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stand-alone solar: an off-grid solution for Australia’s remote regions (plus a bit of a rant)

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According to this article, Australia is leading the world in per capita uptake of rooftop solar, though currently South Australia is lagging behind, in spite of a lot of clean energy action from our government. The Clean Energy Regulator has recently released figures showing that 23% of Australians have installed rooftop solar in the last ten years, and this take-up is set to continue in spite of the notable lack of encouragement from the feds. South Australia is still making plenty of waves re clean energy, though, as it is continually lowering its record for minimum grid demand, through the use of solar PV. The record set a couple of days ago, interestingly on Sunday afternoon rather than in the middle of the night, was 587MW, almost 200MW less than the previous record set only a week or so before. Clearly this trend is set to continue.

It’s hard for me to get my head around what’s happening re disruptive technologies, microgrids, stand-alone solar, EVs, battery research and the like, not to mention the horribly complex economics around these developments, but the sense of excitement brought about by comprehensive change makes me ever-willing to try. Only this morning I heard a story of six farming households described as being ‘on the fringe of Western Australia’s power network’ who’ve successfully trialled stand-alone solar panels (powered by lithium-ion batteries) on their properties, after years of outages and ‘voltage spikes’*. The panels – and this is the fascinating part – were offered free by Western Power (WA’s government-owned energy utility), who were looking for a cheaper alternative to the cost of replacing ageing infrastructure. The high costs of connecting remote farms to the grid make off-grid power systems a viable alternative, which raises issues about that viability elsewhere given the decreasing costs of solar PV, which can maintain electricity during power outages, as one Ravensthorpe family, part of the trial, discovered in January this year. The region, 500 kilometres south of Perth, experienced heavy rain and flooding which caused power failures, but the solar systems were unaffected. All in all, the trial has ‘exceeded expectations’, according to this ABC report.

All this has exciting implications for the future, but there are immediate problems. Though Western Power would like to sign off on the trial as an overwhelming success, and to apply this solution to other communities in the area (3,000 potential sites have been pinpointed), current regulation prevents this, as it only allows Western Power to distribute energy, not to generate it, as its solar installations are judged as doing. Another instance of regulations not keeping up with changing circumstances and solutions. Western Power has no alternative but to extend the trial period until the legislation catches up (assuming it does). But it would surely be a mistake not to change the law asap:

“You’d be talking about a saving of about $300 million in terms of current cost of investment and cost of ongoing maintenance of distribution line against the cost of the stand-alone power system,” Mr Chalkley [Western Power CEO] said.

Just as a side issue, it’s interesting that our PM Malcolm Turnbull, whose government seems on the whole to be avoiding any mention of clean energy these days, has had solar panels on his harbourside mansion in Point Piper, Sydney, for years. He now has an upgraded 14 kW rooftop solar array and a 14kWh battery storage system installed there, and, according to a recent interview he did on radio 3AW, he doesn’t draw any electricity from the grid, in spite of using a lot of electricity for security as Prime Minister. Solar PV plus battery, I’m learning, equals a distributed solar system. The chief of AEMO (the Australian Energy Market Operator), Audrey Zibelman, recently stated that distributed rooftop solar is on its way to making up 30 to 40% of our energy generation mix, and that it could be used as a resource to replace baseload, as currently provided by coal and gas stations (I shall write about baseload power issues, for my own instruction, in the near future).

Of course Turnbull isn’t exactly spruiking the benefits of renewable energy, having struck a Faustian bargain with his conservative colleagues in order to maintain his prestigious position as PM. We can only hope for a change of government to have any hope of a national approach to the inevitable energy transition, and even then it’ll be a hard road to hoe. Meanwhile, Tony Abbott, Turnbull’s arch-conservative bête noir, continues to represent the dark side. How did this imbecilic creature ever get to be our Prime Minister? Has he ever shown any signs of scientific literacy? Again I would urge extreme vetting of all candidates for political office, here and elsewhere, based on a stringent scientific literacy test. Imagine the political shite that would be flushed down the drain with that one. Abbott, you’ll notice, always talks of climate change and renewable energy in religious terms, as a modern religion. That’s because religion is his principal obsession. He can’t talk about it in scientific terms, because he doesn’t know any. Unfortunately, these politicians are rarely challenged by journalists, and are often free to choose friendly journalists who never challenge their laughable remarks. It’s a bit of a fucked-up system.

Meanwhile the ‘green religionists’, such as the Chinese and Indian governments, and the German and Scandinavian governments, and Elon Musk and those who invest in his companies, and the researchers and scientists who continue to improve solar PV, wind turbine and battery technology, including flow batteries, supercapacitors and so much more, are improving their developments and disrupting traditional ways of providing energy, and will continue to do so, in spite of name-calling from the fringes (to whom they’re largely deaf, due to the huge level of support from their supporters). It really is an exciting time not to be a dinosaur.



Written by stewart henderson

September 20, 2017 at 9:32 pm

on the Rohingyas, and introducing the first of many heroes, Wai Wai Nu

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Wai Wai Nu, a Rohingya woman, a feminist, a democrat, and a humanist, working to bring communities together in the Arakan region, Myanmar

I haven’t posted for a bit, as I was writing a lengthy piece on the Rohingyas, their history and their plight, but I’ve decided to abandon that as there are many others, investigative journalists, historians and the like, who could do a far better job. Of course the main purpose of my writing is to inform myself, but I soon found, with this Rohingya business, it’s the same old story of ‘they don’t belong here’ ultranationalists, and the political expediency of national leaders who need the support of these types, together with the carping of neighbours who have their own nationalist agendas and sordid histories.

So I want to be more brief and positive, and of course feminist (though I’ll leave references to the more interesting analyses I’ve read about the situation), and write about one heroine who has been inspired by her experiences to do something about this.

I’m thinking this could be the first of many posts about women setting great examples in the world.

Wai Wai Nu is a young Rohingya woman who, as an 18-year-old law student, was imprisoned, along with other family members, by the military dictators of Myanmar in 2005, at a time when thousands of people were locked up for opposing the junta, or indeed for any trivial reason. She was sentenced to 17 years, but was finally released in 2012. She was then able to complete her law degree, but she has described her years of incarceration in an infamous prison as her true university years, years spent among the victimised poor. Having said that, she comes from a political, pro-democratic family, her father having been elected to parliament in 1990, an odd fact considering that a citizenship law of 1982 rendered the Rohingyas officially stateless, which they’ve been ever since – and other laws enacted since have denied them every right that they might possibly be entitled to, including even the right to call themselves Rohingyas.

In recent years Wai Wai has founded two NGOs promoting peace and women’s rights, the Women’s Peace Network – Arakan, and Justice for Women, a legal aid support group for women in Myanmar. Her work is the kind of work women have done for decades at the coal-face, educating the next generation, promoting inter-faith dialogue, empowering women and the poor, and bringing disparate communities together, while being mocked or ignored by bully-boy nationalists with their generally sickening and infantile agendas (but ok, I’m beginning to sound like a bully boy myself…). I would highly recommend listening to this softly spoken but determined woman’s speech at the Oslo Freedom Forum in Norway in May this year.

Rohingyas in Arakan aren’t allowed an identity, and have no freedom of movement outside of Arakan province. They’re not even allowed to marry outside their own group, as that would obviously complicate matters re their extinction within Myanmar. The current aim of the national government appears to be to force them out of the country altogether, but this is as unlikely to be successful as the attempt to assimilate (and so dilute to the point of non-existence) Australia’s indigenous population by earlier governments here. So it will be a long struggle, but with people like Wai Wai Nu doing the kind of work she does, and the ongoing struggles and activities of those she has inspired, we have good reason to hope for a fairer future for the Rohingyas, and for women throughout Myanmar. And here’s hoping Wai Wai Nu doesn’t enter politics, where her talents are likely to be compromised… or maybe not…


Written by stewart henderson

September 17, 2017 at 2:38 pm

Posted in Uncategorized

on dresses, marriage and patriarchy

with 2 comments

the spice of life

Canto: It seems some schools are still intent on having girls wear dresses to their classes. Why?

Jacinta: Because that’s what girls have traditionally worn. Because some schools insist on an absolute distinction between girls and boys.

Canto: Yes but they must be able to come up with good reasons for that, otherwise they’ll look foolish.

Jacinta: Well girls are girls and boys are boys, aren’t they? How can they be treated equally or identically? It’s obvious.

Canto: Ah, the obvious argument. Like Cook obviously discovered Australia. But this absolute differentiation between males and females has always been a horrible thing to behold. When such absolute differences are insisted on, it’s always accompanied by a sense of the superiority of one side of the differential.

Jacinta: Indeed, as one schoolteacher put it in an interview I saw recently, the dress thing in schools is essentially an insistence that girls should dress more for decoration than for practicality.

Canto: Yes, though there are conditions in which dresses are more practical, in which case they should be allowed for all genders. I’d still like to buy one of those kilts I saw advertised on Facebook a while ago.

Jacinta: It’s amazing that this gendered stuff hasn’t been questioned, or raged against, more vigorously before now, but the dress thing could be a wedge to open up a pack of gender issues.

Canto: And research has found that girls exercise less than boys, to a significant degree, and dresses undoubtedly contribute to that. It’s being pointed out that making simple changes to uniform policies might be a much cheaper way to address the problem than a ‘girls be active’ campaign.

Jacinta: And it requires leadership from, well, the leaders. Girls aren’t likely to go it alone and risk being mocked by their peers for being different. And it looks like if senior teachers or principals don’t engage in the exercise of change – at last! – then parents will have to make the move, possibly via legal action.

Canto: Yes, the refusal to allow girls to wear clothes appropriate for tree-climbing, mud-wrestling and other typical schoolyard activities is clearly discriminatory. Bring it on!

Jacinta: Seriously we know that both girls and boys, in terms of their mental and physical activities, cover the whole range. Forcing them into specific, gendered outfits inhibits that range. That’s the last thing the wider society wants. So now, due to the same-sex marriage issue and some silly remark from the no campaign about boys wearing dresses, the issue of girls’ uniforms is grabbing a moment’s attention, but will it die down again with no action taken? Our society’s inertia is lamentable, methinks.

Canto: Maybe we should take it upon ourselves to keep the issue alive after the marriage issue gets dealt with – letters to arch-Catholic schools, veiled threats, dress-burnings outside the railings.

Jacinta: Railings and wailings outside the railings. But not outside of individual schools, that would take forever. We need national action. Federal parliament needs a dressing down. But speaking of marriage, I just heard a sound-bite about a woman from Israel, a parliamentarian, who’s calling for a cancellation of marriage. She wants to get rid of it, apparently. Now that takes me back to the old days.

Canto: Is this a feminist issue? I mean, lots of people aren’t keen on marriage, including myself, but I never thought of it as a feminist issue, though of course it would be in more patriarchal cultures.

Jacinta: Well the ‘cancel marriage’ advocate is Merav Michaeli, who worked mainly as a journalist before entering the Israeli parliament, and in her TEDx talk she clearly sees it as a feminist issue and makes a number of valid points…

Canto: But how can this be relevant to gay marriage?

Jacinta: Yes, that could be an argument against her – marriage can evolve rather than be cancelled. She’s right about the history of the marriage arrangement and how it has disadvantaged women, quite massively in fact, but marriage is what we make of it and we can do a better job of the arrangement in the future. Having said that, I’d be quite happy for it to be scrapped.

Canto: I’ve always been interested in different arrangements for rearing kids, other than the two-parent thing. But let’s return to the small issue of dresses. The Western Australian labor government has upped the ante by making it mandatory for schools to offer girls the choice of wearing pants or a dress.

Jacinta: That’s great. I presume this is for primary school. And maybe high school, Though I recall in my high school, a long long time ago, the senior students were weaned off uniforms, in preparation for sensible adult life when they could at last wear what they wanted.

Canto: I’d love to hear the rationale of those schools who don’t allow girls to wear trousers or shorts. And I don’t think just offering the option of shorts for girls is enough – no girl wants to be the only girl in her class to not be wearing a dress. If shorts and trousers really do encourage girls to engage in more play – and they clearly do, then they should be encouraged, for their health’s sake.

Jacinta: It really is discriminatory, as many experts say. And it doesn’t reflect what grown-up women wear. I teach in a college with predominantly female colleagues. Not one of them wears a dress on a regular basis. Most of them have never worn a dress at work, as far as I can recall.

Canto: Which makes me wonder about the female teachers at these hold-out schools. Do they all wear dresses? Imagine a trousered teacher dictating the dress-only-dress code to her female charges. Wouldn’t be surprised if that hasn’t happened somewhere. It’s a weird weird world.

Jacinta: In some ways it might seem a trivial subject, given all the issues about clean energy and so on, things that we’ve been focusing on lately, but these apparently minor issues of dress go to the heart of patriarchy in many ways. After all, these rules are being forced on girls quite often, and they’re telling them something at a very impressionable age, and that’s not a good thing.

Canto: We must try to keep this one in mind, as the issue is likely to go off the boil again and may take decades to fix. I’d also like to know which schools are enforcing these rules. We might try to shame them.

Jacinta: I hear it’s often the parents that insist on it. They’ve sent their kids to a conservative school for a reason. In any case they should be forced to justify their attitudes. I’d like to see them try.


Written by stewart henderson

September 12, 2017 at 8:39 am

solving the world’s problems, one bastard at a time..

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Canto: Let’s talk about something more gripping for a while. Like, for example, the global political situation.

Jacinta: Mmmm, could you narrow that down a bit?

Canto: No, not really… Okay, let’s take the most politically gripping issue of the moment, the possibility of nuclear annihilation for thousands of South Koreans or Japanese – and then North Koreans – due to the somewhat irresponsible launchings and detonations of massively destructive weaponry by a guy who we can reasonably assume to be intoxicated with his own power – and I do believe power to be the most toxic and dangerous drug ever conceived. And then we can talk about all the other issues.

Jacinta: Well as for the Kim jong-un issue, I suspect I can speak for a lot of people when I say I oscillate between dwelling on it and dismissing it as something I can do nothing about. What else do you want me to say. To say I’m glad we’re not in the way of it all would seem inhumane…

Canto: Do you have any solutions? What should we do from here?

Jacinta: We? You mean ‘the west’? Okay, from here on in, I’d cease all direct communications with Kim – all threats, all comments, everything. That only seems to make him worse.

Canto: But it can hardly get worse. Don’t we need to act to remove his threats, which are a bit more than threats?

Jacinta: Well of course the best solution, out of a bad lot, would be to have him disappear, like magic. Just deleted. It’s impossible, but then I’ve heard some people do six impossible things before breakfast.

Canto: He’s only 33 apparently, and according to Wikipedia he’s married but childless…

Jacinta: I’m not saying deleting him would be a good option, it’d presumably cause chaos, a big power struggle, a probable military takeover, unpredictable action from China, and all the weaponry, such as it is, would still be there. And we have no idea how to do it anyway.

Canto: I’m sure they have some plan of that type. The CIA’s not dead yet.

Jacinta: Yeah I’m sure they have some back-drawer plan somewhere too, but I wouldn’t misunderestimate the incompetence of the CIA.

Canto: So what if we follow your do-and-say-nothing policy? Don’t aggravate the wounded bear. But maybe the bear isn’t wounded at all. NK just detonated something mighty powerful, though there’s some controversy over whether it was actually thermonuclear. Anyway it’s unlikely the country just developed this powerful weapon in the few months that Trump has been acting all faux-macho. Who knows, this may have taken place if Clinton or someone else was in power in the US.

Jacinta: Interesting point, but then why are so many people talking about tit-for-tat and brinkmanship? They may have had the weapon, and maybe a lot more, but Kim’s decision to detonate it now, to show it, seems to have been provoked. It’s classic male display before a rival. Think of the little mutt snapping at the mastiff’s heels. Fuck you, big boy, I’ve got teeth too.

Canto: Yeah, but this little mutt has teeth that can wipe out cities. In any case, now he’s been provoked, and it’s unlikely that Trump and his cronies are going to damp down the belligerent rhetoric, the rest of us seem to be just sitting tight and waiting for this mutt to do some damage inadvertently/on purpose, and then what will happen? Say a missile goes astray and lands on or near a Japanese city? Untold casualties…

Jacinta: I think China will be key here. Not that I have any faith in the Chinese thugocracy to act in any interest other than its own.

Canto: Or the Trumpocracy for that matter.

Jacinta: I suspect China might step in and do something if it came to the kind of disaster you’ve mentioned. Though whether they have a plan I don’t know. I wouldn’t be surprised, actually if they’re having urgent closed-door talks right now on how best to take advantage of the crisis.

Canto: Well don’t worry, Trump and our illustrious leader are have a phone call today to sort it all out.

Jacinta: I’m really not sure what there is to talk about. An American first strike would have horrific cascading effects, and upping the tempo of military exercises in the neighbouring regions will just make Kim more reckless, to go by past experience. So if we don’t have any communication directed at him, he might continue with building bombs, but he would’ve done that anyway. So, though we’re not making matters any better, neither are we making them worse, which we are doing by goading him. Meanwhile we should be talking around NK. It’s like the elephant in the room. No sense talking to the elephant, he doesn’t speak our language (actually that’s a bad example, as intelligent mammals elephants have a lot in common with us…). Anyway we should be talking to significant others to try to build a team that can deal with the elephant.

Canto: Teamwork, that seems highly likely.

Jacinta: Yeah, I know everyone has a different agenda with regard to the elephant, but surely nobody wants to see anyone nuked. And the US shouldn’t be wasting its time talking to Australia, though I suspect Trump will be talking to Turnbull re troop commitments rather than any serious solution.

Canto: And by the way, we’re talking about Trump here, he’s never going to quit with the macho bluster. That’s a given.

Jacinta: All right so all we can do is hope – it’s out of our hands. But it seems to me that all his advisers are telling him a first strike isn’t an option, so maybe he will listen.

Canto: Maybe he’ll listen about the first strike, but he won’t stop the bluster and the goading. So Kim will continue to react by testing missiles and such, until something goes horribly wrong, and Trump will feel justified in delivering a second strike, and things’ll get very bloody and messy.

Jacinta: Okay, you’re getting me depressed, but if I can return to teamwork, the thing to do is get the team on board – the UN as well as the key players, China, Russia and of course South Korea and Japan. That means putting aside all the bad blood and really working as a team.

Canto: To do what? Get NK to stop producing nukes? Putin has already said that would be a no-goer, given their position.

Jacinta: Right, so that would be a starting point for discussion. Why does Putin think that, and what would be his solution, or his advice? And China’s? I’m assuming everybody’s uncomfortable about NK, though some are clearly more uncomfortable than others. So get a discussion going. What does Russia think the US should do about NK? What does China think Russia should do? Does anyone have good advice for South Korea?

Canto: You’re being hopelessly naive. I suspect Russia and China would approach this issue with complete cynicism.

Jacinta: Well let’s be well-meaning rather than naive. I think we’re inclined to be a co-operative species. I think cynicism can dissipate when confronted with a genuine desire to listen and co-operate. You know I’ve described all of the main actors here – Trump, Putin, Li Keqiang and his henchmen, and of course Kim Jong-un, as macho scumbags and the like, but maybe its time to appeal to the better angels of their natures, and ours, to find a peaceful resolution to this mess.

Written by stewart henderson

September 6, 2017 at 12:22 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)

Written by stewart henderson

September 5, 2017 at 10:08 am

who really discovered this land?

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a chart of early human migrations – and discoveries – based on mitochondrial DNA

I recently heard some rather absurd but unsurprising remarks by the conservative commentator Georgina Downer, defending an inscription on a statue of Captain Cook which states that he was the discoverer of Australia. Downer claimed that this is patently, unarguably true, since he was the first person to map the country (or part of it).

But let me be quite precise about the issue. The statue has the inscription: “discovered this territory 1770”. Unfortunately I can’t find video online of Downer’s words, but I’m pretty sure I got the gist of it: to her it was obviously true that Cook was the country’s discoverer – because he mapped it.

As a teacher of English and a person interested in linguistics and the meanings of words, let me just take a look at the verb ‘discover’. A quick googling brings up these two most pertinent meanings: find unexpectedly or during a search; be the first to find or observe. Three other less relevant meanings are given, but of course none of them mention mapping or anything like it. It would certainly be a shocker if mapping was mentioned, in defining the discovery of a territory. Having said that, ‘discover’ is ambiguous in this context. We can be enticed by adverts to discover the Greek Islands, or the wonders of the Great Barrier Reef. This is in line with one of the other definitions, which now maybe seems more relevant: be the first to recognize the potential of (or in this case the more personal to recognise the potential (or beauty) of something for the first time. That’s my own definition, but I think it’s generally acceptable). In this sense it would be fair to say Cook discovered Australia in 1770, but then it would also be fair to say my parents discovered Australia in 1962, when they first arrived here, just as I discovered David Bowie as a sixteen-year-old in 1972. Clearly that’s not the sense of ‘discovered’ intended by the inscription, or by Downer.

But before I continue down that rabbit-hole, let’s look at the inscription’s other keyword. The word ‘territory’ is a little ambiguous here. The statue is in Sidney’s Hyde Park – does the discovery refer to the whole of Australia, the territory in the neighbourhood of the statue, or the part of Australia that Cook mapped (less than a quarter of the country’s coastline, and none of the interior)? Dictionaries won’t be of much help here, so I’ll just hope to be on safe territory in assuming the whole kit and caboodle is intended, i.e. the land now known as Australia.

Downer’s comments added a tiny wind to the storm of controversy raised by the respected Aboriginal journalist and commentator Stan Grant. I find his essays (linked below) on the subject of our history and monuments to be thought-provoking and valuable. What he writes about the hubris of colonising Europeans in earlier centuries is undoubtedly true, though we only see it in hindsight, for what would my attitude have been as a good citizen of Europe from the 16th through to the 19th century?

But I’m not, I’m a more or less global citizen of the 21st century, painfully aware of the thoughtless arrogance of the terra nullius idea and the white colonisation system of the past, not confined of course to this territory. That’s not to say that I can put myself into the minds of those whose ancestors have been in this land for tens of thousands of years, when they read the above-mentioned controversial inscription. I can, though, see clearly that what happened in 1788 was a land-grab, as I’ve already written here and here, and I well understand why two High Court justices have described the consequent dispossession as ‘a legacy of unutterable shame’. So it amazes me that people like Downer can be so cavalier in claiming that Cook’s ‘discovery’ was unarguable. Cook did not discover this territory. The human who did discover it, that first person, will never be known to us. That discovery was made long long before records were kept. It was certainly a momentous discovery, though, for it brought many people to this vast territory, which may then have been very different from the parched land we know today. They spread throughout its vast extent, adapted to and interpreted its varied and changing climate and landscapes, created homes and tools and songs and stories and rituals and languages and knowledge, and endured here – more than endured – for some 60,000 years.

Cook was a very important, indeed decisive figure in Australian history, and he should be remembered as such, but not as the discoverer of this territory. As the cliché goes, if we don’t know our history we’ll be doomed to repeat it.


Written by stewart henderson

August 30, 2017 at 9:01 am

what are capacitors?

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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