Archive for the ‘technology’ Category
some stuff on super-grids and smart grids
In a recent New Scientist article, ‘The rise of supergrids’, I learned that Australia is among 80 countries backing a project, or perhaps an idea for a project, launched at COP26 in Glasgow, called One Sun One World One Grid, ‘a plan to massively expand the reach of solar power by joining up the electricity grids of countries and even entire continents’. My first reaction was cynicism – Australia’s successive governments have never managed to come up with a credible policy to combat global warming or to develop renewable energy, but they love to save face by cheering on other countries’ initiatives, at no cost to themselves.
Our state government (South Australia) did invest in the construction of a giant lithium ion battery, the biggest of its kind at the time (2017), built by Tesla to firm up our sometimes dodgy electricity supply, and, to be fair, there’s been a lot of state investment here in wind and solar, but there’s been very little at the national level.
At the global level, the Chinese thugocracy has been talking up the idea of a ‘global energy internet’ for some years – but let’s face it, the WEIRD world has good reason not to trust the CCP. Apparently China is a world leader in the manufacture and development of UHVDC (ultra-high voltage direct current) transmission lines, and is no doubt hoping to spread the algorithms of Chinese technological and political superiority through a globe-wrapped electrical belt-and-road.
But back in the WEIRD world, it’s the EU that’s looking to spearhead the supergrid system. It already has the most developed international system for trading electricity, according to the Financial Review. And of course, we’re talking about renewable energy here, though an important ancillary effect would be trade connections within an increasingly global energy system. There’s also an interest, at least among some, in creating a transcontinental supergrid in the US.
Renewable sources such as solar and wind tend to be generated in isolated, low-demand locations, so long-distance transmission is a major problem, especially when carried out across national boundaries. Currently the growth has been in local microgrids and battery storage, but there are arguments about meshing the small-scale with the large scale. One positive feature of a global energy network is that it might just have a uniting effect, regardless of economic considerations.
But of course economics will be a major factor in enticing investment. Economists use an acronym, LCOE, the levelized cost of electricity, when analysing costs and benefits of an electrical grid system. This is a measure of the lifetime cost of a system divided by the energy it produces. The Lappeenranta University of Technology in Finland used this and other measures to analyse the ‘techno-economic benefits of a globally interconnected world’, and found that they would be fewer than those of a national and subnational grid system, which seems counter-intuitive to me. However the analysts did admit that a more holistic approach to the supergrid concept might be in order. In short, more research is needed.
Another concept to consider is the smart grid, which generally starts small and local but can be built up over time and space. These grids are largely computerised, of course, which raises security concerns, but it would be hard to over-estimate the transformative nature of such energy systems.
Our current grid system was pretty well finalised in the mid-twentieth century. It was of course based on fossil fuels – coal, gas and oil – with some hydro. The first nuclear power plant – small in scale – commenced operations in the Soviet Union in 1954. With massive population growth and massive increases in energy demand (as well as a demand for reliability of services) more and more power plants were built, mostly based on fossil fuels. Over time, it was realised that there were particular periods of high and low demand, which led to using ‘peaking power generators’ that were often switched off. The cost of maintaining these generators was passed on to consumers in the form of increased tariffs. The use of ‘smart technology’ by individuals and companies to control usage was a more or less inevitable response.
Moving into the 21st century, smart technology has led to something of a battle and an accommodation with energy providers. Moreover, combined with a growing concern about the fossil fuel industry and its contribution to global warming, and the rapid development of variable solar and wind power generation, some consumers have become increasingly interested in alternatives to ‘traditional’ grid systems, and large power stations, which can, in some regions, be rendered unnecessary for those with photovoltaics and battery storage. The potential for a more decentralised system of mini-grids for individual homes and neighbourhoods has become increasingly clear.
Wikipedia’s article on smart grids, which I’m relying on, is impressively fulsome. It provides, inter alia, this definition of a smart grid from the European Union:
“A Smart Grid is an electricity network that can cost efficiently integrate the behaviour and actions of all users connected to it – generators, consumers and those that do both – in order to ensure economically efficient, sustainable power system with low losses and high levels of quality and security of supply and safety. A smart grid employs innovative products and services together with intelligent monitoring, control, communication, and self-healing technologies in order to:
- Better facilitate the connection and operation of generators of all sizes and technologies.
- Allow consumers to play a part in optimising the operation of the system.
- Provide consumers with greater information and options for how they use their supply.
- Significantly reduce the environmental impact of the whole electricity supply system.
- Maintain or even improve the existing high levels of system reliability, quality and security of supply.
- Maintain and improve the existing services efficiently.”
So, with the continued growth of innovative renewable energy technologies, for domestic and industrial use, and in particular with respect to transport (the development of vehicle-to-grid [V2G] systems), we’re going to have, I suspect, something of a technocratic divide between early adopters and those who are not so much traditionalists as confused about or overwhelmed by the pace of developments – remembering that most WEIRD countries have an increasingly ageing population.
I’m speaking for myself here. Being not only somewhat long in the tooth but also dirt poor, I’m simply a bystander with respect to this stuff, but I hope to to get more integrated, smart and energetic about it over time.
References
Global supergrid vs. regional supergrids
electric vehicles in Australia – how bad/good is it?
Following on from the interview with Prof Mark Howden that I reported on recently, I’m wondering what the situation is for anyone wanting to buy an EV in Australia today. What’s on the market, what are the prices, how is the infrastructure, and what if, like me, you might want just to hire an EV occasionally rather than own one?
Inspired by Britain’s Fully Charged show, especially the new episodes entitled Maddie Goes Electric, I’m going to do a little research on what I fully expect to be the bleak scenario of EV availability and cost in Australia. Clearly, we’re well behind the UK in terms of the advance towards EV. One of Maddie’s first steps, for example, in researching EVs was to go to a place called the Electric Vehicle Experience Centre (EVEC), for a first dip into this new world. I cheekily did a net search for Australia’s EVEC, but I didn’t come up completely empty, in that we do have an Australian Electric Vehicle Association (AEVA) and an Electric Vehicle Council (EVC), which I’ll have to investigate further. Maddie also looked up UK’s Green Car Guide, and I’ve just learned that Australia has a corresponding Green Vehicle Guide. I need to excuse my ignorance up to this point – I don’t even own a car, and haven’t for years, and I’m not in the market for one, being chronically poor, and not having space for one where I live, not even in terms of off-street parking, but I occasionally hire a car for holidays and would love to be able to do so with an EV. We shall see.
So the Green Vehicle Guide ranks the recently-released all-electric Hyundai Ioniq as the best-performing green vehicle on the Australian market (that’s performance, not sales, where it seems to be nowhere, probably because it’s so new). It’s priced at somewhere between about $35,000 and $50,000. Here’s what a car sales site has to say:
The arrival of the Hyundai IONIQ five-door hatchback signals Australia is finally setting out on its evolution to an electrified automotive society. The IONIQ is the cheapest battery-electric vehicle on sale in Australia and that’s important in itself. But it’s also significant that Australia’s third biggest vehicle retailer has committed to this course when most majors aren’t even close to signing off such a vehicle. In fact, just to underline Hyundai’s push into green motoring, the IONIQ isn’t just a car; it’s a whole range with three drivetrains – hybrid, plug-in and EV.
I need to find out the precise difference between a hybrid and a plug-in… It’s steep learning curve time.
Anyway, some reporting suggests that Australia’s bleak EV situation is turning around. This Guardian article from August 2019 predicts that EV sales are set to rise significantly, regardless of government inaction:
Modelling suggests the electric vehicle share of new car sales in Australia will rise from about 0.34% today to 8% in 2025. It is predicted to then leap to 27% of new car sales in 2030 and 50% in 2035 as prices of electric car technology fall.
2025 isn’t far off, so I’m a bit skeptical of these figures. Nevertheless, I’ll be monitoring the Australian EV scene more closely from now on.
References
https://www.iea.org/policies/7885-a-national-strategy-for-electric-vehicles
https://www.greenvehicleguide.gov.au/
Maddie Goes Electric, Episode 1: Choosing your electric car (A beginner’s guide) | Fully Charged
notes on the electrification of air travel
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
technomagic – the tellingbone
The telephone remains the acme of electrical marvels. No other thing does so much with so little energy. No other thing is more enswathed in the unknown.
Herbert Casson ‘The history of the telephone”, 1910. Quoted in “The Information”, J Gleick
I recently had a conversation with someone of my generation about the technology of our childhoods, and how magical they seemed to us. So let me start with the motor car, or auto-mobile. Our first family car was a Hillman Minx, which was bought in maybe 1964 or so, not too long after we arrived in Australia. The model probably dated from the early or mid-fifties – we certainly weren’t wealthy enough to buy a brand new car. But that didn’t make it any less magical. How was it that you could turn a key and bring an engine to life, and with a bit of footwork and handiwork get the beast to move backward and forward and get its engine to putter or roar? I hadn’t the foggiest.
Next in the mid-sixties came the television box, fired by electrickery. Somehow, due to wires and signals, we could see a more or less fuzzy image of grey figures from faraway, giving us news of Britain and the World Cup, and shows from the USA like Hopalong Cassidy and the Cisco Kid, all made from faraway – even one day from the moon – for our entertainment and enlightenment. Wires and signals, I mean, WTF?
Next we became the first people in the street to have our own tellingbone (or that’s what we proudly told ourselves, actually we had no idea). So people would ring us from the other side of town and then talk to us as if they were standing right next to us!! It was crazy-making, yet people seemed generally to remain as sane as they had been. I would lie in bed trying to work it out. So someone would dial a number, and more or less instantaneously a ringing sound would come out of the phone miles and miles away, and a person there would pick up this bone-shaped piece of plastic with holes in it, and they would talk into one end and listen through the other end, and they could hear this person on the ‘end of the line’ miles away far better than they could hear someone else talking in the next room, all thanks, we were informed, to those wires and signals again.
So, forward to adulthood. One of the most informative books I’ve read in recent years is titled, appropriately enough, The Information, by James Gleick. It’s a history of information processing and communication from tribal drumming to the latest algorithms, and inter alia it tells the story of how the telephone became one of the most rapidly universalised forms of information transfer in human history in the period 1870-1900, approximately. And of course it didn’t come into existence out of nowhere. It replaced the telegraph, the first electrical telecommunications system, itself only a few decades old. Previous to this there were many experiments and developments in the field by the likes of Alessandro Volta, Johann Schweigger and Pavel Schilling. Studying electricity and its potential was the hottest of scientific activities throughout the 19th century, especially the first half.
The telegraph, though, was a transmission-reception system run by experts, making it very unlike the telephone. Gleick puts it thus:
The telegraph demanded literacy; the telephone embraced orality. A message sent by telegraph had first to be written, encoded and tapped out by a trained intermediary. To employ the telephone, one just talked. A child could use it.
Nevertheless the system of poles and wires, the harnessing of electricity, and the concepts of signal and noise (both abstract and exasperatingly practical) had all been dealt with to varying degrees of success well before the telephone came along.
So now let’s get into the basic mechanics. When we talk into a phone we produce patterned sound waves, a form of mechanical energy. Behind the phone’s mouthpiece is a diaphragm of thin metal. It vibrates at various speeds according to the patterned waves striking it. The diaphragm is attached to a microphone, which in the early phones consisted simply of carbon grains in a container attached to an electric current, which were compressed to varying degrees in response to the waves vibrating the diaphragm, modulating the current. That current flows through copper wires to a box outside your home which connects with other wires and cables in a huge telecommunications system.
Of course the miracle to us, or to me, is how a sound wave signal, moving presumably more or less at the speed of sound, and distinctive for every human (not to mention dogs, birds etc), can be converted to an electrical signal, moving presumably at some substantial fraction of the speed of light, then at the end of its journey be converted back to a mechanical signal with such perfect fidelity that you can hear the unmistakeable tones of your grandmother at the other end of the line in real time. The use of terms such as analogue and digitising don’t quite work for me, especially when combined with the word ‘simply’, which is often used. In any case, the process is commonplace enough, and has been used in radio, in recorded music and so forth.
It all bears some relation to the work of the greatest physical theorist of the 19th century, James Clerk Maxwell, who recognised and provided precise relationships between electrical impulses, magnetism and light, bringing the new and future technologies together, to be amplitude-modified by engineers who needed to understand the technicalities of input, output, feedback, multiplexing, and signal preservation. But as the possibilities of the new technology expanded, so did technological expertise, and switchboards and networks became increasingly complex. They eventually required a numbering system to keep track of users and connections, and telephone directories were born, only to grow in size and number, costing acres of forestry, until in the 21st century they didn’t. I won’t go into the development of mobile and smartphones here, those little black boxes of mystery which I might one day try to peer inside, but I think I’ve had enough armchair demystifying of the technomagical for one day.
Yet something I didn’t think of as a child was that the telephone was no more technomagical than just speaking and listening to the person beside you. To speak, to make words and sentences out of sounds, first requires a sound-maker (a voice-box, to employ a criminally simplistic term), then a complex set of sound-shapers (the tongue, the soft and hard palates, the teeth and lips) into those words and sentences. Once they leave the speaker’s lips they make waves in the air – complex and variable waves which carry to the hearer’s tympanum, stimulating nerves to send electrical impulses to the auditory cortex. This thinking to speaking to listening to comprehending process is so mundane to us as to breed indifference, but no AI process comes close to matching it.
References
The information, James Gleick, 2011
https://electronics.howstuffworks.com/telephone1.htm
reflections on base load, dispatchable energy and SA’s current situation
Canto: So now we’re going to explore base load. What I think it means is reliable, always available energy, usually from fossil fuel generators (coal oil gas), always on tap, to underpin all this soi-disant experimental energy from solar (but what about cloudy days, not to mention darkness, which is absence of light, which is waves of energy isn’t it?) and wind (which is obviously variable, from calm days to days so stormy that they might uproot wind turbines and send them flying into space, chopping up birds in the process).
Jacinta: Well we can’t think about base load without thinking about grids. Our favourite Wikipedia describes it as ‘the minimal level of demand on an electrical grid over a span of time’. So the idea is that you always need to cover that base, or you’ll be in trouble. And an electrical grid is a provision of electrical service to a particular community, be it a suburb, a city or a state.
Canto: Right, I think, and what I like about Wikipedia is the way it sticks it to the back-facing thinkers, for whom base load always means provision from traditional providers (coal oil gas).
Jacinta: Yes, let’s rub it in by quoting Wikipedia on this.
When the cheapest power was from large coal and nuclear plants which could not be turned up or down quickly, they were used to generate baseload, since it is constant, and they were called “baseload plants.” Large standby reserves were needed in case of sudden failure of one of these large plants. Unvarying power plants are no longer always the cheapest way to meet baseload. The grid now includes many wind turbines which have such low marginal costs that they can bid lower prices than coal or nuclear, so they can provide some of the baseload when the wind blows. Using wind turbines in areas with varying wind conditions, and supplementing them with solar in the day time, dispatchable generation and storage, handles the intermittency of individual wind sources.
Canto: So the times are a-changing with respect to costs and supply, especially as costs to the environment of fossil fuel supplies are at last being factored in, at least in some parts of the world. But let’s keep trying to clarify terms. What about dispatchable generation, and how does it relate to base load?
Jacinta: Well, intermittent power sources, such as wind and solar, are not dispatchable – unless there’s a way to store that energy. Some renewable energy sources, such as geothermal and biomass, are dispatchable, but they don’t figure too much in the mix at present. The key is in the word – these sources are able to be dispatched on demand, and have adjustable output which can be regulated in one way or another. But some sources are easier, and cheaper, to switch on and off than others. It’s much about timing; older generation coal-fired plants can take many hours to ‘fire up’, so their dispatchability, especially in times of crisis, is questionable. Hydroelectric and gas plants can respond much more quickly, and batteries, as we’ve seen, can respond in microseconds in times of crisis, providing a short-term fix until other sources come on stream. Of course, this takes us into the field of storage, which is a whole other can of – what’s the opposite of worms?
Canto: So this question of base load, this covering of ‘minimal’ but presumably essential level of demand, can be a problem for a national grid, but you can break that grid up presumably, going ‘off grid’, which I’m guessing means going off the national grid and either being totally independent as a household or creating a micro-grid consisting of some small community…
Jacinta: Yes and this would be the kind of ‘disruptive economy’ that causes nightmares for some governments, especially conservative ones, not to mention energy providers and retailers. But leaving aside micro-grids for now, this issue of dispatchability can be dealt with in a flexible way without relying on fossil fuels. Energy storage has proven value, perhaps especially with smaller grids or micro-grids, for example in maintaining flow for a particular enterprise. On the larger scale, I suppose the Snowy 2 hydro project will be a big boon?
Canto: 2000 megawatts of energy generation and 175 hours of storage says the online ‘brochure’. But the Renew Economy folks, who always talk about ‘so-called’ base load, are skeptical. They point to the enormous cost of the project, which could escalate, due, among other things, to the difficulties of tunnelling through rock of uncertain quality. They feel that government reports have over-hyped the project and significantly downplayed the value of alternatives, such as battery electric storage systems, which are modular and flexible rather than this massive one-off project which may be rendered irrelevant once completed.
Jacinta: So let’s relate this to the South Australian situation. We’re part of the national grid, or the National Energy Market (NEM), which covers SA and the eastern states. This includes generators, transformers (converting low voltage to high voltage for transport, and then converting back to low voltage for distribution), long distance transmission lines and shorter distance distribution lines. So that’s wholesale stuff, and it’s a market because different companies are involved in producing and maintaining the system – the grid, if you like.
Canto: I’ve heard it’s the world’s largest grid, in terms of area covered.
Jacinta: I don’t think so, but it depends on what metric you use. Anyway, it’s pretty big. South Australia has been criticised by the federal government for somehow harming the market with its renewables push. Also, it was claimed at least a year ago that SA had the highest electricity prices in the world. This may have been an exaggeration, but why are costs so high here? There are green levies on our bill, but I think they’re optional. Also, the electricity system was privatised in the late 90s, so the government has lost control of pricing. High-voltage transmission lines are owned by ElectraNet, part-owned by the Chinese government. The lower voltage distribution lines are operated by SA Power Networks, majority-owned by a Hong Kong company, and then there are the various private retailers. It’s hard to work out, amongst all this, why prices are so high here, but the closure of the Northern coal-fired power station in Port Augusta, which was relatively low cost and stable, meant a greater reliance on more expensive gas. Wind and solar have greater penetration into the SA network than elsewhere, but there’s still the intermittency problem. Various projects currently in the pipeline will hopefully provide more stability in the future, including a somewhat controversial interconnector between SA and NSW. Then there’s the retail side of things. Some retailers are also wholesalers. For instance AGL supplies 48% of the state’s retail customers and controls 42% of generation capacity. All in all, there’s a lack of competition, with only three companies competing for the retail market, which is a problem for pricing. At the same time, if competitors can be lured into the market, rather than being discouraged by monopoly behaviour, the high current prices should act as an incentive.
Jacinta: I don’t know about that, but before the Tesla battery came online the major gas generators – who are also retailers – were using their monopoly power to engage in price gouging at times of scarcity, to a degree that was truly incredible – more so in that it was entirely legal according to the ACCC and other market regulators. The whole sorry story is told here . So I’m hoping that’s now behind us, though I’m sure the executives of these companies will have earned fat bonuses for exploiting the situation while they could.
Canto: So prices to consumers in SA have peaked and are now going down?
Jacinta: Well the National Energy Market has suffered increased costs for the past couple of years, mainly due to the increased wholesale price of gas, on which SA is heavily reliant. It’s hard to get reliable current data on this online, but as of April this year the east coast gas prices were on their way down, but these prices fluctuate for all sorts of reasons. Of course the gas lobby contends that increased supply – more gas exploration etc – will solve the problem, while others want to go in the opposite direction and cut gas out of the South Australian market as much as possible. That’s unlikely to happen though, in the foreseeable, so we’re likely to be hostage to fluctuating gas prices, and a fair degree of monopoly pricing, for some time to come.
an assortment of new technology palaver
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
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.
the tides – a massive potential resource?
A floating tidal turbine, Orkney islands, as seen on Fully Charged
A recent episode of Fully Charged, the Brit video series on the sources and harnessing of clean energy, took us again to the very windy Orkney Isles at the top of Scotland to have a look at some experimental work being done on generating energy from tidal forces. When you think of it, it seems a no-brainer to harness the energy of the tides. They’re regular, predictable, unceasing, and in some places surely very powerful. Yet I’ve never heard of them being used on an industrial scale.
Of course, I’m still new to this business, so the learning curve continues steep. Tide mills have been used historically here and there, possibly even since Roman times, and tidal barrages have been operating since the sixties, the first and for a long time the largest being the La Rance plant, off the coast of Brittany, generating 240 MW. A slightly bigger one has recently been built in Korea (254 MW).
But tidal barrages – not what they’re testing in the Orkneys – come with serious environmental impact issues. They’re about building a barrage across a bay or estuary with a decent tidal flow. The barrage acts as a kind of adjustable dam, with sluice gates that open and close, and additional pumping when necessary. Turbines generate energy from pressure and height differentials, as in a hydro-electric dam. Research on the environmental impact of these constructions, which can often be major civil engineering projects, has revealed mixed results. Short-term impacts are often devastating, but over time one type of diversity has been replaced by another.
Anyway, what’s happening in the Orkneys is something entirely different. The islanders, the Scottish government and the EU are collaborating through an organisation called EMEC, the European Marine Energy Centre, to test tidal power in the region. They appear to be inviting innovators and technicians to test their projects there. A company called ScotRenewables, for example, has developed low-maintenance floating tidal turbines with retractable legs, one of which is currently being tested in the offshore waters. They’re designed to turn with the ebb and flood tides to maximise their power generation. It’s a 2 MW system, which of course could be duplicated many times over in the fashion of wind turbines, to generate hundreds if not thousands of megawatts. The beauty of the system is its reliability – as the tidal flow can be reliably predicted at least eighteen years into the future, according to the ScotRenewables CEO. This should provide a sense of stability and confidence to downstream suppliers. Also, floating turbines could easily be removed if they’re causing damage, or if they require maintenance. Clearly, the effect on the tidal system would be minimal compared to an estuarine barrage, though there are obvious dangers to marine life getting too close to turbines. The testing of these turbines is coming to an end and they’ve been highly successful so far, though they already have an improved turbine design in the wings, which can be maintained either in situ or in dock. The design can also be scaled down, or up, to suit various sites and conditions.
rotors are on retractable legs, to protect from storms, etc
Other quite different turbine types are being tested in the region, with a lot of government and public support, but I got the slight impression that commercial support for this kind of technology is somewhat lacking. In the Fully Charged video on this subject (to which I owe most of this info), Robert Llewelyn asked the EMEC marketing manager whether she thought tidal or wave energy had the greatest future potential (she opted for wave). My ears pricked up, as wave energy is another newie for me. Duh. Another post, I suppose.
As mentioned though in this video, a lot of the developments in this tidal technology have come from shipbuilding technology, from offshore oil and gas technology, and from maritime technology more generally, as well as modern wind turbine technology, further impressing on me that skills are transferable and that the cheap clean energy revolution won’t be the economic/employment disaster that the fossil fuel dinosaurs predict. It’s a great time for innovation, insight and foresight, and I can only hope that more government and business people in Australia, where I seem to be stuck, can get on board.
fixed underwater tidal turbine being tested off the Orkney Islands
capacitors, supercapacitors and electric vehicles
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://articles.sae.org/11845/
https://www.ptua.org.au/myths/tram-emissions/
http://www.europlat.org/capabus-the-finest-advancement-for-electric-buses.htm
what are capacitors?
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.