Some thoughts on energy storage

A lot of the discussion of my last post on energy issues was devoted to discussion of energy storage. Rather than get involved in that, I thought I’d collect my own thoughts on this. Broadly speaking, Here are some observations, labelled for convenience and partly derived from this study by the US Department of Energy

(a) Any reversible energetic process represents a potential storage technology. Reversibility entails that some energy is stored (as potential or chemical energy) when the process goes one way, and released when it goes the other. Of course, the Second Law of Thermodynamics implies that we will always add entropy (that is, lose useful energy) in this process
(b) Any technical or social change that shifts the time at which energy is finally used replicates the effects of storage
(c)Energy storage is in much the same position as renewable electricity generation was, say, 15 years ago.
(d) There are a lot of potential approaches, most of which have been developed in niches where particular characteristics are required. For example, car batteries need to store a lot of energy for given weight, household batteries need to store energy for a long time and so on. The needs of a renewable-dominated electricity system are very different and will require substantial modifications of these technologies
(e) With one big exception, there is currently no price incentive, in most jurisdictions to use storage technologies and therefore none are used
(f) The big exception is off-peak hot water. Coal and nuclear systems generate baseload supply when it is not needed for consumption. Price incentives are used to encourage people to store the resulting excess energy in the form of hot water
(g) There’s no technological obstacle, given the availability of smart meters, to changing the timing of hot water systems to reflect actual availability of excess electricity rather than reflecting the assumptions of a coal-based system
(h) All of this applies to electric cars. Even ignoring the possibility of feeding power back into the grid, the economics of electric cars would be drastically improved if they could be charged using low-cost power in times of excess supply (in the case of solar PV, around midday when lots of cars are sitting in parking lots)
(i) Something I just found out from the DoE study: Electric car batteries are considered unfit for services when they fall to 80 per cent of their original charge capacity (recall that energy density is critical for car batteries). But they still have a long potential life as static storage devices. This enhances both the economics of electric cars (since the battery has resale value) and of storage (since the opportunity cost is zero)

Here’s an older post, with a really simple example of how the argument works, once you get away from the fixation on replicating the characteristics of a coal-fired system.

107 thoughts on “Some thoughts on energy storage

  1. My answer to your main point, Hermit, the “rainy week” defense, is that in my preferred model cooking is done with gas. This dramatically alters the primary energy load for the system at the expense of a small amount of CO2 emission. Solar still generates on cloudy days 25 to 30% so refrigeration, lighting and entertainment are secured from that solar “base” capacity. that leaves washing clothes, pumping the pool and a bunch of other things which can be delayed until full capacity is restored. It is all a matter of specifying the system appropriately. It is tempting to say that there is the Whisper gen for backup but that is not working out so well in Europe.

    There is a trend with denialist comment to assume that the technology game is over. What we’ve got is all there will be and the future swings on that for renewables. But for nuclear one can imagine just about anything to be certain no matter how whacky.

    My reading tells me that fuel cells for energy backup are realistic and the preferred one will operate using sugars as fuel, but I don’t want to hang my hat on that. Where I am I can use fireword for backup and we would have to think back to our Julius Sumner Miller Summer Science Series to see how that can provide electrical backup as well as heat.

    Of coarse most houses will remain connected to the grid and balance their power that way, but 10 years out that may become increasingly more optional.

  2. @Hermit

    Solar convection towers work 24/7! We can always have reliable, renewable power at night! Do you understand the principle of such towers? Do you understand the practical impact?

    As I wrote elsewhere, solar convection towers may not be as efficient as solar PV but by obviating much need for energy storage they will be part of the solution for a 24 hour renewable grid.

    A renewable grid can supply adequate power 24/7 by a combination of;

    (a) wide geographical distribution;
    (b) different types of generation (Solar PV, Solar Convection, Wind, Geothermal etc.)
    (c) energy storage;
    (d) computerised projection and control of production, consumption and pricing.
    (e) switching in and out of time-moveable and discretionary loads.*
    (f) passive design including good insulation and efficiency to reduce load demands.
    (g) if necessary dedicated 24/7 generators for heavy industrial power (these will be hydro systems and large solar convection towers about 1000m high.)

    * Electrical hot water heating is often time-moveable. Domestic air-conditioning can be remotely switched on and off on a rolling basis such that no individual room or home will noticeably heat up but power peaks will be flattened on a grid-wide basis. People who don’t want their air-con de-powered at such times on hot days can have back-up solar panels to keep their air-con running.

    Hermit, there are so many possibilities it is positively exciting, extremely interesting and challenging. However, you close your mind totally to all of these possibilities. I wonder if it is because you are not taking the trouble to comprehend complex, interacting, synergistic solutions. You seem to only comprehend or want to comprhened single, massive, silver bullet (uranium bullet!?) solutions. Energy comes in many forms and can be harnessed in many ways. The whole energy problem lends itself to eclectic, diverse, complex and synergistic solutions. Being invested in a single massive crash or crash-through solution is not the way to address the many-faceted energy problem.

  3. I think it’s a matter of doing things a step at a time; we don’t need to begin with sufficient storage to do days or weeks of peak consumption even if that’s a long term goal. A few hours will let solar help shave the top off the evening peak as well as the daytime peak and that’s a good start. It’s the difference between fossil fuel plants sitting idle by day and ramping up every afternoon in the presence of low cost PV solar and sitting idle for days and weeks at a time.

    Storage R&D is only just beginning to get more than the energy funding leftovers, as an afterthought. I’d like to see major efforts to incorporate storage into the grid but I suspect it will be households with solar incorporating storage in order to avoid excessive and intentionally anti-solar billing practices that lead the way. A few KWhrs would see self consumption by PV fitted homes increase significantly whilst reducing evening load. Time of use metering will be a major incentive.

    Other points – the costs of fuel cells has dropped significantly in recent times and electolysers have improved; hydrogen may still have a role to play, especially in transport. Relevant is direct solar electrolysers – solar cells that make hydrogen and oxygen – which have a lot of potential in my opinion for domestic heating, cooling and cooking, given that such an application would not require the high levels of compression of H2 that go with transport.

  4. @Ken Fabian

    I am not convinced that hydrogen for fuel cells or directly for cooking has any chance of widespread application. Specialised applications for hydrogen fuel cells do have a future (especially in the military) but major transport systems will never run on them. It would be cheaper and easier to synthesise methane (CH4) and use that. Engine conversions are easier, piping, transport and storage are easier and energy density per unit volume is higher (talking compressed gases).

    However, clear away all the subsidies, implement appropriate safety standards for all energy forms, cost the negative externalities reasonably accurately and then let them compete in the market. That’s a policy with broad appeal I would think.

  5. @Ikonoclast
    I paid $11 for electricity last year. I did a 500 km trip never calling into a service station thanks to fuel made from cooking oil. I’m working on a microhydro and another renewable energy project. Please tell me where I’ve gone wrong.

  6. @Ikonoclast
    I’m not convinced about H2 at this point but the ground keeps shifting, sometimes quite quickly. I mentioned household use because cells that make it using sunlight do exist, didn’t sound outrageously costly and it has to be easier to deal with hydrogen on site at low pressures than at high pressures for transporting or use in vehicles. Electrolytic production of liquid fuels makes sense for transport in the absence of suitable batteries.

    The scale of the global situation seems daunting; whatever energy solutions need to be mass manufacturable. It’s starting off a low or non-existent base, yet we only need to look around to see complex technologies mass produced on huge scales, only to be obsolete and outmarketed in a couple of years. Compared to the vehicular requirements of a modern Australian family the addition to their home of PV plus storage sufficient for an evening is not that great a burden, even with exiting technologies. As the numbers doing so get very large, new challenges arise; they aren’t necessarily unforeseen or impossible. But ultimately I think that economies of scale can keep the electricity grid at the centre of the game. If those involved with it can get over their aversion to renewables.

  7. @Hermit

    You keep supporting nuclear power over renewable which is a big mistake. You don’t appear to pay attention to the wealth of research and advances in renewable power, energy storage and supply/demand prediction and management. Apart from that congrats, you are doing very well.

    BTW, my rooftop solar supplies all my electricity, hot water and a healthy profit of about $500 a quarter. Although, technically no profit will be realised for about 3 or 4 years as I pay off the capital and interest costs. After that it’s money for sunshine.

    Recent research shows that solar bonuses for grid input are deserved, economically speaking. The savings on grid infrastructure costs by flattening peaks are worth more than the solar bonuses paid. When I find the link again I will post it.

    Grid scale energy storage is being shown to assist conventional generation as well as renewable generation in terms of peak demand, rapid response dispatchability issues, frequency regulation and general dependability. The integration of renewables and energy storage is evolutionising our grids for the better.

  8. Oops I meant “revolutionising” but I suppose “evolutionising” is an almost acceptable neologism.

  9. A great many people seem to think that renewables require requires energy storage but this is not the case. The number of kilowatt-hours of storage the Australia’s electricity sector needs to add to go carbon neutral is zero. However, we may end up with a significant amount of storage as people find it profitable to store energy when it is cheap and then use or sell it when it is expensive. But even without any new storage Australia’s existing hydroelectric capacity, a change to retail spot pricing, and the ability to burn natural gas in existing power stations and then remove and sequester the CO2 released makes energy storage unnecessary. Note that this of course does not mean that low cost energy storage would not be useful, it just means it’s not required.

  10. Ronald, as a nation, no, we don’t need electricity storage (at a grid level anyway). But it seems certain to me that we’re not going to see a transition to renewable energy at a grid level either. That’s a political decision and the vote is overwhelmingly against the transition.

    So the question is: how can I, as a household or individual, go 100% renewable? With electricity it’s currently easier to just buy 100% wind power from one of the more ethical retails. But that leaves me open to the stupid games currently being talked about, where either I pay a significant price premium so that my neighbours can run their air conditioners buring heatwaves, and I might also get “selective” blackouts if the problem gets too bad. Or I go off grid. The blackout option means I might want to go “off grid” anyway, although in that case it’s more the grid going off me…

  11. @Moz in Oz

    It’s possible to have a solar power system connected to your house, to the grid and to your back-up battery bank. This system is then programmable with parameters to allow it to take power each hour (or each minute for that matter) from the cheapest source and feed the excess to the best destination based on prices.

    Your house will continue to have power during a blackout under this set-up. The size of your battery bank will determine to some extent what you can run. During an extended blackout (days on end) you might have to ration power to the fridge, one TV, one computer and a few lights altho I suspect you could power quite a bit more than this with a nominal 5.5 kW system which will generate at a a rate of 4 kW to 5 kW on a sunny day (for about 6 to 8 hours). On an overcast day you still get about 2 kW and on a dark, gloomy rainy day you get about 1 kW. Your solar hot water which you should have will also deliver hot or at least warm water if you are sparing with it. Forget aircon while the mains power is out and revert to hand-washing dishes and clothes.

    The above measures still represent a rather civilized existence during a blackout. If you live on acreage you can buy a back-up diesel generator, good brand for about $1,250 to $2,500 depending on capacity. On a city block the generator might be a bit annoying for neighbours.

    Admittedly the above options are not 100% renewable but they represent a good compromise. If you want to go 100% renewable then buy “hypothetical” wind power or go off grid. All electro motive force is created equal so the EMF at your house is the net result of all generation and all demand. It’s hypothetical to call it renewable if the grid generates a combination of renewable and non-renewable power. No doubt, the premium price you pay is not hypothetical.

    Bottom line, going 100% renewable off-grid is capital intensive up front and to be reasonably cost-effective you might need to accept a more energy-frugal lifestyle. Such a liefstyle would do most of us good, making us hardier and fitter.

  12. Moz, from an environmental point of view about the best thing a homeowner can do is send a lot of solar generated electricity into the grid as each kilowatt-hour sent out will be a kilowatt-hour that won’t be generated from coal or gas. Unfortunately supply charges give people with solar an incentive to drop off the grid and they may not be reduced or eliminated until people start leaving the grid. If you want to lead the charge, pease feel free to go for it, but it would be greener to stay on the grid and the value of the investment you made in going off grid will be reduced if supply charges are then removed. You may instead want to look into getting energy storage but staying on grid as with the right system you may soon be able to save money while still helping others by sending out your surplus solar electricity.

  13. Ikonoclast: we’re already a lot of the way there, having mostly the housemate who is wasteful and a fridge that will be replaced with a decent one when it breaks.

    I’ve actually got a wee spreadsheet running that I update every now and then to track the cost of running our current lifestyle off storage-backed PV, and it’s quite doable now even without cheap batteries. When we do it for real I suspect I will end up paying much less than my casual guesstimates, just from doing a bit of research into what’s available and how it works.

    I have thought of hiring an IR video camera and running round on a hot day looking for panels that are not working so I can offer to buy them cheap 🙂

  14. Ronald, I know, but there’s a limit to how much I’m willing to pay for the privilege of being allowed to make the system work better.

  15. Moz, good luck to you. Your jumping ship may result in improvements for the rest of us such as the dumping of supply charges that act as a subsidy paid by electrically frugal to the electrically prolifigate, and of course from the poor to the rich.

  16. Ronald, supply charges are at heart a reasonable idea. The cost of the grid is to some extent determined by its reach, so every subscriber should pay something. Unfortunately we’re now at the point where the larger part of the grid charge is for increasing capacity to cope with the profligate, and increased profitability (also to cope with the profligate :)) I have heard mention of charging big residential users a grid access premium, but that will be extremely unpopular withe the voters who count (the “marginal mcmansion battlers” and the “liberal-voting elite”) so I don’t think it will happen even if we get wall-to-wall ALP governments. Hence my expectation that at some point we will transition from grid-interactive to off-grid.

    I was wondering the other day about how exactly electricity connections are restricted, and whether we could get together with our neighbours and have one connection that we pay for as a co-op, splitting the bills internally as we see fit. Having done no research at all on this, I suspect there will be a restriction but I’m curious about how hard it would be to bypass (this caused, of course, by getting another power bill where the supply charge was significantly bigger than the consumption charge – and this in an apartment with no PV)

    I have to admit that some of my interest in this is pure technophilia.

  17. Ikonoclast, if people have a large enough battery storage system to meet their day to day needs, then most people should only need a small, cheap generator for backup as they can let it run and charge up the batteries. And a small one should also be quieter and less malodorous.

  18. Moz, supply charges are at heart about profit maximisation, not paying for distribution. They don’t even come close to covering the costs of distribution. Most of people’s electricity bills pay for distribution with only a small portion being the actual price paid to generators to produce electricity. Without supply charges electricity prices would go up per kilowatt-hour to keep revenue constant but poor people would pay less overall as they tend to use less electricity and rich people, or at least people who use a lot of grid electricity, would pay more. Having supply charges means the price per kilowatt-hour is lower than it would be without them and this discourages efficiency which is obviously something that appeals to a companies that make money selling electricity. But if the alternative is their customers simply start to disappear by going off grid, then electricity distribution companies would rather keep their customers and sell them a small amount of expensive but cheaper than diesel generator electricity than no electricity at all. If they are permitted, I would not be surprised if they attempt to keep supply charges for poor people while offering a special no supply charge deal for people with rooftop solar and energy storage.

  19. Ronald, I would love to have zero supply charge and only pay for consumption. But I can also see that that would make the “PV owners are not paying their fair share” argument unassailable. So politically it’s a dumb ask.

    I was in Melbun during the unexpected success of the “Target 155” campaign, where water consumption fell low enough to endanger the “profitability” of the citizen owned water companies. While I don’t like the way they’re set up, I can sympathise with the desire for a reasonably consistent income stream to allow the company to budget effectively. With declining electricity consumption and pressure on prices, I can see a real temptation for the companies to keep hiking the supply charge.

    Until we can get control of our grid back from “state owned companies” it’s very hard to make welfare-based arguments about how they should operate. When you add the confounding problems with funding our state governments, there’s a rare consensus between the libertarian “simplify the bureaucrazy” ethos and a left-wing “social infrastructure” argument. It would be cheaper and more equitable to fund government from direct taxes, not faux-company structures designed to funnel money to governments via usage charges for essential utilities while paying bureacrats inflated private-sector wages. But we’re moving away from that right now.

  20. Moz, it doens’t matter if politically it’s a dumb ask or not. If PV owners start dropping off grid they won’t be paying anything at all. In order for power companies to maximise their revenue they are going to need to keep people on the grid so they can sell them some electricity rather than no electricity. One way to keep people on grid might be to break the kneecaps of people who does go off grid. Another way would be to eliminate or greatly reduce supply charges but increase the cost of electricity per kilowatt-hour. Personally I’m hoping we get reduced supply charges. But I’m still investing in a sturdy pair of knee pads just in case.

  21. Ronald Brak :
    Ikonoclast, if people have a large enough battery storage system to meet their day to day needs, then most people should only need a small, cheap generator for backup as they can let it run and charge up the batteries. And a small one should also be quieter and less malodorous.

    Or you could just buy some power from avery big generator somewhere else :-_

  22. John Brookes, I take it you’ve come late to the conversation. The situation is that Australia faces the danger that if energy storage costs continue to decline and or retail electricity prices continue to rise, then with the current way people are charged for electricity those with solar PV may find it cheaper to purchase battery systems and a small generator and go off grid rather than remaining connected. Now it would be really stupid if we drove people off the grid by keeping pricing structures that are a relic of the coal age rather than changing the way people are charged for electricity and keeping them on the grid where their surplus solar energy can be utilized by others and they can purchase electricity at a lower cost than using a home generator. And if you don’t think we are close to the point where people are considering dropping off grid I will mention that my last electricity bill came to a total of 46 cents per kilowatt-hour I used and if I take it from the start of the new when prices increased it comes to just under 48 cents a kilowatt-hour.

  23. Large scale grid energy storage is probably something of a distraction right now: more renewables and dispatchable generation is better value for money regardless of carbon price until renewable penetration goes over 50% or so.

    However, the claim that pumped hydro is unfeasible for energy storage for a week or so appears to be wrong: many pumped schemes are sized for daily storage because this is what is needed, rather than what is possible. Norway’s pumped dams are a notable exception. Current non-pumped hydro schemes are designed to store around a year of energy at full output (to average over seasonal fluctuations).

    If you could install pumped hydro available between the existing dams in the snowy river scheme, moving water between Eucumbene and Blowering would give you about three weeks of power at 5GW.

    How much variation in wholesale power price you would need to make a decent return on investment is another issue.

  24. the economics of electric cars would be drastically improved if they could be charged using low-cost power in times of excess supply (in the case of solar PV, around midday when lots of cars are sitting in parking lots)

    If and when the day comes that solar PV actually generates an excess supply (which will be much further off in winter than in summer), then this may happen. Until then, it’s vaporware.

  25. We are always so serious, I can’t help posting this. 😀

    (Could be the ultimate thread derailer.)

  26. Chris O’Neill, at around noon today South Australia’s solar capacity was producing over two thirds as much electricity as the state’s coal power and meeting over 15% of demand. That’s pretty substantial for vapourware, which is software or hardware that has been advertised but isn’t available for purchase. Since solar power systems can be purchased right now and a number of people have purchased them and have them installed right at this moment, I’d be inclined to say it’s not vapourware at all. And while South Australia’s wholesale electricity prices still average higher during the day than they do in the wee hours of the morning, they are lower than what they were and getting lower as more solar is installed. On days of low demand its possible for wind and solar to result in very low daytime wholesale electricity prices, so solar power resulting in low electricity prices at around noon isn’t vapourware, but something that already happens at times in this state.

  27. Ronald, I think what Chris meant was that to be producing excess supply so as to be an off-peak power source for EVs, solar (or renewables) would need to be producing more than 100% of current demand. Clearly it’s well off that at this stage, although that’s not to say that it can’t or won’t get there.

  28. Tim, sometimes in South Australia renewables (wind and solar) do meet all demand. And in Tasmania thanks to their hydroelectricity capacity it happens all the time.

  29. @hix

    50cent per kwh for lion battery storage is far to high, … Standard battery prices are below 200 dollar/kwh.

    Li-ion are not standard batteries.

  30. @Tim Macknay

    Of course, Chris’s appeal misses the point. One can’t simply await the day that renewables can produce more than is demanded and then in one fell swoop summon the requisite PEV storage into existence — not in a market-driven system anyway. So to appeal against the utility of PEV storage on the basis that the supply system doesn’t yet consistently produce an excess is specious.

    One might also add that in a strictly market-driven system, excess supply is a market failure, punished by falling price and ROI.

  31. Moreover, there are indeed moments when renewable output exceeds supply. That is the point of storage after all — to balance those moments of under-supply with energy stored during over supply. Confusing that task with the overall net supply-demand relationship is likewise specious.

  32. In an earlier link I referred to the documentary “Who Killed the Eelctric Car?” This was about the electric car being killed in its first modern interation in the early 1990s. A second attempt is being made now to bring back the electric car.

    As the documentary makes clear Big Oil and Big Auto colluded to kill the electric car. GM made an electric car, refused to sell it (only leasing it), then withdrew it and destroyed it. Hundreds of good cars went to the crusher. They also made no proper effort to promote it. This was in the face of consumer demand (initially niche demand) for it. We can add the historical tearing up of America’s tram and rail systems to this pattern of killing electric and mass transit in favour of the gasoline automobile.

    This illustrates the way in which the Big Oil – Big Auto industrial complex actively kills possibilities. Any intiative that would be socially and industrially advantageous for us long term is deliberately killed. Possibilities are foreclosed if not for ever then for decades at a time.

    As one electric car pundit admitted way back in the early 1990s: “Electric cars aren’t for everyone. They are only suitable for 93% of all daily auto journeys.”

    Today we have the same thing with power generation. Big Oil, Big Coal and Big Nuclear have been actively trying to kill wind and solar power. The astonishing thing is that these renewable generation methods have progressed to the point they have. It’s a testament to their viability that they have progressed despite protracted and deliberate disinformation campaigns against them and in the face of MASSIVE subsidy biases towards Big Oil, Big Coal and Big Nuclear.

    The real crime by Big Oil, Big Coal and Big Nuclear was and is the deliberate killing of alternative technologies and the foreclosure of possibilities. The main possibilities foreclosed were the possibilities of saving the biosphere for continued human existence. Our chances are now much reduced. Every decade of delay does enormous damage to our chances of survival.

  33. It’s 10:53 am local time and solar is supplying about 15% of South Australia’s electricity use. Just thought I’d mention that now as I’m heading out.

  34. @Ronald Brak
    Ronald, I wasn’t aware that renewables do occasionally cover 100% of demand in SA – thanks for that. I think Tasmania is a little different as hydro power is dispatchable and shouldn’t really produce power excess to demand. With its hydro and wind resources, Tasmania ought to be an ideal test lab for transitioning to 100% renewable (including transport).

  35. @Tim Macknay
    The latest idea for Tasmania since they perceive themselves to be awash in clean energy is to build a silicon smelter. The new thinking seems to be to get high spot prices for hydro via Basslink cable then reimport cheap brown coal power at other times. Two flaws in that thinking- the dams might not refill when needed and wasting clean energy on air conditioners not industry. If they build another underwater cable it should have excess capacity in case excess mainland power is stored as pumped hydro, though it’s not really economical. Stored energy retrieval should be no more than an extra 5c per kwh or 1.5c/MJ at the point of use.

    @ikonoclast from what I can work all the solar updraft towers ever built have fallen in a heap. At least dry rock geothermal has a single megawatt power plant in the middle of the desert about 500 km from anyone who can gainfully use the power.

  36. Fran Barlow :Interesting
    http://shar.es/Qcp20

    so it looks like the businesses of conventional energy are,with the conservative/coalition regimes, flogging a failed market model

    while

    the creative,new energy model is hitting the spot with a free,transparent and competitive open market model.

    no?

  37. Tim, Tasmania is planning to go all renewable by 2020 in its electricity sector. As they are connected to the rest of the National Electricity Market I thought that might mean they will be producing more kilowatt-hours from renewable resources than they consume. But the interesting thing is that since demand has been declining in Tasmania they seem to be around that point already and it doesn’t look like to would take much to get them clearly past it. The output of hydro power varies, but perhaps from this year Tasmania will consistently produce more electricity from renewables than it consumes. Of course, according to this graph I’m looking at it wasn’t that long ago that Tasmanian electricity was basically all hydro.

  38. Hermit, I read a bit about aluminium smelters a little while back and good news! It appears that your fears about them were almost entirely unfounded. It seems that provided they are not actually turned off they can be very variable in the rate at which they smelt and this means they can work very well in a grids that have a lot of wind and solar pentration as they can take advantage of the low prices they cause when it’s sunny and/or windy to smelt at full capacity and then at other times when electricity prices are higher they can slow down their smelting rate and greatly reduce energy use. Slowing down smelting will increase the capital cost of aluminium per kilogram produced but it can be well worth it, particularly since aluminium smelting capital isn’t worth much in the world today.

  39. I think the 2013 figure was that Tasmania was 86% powered by renewables. However that comes of top of a run of rainy years which may or may not happen again for a while. Because of the immediate power ramp rate for hydro unlike most thermal plant (especially those using steam) they can use a lot of wind power when the wind is blowing and open the hydro valves when the wind drops. It’s a shame there’s not really any good nimby free transmission linked sites to build large new dams. Maybe we should have an underwater cable to PNG.

    The ability of some big power users to cut back in heatwaves seems to be better than anticipated. Some metal winning processes are aqueous (Cu) and can be halted others (Al, Fe-Mn alloy) require molten metal and/or salt flux which has to be kept hot. It would be nice to know what sweeteners were offered. If it means overgenerous power discounts later we’re all paying.

  40. @Ronald Brak
    Ronald. I watch aluminium ‘slugs’ or castings getting exported and wonder if that means re-smelting – with consequent energy use – to produce end product extrusions etc, why that process could not be done initially.

  41. Peter, most of the energy goes into separating the elemental aluminoum from the ore and this requires a lot of electricity. After that’s done the slugs are transported and more energy is used to melt the aluminium for say die casting, but this requires heat energy which is cheaper per joule than electricity and the melting point of aluminium is low, or at least it is compared to iron. So the energy required to process the aluminium slugs is much less than what’s requires to make the slugs in the first place. Now maybe when the aluminium is extracted from the ore it would be possible to make it into a more convenient shape than a slug, but I have no idea how that might be done in practice.

  42. A US firm is supplying fridge sized lithium ion batteries and predictive management systems that are being taken up by convenience stores to help reduce power bills in hot weather
    http://www.greenchargenet.com/products.html
    The batteries have their own cooling systems. Peak pricing appears to be more commonplace in the US than in Australia where we tend to have time of day of day pricing regardless of weather.

    Can something like this eventually be done for pensioners trying to survive 47C heat in a brick veneer home?

  43. That’s an interesting page you’ve linked to, Hermit. I didn’t know they were doing this sort of thing in the US yet. While the US has very low electricity prices compared to us they can also be hit with a lot restrictions and fees that we don’t have, so electricity over there isn’t quite as cheap as it seems and I guess their fees and restrictions could make something like this worthwhile.

    But as for giving something like this to pensioners to run their air conditioning, it would be fair cheaper to just install solar panels on their roof. (And install air conditioners as well since lots of pensioners don’t have them.) And of course any time we want to we could just give pensioners free electricity with no need for any hardware or software. Just an act of federal or state parliment.

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