The case for flywheel storage in the Philippines
pv-magazine.com
pv-magazine.com
* flywheels are great for sub-second up to a few minutes of correction and adjustments, as they can have enormous output and don’t suffer from degradation from usage; capacity is expensive, so using them for more than a few minutes isn’t economical; they spin down quite fast, depleting in the course of days or weeks, depending on the quality of the barring.
* batteries (notably LFP) offer great potential for longer periods, up to a few hours: capacity is cheaper, and their output is good, but expensive to scale with power electronics; they don’t really deplete after a few months, so great to smooth out daily and weather pattern.
* gravity (notably pumped hydro) is cheap for even more capacity but has limited opportunities, and it’s not nearly as fast to trigger as the other, so it’s better used to store capacity over one week. Evaporation is a problem, but cheaply fixable.
They overlap a lot, so having systems work together, or only one isn’t impossible — but having that structure and quasi-ranking in mind really helps understand what is being discussed.
I wonder whatever happened to the earth piston idea I saw floated a bunch of years ago. It involved cutting a cylindrical piston in the earth and drilling beneath it at an angle. You then pump water down into the space beneath the piston, causing it to lift. To extract the stored energy you simply let the pressure provided by the piston force the water back out through a turbine.
The main trick to getting it all to work is with the surfaces. You want the piston to be able to slide up and down smoothly without water infiltrating the earth or going around the side of the bore, so the whole thing needs to be sealed and smooth like an engine cylinder. The other trick is for your pumps, valves, and turbines to be able to operate reliably with huge water pressures.
I haven’t heard about the idea in years so I have no idea how it went, though I would guess it didn’t pan out for some reason.
Geothermic energy and CO2 storage sound a lot more useful if you’re going to dig that much
Another proposed idea for places that have deep seas or lakes is pumping air down into a storage at the bottom of the water. This storage can even being a flexible plastic - there isn't any high loading on it because the pressure balances out. The issue with that tech is that it's not that efficient, as compressing the air going down generates a lot of heat - some of that could potentially be recovered, but there's a trade-off with simplicity. Also if the containment fails then a lot of air bubbles to the surface, potentially sinking any ship on the surface at the time.
Put another way: Today in Denmark, electricity is free. Literally 0 cents (øre) before taxes and transport fees (of about 5 cents, 36 øre). Just before Christmas it was about $1 (700 øre) per kWh. There's no inefficiency where it would be bad to store energy with swings like that.
There are standalone flywheel systems but they're not nearly as common now that genset flywheels are around, in part because they have atrocious recovery time, they're far more complex and expensive (they tend to spin at significantly higher speeds, do so in a low-viscocity gas or vacuum, etc..and don't utilize a power unit that already exists) and they cannot help start a generator whose starter has failed.
Their main advantage, like you said, is that they don't degrade with age or use, but they're also compact and far less hazardous than large battery rooms.
Their major downside is that their recovery time is atrocious. There was a huge outage at an SF datacenter many years ago that was caused by multiple short outages. The flywheels didn't have time to spool back up between outages and eventually didn't have enough kinetic energy to carry things until the generators came back on.
Pumped hydro operates on a scale orders of magnitude larger than flywheels and batteries and has a response time of seconds, which is plenty sufficient for a grid-scale operator, because the grid has enormous inertia. It's the fastest responding form of large-scale power generation (natural gas takes minutes or more, nuclear takes days.)
One of its major successes has been in the UK, where for decades pumped hydro has helped the grid sustain "TV Pickup" - everyone flipping on their electric kettle between BBC programs.
PHES is for peaking and grid stability, not long term storage.
If you can buy cheap and sell for 4x the price the next day[1], that ought to cover the infrastructure costs very rapidly right?
[1] e.g. https://www.nordpoolgroup.com/en/Market-data1/Dayahead/Area-...
My conclusion was that simple electricity arbitrage using refurbished lithium ion batteries would be reasonably profitable right now but that business case depends on volatility staying high. The CAPEX is approximately 500 EUR per kWh storage capacity, and you can maybe make 0.25 EUR per kWh and day doing arbitrage. It’s hard to know what the electricity market will look like in the relevant timeframe.
Big utility battery installations are around $400/KWh IIRC and can cope with at least 2000 cycles[1]. Looking at the table you provided it looks like you'd be able to do around €50-€100 EUR per MWh sale per week on average if you're good at buying low and selling high but lack a crystal ball. So €0.05 per KWh and 2000 cycles still puts you in the red on your battery installation. :(
[1] https://www.pnnl.gov/sites/default/files/media/file/Final%20...
Besides, a flywheel is perhaps best operated underground where the bedrock can absorb the energy if it should fly apart.
My personal preference is a global HVDC power grid, which would be fine from a technical point of view even with current standard cables. (There are non-technical problems, but 60% resistive losses are genuinely ignorable given how cheap optimal PV is).
I have not looked into pressurised air storage, but I can easily believe it’s also something where the losses, whatever they are, are just not a big deal any more.
"From standstill, a single 450-tonne generator can synchronise and achieve full load in approximately 75 seconds. With all six units synchronised and spinning-in-air [...], 0 MW to 1800 MW load can be achieved in approximately 16 seconds.[13] Once running, at full flow, the station can provide power for up to six hours before running out of water"
https://en.wikipedia.org/wiki/Dinorwig_Power_Station#Specifi...
16 secs ain't too lazy. IIRC they have a spun-up metal flywheel to take the load in those few seconds before handoff to the hydro, though I can't find a reference.
Millions of people turning on water heaters within a few minutes will have an impact on any electric supply.
So, when a TV studio broadcasts, the electricity for everyone to watch it is paid for by the viewers. The studio only pays for the power to either broadcast from the TV antenna, or the power to send the signal to the cable company.
But when you watch a broadcast on the internet, not only are the viewers paying for it (their internet), but also the company is paying for the internet on their end (all clients connecting at once, using all that bandwidth), as well as all the servers to handle all those connections.
If TV broadcasts worked the way the internet did, a broadcasting company would have to be able to handle the incoming power load of every household's power bill combined, simultaneously.
It seems like the internet is poorly architected! The company should be able to send its one broadcast stream out, and it should be distributed to all the client machines, without the broadcast company needing to directly connect to (and duplicate) the signal across every client themselves.
These days, only IPv6 capable networks (so half of the web or so) satisfy the necessary requirements for such a system and internet multicast has wisely been turned off for the enormous DDoS/bandwidth waste it implies.
This mechanism is still used on some TV networks, though, especially digital ones that come over fiber. There is a single stream of packets generated to send to all subscribers that the subscriber devices can then subscribe to with the proper network config. This is often accomplished through IGMP and other such multicast protocols.
As for sending a single broadcast stream out, that's exactly what online streaming services do. A 30mbps Twitch stream with a million viewers doesn't require you to get a data center's worth of internet capacity at home; instead, you upload a single stream to your favourite service and that service replicates the stream for you. You can set up such a system yourself if you want to stream from home, have a cloud server with good internet, but only cable or DSL upload speeds through somerhing as simple as nginx with RTMP enabled.
I wonder if these days the grid operators also monitor internet statistics in some way.
Can you please elaborate on the scaling costs ?
I have been told that packs will output 400vDC as-is. But turning this into a grid AC connection is "complicated" ?
Batteries put out DC - the grid is AC.
If you prefer web to PDF: https://www.pnnl.gov/ESGC-cost-performance
And if you just want a quick 2 table summary (INCLUDING flywheels!) look at pages 8 and 8 of this: https://www.energy.gov/sites/default/files/2019/07/f65/Stora...
Flywheels are the best when you need to store only a few seconds' worth of power, and may need to store or retrieve it at a very high rate.
Still, spinning spare "Starship" cans on the ends of a girder might be a good way to store solar energy on the moon, during the long night. Maybe the girder is made from basalt fiber.
The blast occurred June 10 at Quantum Energy Storage at 13350 Gregg St. The California Division of Occupational Safety and Health (Cal/OSHA) announced Wednesday it had fined Quantum $58,025 for 16 health and safety violations after determining the explosion was caused by an “out-of-control” 11,000 pound, seven-foot diameter metal flywheel.
One worker suffered a broken ankle and three others had abrasions caused by flying debris. None of the injuries were life-threatening.”
https://www.10news.com/news/11k-pound-flywheel-caused-poway-...
From the article:
> The M32 system is a 5,000 kg, four-hour Kinetic Energy Storage System (KESS) flywheel technology. It can store 32 kWh of energy in a 2 ton steel rotor
32kWh of energy is 32kW for one hour, which is about the same energy as half a Model 3 battery.
The allure must be the lack of degradation, giving good long term cost (chunks of steel are cheap).
Could someone chime in?
Isn’t 32 kWh enough to power on the order of 2-3 homes?
That’s also enough for a few seconds for 10k homes.
But I've seen homes that have a steady 10 kW load in the US - security systems, central AC, and way too many lights and televisions on were the big constant loads.
American energy use is really on another level.
One of my big electricity users is the gas heating system (inducer and pumps). Clothes dryer is probably the biggest single load.
I think I have 100 amp service. But it's matched to the potential load of the house, not the average load.
[1] https://www.eia.gov/tools/faqs/faq.php?id=97&t=3#:~:text=In%....
In that same year, the comparable number for the US was 29.3 kWh/household/day.[3]
[1] https://www.statista.com/statistics/1236746/consumption-of-e...
[2] https://www.statista.com/statistics/1298672/philippines-aver...
[3] https://web.archive.org/web/20220101185903/https://www.eia.g...
I wonder if cemented rubble, in a steel housing, could be used.
During peak times (when a flywheel would need to discharge), by definition households are using more than average. But it's also true that less than 100% of the electricity demand needs to be time-shifted.
[] Google does "32 kWh to Joules", and https://www.omnicalculator.com/physics/kinetic-energy .
The point not being to throw stones, but to say what sounds like little power to Americans could actually do good for a lot more households than it sounds like.
https://www.metrobank.com.ph/articles/learn/how-to-save-on-e...
Maybe they used numbers from ~a decade ago? Mistakenly using US household size?
The Metrobank article was from 2022, and I feel they are using average household bill. But even that kind of mean is misleading. A single household with central AC would exceed typical US usage, meaning it's negating like what 8 houses?
My wife's family lives in the Visayas and pays like 8 to 12 USD a month in electricity. That's a house averaging 5 or 6 people. Even still, they are used to dealing with load shedding and blackouts.
And they are one of the few families with a small TV, even. In bigger cities like Manila and Cebu, usage is probably a ton more.
I can see arguments for both numbers, depending on your goal. Total electricity gives you a "household size slice" of the total economy, which may be more relevant. On the other hand, conceptually the residential number gives you the actual consumption of an actual average single-family house (with the hitch that they're mixed in with 'units' in multi-unit dwellings).
Philippines has always been adapting new technology, but suffers failures on general governance that prevents them from really changing the country.
Has there been recent success that solved the energy issue within the country? (I really don't know.)
https://en.wikipedia.org/wiki/Bataan_Nuclear_Power_Plant - Didn't work, built by a fault line, fully constructed, never powered the country. Much more political fallout - fun read. You can get tours of the place if you call the right number, which always changes and there is no voicemail or whatsapp/viber/facebook option available.
https://en.wikipedia.org/wiki/Wind_power_in_the_Philippines
Currently all deployments provides 1.6% of energy within the Philippines, but was built and foretasted to provide much more - https://www.doe.gov.ph/sites/default/files/pdf/energy_statis... (from wikipedia)
There are also much more studies and reports that contain fully documented news articles and government press releases, that overestimated capacity during bid/build and actual provided energy. This is another example - https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3907028.
I have nothing against the Philippines, nor am I filipino, but it is interesting to see a country continually promise, promote and market solutions that are somewhat forgotten when they come into fruition. Nonetheless, it will be interesting to see what happens with this solution.
Some background information on the Philippines - it is the most expensive country in South East Asia, for electricity cost - https://ieefa.org/resources/philippine-energy-transition-bui...
And I also find it quite humorous that the beer company, san miguel corp controls 30% energy transmission https://www.sanmiguel.com.ph/page/power-energy and continues to build coal power plants, which are mostly dependent on coal exports from China.
I'm interested, because it seems like a comedy sketch when you put it all together. I'm not saying any other country is perfect, flawless with execution or never has problems but when I look at Philippines performance for South East Asia - they always appear dead last, by a huge margin - while Indonesia and Thailand seem to have proper governance and expands infrastructure services and more to help their population.
The pictures here do not show them mounted underground or surrounded by earthen berms, which seems foolishly hazardous.
The Philippines could store power much more economically by suspending weights from cable reels on a ship, lowering them to the sea floor to extract power. The key to economical operation is to share a big motor-generator and winch, protected from weather, along a single shaft with a long line of reels and weights coupled via clutches.
This is akin to the similar scheme using a mineshaft, but is much more economically viable. Using separate weights, the winch can usefully be of much lower capacity than the mineshaft needs, so available off-the-shelf. The seabed is in many places deeper than common disused mineshafts, and there is plenty of it.
With respect, placing machinery at sea and protecting it from weather are antithetical.
The key is keeping parts necessarily exposed to weather simple and sturdy, and the touchy electro-mechanical stuff well housed. A physical shaft between them safely moves power in or out.
We see the same dichotomy play out in wave-energy extraction systems, where wave action pumps air through a turbine. The air could easily be conducted via a culvert to a turbine onshore, safely indoors, and shared. But somehow people building those seem never think of it.
An old supertanker would work fine. You make tunnels from the bottom up to the reels, for the cables to run through. You would want to let it turn to face waves, but you need and electrical tie-in to shore, or anyway to the nearest wind farm to move power in and out. All the weights hanging deep under water keep it stable.
Motor/generator and winch are maybe where the engine was.
* Water has ~1000x as much drag as air, so you want your weights to be shaped like low-drag bodies.
* Buoyancy will somewhat counteract the weight of your ballast, so there's an incentive to use high-density material (this also reduces hydrodynamic drag). High-density concrete, with a density of 6.0-6.4 g/ml, is an obvious choice.
* The specific material will, of course, need to be tested to withstand pressure cycling at operational depths.
* The natural project locations fall along the continental shelf, as close as possible to the shore. This allows cheap power connections in shallow water, while still enjoying maximum operational depth.
* Since you'll be operating well within the SOFAR channel, you'll probably want to implement acoustic mitigations (eg slower speeds when passing through those depths, sound-dampening tether connections, low-noise shape, low-vibration equipment, project siting away from critical marine ecosystems, etc).
* Semi-submersible vessels are likely worth considering, since that means one end of the cable won't be trying to bob up and down in the waves.
* If you really can covert an existing vessel, I expect the weights will need to be hung in a way that approximates the distribution of the original payload. This would be necessary to avoid invalidating the vessel's original structural and stability calculations.
Thank you. Overall, a very intriguing proposal!
Do you know anyone working on this?
2. The weight on a tether should be as large as an off-the-shelf crane winch can manage, to balance descent speed and cost. Maybe 5000t? Tether descent speed is probably not enough to matter, environmentally or energetically.
3. For best shape and reliability, overlap a series of nets on the tether. Tethers might be cable or chain, or some of each.
3. Site over an ocean trench close to shore. There is a lot of ocean, so only the best sites need be chosen. Taiwan, the whole east coast of South America, S Spain, Monaco, SE Greece, SE India, Sydney, Togo, E South Africa, Madagascar, Monterey (CA), SW Mexico, Cuba, Japan, Hawaii, various Indonesian islands, and the Philippines have deep water right offshore.
3. Calm water might matter more than maximum depth. A thousand meters is usefully deep.
4. The huge mass on all the tethers in deep water -- there is no need to hoist above, say, 100m deep -- aids stability.
5. Tethers may be distributed over the entire length and beam of the vessel, via pulleys. Mount a dozen parallel shafts, with a winch/motor/generator at the end, on each vessel. Shafts run the full length of the vessel, with a reel, clutch, and brake for each tether.
6. You can attach multiple vessels together, side by side, for more stability. There will be a lot of surplus supertankers.
7. The advantage over tethering in a mineshaft is that the winch and motor/generator can be shared among as many tethers as you like, and the winch may be off-the-shelf.
8. Storage beyond a couple of weeks' worth will probably not be a big market. Beyond that, you just order a shipment of NG or, later, ammonia to burn. Building out gravity storage reduces your NG bill.
I don't recall where I saw this mentioned. That company doing winches in mineshafts, Gravitricity, could branch out. All contact with fraudsters at Energy Vault Holdings must be avoided.
That weighs ~79,000 tonnes. So if you use 5000 tonne weights, it has capacity for only about 16 of them. The biggest tankers in use now would handle 32. This is a smaller number than I would have guessed. So, maybe you use 1000 tonne weights instead, and put 80 of them aboard, with 80 cables, reels, and clutches, and maybe five shafts.
If you don't want to build a "moon pool" for each cable through the bottom of the ship, you can run balanced pairs of them over pulleys on opposite gunwales.