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what is electricity? part 9 – the first battery

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from Wikipedia, etc

Canto: So, going back to the eighteenth century, now. The exploration of electricity was becoming thoroughly fashionable. Lightning was an obviously powerful force that scientists of the day were looking to tame and harness. Most of these modern histories begin with Franklin, but what, or who, turned him on to the subject?

Jacinta: Well of course knowledge and influences developed slowly in the eighteenth century and before. I’ve already spoken of William Gilbert’s De Magnete, written some 150 years before Franklin’s work. Gilbert posited that the Earth itself was essentially a gigantic magnet, with an iron core, which was pretty clever in 1600. He studied static electricity, using amber, and called its effects an electric force, the first modern usage. He was one of the first modern experimentalists, undervalued in his own time, most unfortunately by Francis Bacon, who contributed so much to the development of new scientific methods.

Canto: The 1600s were important in Britain, of course, the period of their Scientific Enlightenment, but one of the most intriguing and brilliant experimenters upon electrostatics in that century was the German polymath Otto von Guericke. His work on vacuums and static electricity in the mid 17th century found its way to England and inspired Robert Boyle to experiment in these fields. But no great breakthroughs occurred, at least for electricity, and no real attempts were made to mathematise electrical concepts until the eighteenth and nineteenth centuries.

Jacinta: Yes, we won’t dwell for too long on these pioneers (famous last words), but J L Heilbron’s 1979 book Electricity in the 17th and 18th centuries: a study of early modern physics, much of which is available online, should guide us towards the advances made by Volta and the nineteenth century mathematisers, notably Maxwell.

Canto: Yes, Heilbron divides the physics of this period into three stages, the first, before 1700, was a relatively amateur, narrow form of neo-Aristotelian systemising (pace Gilbert), and the second involved new discoveries and experiments treated without systematic quantising, which gave way to a more modern, mathematical third stage leading to new discoveries and inventions, such as the battery, just at the end of the 18th century.

Jacinta: We’ve mentioned triboelectric effects in an earlier post. These were the first static effects, between all sorts of different materials, experimented with by scientific pioneers such as Newton and many others. The enormous variety of these effects were, and still are, difficult to quantise. Why was their attraction in some cases and repulsion in others? In fact, ACR, the attraction-contact-repulsion process, came gradually to be recognised, but with no understanding of atoms and particles, or elements in the modern sense, little sense could be made of it.

Canto: There were some attempts to characterise the phenomenon, which was considered a fluid in those early days. In 1733 the French chemist Charles DuFay, one of many electrical experimenters of the time, divided these fluids into two types, vitreous and resinous – the positive and negative forms of today, sort of. Perhaps he was trying to define an attracting and a repelling force.

Jacinta: Effluvia was in the air at that time… ‘particles of electrical matter, which effect attraction and repulsion either by direct impact or by mobilising the air’, to quote Heilbron. But I should mention here the work of Stephen Gray, one of those marvellous upwellers from the lower classes with great practical skills and an experimental spirit, who, like Newton, built his own telescope, with which he made discoveries about sunspots and other things. An obviously alert observer, he noted that electricity could be conducted over distances in various substances, while other substances, such as silk, damped down the effect, acting as insulators. These discoveries were of vital importance, but Gray is probably the most underrated and unrecognised of all the electrical pioneers.

Canto: With the ‘discovery’ of the Leyden jar in 1745 the idea of electricity as a fluid, or two fluids, was laid to rest. This instrument, the key components of which were a jar of glass with metal sheets attached to its inner and outer surfaces, and ‘a metal terminal projecting vertically through the jar lid to make contact with the inner foil’ (Wikipedia), was the first type of capacitor, though it took time for their storage capacity, and those of other devices, to be quantised. Today it’s understood that these early Leyden jars could be charged to as much as 60,000 volts.

Jacinta: Another important early device was called an electrophore, or electrophorus, first invented in 1762 and later improved by Alessandro Volta. These instruments, and the increasing realisation throughout the eighteenth century that this mysterious force, substance or capacity called electricity was a Big Thing, with enormous potential, kept interest in the phenomenon bubbling along.

Canto: An electrophore typically consists of a plastic plate, which won’t conduct electricity, connected to a metal conducting disc with an insulating handle. There are some useful demonstration videos of this, and I’m describing one. If you rub the plastic with some silk cloth, this will, as we now know, transfer electrons from the silk to the plastic, giving it a negative charge (the triboelectric effect). Placing the metal disc on the plastic will not enable too much transfer of electrons, or electron flow. It will in fact cause a polarisation in the disc, positively charging it on the side facing the plastic, and negatively charging it on its opposite side, due to like charges repelling, though this wasn’t known in Volta’s time.

Jacinta: The plastic plate, or sheet, has become a dielectric, I think, which is a pretty complicated concept, involving dielectric constants and relatively complicated mathematical formulae, but for our current purpose (and theirs in the 18th century) this electrophore was a useful demonstrator of static electricity. The metal plate was on balance neutral in charge, but in a sense magnetised, with a negative charge on its upper side, which could be grounded at a touch – causing a spark. Being replaced on the plastic, it could again have its charges separated, a cycle which could be endlessly repeated in theory, though not in practice – due ultimately to the second law of thermodynamics, perhaps.

Canto: So, the battery. It was a term coined by Franklin, giving a sense of overwhelming power, though what he created in connecting Leyden jars in an array was a capacitor.

Jacinta: In fact even one Leyden jar is a capacitor. So what he created was a battery of capacitors, though not quite a supercapacitor. I think.

Canto: Volta is famously supposed to have arrived, in a roundabout way, at the construction of an effective battery due to his dispute with a soon-to-be-former friend Louis Galvani (as described in part 4 of this series), and the dispute led him to further experiments. He came to realise that the reason Galvani’s dead frogs were ‘reanimated’ by electricity had to do with the wires being used, and the chemistry of the frogs.

Jacinta: And meanwhile this ‘reanimation’ business became popularised by Galvani’s nephew, Giovanni Aldini, among others, with popular displays and discussions which led to Mary Shelley’s Frankenstein. 

Canto: And meanwhile again, Volta experimented with different wires, including zinc and silver, and with moisture, because he noticed that wetness had an electrifying effect. He soon found that these wires of silver and zinc, connected in a series of water containers, increased the electric effect. Further experimentation with silver and zinc discs, separated by cardboard saturated in salt water, enhanced the effect – the more discs, the stronger the effect. And this effect was permanent (more or less). A battery in the modern sense.

Jacinta: In effect. So voltage is electric potential, as we keep saying. So it’s there even when the battery isn’t connected to anything, a storage device which provides electrical flow when connected. And that potential is measurable, as in a 1.5v battery. Current is the actual flow, which is often quite small, especially in Volta’s original pile, though he was able to build a potential, or voltage of up to 20v. The key to an effective battery, I think, is to get as much current per volt as possible. That’s current flowing steadily, reliably and safely over time. A typical lithium ion phone battery of  3.7 volts delivers between 100 and 400 milliamps of current, whereas Volta’s pile will get you not much more than 1/2 of a milliamp of steady flow. And by the way, why did salt enhance the electrical effect?

Canto: That has to do with with the ionisation of the salt, which when dissolved in water splits into positively charged sodium ions and negatively charged chlorine ions. Sending a current through the water will drive the chlorine ions to the positive terminal and the sodium ions to the negative terminal. This creates a bridge of ions, somehow.

Jacinta: Yeah, great explanation. And apparently one of the most interesting features of Volta’s weak battery, or voltaic pile, at the time was its use in separating H2O into hydrogen and oxygen. This new chemical power – electrolysis – particularly interested Humphrey Davy in England. He proceeded to create the largest battery of the age at the Royal Institution, using it to isolate a large number of elements for the first time, including sodium, calcium, potassium, magnesium, boron and strontium. That was in the first decade of the 19th century – and electricity was really coming of age.

References (just some)

https://books.google.com.au/books?id=UlTLRUn1sy8C&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false

How Volta Invented the First Battery Because He Was Jealous of Galvani’s Frog (video – Kathy loves physics)

https://sciencing.com/salt-water-can-conduct-electricity-5245694.html

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

 

Written by stewart henderson

January 22, 2022 at 7:18 am

what is electricity? part 2 – the mystery gets murkier

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Canto: So we were trying to comprehend early ideas about electricity as a fluid, which led Franklin to define two ‘states’ of the fluid, ‘negative’ for having a deficiency, and ‘positive’ for having an excess. He also called the negative state ‘resinous electricity’ and its opposite ‘vitreous electricity’. Presumably he thought the fluid was in a balanced state before these different elements started rubbing against each other.

Jacinta: And they were trying to regain this balanced state, which made the sparks fly?

Canto: Dunno, but let’s return to Britain, where Francis Hauksbee (1660-1713), a lab assistant to Isaac Newton, was being inventive with air pumps and pneumatic engines, decades before Franklin’s 1840s experiments.

Jacinta: I’d ask you what a pneumatic engine is, but I suppose that’d take us way off topic?

Canto: Probably. It apparently has something to do with compressed air, and some kind of energy derived from un-compressing it, or something. Anyway, air pumps were used to create vacuums, or relative vacuums. Apparently, Hauksbee, an ingenious instrument maker, noted that glass was a really good material for viewing experiments, and in 1705 he performed a remarkable experiment with one of his air pumps and that mercurial, and very dangerous element, mercury (though ‘elements’ in the modern sense, weren’t known or at least defined at the time).

Jacinta: I suppose elements wouldn’t have been defined until the atomic theory became a thing.

Canto: Anyway I’m betting that his experiments with mercury shortened Hauksbee’s poor life (he was accepted into the Royal Academy in 1703, just as Newton became its president with the aim of reinstating its grandeur, but he was given special ‘low class’ status). He’d created a version of Otto von Guericke’s electrical machine, made of glass, with air pumped out, and some mercury inside. He rubbed the sphere to create a charge, and the mercury glowed when he put his hand on it (the globe, not the mercury). Fantastical, but nobody knew what it meant, except that it could be used as a source of night-light, which actually happened, but much later.

Jacinta: But nobody had much idea about whys and wherefores at this time.

Canto: They presumably speculated. A similar phenomenon, in large, was St Elmo’s fire (he was the patron saint of sailors), a bluish glow around a sailing ship, or more recently, around an aircraft. We know now this is a form of plasma, the ionised state of matter. During thunderstorms the voltage differentials are greatest – it requires a particular differential for it to happen, and the shape of the body around which the light is seen is an important factor. Pointy objects create a more intense field (Franklin realized this). The violet-blue light is caused by the nitrogen and oxygen in the atmosphere.

Jacinta: Are you sure you know what you’re talking about?

Canto: I’m never certain about anything, that’s my vocation, or just my fate.

Jacinta: Pneumatic tyres are filled with compressed air, or gas. So that helps to understand what a pneumatic engine might be, maybe.

Canto: So Hauksbee had found a way to accumulate an electric charge, and in 1745, in Leyden, Holland, they found a way to store this charge – an instrument that came to be known as a Leyden jar. Let me quote from the scientific historian, Thomas Crump:

The so-called Leyden jar was simply a substantial glass chamber, with separate layers of metal foils on the inside and outside surfaces. The inside was charged by a metal chain connecting it to a charged body, which then lost its charge to the air.

And this was apparently the first capacitor. We’ve talked about capacitors and supercapacitors before, but of course we barely understand them. In any case this Leyden jar device allowed a lot of electrostatic potential to build up between the inner and outer surfaces – enough to kill small birds who came in contact. Nice.

Jacinta: Or were forced to come into contact. I know they tried it on monks too. Presumably they couldn’t find the nuns.

Canto: Anyway they now had some control over this electricity thing, even if they hadn’t a clue what it was. They had some idea as to how to create and release this electrical charge thingummy.

Jacinta: So now we come to Coulomb?

Canto: No, Alessandro Volta (1745-1827) first. I’m following Crump, for better or worse. But more importantly than people, it’s batteries we’re going to focus on now. And I’m not sure where to begin.

Jacinta: It was a term – battery I mean – first used by Franklin in 1749, but what he actually created were capacitors, devices that accumulated charge, until they were discharged. Batteries – I’m kind of guessing here – are devices that store charge more or less permanently, and can release charge in a controlled way, and be recharged in a controlled way.

Canto: And what is this thing called charge?

Jacinta: Well let’s continue to grope toward an understanding. So I’ll return to Franklin. He wrote a book, Experiments and observations on electricity, made at Philadelphia in America, published in 1751. His researches led him to believe that everything contained charge, positive and negative, but that they were almost always in equilibrium, a neutral state. Or the fluid, which could be ‘negativised’ or ‘positivised’ by friction, could be returned to balance by ‘discharging’ it.

Canto: And surely therein lay a mystery. How or why did this build-up of negativity or positivity get discharged? I just don’t understand it. Not just the discharge but the creation of the charge.

Jacinta: I suppose they – Franklin, Hauksbee and the rest – just made the observation and called it ‘charge’. From whence, ‘discharge’. Maybe you’re just overthinking it. They certainly didn’t know what was going on, they just noted this reliable cause-and-effect behaviour and sought to utilise it, and find out more about it. Anyway, keep on overthinking, it might be a good thing.

Canto: Okay, Franklin was exercised by the discharge side of things. He found that pointy objects – we now call them lightning conductors – were most effective at discharging this build-up of charge, and recreating neutrality, the safe, ‘natural’ condition. A great, practical solution for buildings. But he developed a theory of sorts, of zero-sum conservation of this thing called charge. Whatever was accumulated in, say, a Leyden jar, was restored on discharge, nothing gained and nothing lost. I think.

Jacinta: Well, here’s a quote from Crump’s book, which might unenlighten us further:

Franklin succeeded in giving Leyden jars both positive and negative charges, and showed that the force itself was stored in the glass of the jar with the charge being proportional to its surface area.

Canto: Yeah, that needs unpacking, if possible. The ‘force’ being stored, is that the charge? If so, why does he use different terms? Charge is either negative or positive, isn’t it? So he was able to give these jars either a negative or a positive charge/force, but not both at the same time, though it’s ambiguous in this quote.

Jacinta: What I think he’s saying is there’s this force, which we now call electricity, which can either be negatively or positively charged, and its strength will be proportional to the surface area of the glass jar. I don’t think he was giving the jar different charges at the same time, but how he knew that the charge was sometimes positive, sometimes negative, or what that even means, I’ve no idea.

Canto: Yes, I’m more confused than ever. Let’s try to understand Leyden jars a bit more. Apparently it was invented in 1745 by one Pieter van Musschenbroek as a ‘cheap and convenient source of electric sparks’. That’s from Britannica on electromagnetism. So, to be more precise about this first jar, it was a glass vial partially filled with water, which ‘contained a thick conducting wire capable of storing a substantial amount of charge’.

Jacinta: Presumably that ‘thick conducting wire’ corresponds to the ‘metal chain’ in Crump’s description. I don’t know what the water’s for.

Canto: And Britannica makes no mention of the ‘separate layers [how many???!!] on the inside and outside surfaces’.

Jacinta: Okay, here’s a simplified picture, which might help.

So, in this one there’s no water, but I’ve seen other pics that indicate a jar more than half-filled with water, so who fucking knows. Note that there’s one layer of tin foil on the outside and another on the inside. Note the metal rod passing through a cork into this evacuated jar, and then a wire, presumably of some kind of metal, connecting to the tin foil.

Canto: Is tin a good conductor?

Jacinta: Apparently so. Not as good as silver or copper, but better than lead. And please don’t ask me why some metals are better conductors than others. It’s so frustrating trying to learn from the internet, even when you know which sites to avoid. For example, take this statement on what I’d expect to be a reliable site:

Although Leyden Jars allowed the storage and dissipation of electricity, there were still issues present. One issue was the lack of energy from the charge. While it could only attract small objects like a bit of paper, that was all it could basically do. Also, it could only perform that function after the jar was charged, which also took lots of time.

And then this, from Britannica:

The Leyden jar revolutionized the study of electrostatics. Soon “electricians” were earning their living all over Europe demonstrating electricity with Leyden jars. Typically, they killed birds and animals with electric shock or sent charges through wires over rivers and lakes. In 1746 the abbé Jean-Antoine Nollet, a physicist who popularized science in France, discharged a Leyden jar in front of King Louis XV by sending current through a chain of 180 Royal Guards. In another demonstration, Nollet used wire made of iron to connect a row of Carthusian monks more than a kilometre long; when a Leyden jar was discharged, the white-robed monks reportedly leapt simultaneously into the air.

Canto: Hmmm. One of these descriptions is not like the other. Where’s Micky Faraday when you need him?

Jacinta: I can but do my best. Let’s get back to batteries, again. Franklin’s ‘battery’ was really a capacitor, as mentioned, a way of accumulating more electric charge, and temporarily storing it, until it was required for a sort of ‘big bang’ release, I think. You can do this with Leyden jars linked together:

The above ‘device’ was used for demonstration purposes back in the day. Franklin’s electrostatic machine, though, didn’t look anything like this. It was a mammoth device of cranks and pulleys, created with much help from his friends. The mechanisation was presumably for creating as great an accumulation of charge as possible. Crump writes that Franklin built a glass and lead battery consisting of eleven condensers connected in series – which is clearly not his electrostatic machine. And apparently it wasn’t a battery, either, at least not in the modern sense. And WTF is a condenser? Anyway, this confusion has gone on long enough. We’ll try to clear some of it up next time.

References

Thomas Crump, A brief history of science

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

https://en.wikipedia.org/wiki/St._Elmo%27s_fire

https://www.britannica.com/science/electromagnetism/Invention-of-the-Leyden-jar

https://www.bluesea.com/resources/108/Electrical_Conductivity_of_Materials

https://en.wikipedia.org/wiki/Franklin%27s_electrostatic_machine

 

Written by stewart henderson

December 6, 2021 at 10:57 pm

on fuel cells and electrolysers and other confusions

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Canto: So it seems the more you look towards future technologies, the more future technologies there are to look at. Funny that. Two future developments we want to focus on in these next few posts are the graphene aluminium ion batteries being researched and developed in Queensland for the world, and the whole field of green hydrogen technology, a topic we’ll start on today.

Jacinta: Yes and the two key terms which we’re hoping might enlighten us if we can get a handle on them are fuel cell and electrolyser.

Canto: But first, I’ve just watched a brief video, admittedly five years old, a lifetime it seems in nuevo-tech terms, in which Elon Musk, who I’ve generally considered a hero, describes hydrogen fuels as silly, and seems at the end to be lost for words in expressing his contempt for the technology.

Jacinta: Yes, and the video appears to have been unearthed recently because all the comments, mostly well-informed (as far as I can discern) are only months old, and contradict Musk’s claims. But let’s not dwell on that. What is a fuel cell?

Canto: Well, we’re looking at the possibility of fuel cell electric vehicles (FCEVs), which presumably will operate in direct competition with Tesla’s EVs. Interestingly, one of the claimed deficits of EVs is their long charging times, which the new graphene-aluminium ion technology should greatly reduce. If FCEVs become a thing, the ‘old’ battery driven things will become known as BEVs, even before the EV term has really caught on.. Anyway, fuel cells produce electricity. You don’t have to plug them in, according to BMW.com (which may have a bias towards hydrogen in terms of investment). However, they don’t really show how the hydrogen is produced, and their image, shown above, presents a hydrogen tank without explaining where the hydrogen comes from.

Jacinta: Yes, so here’s how BMW.com begins its explanation:

In fuel cell technology, a process known as reverse electrolysis takes place, in which hydrogen reacts with oxygen in the fuel cell. The hydrogen comes from one or more tanks built into the FCEV, while the oxygen comes from the ambient air. The only results of this reaction are electrical energy, heat and water, which is emitted through the exhaust as water vapor. So hydrogen-powered cars are locally emission-free…

Canto: Which explains nothing much so far. Hydrogen reacts with oxygen. How? By reverse electrolysis. What’s that? The name implies splitting by electricity (but in reverse?), but I’d like more detail.

Jacinta: Yeah we’ll have to go elsewhere for that. In the image above you see a battery pack, much smaller than those in EVs, and an electric engine or motor. The BMW site reckons that the generated electricity from the fuel cell can either flow directly to the electric motor, powering the vehicle, or it can go to the battery, called a ‘peak power battery’, which stores the energy until needed by the motor. Being constantly recharged by the fuel cell, it’s only a fraction of the size of an EV battery.

Canto: Okay, that’s the BMW design, but I want the science nitty-gritty. I’ve heard that fuel cells go back a long way.

Jacinta: Yes, and we may need several posts to get our heads around them. I’ll start with the English engineer Francis Thomas Bacon (illustriously named), who developed the first alkaline fuel cell, or hydrogen-oxygen fuel cell, also known as the Bacon fuel cell, in the 1930s. This type of fuel cell has been used by NASA since the sixties. But the Wikipedia article again skips some steps.

Canto: So alkaline is the opposite of acidic, sort of, and car batteries require acid, but I don’t know what the difference is, in electrical terms.

Jacinta: Hopefully all will be revealed. One basic thing I’ve learned is that a fuel cell requires a cathode, an anode (collectively, two electrodes) and an electrolyte. So let’s take this slowly. The cathode is the one from which the conventional current departs – CCD, cathode current departs. Conventional current is defined as the direction of the positive charge. In the case of hydrogen, that’s just protons. The electrons go in the opposite direction. The anode, which maybe I should’ve mentioned first, is the electrode through which a conventional current enters the fuel cell or device. Think ACID, anode current into device. Now, the cathode and anode must be made of particular materials, which presumably relate to the fuel you’re trying to split, or electrolyse.

Canto: Hmmm, I’m wondering if a fuel cell and an electrolytic cell are the same thing, or one is a subset of the other. Apparently not, according to Wikipedia.

For fuel cells and other galvanic cells, the anode is the negative terminal; for electrolytic cells (where electrolysis occurs), the anode is the positive terminal. Made from, with, or by water.

So, shit, what’s a galvanic cell and how does it differ from an electrolytic cell? From the above description, it sounds like an electrolytic cell (anode positive) is the opposite of a fuel/galvanic cell (anode negative). We need to know what electrolysis actually means – not to mention galvanisis. And I believe reverse electrolysis is a thing.

Jacinta: Shit indeed. So at least from the above we know that electrolysis always involves water. Or does it? Okay, a galvanic cell, also known as a voltaic cell (Luigi Galvani, Alessandro Volta) combines two metals and an electrolyte (in Galvani’s case, a frog’s leg). Galvani and others thought the frog, or some other creature, was necessary for the current – ‘animal electricity’ became a thing for a while. Volta showed that this was not the case, though there was much argy-bargy for a while. But enough easy history, we need to tackle tough science.

Canto: So I don’t know if the currently titled hydrogen fuel cells are correctly described as alkaline fuel cells, but there are some videos, such as one by Philip Russell, describing very simple hydrogen fuel cells, driving a small fan. Russell explains the process very carefully, and I’ll go through it myself for my understanding. He has a tiny blue fuel cell connected by two tubes to two glasses of water. In one glass, hydrogen will be collected from one side of the cell, and oxygen from the other side in the other glass. He connects the fuel cell to a small solar panel via two wires, one red one black. He says that ‘to the negative side [holding the black wire] I’m going to connect to the side [of the cell] that produces hydrogen and the positive side [red] I’m going to connect to the side that produces hydrogen’. And now I’m confused. Both sides will produce hydrogen? How? What does that even mean?

Jacinta: In DC circuitry, black is conventionally negative and red positive. The difference between AC and DC may have to be explored because I think it’s relevant to all this nuevo-tech. Now, considering that Russell plugged the wires into opposite sides of the cell and said twice ‘the side that produces hydrogen’, the logical conclusion is that he made a mistake, but I can’t be sure. After all, what does he want to produce other than hydrogen?

Canto: Actually he said that one of the glasses will be collecting oxygen, so clearly he should’ve said oxygen for one of those two sides. But which one? Let’s continue with the video. So he’s connected the solar panel to the cell and he says ‘now we can collect solar energy and turn it into hydrogen and oxygen’. So the mistake hypothesis seems right, and that might have to be clarified with other videos. We plan to look at about a hundred of them, because our skulls are thick. So Russell next takes us inside the fuel cell. The outside is of blue-tinted glass or plastic. Inside we see ‘a perforated metal sheet’ (at least on one side). Apparently this is a hydrogen flow field, which ‘allows the hydrogen gas to escape from the fuel cell’. This again makes little sense to me. How did the hydrogen get in there in the first place? Hopefully all will be explained – or not. Next to, or behind this flow field is an anode consisting of a palladium catalyst. And in a fuel cell, the anode is negative.

Jacinta: According to Britannica, palladium is a type of platinum metal which makes an excellent catalyst:

Because hydrogen passes rapidly through the metal at high temperatures, heated palladium tubes impervious to other gases function as semipermeable membranes and are used to pass hydrogen in and out of closed gas systems or for hydrogen purification.

Canto: Good, so between the two electrodes is our electrolyte, consisting of a polymer electrolyte membrane (PEM) which ‘allows the transfer of the hydrogen gas and hydrogen ions’. Again this isn’t particularly enlightening but we’ll explore it later. Next to the the electrolyte membrane is the cathode (positive), and then comes the oxygen flow field, ‘which allows the oxygen to come in and escape from the fuel cell’. Again unclear.

Jacinta: It’s a start, sort of. We’ll glean what we can from this little video and supplement it from other videos and info sites. So electricity is coming into the fuel cell which breaks down the water coming from the two glass jars. I’m confused, though, about the glass jars and the tubes leading to, or from, the fuel cell. They’re filled with water (which I’m presuming is highly purified) and they’re delivering water to either side of the fuel cell, via these tubes, which are attached, in each of the glasses, to something like a suction cup, which will, it seems, have something to do with gas coming from the fuel and being sent through the tube to the bottom of the glass jars – hydrogen along one tube, oxygen along the other. So the water is presumably being depleted from the jars and the two gasses are being collected at the bottom of the jars, to judge from the look of the setup. But how are these tubes able to deliver water one way and collect gas in the other direction at the same time?

Canto: Haha and we’re only halfway through this teeny video. And we next go to a diagram which again upsets our thinking, as it shows the anode as positive, whereas Wikipedia says the anode is negative in fuel cells. It seems we’re being stumped by nomenclature. What Philip Russell is demonstrating appears to be an electrolytic cell or an electrolyser, but it’s being called a fuel cell. A website from energy-gov, linked below, has a diagram of a fuel cell/electrolyser very similar to Russell’s. They call it an electrolyser. They’re conspiring to confuse us!

Illustration of a PEM electrolyzer

 

Jacinta: Anyway, Russell explains his thingummmy, and I quote: ‘We have, in the middle, this polymer electrolyte membrane [PEM] surrounded by the electrodes, and on either side, the anode and cathodes[!]. When we start, water enters through the anode, and here, when it reaches the cathode and anode [!] things start to happen. The water is broken down into hydrogen ions by the electrons in the battery, and this then produces oxygen gas. The hydrogen ions travel across/through the PEM where they are reacted with electrons and this forms hydrogen gas which escapes through to the cathode side of the fuel cell’.

Canto: Yes, clear as far as it goes. So this is electrolysis he’s talking about isn’t it? Is it really this simple? Probably not, in scaled up versions. Anyway, Russell finishes up by disconnecting his wires from the solar panel and connecting them to a small fan, which immediately starts to function. The fuel cell has reversed, according to Russell, and is producing electricity from H2 and O2. 

Jacinta: Yes, the way he presents it, it’s all very simple. But I don’t think so. We’ve scratched the surface of this technology, and informed ourselves in very small part, but there’s a long way to go. We need to struggle on, in our brave, heroic way.

 

References

https://www.bmw.com/en/innovation/how-hydrogen-fuel-cell-cars-work.html

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

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

https://www.britannica.com/science/palladium-chemical-element

https://www.energy.gov/eere/fuelcells/hydrogen-production-electrolysis

 

Written by stewart henderson

July 3, 2021 at 11:50 am

notes on the electrification of air travel

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stolen from NASA – hope I didn’t let the batt out of the bag

Air travel has become noticeably more popular over the past few decades – due largely to affordability. Even I can afford to catch a plane occasionally these days. And yet …

I realised something was out of kilter when I discovered that, in Europe, you can fly relatively cheaply from one major city to another by plane, whereas travelling by train costs more (sometimes much more) while being more efficient in terms of carbon emissions. So why is that, and what can be done about it?

Planes are generally more costly to run and, especially, to maintain than trains, and labour costs, too, are higher. Yet some of the larger airline companies are prepared to lose money on high-demand short-haul flights to maintain their profile, knowing they can gain on international flights. They can also be (or are) more flexible with their pricing, as this article points out, so that they can get bums on seats at suddenly slashed rates, filling their aircraft for each flight, unlike trains, which have basically operated under the same half-arsed system for over a century.

So, with the steady increase in domestic and international flights, and the lack of government oversight – e.g. taxation – of international airlines that transcend political borders, the carbon footprint of air flight (if that makes sense) is growing. A 2018 report on CO2 emissions stated that ‘using aviation industry values’ there was a 32% increase in aviation emissions in the previous five years. Which of course raises the question – how do we solve the problem of over-use of costly, environmentally-unfriendly jet fuel? The answer, of course, is electric propulsion. No? An electric motor is far simpler and easier to maintain than a jet engine (a turboprop engine has between 7000 and 10,000 moving parts). Energy costs are also cheaper, once a few problems are worked out – ahem.

The biggest problem, of course, is the battery. I’ve heard that AA batteries mightn’t be enough. Nor are the current generation of lithium-ion batteries, though innovation and research in this area is being driven by electric cars hoho. Clearly electric aircraft have to start small and short-haul, and they’re already doing so. I’ve written about this before, but it’s time for an update. Some of the companies involved include Pipistrel, Harbour Air and Eviation, but this is still extremely small-scale stuff as everybody waits for the battery boffins to perform the next miracle. Meanwhile, as with the motor vehicle industry, hybrids have been developed as a kind of stop-gap for larger capacity flights. Another company, Ampaire, has developed small hybrid aircraft with which it hopes to start daily operations in Hawaii in the near future. It’s also working in Norway, where they’re hoping to have all flights of 90 minutes or less to be be either fully electric or hybrid by 2040. I’m glad to hear that my birth country, Scotland is also investing in electric and hybrid planes for similar purposes. If these planes could be shown to be economically viable, then larger aeroplane companies will surely invest in them, as they tend to lose money on regional routes (small turbine engines being very inefficient). This could be the real game-changer, providing reason to invest in battery and other technology for longer electric flight. Changes in technology, combining standard aircraft design with helicopter design, are likely to make air flight more personalised in future, with less need to depend on airports. Of course this will come with regulatory and other issues, but it all makes for a more interesting future in the sky….

References

https://www.independent.co.uk/travel/news-and-advice/cheap-flights-ryanair-train-tickets-rail-price-fares-budget-plane-a8969291.html

Why don’t we have electric planes yet? CNBC video

Written by stewart henderson

December 29, 2019 at 4:14 pm

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

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

an assortment of new technology palaver

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I like the inset pic – very useful for the Chinese

Western Australia lithium mining boom

I’m hearing, better late than never, that lithium carbonate from Western Australia is in big demand. The state already provides most of the world’s lithium for all those batteries used to run smart devices, electric vehicles, and large-scale storage batteries such as South Australia’s Tesla-Neoen thingy at Jamestown (now 80% complete, apparently). Emissions legislation around the world will only add to the demand, with the French and British governments planning to ban the sale of petrol and diesel vehicles by 2040, following similar plans by India and Norway, and the major investments in EVs in China. Australia’s government, of course, is at the other end of the spectrum re EVs, but I’ve no doubt we’ll get there eventually (we’ll have to!). Tesla, Volvo, Nissan, Renault, Volkswagen and Mercedes are all pushing more EVs into the marketplace. So now’s the time, according to Money Boffins Inc, to buy shares in lithium and other battery minerals (I’ve never bought a share in my life). This lithium mining boom has been quite sudden and surprising to many pundits. In January of this year, only one WA mine was producing lithium, but by mid-2018 there will be eight, according to this article. The battery explosion, so to speak, is bringing increased demand for other minerals too, including cobalt, nickel, vanadium and graphite. Australia’s well-positioned to take advantage. Having said that, the amount of lithium we’re talking about is a tiny fraction of what WA exports in iron ore annually, but it’s already proving to be a big boost to the WA economy, and a big provider of jobs.

battery recycling

Of course all of this also poses a problem, as mentioned in my last post, and it’s a problem that the renewable energy sector should be at least ideologically driven to deal with: waste and recycling. Considering the increasing importance of battery technology in our world, and considering the many toxic components of modern batteries, such as nickel, lead acid, cadmium and mercury, it’s yet another disappointment that there’s no national recycling scheme for non-rechargeable batteries. Currently only lead acid batteries can be recycled, and the rest usually end up in landfill or are sent to be recycled overseas. So it’s been left to the industry to develop an Australian Battery Recycling Initiative (ABRI), which has an interesting website where you can learn about global recycling and many other things batterial – including, of course, how to recycle your batteries. Also, an organisation called Clean Up Australia has a useful battery recycling factsheet, which, for my own educational purposes I’m going to recycle here, at least partly. Battery types can be divided into primary, or single-use, and secondary, or rechargeable. The primary batteries generally use zinc and manganese in converting chemical to electrical energy. Rechargeable batteries use a variety of materials, including nickel cadmium, nickel metal hydride and of course lithium ion chemistry. Batteries in general are the most hazardous of waste materials, but there are also environmental impacts from battery production (mining mostly) and distribution (transport and packaging). As mentioned, Australian batteries are sent overseas for recycling – ABRI and other groups are trying to set up local recycling facilities. Currently a whopping 97% of these totally recyclable battery units end up in landfill, and – another depressing factoid – Australia’s e-waste is growing at 3 times the rate of general household waste. So the public is advised to use rechargeable batteries wherever possible, and to take their spent batteries to a proper recycling service (a list is given on the fact sheet). The ABRI website provides a more comprehensive list of drop-of services.

2015 registrations: Australia’s bar would be barely visible on this chart

EVs in Australia – a very long way to go

I recently gave a very brief overview of the depressing electric vehicle situation in Australia. Thinking of buying one? Good luck with that. However, almost all motorists are much richer than I am, so there’s hope for them. They’re Australia’s early adopters of course, so they need all the encouragement we can give them. Journalist Timna Jacks has written an article for the Sydney Morning Herald recently, trying to explain why electric vehicles have hit a dead end in Australia. High import duties, a luxury car tax and a lack of subsidies and infrastructure for electric vehicles aren’t exactly helping the situation. The world’s most popular electric car, the Nissan Leaf, is much more expensive here than in Europe or the US. And so on. So it’s hardly surprising that only 0.1% of all cars sold in Australia in 2015 were electric cars (compared with 23% and rising in EV heaven, aka Norway, 1.4% in France and 0.7% in the US). Of course Australia’s landscape’s more or less the opposite of compact, dense and highly urbanised Europe, and range anxiety might be a perennial excuse here. We have such a long way to go. I expect we’ll have to wait until shame at being the world’s laughing-stock is enough of a motivation.

Adelaide’s Tindo

I’ve been vaguely aware of Adelaide’s ‘green bus’ for some years but, mea culpa, haven’t informed myself in any depth up until now. The bus is called Tindo, which is a Kaurna aboriginal word meaning the sun. Apparently it’s the world’s first and only completely solar powered electric bus, which is quite amazing. The bus has no solar panels itself, but is charged from the solar panels at the Franklin Street bus station in the city centre. It’s been running for over four years now and I’m planning to take a trip on it in the very near future. I was going to say that it’ll be the first time I’ve been on a completely electric vehicle with no internal combustion engine but I was forgetting that I take tram trips almost every day. Silly me. Still, to take a trip on a bus with no noisy engine and no exhaust fumes will be a bit of a thrill for me. Presumably there will be no gear system either, and of course it’ll have regenerative braking – I’m still getting my head around this stuff – so the ride will be much less jerky than usual.

So here are some of the ‘specs’ I’ve learned about Tindo. It has a range of over 200 kilometres (and presumably this is assisted by the fact that its route is fixed and totally urban, so the regen braking system will be charging it up regularly). It uses 11 Swiss-made Zebra battery modules which are based on sodium nickel chloride, a type of molten salt technology. They have higher energy density, they’re lightweight and virtually maintenance free. According to the City of Adelaide website the solar PV system on the roof of the bus station is (or was – the website is annoyingly undated) ‘Adelaide’s largest grid-connected system, generating almost 70,000 kWh of electricity a year’. No connection to the ‘carbon-intensive South Australian electricity grid’ is another plus, though to be fair our grid is far less carbon intensive than Victoria’s which is almost all brown coal. South Australia’s grid runs on around half gas and half renewables, mostly wind. The regen braking, I must remind myself, means that when decelerating the bus uses no energy at all, and the motor electronically converts into an electrical generator, which generates electricity with the continued forward motion of the bus. There are many more specs and other bits of info on this Tindo factsheet.

battery technology and the cobalt problem

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The battery in my iPhone 6+ is described as a lithium polymer, or Li-ion polymer battery. I’m trying to find out if it contains cobalt. Why? Because cobalt is a problem.

According to this Techcrunch article, most of the world’s cobalt is currently sourced from Africa, especially the Congo, one of the world’s poorest countries. Child labour is regularly used in the mines there, under pain of beatings and other forms of coercion. The battery industry uses about 42% of global cobalt production, and the rest is used in a range of essential military-industrial applications.

Incidentally, this article from teardown.com blog goes deep inside the iPhone 6+ battery, showing that it uses lithium cobalt oxide (LiCoO2) for the cathode.

I can think of three possible ways out of this problem. 1. Stop sourcing cobalt from the Congo, or anywhere else that has exploitative labour practices. 2. Reform those labour practices, to improve the lives of the workers and provide them with a fairer share of the tech revolution profits. 3. Find an alternative to cobalt for batteries and other applications.

I didn’t say there were easy solutions haha. Anyway, let’s examine them.

An online Fortune article from March this year, which by the way confirms that cobalt is indeed used in iPhone and iPad batteries, reported that Apple has responded to investigative articles by Washington Post and Sky News by no longer buying cobalt from companies that employ child labour. Of course, even if we take Apple at its word – and considering that the Congo provides 60% of the world’s cobalt, and other African sources may have similar problems, how else will Apple be able to source cobalt cheaply? – the problem of Congolese child labour remains. The Washington Post report focused on a Chinese company, Zhejiang Huayou Cobalt Company, which purchases a large percentage of Congolese cobalt. It seems highly unlikely that such a company will be as affected by public or media pressure as Apple. However, there are some positive signs. A report in the Financial Times from a year ago, entitled ‘China moves to quell child labour claims in Congo cobalt mines’, says that China has launched a ‘Responsible Cobalt Initiative’ to improve supply chain governance and transparency. Whether this means applying solution 1 or solution 2 to the problem is unclear, but presumably it’s solution 2, and it really is a serious initiative, put forward by the Chinese Chamber of Commerce for Metals, Minerals and Chemicals Importers and Exporters, backed by the OECD and involving a number of international tech companies. Of course we’ll have to wait for reports on how this initiative is faring, and on whether these companies are concerned to improve the lives of cobalt miners or simply to ban the under-age ones while still paying very little to the remainder. Continued scrutiny is obviously necessary.

Of course, solution 3 would be of most interest to tech-heads (though presumably the effect on the Congolese economy would be terrible). According to this marketing article, there isn’t too much cobalt available, and the demand for it is increasing sharply. One problem is that cobalt isn’t generally mined on its own as ‘primary cobalt’ but as a byproduct of copper or nickel, and both of these metals are experiencing a worldwide price plunge, with many mines suspending activities. Also the current supply chain for cobalt is being dominated by Chinese companies. This could have a stifling effect especially on the EV revolution. Governments in advanced countries around the world – though not in Australia – are mandating the adoption of electric vehicles and the phasing out of fossil-fuel-based road transport. The batteries for these vehicles all contain cobalt.

In the TechCrunch article mentioned above, journalist Sebastien Gandon examines the Tesla situation. The company has a target of 500,000 vehicles a year by 2018, with cobalt sourced exclusively from North America. On the face of it, this seems unrealistic. Canada and the US together produce about 4% of the world’s cobalt supply, and  acccording to Gandon the maths just doesn’t add up, to say the least. For a start, the mining companies Tesla is looking to rely on are not even operational as yet.

However, there are a few more promising signs. The Tesla model S has been using high energy density nickel-cobalt-aluminium-based (NCA) battery cells, which have a lower cobalt content than the nickel-manganese-cobalt (NMC) batteries of most other companies. There is also the possibility of adopting lithium-iron-phosphate (LFP) chemistry, or lithium-manganese-oxide (LMO), neither of which use cobalt, though their lower energy density is a problem. In any case, battery technology is going through a highly intensive phase at present, as I’ve already reported, and a move away from cobalt has become a distinct possibility. Nickel is currently being looked at, but results so far have been disappointing. There are certainly other options in the offing, and cobalt itself, which unlike oil is completely recyclable, could still be viable with greater focus. It isn’t so much that it is scarce, it’s more that, in the past, it hasn’t been a primary focus, but mining it as a primary source will require substantial upfront costs, and substantial time delays.

So, all in all, it’s a problematic future, at least in the short term, for vehicles and technologies using cobalt-based battery systems. We can only wait and see what comes out of it.

Written by stewart henderson

October 28, 2017 at 12:55 pm

capacitors, supercapacitors and electric vehicles

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from the video ‘what are supercapacitors’

Jacinta: New developments in battery and capacitor technology are enough to make any newbie’s head spin.

Canto: So what’s a supercapacitor? Apart from being a super capacitor?

Jacinta: I don’t know but I need to find out fast because supercapacitors are about to be eclipsed by a new technology developed in Great Britain which they estimate as being   ‘between 1,000 and 10,000-times more effective than current supercapacitors’.

Canto: Shite, they’ll have to think of a new name, or downgrade the others to ‘those devices formerly known as supercapacitors’. But then, I’ll believe this new tech when I see it.

Jacinta: Now now, let’s get on board, superdisruptive technology here we come. Current supercapacitors are called such because they can charge and discharge very quickly over large numbers of cycles, but their storage capacity is limited in comparison to batteries…

Canto: Apparently young Elon Musk predicted some time ago that supercapacitors would provide the next major breakthrough in EVs.

Jacinta: Clever he. But these ultra-high-energy density storage devices, these so-much-more-than-super-supercapacitors, could enable an EV to be charged to a 200 kilometre range in just a few seconds.

Canto: So can you give more detail on the technology?

Jacinta: The development is from a UK technology firm, Augmented Optics, and what I’m reading tells me that it’s all about ‘cross-linked gel electrolytes’ with ultra-high capacitance values which can combine with existing electrodes to create supercapacitors with greater energy storage than existing lithium-ion batteries. So if this technology works out, it will transform not only EVs but mobile devices, and really anything you care to mention, over a range of industries. Though everything I’ve read about this dates back to late last year, or reports on developments from then. Anyway, it’s all about the electrolyte material, which is some kind of highly conductive organic polymer.

Canto: Apparently the first supercapacitors were invented back in 1957. They store energy by means of static charge, and I’m not sure what that means…

Jacinta: We’ll have to do a post on static electricity.

Canto: In any case their energy density hasn’t been competitive with the latest batteries until now.

Jacinta: Yes it’s all been about energy density apparently. That’s one of the main reasons why the infernal combustion engine won out over the electric motor in the early days, and now the energy density race is being run between new-age supercapacitors and batteries.

Canto: So how are supercapacitors used today? I’ve heard that they’re useful in conjunction with regenerative braking, and I’ve also heard that there’s a bus that runs entirely on supercapacitors. How does that work?

Jacinta: Well back in early 2013 Mazda introduced a supercapacitor-based regen braking system in its Mazda 6. To quote more or less from this article by the Society of Automotive Engineers (SAE), kinetic energy from deceleration is converted to electricity by the variable-voltage alternator and transmitted to a supercapacitor, from which it flows through a dc-dc converter to 12-V electrical components.

Canto: Oh right, now I get it…

Jacinta: We’ll have to do posts on alternators, direct current and alternating current. As for your bus story, yes, capabuses, as they’re called, are being used in Shanghai. They use supercapacitors, or ultracapacitors as they’re sometimes called, for onboard power storage, and this usage is likely to spread with the continuous move away from fossil fuels and with developments in supercaps, as I’ve heard them called. Of course, this is a hybrid technology, but I think they’ll be going fully electric soon enough.

Canto: Or not soon enough for a lot of us.

Jacinta: Apparently, with China’s dictators imposing stringent emission standards, electric buses, operating on power lines (we call them trams) became more common. Of course electricity may be generated by coal-fired power stations, and that’s a problem, but this fascinating article looking at the famous Melbourne tram network (run mainly on dirty brown coal) shows that with high occupancy rates the greenhouse footprint per person is way lower than for car users and their passengers. But the capabuses don’t use power lines, though they apparently run on tracks and charge regularly at recharge stops along the way. The technology is being adopted elsewhere too of course.

Canto: So let me return again to basics – what’s the difference between a capacitor and and a super-ultra-whatever-capacitor?

Jacinta: I think the difference is just in the capacitance. I’m inferring that because I’m hearing, on these videos, capacitors being talked about in terms of micro-farads (a farad, remember, being a unit of capacitance), whereas supercapacitors have ‘super capacitance’, i.e more energy storage capability. But I’ve just discovered a neat video which really helps in understanding all this, so I’m going to do a breakdown of it. First, it shows a range of supercapacitors, which look very much like batteries, the largest of which has a capacitance, as shown on the label, of 3000 farads. So, more super than your average capacitor. It also says 2.7 V DC, which I’m sure is also highly relevant. We’re first told that they’re often used in the energy recovery system of vehicles, and that they have a lower energy density (10 to 100 times less than the best Li-ion batteries), but they can deliver 10 to 100 times more power than a Li-ion battery.

Canto: You’ll be explaining that?

Jacinta: Yes, later. Another big difference is in charge-recharge cycles. A good rechargeable battery may manage a thousand charge and recharge cycles, while a supercap can be good for a million. And the narrator even gives a reason, which excites me – it’s because they function by the movement of ions rather than by chemical reactions as batteries do. I’ve seen that in the videos on capacitors, described in our earlier post. A capacitor has to be hooked up to a battery – a power source. So then he uses an analogy to show the difference between power and energy, and I’m hoping it’ll provide me with a long-lasting lightbulb moment. His analogy is a bucket with a hole. The amount of water the bucket can hold – the size of the bucket if you like – equates to the bucket’s energy capacity. The size of the hole determines the amount of power it can release. So with this in mind, a supercar is like a small bucket with a big hole, while a battery is more like a big bucket with a small hole.

Canto: So the key to a supercap is that it can provide a lot of power quickly, by discharging, then it has to be recharged. That might explain their use in those capabuses – I think.

Jacinta: Yes, for regenerative braking, for cordless power tools and for flash cameras, and also for brief peak power supplies. Now I’ve jumped to another video, which inter alia shows how a supercapacitor coin cell is made – I’m quite excited about all this new info I’m assimilating. A parallel plate capacitor is separated by a non-conducting dielectric, and its capacitance is directly proportional to the surface area of the plates and inversely proportional to the distance between them. Its longer life is largely due to the fact that no chemical reaction occurs between the two plates. Supercapacitors have an electrolyte between the plates rather than a dielectric…

Canto: What’s the difference?

Jacinta: A dielectric is an insulating material that causes polarisation in an electric field, but let’s not go into that now. Back to supercapacitors and the first video. It describes one containing two identical carbon-based high surface area electrodes with a paper-based separator between. They’re connected to aluminium current collectors on each side. Between the electrodes, positive and negative ions float in an electrolyte solution. That’s when the cell isn’t charged. In a fully charged cell, the ions attach to the positively and negatively charged electrodes (or terminals) according to the law of attraction. So, our video takes us through the steps of the charge-storage process. First we connect our positive and negative terminals to an energy source. At the negative electrode an electrical field is generated and the electrode becomes negatively charged, attracting positive ions and repelling negative ones. Simultaneously, the opposite is happening at the positive electrode. In each case the ‘counter-ions’ are said to adsorb to the surface of the electrode…

Canto: Adsorption is the adherence of ions – or atoms or molecules – to a surface.

Jacinta: So now there’s a strong electrical field which holds together the electrons from the electrode and the positive ions from the electrolyte. That’s basically where the potential energy is being stored. So now we come to the discharge part, where we remove electrons through the external surface, at the electrode-electrolyte interface we would have an excess of positive ions, therefore a positive ion is repelled in order to return the interface to a state of charge neutrality – that is, the negative charge and the positive charge are balanced. So to summarise from the video, supercapacitors aren’t a substitute for batteries. They’re suited to different applications, applications requiring high power, with moderate to low energy requirements (in cranes and lifts, for example). They can also be used as voltage support for high-energy devices, such as fuel cells and batteries.

Canto: What’s a fuel cell? Will we do a post on that?

Jacinta: Probably. The video mentions that Honda has used a bank of ultra capacitors in their FCX fuel-cell vehicle to protect the fuel cell (whatever that is) from rapid voltage fluctuations. The reliability of supercapacitors makes them particularly useful in applications that are described as maintenance-free, such as space travel and wind turbines. Mazda also uses them to capture waste energy in their i-Eloop energy recovery system as used on the Mazda 6 and the Mazda 3, which sounds like something worth investigating.

References (videos can be accessed from the links above)

http://www.hybridcars.com/supercapacitor-breakthrough-allows-electric-vehicle-charging-in-seconds/

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

http://www.power-technology.com/features/featureelectric-vehicles-putting-the-super-in-supercapacitor-5714209/

http://articles.sae.org/11845/

https://www.ptua.org.au/myths/tram-emissions/

http://www.europlat.org/capabus-the-finest-advancement-for-electric-buses.htm

Written by stewart henderson

September 5, 2017 at 10:08 am

what are capacitors?

with one comment

the shapes and sizes of capacitors – a screenshot taken from the youtube vid – What are Capacitors? – Electronics Basics 11

Jacinta: We’re embarking on the clearly impossible task of learning about every aspect of clean (and sometimes dirty because nothing’s 100% clean or efficient) technology – batteries, photovoltaics, turbines, kilo/megawatt-hours, glass electrolytes, powerwalls, inverters, regen, generators, airfoils, planetary gear sets, step-up transformers, nacelles AND capacitors.

Canto; Enough to last us a lifetime at our slow pace. So what, in the name of green fundamentalism, is a capacitor?

Jacinta: Well I’ve checked this out with Madam Youtube…

Canto: Professor Google’s co-dependent…

Jacinta: And in one sense it’s simple, or at least it sounds simple. Capacitors store electric charge, and the capacitance of a capacitor relates to how much charge it can hold.

Canto: So how does it do that, and what’s the purpose of storing electric charge?

Jacinta: Okay now you’re complicating matters, but basic to all capacitors are two separated pieces of conducting material, usually metal. Connected to a battery, they store charge…

Canto: Which is a kind of potential energy, right?

Jacinta: Umm, I think so. So take your battery with its positive and negative terminals. Attach one of the bits of conducting material (metal) to the positive terminal and you’ll get a flow of negatively-charged electrons to that terminal, because of ye olde law of attraction. This somehow means that electrons are repelled from the negative terminal  (which we’ve hooked up to the other bit of metal in the capacitor). So because the first strip of metal has lost electrons it has become positively charged, and the other bit of metal, having gained electrons, has an equal and opposite charge. So each piece of metal has the same magnitude of charge, measured in coulombs. This is regardless of the size and shape of the different metal bits.

Canto: But this process reaches a limit, though, yes? A kind of saturation point…

Jacinta: Well there comes a point where, yes, the accumulated charge just sits there. This is because there comes a kind of point of equilibrium between the positive battery terminal and the now positively charged strip of metal. The electrons are now caught between the attractive positive terminal and the positive strip.

Canto: Torn between two lovers, I know that foolish feeling.

Jacinta: So now if you remove the battery, so breaking the circuit, that accumulated charge will continue to sit there, because there’s nowhere to go.

Canto: And of course that accumulated or stored charge, or capacitance, is different for different capacitors.

Jacinta: And here’s where it gets really complicated, like you know, maths and formulae and equations. C = Q/V, capacitance equals the charge stored by the capacitor over the voltage across the capacitor. That charge (Q), in coulombs, is measured on one side of the capacitor, because the charges actually cancel each other out if you measure both sides, making a net charge of zero. So far, so uncomplicated, but try and get the following. When a capacitor stores charge it will create a voltage, which is essentially a difference in electric potential between the two metal strips. Now apparently (and you’ll have to take my word for this) electric potential is high near positive charges and low near negative charges. So if you bring these two differently charged strips into close proximity, that’s when you get a difference in electric potential – a voltage. If you allow a battery to fully charge up a capacitor, then the voltage across it (between the two strips) will be the same as the voltage in the battery. The capacitance, Q/V, coulombs per volt, is measured in farads, after Micky Faraday, the 19th century electrical wizz. I’m quoting this more or less verbatim from the Khan Academy video on capacitors, and I’m almost finished, but here comes the toughest bit, maths! Say you have a capacitor with a capacitance of 3 farads, and it’s connected to a nine volt battery, the charge stored will be 27 coulombs (3 = 27/9). 3 farads equals 27 coulombs of charge divided by nine volts, or 27 coulombs of charge is 3 farads times 9 volts. Or, if a 2 farad capacitor stores a charge of 6 coulombs, then the voltage across the capacitor will be 3 volts.

Canto: Actually, that’s not so difficult to follow, the maths is the easiest part for me… it’s more the concepts that get me, the very fact that matter has these electrical properties…

Jacinta: Okay here’s the last point made, more or less verbatim, on the Khan Academy video, something worth pondering:

You might think that as more charge gets stored on a capacitor, the capacitance must go up, but the value of the capacitance stays the same because as the charge increases, the voltage across that capacitor increases, which causes the ratio to stay the same. The only way to change the capacitance of a capacitor is to alter the physical characteristics of that capacitor (like making the pieces of metal bigger, or changing the distance between them).

Canto: Okay so to give an example, a capacitor might be connected to an 8 volt battery, but its capacitance is, say, 3 farads. It will be fully charged at 24 coulombs over 8 volts. The charge increases with the voltage, which has a maximum of 8. The ratio remains the same. Yet somehow I still don’t get it. So I’m going to have a look at another video to see if it helps. It uses the example of two metal plates. They start out as electrically neutral. You can’t force extra negativity, in the form of electrons, into one of these plates, because like charges repel, and they’ll be forced out again. But, according to the video, if you place another plate near the first, ‘as electrons accumulate in the first metal plate, they will repel the electrons in the second metal plate’, to which I want to respond, ‘but electrons aren’t accumulating, they’re being repelled’. But let’s just go with the electron flow. So the second metal plate becomes depleted of electrons and is positively charged. This means that it will attract the negatively charged first metal plate. According to the video, this makes it possible for the first plate to have more negative than positive particles, which I think has something to do with the fact that the electrons can’t jump from the first plate to the second, to create an equilibrium.

Jacinta: They’re kind of attracted by absence. That’s what they must mean by electric potential. It’s very romantic, really. But what you’ve failed to notice, is that a force is being continually applied, to counteract the repulsion of electrons from the first plate. If the force no longer applies then, yes, you won’t get that net negative charge in the first plate, and the consequent equal and opposite charge in the second. My question, though, is how can the capacitance increase by bringing the plates closer together? I can see how it can be changed by the size of the conducting material – more electrons, more electric potential. I suppose reducing the distance will increase the repulsive force…

Canto: Yes, let’s assume so. Any, a capacitor, which stores far less charge than a similarly-dimensioned battery can be used, I think, to briefly maintain power to, say, a LED bulb when it is disconnected from the battery. The capacitor, connected to the bulb will discharge its energy ‘across’ the bulb until it achieves equilibrium, which happens quite quickly, and the bulb will fade out. If the capacitor is connected to a number of batteries to achieve a higher voltage, the fully charged capacitor will take longer to discharge, keeping the light on for longer. If the metal plates are larger, the capacitor will take longer to charge up, and longer to discharge across the LED bulb. Finally, our second video (from a series of physics videos made by Eugene Khutoryansky) shows that you can place a piece of ‘special material’ between the two plates. This material contains molecules that change their orientation according to the charges on the plates. They exert a force which attracts more electrons to the negative plate, and repel them from the positive plate, which has the same effect as increasing the area of the plates – more charge for the same applied voltage.

Jacinta: An increase in capacitance.

Canto: Yes, and as you’ve surmised, bringing the two plates closer together increases the capacitance by attracting more electrons to the negatively charged plate and repelling them from the positively charged one – again, more charge for the same voltage.

Jacinta: So you can increase capacitance with a combo of the three – increased size, closer proximity, and that ‘special material’. Now, one advantage of capacitors over batteries is that they can charge up and discharge very quickly. Another is that they can endure many charge-discharge cycles. However they’re much less energy dense than batteries, and can only store a fraction of the energy of a same-sized battery. So the two energy sources have different uses.

Canto: Mmmm, and we’ll devote the next post to the uses to which capacitors can be put in electronics, and EVs and such.

 

Written by stewart henderson

August 28, 2017 at 6:27 pm