Now that renewable energy sources like solar and PV are cheaper than new coal-fired power stations in most jurisdictions (anywhere with either favorable conditions or a reasonable carbon price), the big remaining question is that of supply variability/intermittency. As I’ve argued before, this problem is greatly overstated by critics of renewables who assume that the constant 24/7 supply characteristic of coal is the ideal. In fact, this constant supply produces a mismatch with variable demand and current pricing structures are set up to deal with this. A system dominated by renewables would have different kinds of mismatch and require different pricing structures.
That said, for a system dominated by solar PV, meeting demand in the late afternoon and evening will clearly depend on a capacity to store energy in some form or another. There are lots of options, but it makes sense to look first at relatively mature technologies like lithium and lead-acid batteries. Renewable News is reporting a project in Vermont, which integrates solar PV and storage.
The 2.5-MW Stafford Hill solar project is being developed in conjunction with Dynapower and GroSolar and includes 4 MW of battery storage, both lithium ion and lead acid, to integrate the solar generation into the local grid, and to provide resilient power in case of a grid outage.
The project cost is stated at $10 million, or $4m/Mw of generation capacity.
Assuming this number is correct, let’s make some simplifying assumptions to get a rough idea of the cost of electricity and the workability of storage. If we cost capital and depreciation at 10 per cent, assume 1600 hours of full output per year and, ignoring operating costs, the cost of electricity is 25c/KwH. There would presumably be some distribution costs, given the need to connect to the grid. Still, given that Vermont consumers are currently paying 18c/Kwh, this doesn’t look too bad. A carbon tax at $75/tonne would make up the difference.
How would the storage work? I’m starting from scratch here, so I’ll be interested in suggestions and corrections. I assume that the storage is ample to deal with short-term (minute to minute or hour to hour) fluctuations, which are more of a problem for wind.
How about on a daily basis? It seems to me that the critical thing to look at is the point in the afternoon/evening at which consumption exceeds generation (As I mentioned, prices matter a lot here). This is the point at which we would like the batteries to be fully charged. The output assumption suggests an average of about 12 MWh generated per day. If we simplify by assuming that the cutoff time is 6pm and that output drops to zero after that, the system requires that 8MWh be used during the day and 4MWh at night. That wouldn’t match current demand patterns, but if you added in some grid connected power (say, from wind, which tends to blow more at night) and shifted the pricing peak to match the demand peak, it would probably be feasible.
As regards seasonal variability, this would be a problem in Vermont, where (I assume) the seasonal demand peak is in winter. But in places like Queensland, with a strong summer peak, a system with lots of solar power should do a good job in this respect.
What remains is the possibility of a long run of cloudy days, during which solar panels produce 50 per cent or less of their rated output. Dealing with such periods will require a combination of pricing (such periods can be predicted in advance, so it’s just a matter of passing the price signals on to consumers), load-shedding for industrial customers and dispatchable reserve sources (hydro being the most appealing candidate, given that potential energy can be stored for long periods, and turned on and off as needed).
To sum up, we aren’t quite at the point where PV+storage is a complete solution, but we’re not far off.
John Quiggin 
Writing in The Conversation Associate Professor Mark Diesendorf says that he and his colleagues at UNSW “have performed thousands of computer simulations of the hour-by-hour operation of the NEM with different mixes of 100% commercially available renewable energy technologies scaled up to meet demand reliably.
We use actual hourly electricity demand and actual hourly solar and wind power data for 2010 and balance supply and demand for almost every hour, while maintaining the required reliability of supply. The relevant papers, published in peer-reviewed international journals, can be downloaded from my UNSW website.
“Using conservative projections to 2030 for the costs of renewable energy by the federal government’s Bureau of Resources and Energy Economics (BREE), we found an optimal mix of renewable electricity sources. The mix looks like this:
• Wind 46%;
• Concentrated solar thermal (electricity generated by the heat of the sun) with thermal storage 22%;
• Photovoltaic solar 20% (electricity generated directly from sunlight)”
• Biofuelled gas turbines 6%; and
• Existing hydro 6%.”
(My formatting) From http://theconversation.com/renewable-energy-is-ready-to-supply-all-of-australias-electricity-29200
I think we need to look at all renewable energy generation options and all energy storage options. I think the solution, if it comes, will come from a distributed network with some macro generation nodes and many micro-generation nodes. Storage will show the same characteristic; some major energy storages, like hydro dams and many minor energy stores like rooftop solar hot water tanks with hot water stored from the day.
We should start with energy as it must be generated or acquired before it can be stored as potential. In the list below the terms “micro” and “macro” refer to the size of each individual generating node, not its number or total contribution. Leaving out non-renewables we feasibly will have;
Solar PV panels (micro and macro);
Solar concentrating thermal (micro and macro);
Solar updraft towers (probably only macro);
Wind power (micro and macro);
Tidal power (probably only macro);
Stream power (micro and micro);
Hydro (macro);
Biomass where it is carbon neutral, renewable and does not supplant food production (micro and micro); and
Geothermal (macro).
Storage is dependent on energy type of course but will likely include;
Dams (gravity potential) – macro
Molten Salt Tanks (heat) – macro
Batteries (chemical) – micro and macro
Home heated water (heat) – micro;
Dynamos and fly-wheels – (used in specialised grid load equalising);
Compressed gas – micro mostly
Biomass stores – micro and macro
This does not exhaust the list.
An important thing not to forget is that solar updraft towers could provide power at night and thus obviate considerable storage requirements. Solar updraft towers are not as cost efficient as solar PV or solar thermal concentrating for generating power but on the plus side there are savings on energy storage. This might yet make solar updraft towers cost feasible.
And dont forget wind power. It is very cheap and can be over-built economically to give good power in light winds. A wide (sub-continental) grid with distributed micro and macro generation will go a long way to making power available at all times as well.
All this is do-able but Fossil Capital has to be over-thrown. Can Renewable Capital do it? Maybe, but I doubt it will do it fast enough without a major global dirigist government effort. One thing is sure, you can’t trust your future to unfettered capitalism.
Regarding you scratching your head John why don’t you just get Mark Diesendorfs very recent book “‘Sustainable Energy Solutions for Climate Change’.”
It includes loads of modelling of a variety of alternative scenarios done by Mark and his students. An important feature is the discarding of the concept of Baseload power.
You can read more here http://www.ies.unsw.edu.au/about-us/news-activities/2014/01/new-book-sustainable-energy-solutions-climate-change
@Ikonoclast
Quibble time! (a minor one) 😉
Geothermal should be macro and micro. Micro-geothermal is already popping up around the place – i.e. ground-sourced heat pumps for household heating, and geothermal heating of municipal swimming pools.
Thanks to Neil Harris for mentioning the hour-by-hour computer simulations of 100% renewable electricity in the National Electricity Market by Ben Elliston, Iain MacGill and myself at UNSW. In relation to storage, I would like to emphasise that our mixes of commercially available renewable energy technologies have no electrical storage, which is still expensive. The storage in the system comprises the dams associated with existing hydro-electricity, thermal storage associated with concentrated solar thermal power, and the liquid or gaseous biofuels of the gas turbines.
The latter play a vital role on several occasions on winter evenings following those overcast days that also have low wind energy. Gas turbines have low capital cost and, because they are operated infrequently and only for short periods of time (e.g., 1-2 hours), low running costs. They can be considered to be a low-cost storage that provides reliability insurance with a low premium.
@Tim Macknay
You are almost certainly right. I wasn’t all that aware of it. But I do recall reading somewhere that there are towns in cold places that use geothermal heating on a house-by-house basis. Then again some use a system of storing summer heat in large undergound stores (water? water circulating through rock aggregate?) and then using that heat all winter. Or something like that. However, the moral of the story is that there is and will be a 101 ways of getting, storing and using micro and macro renewable energy. We just have to get smart about and put a stake through the heart of Vampire Fossil Capital.
There’s always a party pooper and here he comes. When natural gas runs out there won’t be enough biogas to run gas turbines as Sweden is currently finding out. Biomethane contains up to 40% CO2 a fire retardant not good for fuel. Once that is removed, the gas is used to heat the digesters in cold weather and to power tractors and muck spreaders my guess is the EROEI is very low. No I don’t have a number for a closed loop system someone else come up with one. Start here
http://theenergycollective.com/jared-anderson/461211/usda-biogas-opportunities-roadmap
Pumped hydro storage is another that probably won’t scale up. Find ROAM Reporting’s report for DCEE which includes also seawater storage in clifftop tanks.
The next hot shot battery is said to the 60 kwh Li-ion costing $10k from Tesla’s yet to be built factory. We can get non straight line depreciation via cycle life. If we can get 2,000 cycles of 80% depth of discharge that’s 2,000 X 48 kwh = 96,00 kwh throughput. Dividing into $10k gives 10.4c per kwh not too shabby. If the average home uses 22 kwh per day one battery will last up to 2 and a bit rainy days, remembering we’re keeping depth of discharge to 80%. Presumably the biogas turbines will power the grid on a rainy week. Except we don’t have millions of homes with these batteries and nor enough biogas turbines to replace coal, natgas etc. In Australia that averages about 24 GW consumption out of 54 GW generating installed.
I respectfully submit that the numbers don’t add up.
@Hermit
You can respectfully submit all you want, but showing would be more convincing. The numbers look pretty good. As an argument against millions of homes having batteries “they don’t have them yet” is not exactly convincing.
Mark Diesendorf’s book is very good. I’d be interested in discussions between the groups who have modeled for Australia – there are I think 3 so far? And there are some differences between the UNSW and the Beyond Zero Emissions scenarios – it would be interesting to hear more discussion on these differences and why.
Do current batteries allow for high usage? I lived in a house with solar and batteries some time ago and the diesel generator had to be run at times – but this May gave been due to the age of the technology?
Also I wonder about other countries? I know Marc Jacobsen has stated 100% renewable energy is possible globally – but I spoke with someone recently returned from Vietnam and they said there was a lack of research but it looked more difficult there than in Australia. I’ve looked at Kenya and the prospects are good there. But what about other countries? More funds and people are definitely needed to do research at the moment, as well as starting what we can now.
Typical capitalists;
There’s your problem – this weird, crisis generating, political demand by Capital for a rate of return greater than economic growth rate.
Apparently (and I have saurdigger to thank for digging this up) the Stafford Hill energy storage will have 2 megawatts of inverter capacity, and 1 megawatt-hour of lithium ion battery storage with a maximum output of 2 megawatts, and 2.4 megawatt-hours of advanced lead acid battery storage with a maximum output of 2 megawatts.
So if the batteries weren’t limited by the inverter capacity and discharged at their maximum power output, they would provide 4 megawatts for 51 minutes. So even if the batteries were fully cycled twice a day, once from solar power in the daytime and once from cheap off peak electricity in the early morning, they would only deliver 4 megawatts for 1 hour and 42 minutes a day or 310 hours a year.
This does not look good for the economics of battery storage. However, rather than looking at a first of a kind installation that may be designed for specific requirements at its site, I think it might be more useful to look at the price of a battery pack that has been in production for at least a short while now and is much smaller. Smaller being important, since with current retail electricity prices and solar feed in tariffs, energy storage in Australia appears much more likely to end up in homes and businesses than on the grid.
Nissan will now replace the 24 kilowatt-hour (about 19 kilowatt-hours usable capacity) battery pack for its Leaf electric car for $5,500 US. Even assuming that the battery pack only provides enough electricity to meet its eight year/160,000 km warranty and then dies, that comes to roughly 17 US cents a kilowatt-hour. In reality, since battery packs used for stationary storage don’t have to drive anywhere and can continue to usefully function even if the battery becomes considerably degraded, the actual cost per kilowatt-hour is likely to be much less than this.
Now just to be clear, these battery packs aren’t currently available for purchase for home energy storage. I’m sure Nissan isn’t currently making any money on them. The $5,500 dollar price may well be below the current marginal cost of producing the battery pack, but Nissan thinks it’s worth the loss to promote sales of its electric car. And they may be reconditioning old packs to save on costs. (The deal requires the old battery pack be traded in.) However, this is still a good sign. Nissan would not offer this replacement price unless it was confident the marginal cost of battery packs would fall below this price before they have to replace too many.
The battery pack of the Tesla electric is more or less without a doubt cheaper than the Nissan battery pack. However, the Nissan battery pack is higher performance and its 0.5 kilowatt-hour modules could better stand the demands of being used in a small home energy storage system. (The Tesla battery pack relies on its larger size to deliver high performance and long life.) So the cost of the Nissan battery pack may be more relevant than that of the Tesla.
Is there enough Lithium in the world to make all these batteries.
Is there a reason that batteries for off-peak daytime power are preferable to just adding more solar panels? Obviously when there is no sun it’s a problem but is there a particular reason for choosing a battery storage system for the 5pm time slot instead of just increasing the number of solar panels?
And is wind 46% feasible?
Crocodile, don’t worry, there is enough lithium in the world to make the batteries. Current reserves are very roughly enough for about one billion Nissan Leaf electric cars and there is no need for stationary energy storage to use lithium batteries. It’s just that stationary energy storage is piggy-backing on research put into electric car battery packs and associated cost reductions. And if there ever is some sort of lithium shortage it can be extracted from seawater. And I don’t mean in the sense that we can extract gold from seawater if we really wanted to, I mean it has been done commercially in the past. So there is no shortage of lithium now and I imagine that in the future other battery chemistries will prove to be superior to lithium. Then we might worry about shortages of materials for them, but carbon is looking good for future batteries or ultracapacitors and we’ve got plenty of that. (Too much of it in some places.)
Lithium is an interesting story. Lithium is about as common as chlorine in the Earth’s upper continental crust, on a per-atom basis. However, recoverable (commercially mineable) lithium is relatively rare on land. According to the Handbook of Lithium and Natural Calcium, “Lithium is a comparatively rare element, although it is found in many rocks and some brines, but always in very low concentrations. There are a fairly large number of both lithium mineral and brine deposits but only comparatively few of them are of actual or potential commercial value. Many are very small, others are too low in grade.”
Extraction from seawater looks unlikely with Li+ (lithium ions) being about 50,000 times less common than Na+ (sodium ions) if my maths is correct. This means we will probably have to rely on land deposits. Known commercially viable land reserves are estimated at 13,000,000 tonnes by US Geo but other estimates put reserves as high as 39,000,000 tonnes. Which is right? I don’t know. A study reports we might need up to 20,000,000 tonnes from now to 2100 if use really takes off with electric cars. So, we might be OK for lithium.
http://www.nytimes.com/gwire/2011/07/28/28greenwire-global-lithium-deposits-enough-to-meet-electri-67078.html
Footnote: This has little to do with the topic but the world economy is facing a huge sulphur over-supply. Due to the amount of sour (containing lots of sulphur compounds) oil crude now being processed, a great quantity of surplus sulphur is being stockpiled in places like Saudi Arabia and Canada. Google, Sulphur Piles Larger than Buildings or Alberta Oil Sands Produces 1.2 Million Tonnes Of Sulphur Annually.
Crocodile, when I said lithium in the world, I should have written lithium reserves, which is an estimate of economically extractable lithium. This is not a set figure and changes with the price of lithium. The total amount of lithium in the world is vastly more than what is required for a billion electric car battery packs.
I am somewhat dubious of mineral estimations. Mining companies and governments do not currently employ great numbers of exploration geologists to go and do all the researching unless they’re thinking of mining somewhere in the nearish future – so for most of the areas where these estimates are said to be I doubt there has been extensive geological research into the amount of the deposit and how it could best be extracted then the land rehabilitated.
So if all this exploration geology has not been done – how accurate do you think the estimations can be? If they are not especially accurate I’m not sure we should expect to be able to rely on them…
@John Quiggin
I see Hermit has mentioned “hydro storage” en passant but you, having already got into relevant calculations are the obvious person to pose my question to.
I have tried it on a sceptical friend who doesn’t like wind farms (admittedly capable of blighting great landscapes with consequent capital loss by damage to money values) but he has failed me. So, over to you….
Why would it not pay to use wind power to raise water to storage which could be used for peak hour hydro electricity production?
Another question on which you would qualify as expert witness:
It is often said that it pays for Australia to move early on the various ways of replacing coal fired electticity generation. Likewise that it will cost more if we delay. Can you please spell out the conditions under which this is not nonsense?
A further thought for your consideration. When coal, especially brown coal can be bought for no more than what its cost of transport and a few dollars a ton for extraction or loading added to that what will be done with the coal and how much CO2 is likely to be released as a result, especially if it is shipped out of Australia?
A friend who owns a disused quarry in or near future suburban development speculated recently that he could burn coal to provide hot water to a new housing development…. Then there are the chemists…
Confusing power units with energy units? I’m not sure I’d trust these numbers.
Do we know the expected lifetime of the batteries if they operate on a full daily cycle? I’d be suprised is they lasted longer than a year. If you have to spend hundreds of thousands of dollars every year or so to replace the batteries, your numbers will change quite significantly.
@desipis
I’ve seen cycle life figures of 3,000 cycles for lithium iron phosphate batteries (so, ~8 years if cycled daily).
@ZM
I am also dubious about most (but not all) mineral resource estimates. As a rule of thumb, I think of them in 3 simple categories. (“Peak” means peak production not practical exhaustion.)
(A) Known to have peaked (Eg. Conventional Oil, Uranium)
(B) Due to peak within 25 years (Eg. Coal*)
(C) Cannot yet estimate a peak (Eg. Lithium).
Where a peak cannot be estimated it might be due to uncertainty about reserves, uncertainty about future requirements due to technological progress or uncertainty about future historical events. Where a possible resource peak is likely to be more than 25 years ahead it is difficult to extrapolate anything. Too many things can change. So I am not going to worry my ugly big head about lithium. There are far too many clear and present worries to be concerned about. For now, I am going to keep hoping the electrical economy will save us or at least some of us.
Note* : “…the date of peak annual energetic extraction from coal will likely come earlier than the date of peak in quantity of coal (tons per year) extracted as the most energy-dense types of coal have been mined most extensively.” – Wikpedia paraphrasing Richard Heinberg.
@Ben There are a few quoting 2,000 cycles then reducing to 80% capacity with a full warranty of 3 years. This can give an effective 3-5,000 cycles over 10 years.
For marine applications LiFePo4 batteries coupled with a combination of wind/solar/fuel cell generators are revolutionary.
John’s 10% depreciation is a tad optimistic – Li batteries have an average life around 8 years and lead-acid 10 with careful maintenance. But I agree that we can go carbon-neutral with mostly minor inconvenience if we put our minds to it. the problem is, as always, more political than technological.
John, I don’t think Vermont has a winter peak. They have a demand management program to reduce summer peak demand. Almost all of the United States has a summer peak. Some states are close, but I think Alaska may be the only state that has a winter peak. And much of the population of Canada also lives in places with summer peaks. However, in the US and Canada, unlike here, they don’t use much electricity for heating, so it’s not as strange as it may sound.
Ronald, don’t they use oil for heating? If so, there will be a winter peak once the oil is phased out, surely?
About half of the US use natural gas for heating
http://www.eia.gov/todayinenergy/detail.cfm?id=13311
@faustusnotes
Faust, oil for heating has mostly been phased out in the US because of its expense. Looking at the link Rog kindly provided I am surprised to how much of that oil has been replaced by electricity, but the largest single source of heating is natural gas. I presume that by electricity they generally mean heat pumps, and they are pretty efficient, so as America moves away from natural gas and the remaining oil use, and building energy efficiency improves, we may not see a change to a winter peak, although perhaps some of the states that are close may flip over. However, average temperatures are unfortunately a moving target, and as in Australia, the United States is warming up, reducing the need for winter heating:
http://xkcd.com/1321/
Gel-filled lead acid batteries have been around for 15 years. Zero maintenance. (I think it’s CSIRO technology but of course the batteries are not made in Australia.) We have them in our PV set-up and they’re in their 12th year, still delivering as specified every time we get a power outage, which is several times a year in the Adelaide suburbs. That’s not a full daily discharge cycle, of course, but it illustrates how battery worries need nore real evidence to back them up.
@Hermit
“Pumped hydro storage is another that probably won’t scale up.” How come the Japanese have 25GW of it? Built, incidentally, as a reserve for their nuclear plants. Even think-small Britain has the 1.7GW Dinorwig plant in Wales, which is designed to be able to reboot the entire national grid after a catastrophic failure.
@yuri
“A further thought for your consideration. When coal, especially brown coal can be bought for no more than what its cost of transport and a few dollars a ton for extraction or loading added to that what will be done with the coal and how much CO2 is likely to be released as a result, especially if it is shipped out of Australia?”
Can’t find the thought.
Something not all that widely considered for energy storage although I do see some google hits is the flywheel. I can remember waay back in the 1970s some discussion about using flywheels to power buses in Switzerland but the composites technology (IIRC) was not good enough to prevent the occasional flywheel splintering and taking out the bus and a lot of bystanders so it was never used.
CBC recently had a small piece about flywheel storage http://www.cbc.ca/news/business/nrstor-to-store-ontario-electricity-using-new-technology-1.2720669 but no costing. However it looked like most of the gizmo was metal which might be a plus compared to battery power since recycling sounds easier but since I know -0 about the topic …. I have no idea about costs but if someone is putting what appears to be quite a bit of money into a prototype the costs may not look that bad
An interesting approach but for something more than individual homes.
As Ronald Brak points out many parts of inhabited Canada are likely to have peak electricity use in the summer as many/most urban detached and semi-detactched homes will heat with natural gas, oil is competitive in rural areas and some large organizations will have steam heat (usually
Flywheel energy storage has a number of specialised applications for short-term bursts of high energy and for load levelling in electric grids. Flywheels are not good long term stores of large amounts of energy.
http://en.wikipedia.org/wiki/Grid_energy_storage#Flywheel
James, japan has a lot of mountains and rivers very close to urban centers, and basically none of those rivers are natural anymore. It’s a geographical and environmental solution that can’t be easily repeated in oz, I suspect.
@Faustusnotes
Hermit’s question was whether pumped storage would scale up. It does. It may be unusually expensive in Australia, the driest continent.
Yuri, you asked John some questions and I’ll chime in on them.
It is much easier and cheaper to use use wind turbines to generate electricity and then use that electricity to pump water than to use wind to directly pump water mechanically. This is because wind turbines are very efficient at turning wind energy into electricity and electric pumps are very efficient at using that electricity to move water. The pipes and parts needed for direct pumping are not cheap and the windmills would need to be located exactly where the water is being pumped instead of where it is convenient.
Coal power is more expensive than renewable power in Australia, so on the face of it any new coal capacity is a money losing proposition compared to the alternatives. Also, coal has extremely high externalities that are not factored into its cost. These externalities which include both damage to health and the environment make coal our most expensive form of electricity generation.
No one wants our brown coal, Yuri. It is worthless. It doesn’t even make economic sense to transport brown coal from deposits in Victoria to the brown coal Northern Power Station in South Australia. (And it doesn’t make economic sense to transport black coal there either.) Brown coal is much more bulky than black coal and has to be handled carefully as it can on occasion auto ignite. Its bulk makes it uneconomical to transport any significant distance. With the world moving away from black coal there will never be any demand for Australian brown coal to be exported. As for building new coal plants next to brown coal deposits so it doesn’t need to be transported, renewables are cheaper than new coal capacity. So we will never build another coal power plant in Australia whether it burns black or brown coal, not now and certainly not when we start pricing carbon again or otherwise restrict emissions.
As for using coal for heating in Australia, the reasons why we stopped doing that are still in place and its prospects have only grown worse.
@James Wimberley
Here’s an intriguing idea for hydraulic storage, which seems eminently scalable to me.
https://www.youtube.com/watch?v=m3p_daUDvI8
Australia has over two gigawatts of pumped storage capacity. It consists of the Tumat Hydroelectric Power Station 3 which is part of the Snowy Mountains Hydroelectric scheme and was upgraded in 2011, so its capacity is now about 1.7 gigawatts. And there is the Wivenhoe Power Station in Queensland. Its capacity is half a gigawatt and can provide power for 10 hours and it takes about 14 hours to fill the damn again. While Australia is not a great location for hydropower, and all the good sites have been taken, its low population density means it gets a significant amount of electricity from it. Recently it supplied about 8% of grid electricity, but only because Tony Abbott caused water supplies to be run down by promising to remove our carbon price. But apart from the rundown in water supplies, hydropower has been increasing as a percentage of generation as demand for grid electricity has dropped over 8% from its peak. With solar power reducing the need for hydroelectricity during the day, hydropower has seen more use in the evening which has helped to keep electricity prices down after the sun sets.
Hmm,
As has been mentioned above, the specs on the project call for 2.5 MW DC power but only 2MW AC power supplied to the grid. The $10 million capital cost of the project should therefore probably be pegged at $5 million per MW grid output. At your 10 percent discounting and 18 percent capacity factor (optimistic for Vermont, especially considering round-trip losses for battery storage) and a 35-year project lifetime, the NREL calculator gives an LCOE of 33 cents per KWh, not counting O and M costs. That’s really expensive—twice the current Hinkley C strike price for a drastically less reliable power plant.
As has also been mentioned above, the storage capacity of the project, 3.4 MWh, is pretty trivial. The batteries can smooth output on a day with passing clouds and that helps with grid stability, which is the project’s main selling point according to your source. But they will run dry after 51 minutes at full power (4 MW); the plant will be dead as a doorknob by 7 pm, 7:42 pm if we assume they output the plant’s 2 MW nameplate output. But that’s assuming the batteries were fully charged at 6 pm, which they will likely not be if they have been drained for smoothing output during the day, and definitely will not be on an overcast day. Since most days in Vermont are partly cloudy to overcast, the plant will make little contribution to meeting nighttime demand.
The project would make somewhat more sense in the Australian desert, but not as much as one could wish, especially if we envision scaling it. That’s again because of the limited storage capacity, which will make it hard for the system to absorb all the surplus electricity during times of overproduction. On a cloudless summer day the batteries can be fully charged during the one and a half hour period centered on solar noon, assuming full 2.5 MW DC output; i.e., they could fill up pretty fast. That’s not a problem at low penetrations, but at high penetrations with redundant solar capacity on the grid, much of the solar overproduction will be spilled after the batteries fill up. A solar-dominated grid that could, at high penetrations, store all the solar overproduction for later use during deficits would likely need more MWh storage per MW generation than the Stafford Hill project has, and be even more expensive. Battery storage is very costly and you need a lot of it to cope with the extremes of solar overproduction and deficit.
So Stafford Hill doesn’t strike me as a great advance. Adding the battery storage probably doubled the cost of the project in exchange for negligible enhancements in performance and reliability. I think battery storage has a long way to go before it’s cost-effective.
Some recent work at the ANU suggests there is considerable potential for smaller scale pumped hydro storage in Australia using artifical reservoirs.
Tim, more pimped storage could be built in Australia but it doesn’t look like anyone is going to be able to make money doing that at the moment. Wholesale electricity prices are very low and there is an awful lot of generating capacity either sitting in mothballs or operating at well below capacity, with the amount increasing all the time as demand for grid electricity drops. And the situation still wouldn’t be favorable even if we hadn’t tragically lost our carbon price and effectively signed the death warrants of an unknown number of people throughout the world. And what will really blow the case for pumped hydro right out of the water, or maybe right into the water since pumped hydro is always built right next to a dam, is the spread of on grid home and business energy storage. Now with Australia’s retail electricity prices and low to non-existent solar feed-in tariffs, batteries are already cost effective, but they need to be put in a box with the proper electronics required to control the system and that box needs to be installed at a low price. Currently it’s looking like the cheapest place to shove the batteries and electronics for household energy storage is in a solar inverter. Now of course it doesn’t have to go in a solar inverter, but this does look like where it might take off. Currently the market for on grid energy storage is very small in Australia, as most people with solar are still on the old higher feed-in tariffs. But the market will rapidly expand in 2016 both due to an increasing number of people with new low to no feed-in tariff and as a large number of people in New South Wales come off their old feed-in tariff. In Germany and Japan there has been work on home energy storage for a while now with a variety of products being produced, and with Germany being of more direct help since they have similar current. Unfortunately there may be hesitation about breaking into the Australian market thanks to our government’s obvious determination to damage solar energy as much as possible as soon as possible. Deciding to wait until there is intelligence repair in Australia could be business choice that results. But anyway, it only takes a small amount of home energy storage to start reducing peak wholesale electricity prices, further damaging the profitability of pumped storage.
What we may see is an improvement in the power output of existing pumped storage. Thanks to solar and also wind, periods of peak demand are now much shorter than they used to be and increasing the power output of exisiting pumped storage may make economic sense. For example if the turbines were doubled at Wivenhoe it could produce a gigawatt of electricity over 5 hours instead of half a gigawatt over 10. This means it could be charged with cheap solar electricity during the day and used to help meet demand during the late afternoon and evening peak, and then it could be charged with cheap windpower in the early hours of the morning and used to meet demand during the morning peak.
Qld seems determined to stop future solar if this is true
http://reneweconomy.com.au/2014/the-500-a-day-service-charge-designed-to-kill-solar-71705
Sorry Link didn’t work
@Ronald Brak
Ronald, my point in linking to that article was that it appears that there is scope for substantially expanding pumped storage in Australia, were it required. Obviously in current conditions, where even the continuation of the RET is in question, nobody is going to be building any.
Personally I’m dubious about the claim that PV with battery storage is cost effective in Australia right now (except in remote locaitons), although I admit I’m unfamiliar with the new developments in Japan and Germany you speak of. Here’s hoping, though.
@Ratee
Yes, the Queensland government does appear determined to kill grid-connected solar. Based on the information in the article (which is probably incomplete and simplied, admittedly) it seems unlikely that the utility’s claim that the new fee is a “service charge” could survive a legal challenge. More likely it would be ruled an illegal penalty, unless the utility could make a realistic case that the $500 per day was an accurate estimate of the costs of providing the service to grid-connected business customers. It will be interesting to see how that situation develops.
@desipis I did my 4th year dissertation on solar /diesel hybrid systems in remote communities almost 20 years ago. For remote systems, solar hybrid systems already looked good back then. I think it will be the remote locations and supply augmentations that will be the best bets for alternative energy for the foreseeable future.
Battery life (effectively large truck batteries) was a big problem 20 years ago, but they were still lasting 18 moths to 2 years if I remember correctly. And that was in extremely demanding (hot) circumstances where batteries decline faster.
@Ratee
The huge daily tariff seems to be the height of vindictiveness.
Tim, if one is paying about 30 cents a kilowatt-hour for grid electricity and getting zero cents for surplus solar electricity supplied to the grid, which is the situation some people now find themselves in, then it’s pretty clear that will cover the cost of batteries. It is the control module which seems to be excessively overpriced and without adequate warranty at the moment, but that looks like it’s coming good.
@willboisvert
I’m not sure that’s as big a problem as you suggest here. If the growth of both wind and solar continues, the risks will be on the spill side. It’s hard to imagine that solar PV won’t keep growing here, and wind too should continue to grow as well. That’s a lot of excess power to store and if the operator of the storage has most of the time between 16.00 and 22.00 and between 5.00 and 10.00 (in addition to other times when some supply anomaly occurs) to sell it above the purchase price the business should be viable.
Moreover, it’s conceivable that in the transition period to decarbonisation, fossil HC generators may want the flexibility to sell their surpluses to the storage operator while they are ramping down. Given that we have excess capacity, that seems likely. Equally, the arrival of grid scale storage would probably put the final nail in the coffin of FHC since the arguments against intermittent generation would collapse into much narrower questions of cost.
Except for the price quoted I would expect the majority of the “lithium ion and lead acid” batteries to be on the lead acid side. I would estimate that having 4MWh of lithium ion batteries would drive the cost up by $3-4 million, which again is enough to skew the economics unfavourably against a pure solar+storage option when compared to other options.
I agree it’s a viable option for remote locations where you don’t have the same scales of economy that are available to large coal or gas power plants connected to the grid.
If I were in need of home storage I would go for Nickel-Iron batteries. There have been major advances in recent years and while initially expensive, they have a very long life with minimal maintenance. I think for grid scale storage Flow batteries are looking promising.
One must not overlook the capacity to reduce energy usage at peak times. My own home has a 1.5kw pv system with no double glazing, the minimum insulation standards set 25yrs ago, no attention to stopping draughts, a freezer which uses 4kw/hrs per day and an air conditioner which is only COP 2.
It would be silly of me to raise the system capacity further before attending to the passive inefficiencies and waste.
It really is a shame that double glazing is so expensive ATM. It’s a pity that energy efficiency measures aren’t as sexy as some of the high-tech battery research.
One could add ‘changing consumer behaviour’ to energy efficiency measures.
You raise an important point, Salient Green.
I’ve had a look at energy saving options for my own oversized poorly built house but most of them are very expensive (at least 25-30 grand) but I have no way of accurately calculating whether they are worth it.
If you don’t have sliding windows (unfortunately I do), there are cheap double glaze retrofit options availavble.
Ultimately building standards need to be raised so that homes are properly insulated.