written by stewart henderson

March 1, 2019 at 4:31 pm

reflections on base load, dispatchable energy and SA’s current situation

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just to restate the point that SA’s power outages are due to transmission/distribution lines being damaged, nothing to do with renewable energy

Canto: So now we’re going to explore base load. What I think it means is reliable, always available energy, usually from fossil fuel generators (coal oil gas), always on tap, to underpin all this soi-disant experimental energy from solar (but what about cloudy days, not to mention darkness, which is absence of light, which is waves of energy isn’t it?) and wind (which is obviously variable, from calm days to days so stormy that they might uproot wind turbines and send them flying into space, chopping up birds in the process).

Jacinta: Well we can’t think about base load without thinking about grids. Our favourite Wikipedia describes it as ‘the minimal level of demand on an electrical grid over a span of time’. So the idea is that you always need to cover that base, or you’ll be in trouble. And an electrical grid is a provision of electrical service to a particular community, be it a suburb, a city or a state. 

Canto: Right, I think, and what I like about Wikipedia is the way it sticks it to the back-facing thinkers, for whom base load always means provision from traditional providers (coal oil gas). 

Jacinta: Yes, let’s rub it in by quoting Wikipedia on this. 

When the cheapest power was from large coal and nuclear plants which could not be turned up or down quickly, they were used to generate baseload, since it is constant, and they were called “baseload plants.” Large standby reserves were needed in case of sudden failure of one of these large plants. Unvarying power plants are no longer always the cheapest way to meet baseload. The grid now includes many wind turbines which have such low marginal costs that they can bid lower prices than coal or nuclear, so they can provide some of the baseload when the wind blows. Using wind turbines in areas with varying wind conditions, and supplementing them with solar in the day time, dispatchable generation and storage, handles the intermittency of individual wind sources.

Canto: So the times are a-changing with respect to costs and supply, especially as costs to the environment of fossil fuel supplies are at last being factored in, at least in some parts of the world. But let’s keep trying to clarify terms. What about dispatchable generation, and how does it relate to base load?

Jacinta: Well, intermittent power sources, such as wind and solar, are not dispatchable – unless there’s a way to store that energy. Some renewable energy sources, such as geothermal and biomass, are dispatchable, but they don’t figure too much in the mix at present. The key is in the word – these sources are able to be dispatched on demand, and have adjustable output which can be regulated in one way or another. But some sources are easier, and cheaper, to switch on and off than others. It’s much about timing; older generation coal-fired plants can take many hours to ‘fire up’, so their dispatchability, especially in times of crisis, is questionable. Hydroelectric and gas plants can respond much more quickly, and batteries, as we’ve seen, can respond in microseconds in times of crisis, providing a short-term fix until other sources come on stream. Of course, this takes us into the field of storage, which is a whole other can of – what’s the opposite of worms?

Canto: So this question of base load, this covering of ‘minimal’ but presumably essential level of demand, can be a problem for a national grid, but you can break that grid up presumably, going ‘off grid’, which I’m guessing means going off the national grid and either being totally independent as a household or creating a micro-grid consisting of some small community…

Jacinta: Yes and this would be the kind of ‘disruptive economy’ that causes nightmares for some governments, especially conservative ones, not to mention energy providers and retailers. But leaving aside micro-grids for now, this issue of dispatchability can be dealt with in a flexible way without relying on fossil fuels. Energy storage has proven value, perhaps especially with smaller grids or micro-grids, for example in maintaining flow for a particular enterprise. On the larger scale, I suppose the Snowy 2 hydro project will be a big boon? 

Canto: 2000 megawatts of energy generation and 175 hours of storage says the online ‘brochure’. But the Renew Economy folks, who always talk about ‘so-called’ base load, are skeptical. They point to the enormous cost of the project, which could escalate, due, among other things, to the difficulties of tunnelling through rock of uncertain quality. They feel that government reports have over-hyped the project and significantly downplayed the value of alternatives, such as battery electric storage systems, which are modular and flexible rather than this massive one-off project which may be rendered irrelevant once completed. 

Jacinta: So let’s relate this to the South Australian situation. We’re part of the national grid, or the National Energy Market (NEM), which covers SA and the eastern states. This includes generators, transformers (converting low voltage to high voltage for transport, and then converting back to low voltage for distribution), long distance transmission lines and shorter distance distribution lines. So that’s wholesale stuff, and it’s a market because different companies are involved in producing and maintaining the system – the grid, if you like.

Canto: I’ve heard it’s the world’s largest grid, in terms of area covered.

Jacinta: I don’t think so, but it depends on what metric you use. Anyway, it’s pretty big. South Australia has been criticised by the federal government for somehow harming the market with its renewables push. Also, it was claimed at least a year ago that SA had the highest electricity prices in the world. This may have been an exaggeration, but why are costs so high here? There are green levies on our bill, but I think they’re optional. Also, the electricity system was privatised in the late 90s, so the government has lost control of pricing. High-voltage transmission lines are owned by ElectraNet, part-owned by the Chinese government. The lower voltage distribution lines are operated by SA Power Networks, majority-owned by a Hong Kong company, and then there are the various private retailers. It’s hard to work out, amongst all this, why prices are so high here, but the closure of the Northern coal-fired power station in Port Augusta, which was relatively low cost and stable, meant a greater reliance on more expensive gas. Wind and solar have greater penetration into the SA network than elsewhere, but there’s still the intermittency problem. Various projects currently in the pipeline will hopefully provide more stability in the future, including a somewhat controversial interconnector between SA and NSW. Then there’s the retail side of things. Some retailers are also wholesalers. For instance AGL supplies 48% of the state’s retail customers and controls 42% of generation capacity. All in all, there’s a lack of competition, with only three companies competing for the retail market, which is a problem for pricing. At the same time, if competitors can be lured into the market, rather than being discouraged by monopoly behaviour, the high current prices should act as an incentive. 

Canto: Are you suggesting that retailers are profiteering from our high prices?

Jacinta: I don’t know about that, but before the Tesla battery came online the major gas generators – who are also retailers – were using their monopoly power to engage in price gouging at times of scarcity, to a degree that was truly incredible – more so in that it was entirely legal according to the ACCC and other market regulators. The whole sorry story is told here . So I’m hoping that’s now behind us, though I’m sure the executives of these companies will have earned fat bonuses for exploiting the situation while they could. 

Canto: So prices to consumers in SA have peaked and are now going down?

Jacinta: Well the National Energy Market has suffered increased costs for the past couple of years, mainly due to the increased wholesale price of gas, on which SA is heavily reliant. It’s hard to get reliable current data on this online, but as of April this year the east coast gas prices were on their way down, but these prices fluctuate for all sorts of reasons. Of course the gas lobby contends that increased supply – more gas exploration etc – will solve the problem, while others want to go in the opposite direction and cut gas out of the South Australian market as much as possible. That’s unlikely to happen though, in the foreseeable, so we’re likely to be hostage to fluctuating gas prices, and a fair degree of monopoly pricing, for some time to come. 


Written by stewart henderson

November 26, 2018 at 11:37 am

the continuing story of South Australia’s energy solutions

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In a very smart pre-election move, our state Premier Jay Weatherill has announced that there’s a trial under way to install Tesla batteries with solar panels on over 1,000 SA Housing Trust homes. The ultimate, rather ambitious aim, is to roll this out to 50,000 SA homes, thus creating a 250MW power plant, in essence. And not to be outdone, the opposition has engaged in a bit of commendable me-tooism, with a similar plan, actually announced last October. This in spite of the conservative Feds deriding SA labor’s ‘reckless experiments’ in renewables.

Initially the plan would be offered to public housing properties – which interests me, as a person who’s just left a solarised housing association property for one without solar. I’m in community housing, a subset of public housing. Such a ‘virtual’ power plant will, I think, make consumers more aware of energy resources and consumption. It’s a bit like owning your own bit of land instead of renting it. And it will also bring down electricity prices for those consumers.

This is a really important and exciting development, adding to and in many ways eclipsing other recently announced developments in SA, as written about previously. It will be, for a time at least, the world’s biggest virtual power plant, lending further stability to the grid. It’s also a welcome break for public housing tenants, among the most affected by rising power bills (though we’ll have to wait and see if prices do actually come down as a result of all this activity).

And the announcements and plans keep coming, with another big battery – our fourth – to be constructed in the mid-north, near Snowtown. The 21MW/26MWh battery will be built alongside a 44MW solar farm in the area (next to the big wind farm).

 

South Australia’s wind farms

Now, as someone not hugely well-versed in the renewable energy field and the energy market in general, I rely on various websites, journalists and pundits to keep me honest, and to help me make sense of weird websites such as this one, the apparent aim of which is to reveal all climate scientists as delusionary or fraudsters and all renewable energy as damaging or wasteful. Should they (these websites) be tackled or ignored? As a person concerned about the best use of energy, I think probably the latter. Anyway, one journalist always worth following is Giles Parkinson, who writes for Renew Economy, inter alia. In this article, Parkinson focuses on FCAS (frequency control and ancillary services), a set of network services overseen by AEMO, the Australian Energy Market Operator. According to Parkinson and other experts, the provision of these services has been a massive revenue source for an Australian ‘gas cartel’, which has been rorting the system at the expense of consumers, to the tune of many thousands of dollars. Enter the big Tesla battery , officially known as the Hornsdale Power Reserve (HPR), and the situation has changed drastically, to the benefit of all:

Rather than jumping up to prices of around $11,500 and $14,000/MW, the bidding of the Tesla big battery – and, in a major new development, the adjoining Hornsdale wind farm – helped (after an initial spike) to keep them at around $270/MW.

This saved several million dollars in FCAS charges (which are paid by other generators and big energy users) in a single day.

And that’s not the only impact. According to state government’s advisor, Frontier Economics, the average price of FCAS fell by around 75 per cent in December from the same month the previous year. Market players are delighted, and consumers should be too, because they will ultimately benefit. (Parkinson)

As experts are pointing out, the HPR is largely misconceived as an emergency stop-gap supplier for the whole state. It has other, more significant uses, which are proving invaluable. Its effect on FCAS, for example, and its ultra-ultra-quick responses to outages at major coal-fired generators outside of the state, and ‘its smoothing of wind output and trading in the wholesale market’. The key to its success, apparently, is its speed of effect – the ability to switch on or off in an instant.

Parkinson’s latest article is about another SA govt announcement – Australia’s first renewable-hydrogen electrolyser plant at Port Lincoln.

I’ve no idea what that means, but I’m about to find out – a little bit. I do know that once-hyped hydrogen hasn’t been receiving so much support lately as a fuel – though I don’t even understand how it works as a fuel. Anyway, this plant will be ten times bigger than one planned for the ACT as part of its push to have its electricity provided entirely by renewables. It’s called ‘green hydrogen’, and the set-up will include a 10MW hydrogen-fired gas turbine (the world’s largest) driven by local solar and wind power, and a 5MW hydrogen fuel cell. Parkinson doesn’t describe the underlying technology, so I’ll have a go.

It’s all about electrolysis, the production of hydrogen from H2O by the introduction of an electric current. Much of what follows comes from a 2015 puff piece of sorts from the German company Siemens. It argues, like many, that there’s no universal solution for electrical storage, and, like maybe not so many, that large-scale storage can only be addressed by pumped hydro, compressed air (CAES) and chemical storage media such as hydrogen and methane. Then it proceeds to pour cold water on hydro – ‘the potential to extend its current capacity is very limited’ – and on CAES ‘ – ‘has limitations on operational flexibility and capacity. I know nothing about CAES, but they’re probably right about hydro. Here’s their illustration of the process they have in mind, from generation to application.

Clearly the author of this document is being highly optimistic about the role of hydrogen in end-use applications. Don’t see too many hydrogen cars in the offing, though the Port Lincoln facility, it’s hoped, will produce hydrogen ‘that can be used to power fuel cell vehicles, make ammonia, generate electricity in a turbine or fuel cell, supply industry, or to export around the world’.

So how does electrolysis (of water) actually work? The answer, of course, is this:

2 H2O(l) → 2 H2(g) + O2(g); E0 = +1.229 V

Need I say more? On the right of the equation, E0 = +1.229 V, which basically means it takes 1.23 volts to split water. As shown above, Siemens is using PEM (Proton Exchange Membrane, or Polymer Electrolyte Membrane) electrolysis, though alkaline water electrolysis is another effective method. Not sure which which method is being used here.

In any case, it seems to be an approved and robust technology, and it will add to the variety of ‘disruptive’ and innovative plans and processes that are creating more regionalised networks throughout the state. And it gives us all incentives to learn more about how energy can be produced, stored and utilised.

Written by stewart henderson

February 14, 2018 at 4:50 pm