Gravity batteries try to beat chemical ones with winches, weights, mine shafts
sciencemag.org
sciencemag.org
Gravity Energy Storage: Alternative to batteries for grid storage - https://news.ycombinator.com/item?id=25650551 - Jan 2021 (167 comments)
Gravity-Based Energy Storage Begins Trials 2021 - https://news.ycombinator.com/item?id=24337537 - Sept 2020 (2 comments)
To Store the Wind and Sun, Energy Startups Look to Gravity - https://news.ycombinator.com/item?id=22394154 - Feb 2020 (2 comments)
Lifting rocks as a form of long term energy storage - https://news.ycombinator.com/item?id=21736607 - Dec 2019 (1 comment)
Gravity Battery - https://news.ycombinator.com/item?id=6750276 - Nov 2013 (1 comment)
Gravity Battery Concept - https://news.ycombinator.com/item?id=6739349 - Nov 2013 (72 comments)
Others?
Assuming the full scale version delivers peak power for 11 seconds like the prototype, 2MW peak power would be 6 kilowatt hours of energy.
That's terrible. We're taking about dropping hundreds, maybe thousands of tons down a mine shaft to get the same amount of power as $700 of lithium batteries you could carry in a backpack. For instantaneous loads you're way better off using flywheels, which we've already had for decades.
Gravity is weak, literally. The only realistic use case for gravity generation is hydro power. And MAYBE reverse hydro power where we put giant gas bags underwater and they make energy floating up
Gravity solutions like these will never be feasible, because as you point out, gravity is just plain too weak of a force. I mean, it looks like pumped hydro will be viable, but when you think of the sheer mass of water that can be pumped behind the Hoover damn you realize stacking a bunch of bricks is ridiculous in comparison.
There was another recent article on HN about a giant tidal generator, and I was glad to see the top comment pointing out that basically over 50 years all these tidal projects have been failures (at least when it comes to ever being able to provide decent power in a fashion that shows it can scale).
It's time we start calling out these schemes for what they are, because they take funding away from solutions that we now we'll need now to fight climate change.
In my head, liquid must be easier to play with than a solid.
So displacement of water or air should be done.
The displacement of air, being pumped into a balloon under water seems like a great idea.
I know many solutions must have been thought of, but is the inflate balloon under water , then let it float up - the most efficient way of storing energy?
Lithium batteries wear out, but are more energy dense and so arent comparable ( regardless of size).
Forgive me for ruminating I think this is a problem with an already identified solution though?
When speaking about LI packs, especially to enterprises deploying them at grid scale, their expected life has to enter into the equation. Maybe 15 years? 25? So, millions up-front, and millions more every couple decades; its not an impossible sale, but relative to other options (like hydro storage, which is excellent but also limited to areas with existing reservoirs) its not obviously the best option.
They may be better, but I don't feel that means gravity batteries don't have a place. The mechanical pieces to raise and harvest the energy likely aren't carbon-zero, but the weight itself can be built out of anything. They don't experience leakage of stored energy over time (barring a failure of the retention system keeping the weight elevated) (though, obviously, there is loss in the addition of energy to the storage, as the machines which raise the weights are not perfect). They can be reused essentially indefinitely (excepting continuing upkeep of the retention and raise/harvest systems, and proper weather protection of the weight). Their failure mode is "falls", which can be designed far, far safer than a typical LI pack failure of "explodes in a fire that literally cannot be put out". None of the systems in-play are particularly technically advanced, and a ton of the cost is up-fronted. There's a lot of reasons to think they will represent a component of green energy storage in the future; likely not as large at LIo packs, but the world is a big place.
If anything lithium refining and production into high quality is far closer to the bottleneck.
> mostly outsourced to countries where we don't think much about it (Australia is a big one right now, but in terms of untapped reserves, Chile Argentina and China are all huge)
This is also very questionable. Lithium exists basically everywhere. Basically one of the most common elements. Pretty much in every desert you have tons. There is tons in water brines all over the world. There are huge hard rock reserves all over the world (US, Wales, Canada, Australia, Czech Republic and so on). There are even larger clay reserves, Nevada alone has lithium enough for all US needs. Mexico has huge amounts of brine as well.
South American brine is losing market share quickly and they will never get it back.
> They require complicated manufacturing processes that are centralized into maybe four or five advanced manufacturing companies around the planet.
This is true but many more companies are currently working on it all over the world. It is difficult but not its not some totally crazy technology.
Other technology have a place, but I don't know if gravity battery is one of those. Liquid air batteries, liquid metal batteries and others might be better solutions.
Reading the rest of your comment, I'm not sure you did the math yourself...
> Assuming the full scale version delivers peak power for 11 seconds like the prototype
The prototype is a 4-storey tower (i.e. less than 20m).
> That's terrible. We're taking about dropping hundreds, maybe thousands of tons down a mine shaft
A mine shaft can be expected to be significantly deeper than a 4-storey tower is tall.
So it seems you've invalidated the assumption upon which your argument is based in the paragraph immediately following it?
> the same amount of power as $700 of lithium batteries you could carry in a backpack
From TFA itself, they estimate they can offer a price of $171/MWh, while Lithium-ion batteries cost $367/MWh.
With absolutely nothing to explain the cost estimate, so you can put away "TFA" thank you.
A system like this with only a single weight is going to be a huge amount of work to set up each unit of capacity.
Also looking up the info I can find, I think they're calculating that rate over a 60 year lifetime.
Edit: Uh, did I say something offensive?
No that I see. It's just really easy to read your comments in a haughty tone, which naturally selects for downvotes. The content of your posts, on the other hand, seems to encourage deeper investigation, so that's probably on point.
Communication is hard.
There's not many deep mineshafts that aren't filled with water. And dewatering mines is insanely expensive. And 600 Kwh is nothing. Enough to power maybe 30 houses for a day.
My math is bad, but there's no math where this will ever work out profitably
But Advanced Rail Energy Storage?[0] Different story, has potential (bad pun, I know). There are some nice synergies, like a system such as this can reuse the generators from a decommissioned coal or natural gas plant.
It can definitely play a part in a broad-spectrum energy policy.
There's realistic gravity based projects, but dropping ACME style anvils down mineshafts isn't one :)
A wind turbine is already equipped with a generator, so it'd be a matter of building some sort of "switch" which would make it either: (a) generate electricity using the turbine, as per usual; (b) raise the weight using the turbine, thus not producing electricity; (c) generate electricity by connecting the weight to the rotor/generator, while lowering the weight.
First, there's not really any room in there, wind towers are built for the job, we don't add twice the amount of steel and an elevator shaft for funsies.
Second, even if there were some room it would be inconsequential, you need a lot of crap very high up to get significant amount of energy.
As demo, let us take the largest turbine available right now and lift the entire thing up and down its tower.
The Haliade-X has a hub height of 150m, a 600t nacelle, and 165t blades. In normal operations it's rated for 14MWe.
765t at 150m is 250kWh. You can get electric buses with larger battery packs than that. For reference, US households use about 29kWh/day.
That's the issue with gravity: it's really not that strong, so to store significant amounts of energy you need either ridiculous amounts of weight (hence dams and pumped hydro which can manage unfathomable weights), or extreme height difference (hence… still dams, pumped hydro a bit less so I think).
As a point of comparison, Bath County (the largest pumped-storage station in the world) has a hydraulic head of 270~385m and the upper reservoir stores 44 million tons of water.
Now taking in account that you can't really empty the entire thing, that it's not perfectly efficient, etc… Bath has a storage capacity of "only" 24GWh, it's not actually moving 44 million tons up and down 400m.
Going to be a lot of flexing though.
Nice thing is that some of the “inefficient” heat may be usable on-site: and you may get compressed air as an output that could be usable directly.
Then you've got no height. Plus buildings are not dense so it's a pain in the ass, and when (not if) the jacks fail you're out a building.
Gravity is weak.
The weakest of all forces, isn’t it?
btw anyone saying that gravity is weak should try getting of this planet...
I’d love for someone to explain more though.
It doesn't make sense to invest so much land, machinery, and labor into something that generates and stores so little energy
The tower would probably need reinforcements for the additional weight, but I have no idea about the magnitude required.
Bad math, let's say we can use a lead weight 2 meters in diameter, 3 meters tall (107,000 kg) with 120 meters of drop available.
All of that gets us 35 kWh, or 0.035 megawatt hours of energy. Compared to a 2 MW turbine, it's a negligably small amount of stored energy, even if we scaled every dimension up by a factor of 2 (getting us to 0.28 MWh).
It would cost much more and be way more complicated & less reliable than… just getting the two separately and using battery grid storage on the output of the windfarm.
Even for a backyard turbine it wouldn't make much sense, for maintenance reasons you'd want to manage your turbine and storage separately, and if, say, you add solar panels, you want that to feed into your battery bank as well.
(Yes, I am aware that it is not storing the water at the top :)
For reference (https://en.m.wikipedia.org/wiki/Coal-fired_power_station):
> As of 2018 coal power under construction was 236 GW, planned 339 GW, and 50 GW was commissioned and 31 GW retired
If we want to replace those new plants we'll need 100.000 of those shafts. And that's not counting the existing plants, and the other fossil-fuel based plants. Think of the quantity of concrete that involves. That's just insane. If we want to actively tackle electricity generation we need to use the most efficient low-carbon tech that we already know.
Also, we already have gravity-based systems, only nature does all the work of raising the payload for us in gaseous form, and we let it fall in liquid forms. But it takes so much dam place.
For the sake of Fermi estimation, I assume average electricity use in a developed nation is 1kW/person, and that average all-forms power use in the same is 5kW/person.
Transportation is almost certainly going to be batteries or synthesised fuels like hydrogen, and can only be backed by gravity storage if you have the kind of beamed power that would be banned by international treaty on the grounds of being too easily weaponizable[1].
If you’ll permit me to assume grid interconnects and lower nighttime demand than at present due to different pricing incentives, we might be able to need a mere 3kW-hours/person of electricity storage per night.
Using the lifetime cost estimates in the article, 3kWh/person/night is about $0.51/person/night for gravity storage and $1.10/person/night for LiIon. Neither is bank-breaking, but cheaper is better.
However, the volume required is a different question: 3kWh of batteries has a volume of 4.3 to 12 litres, while 3kWh of gravity storage is 1.1 metric ton kilometres[2].
You can make the distance required smaller by using more mass, but if I assume the average home mass is about 200 tons, you’d still have to raise the entire building 5.5 meters every day to store the same energy as a backpack of batteries. I do not expect construction on this scale to be the optimal solution in general, despite it being a very good idea in some specific cases such as hydro dams and preexisting deep shafts.
[0] Armchair opinion — I’m a software engineer not a civil engineer.
[1] Assuming they’ve read or watched any Larry Niven, the Bobbiverse, The Expanse, Babylon 5, or the news at any point in the decade following the second week of September 2001 — 'A reaction drive's efficiency as a weapon is in direct proportion to its efficiency as a drive.'
[2] http://www.wolframalpha.com/input/?i=3kWh%2F%289.8m%2Fs%2Fs%...
Excess capacity is required for storage to work and reduces the need for energy storage. But, once you start talking excess capacity, transmission dramatically reduces the need for storage.
Assuming storage costs say 2x as much as wind generation then building excess wind capacity is worth it until ~1/2 of a wind turbines output is wasted. Thus if we are looking at 3kWh of storage that can be banked at any time of the day we are looking at a lot of excess capacity, yet somehow still supposed to have a 3kWh per night deficit.
Once you can get it up in the air then the higher you can go you're doubling your storage in a linear fashion. Hoist one of those trucks to 50 meters (perhaps you have a handy cliff in your backyard) and you've stored as much as the ten trucks did at 5 meters.
So yeah scale seems hard, but the low technology/materials requirements and potential for gradual scale-up make this worthy of deep investigation. I think there's a lot of wandering off into dead-ends as far as limitations go though - Solutions that depend on a lot of concrete pouring, for example, are a no-go if the end goal is reducing atmospheric carbon.
The storage might scale this way but not the output when demand is high.
How so?
There will be a maximum drop rate that is supported by the machinery being built, and it seems reasonable, though not mandatory, that a 5x weight system will be designed to handle more generation than whatever it's 5x of.
m * g * z
This would be rather simple tech, that can supplement solar and wind on your farm, lodge, campsite or island. Another piece in the puzzle for smaller scale independence.
Not to replace metropolis-scale energy demands, as grandparent implies, but to smooth out fluctuations on hourly, household scale.
Trucks, while impressive as an illustration, are not quite dense enough to be practical or applicable in an energy-storage scenario.
Assuming you used cast iron as weights that has a density of ~7800kg/m³ at regular temperatures, so you're looking at about 10 cubic meters for that 1kWh of potential energy storage using an abundantly available, non-toxic material that will endure.
"ADVANCED RAIL ENERGY STORAGE"
By comparison, a pint of gasoline stores about 4 kilowatt hours.
https://www.smh.com.au/national/farmer-planning-diesel-tree-...
A fairer comparison is current battery tech, you can pack something like 40kwh in 200kg of batteries (rough guess based on leaf ev battery modules). So vastly more in the same space/weight. But those are complex and energy intensive to manufacture, and have limited lifespans before further energy investment is required to recycle/replace them. The relative simplicity and long lifespan of gravity storage seems like it has potential. Not to mention the potential for owner/operator to self install, which could be great for developing nations.
They can, however, be configured to cover huge surge loads for short moments, or smooth out small discrepancies over a longer span, in more or less the same footprint.
If you want a GW of coal, you need a GW plant, whereas with batteries you can decide between a gigawatt-hour or a 1000 megawatt-hour using a similiar footprint (scale to capacity of chosen technology).
This reduces the need for significant unclean backup capacity, and either decommissioning them or reducing their usage.
The reasoning roughly goes like this: wind and solar capacity varies because wind doesn't always blow and the sun doesn't always shine. This is very obviously true of course. Except these effects are local, temporary and typically result in a reduced capacity rather than a complete collapse. You always get some output out of solar panels (except at night). And wind turbines might stop spinning but it's extremely rare for that to be a continent wide thing. Offshore wind is pretty reliable. Also these effects are kind of predictable via weather forecasts so we can plan for them. Same with seasonal patterns. Simple cables rather than batteries are the key technology that we need. And we mostly have that in place already.
The grid connects power plants via cables. So, we can compensate for local dips in power with remote peaks. What matters is the collective performance of the grid. That still fluctuates but not nearly so dramatically that you'd need a lot of battery. E.g. the European grid is very connected. So, you might get power from Norwegian hydro, North Sea offshore wind, German on shore wind, solar plants in Spain, France, Germany, etc. or any of the gazillions of solar panels on people's houses. And of course there are coal, gas and nuclear still on the grid as well (for now).
All of that failing 100% at the same time is simply not a thing. Not even close. It's not something grid operators plan for. It might dip by 20-30% but it might also peak by that much. And it's likely to average out over time in a very predictable way. All that means is that we need to have a little more capacity. 2x would be overkill. 1.2 to 1.3x plus some battery will probably do the trick.
Batteries on the grid are intended for and used exclusively for absorbing short term peaks and dips in both supply and demand. Short term as in hours/minutes; not days or weeks. They are very good at that.
This is why modest amounts of lithium ion batteries are being used successfully in various countries. These batteries can provide large amounts of power (MW/GW) for typically not more than a few hours. The reason that is cost effective (despite the cost of these batteries) is that taking e.g. gas peaker plants online for a few hours/minutes and then offline again is expensive and slow. And of course with cheaper wind and solar providing cheap power most of the time, gas plants are increasingly pushed in that role because they are more expensive per kwh to operate. Gas plants on stand by still cost money. And turning them on costs more money. Batteries basically enable grids to have fewer (and eventually none) of those plants. These gravity based batteries have the same role. It's a cheaper alternative to lithium ion batteries.
Currently, clean energy is the dominant form of energy in many countries already (e.g. Europe, China, parts of the US). In some countries it's well over 50%. This proves the point because these grids don't feature a lot of battery currently and the combined capacity of peaker plants (i.e. not operating continously) is far smaller than the presumed need for batteries. If you were right, these countries would be facing massive blackouts all the time as their dominant form of energy disappears for days/weeks on end. That's obviously not a thing.
I'd like to add that with the rapid electrification of car- and soon truck and ships- fleets, we are already rolling out that giant battery-pack, as we speak.
+1 for the post, but I don't see this that much.
Whenever I see the debate come up, it's when someone is directly comparing the cost of solar to nuclear/natgas without factoring in the additional cost of batteries and DC lines, which obviously leads to an invalid (or at least incomplete) comparison.
The required battery storage cost to guarantee my 3 KW electric clothes dryer could theoretically operate 24x7 when needed after three weeks of cloudy windless weather at midnight is staggering. The alternative is demand based billing and program my dryer to never accept a KWh that costs more than say, seven cents. On a minute by minute basis I don't care if my "hour" dryer cycle takes 65 minutes because a cloud passed overhead and it slept for five minutes. Its also worth considering that "in theory" people who design for max theoretical load MUST assume my clothes dryer will run for 24 hours a day 7 days a week, when in practice I have never done more than five hour long loads of laundry in a row, and that was after traveling out of country for two weeks (after zero electrical demand for 14 days)
Even data centers can do stuff like vmware vmotion running virtual hosts off a cloudy cloud data center to a sunny cloud data center with no user interruption.
The idea that the wall outlet is an infinite source of energy is going away, or if its demanded for a hospital operating room or nuclear power plant or something, those KWh are going to cost like $5 or something similar and that's just how its going to be. Its not going to be that much suffering; right now my multi KW airconditioner instantly starts up when the thermostat says go, and in a decade maybe the electric company contract says it's guaranteed to start within the next ten minutes 99% of the time, and that sounds like a nice deal if it cuts my bill in half and eliminates CO2 output.
Like tea time in the UK where apparently millions of people turn on their kettles (2 kilowatts each) in synchrony to get some hot water.
What if they also like to cook something with their stove (another 2 KW) to get a nice dinner, around the same time?
I'm skeptical-- but probably for different reasons that you.
W/ PG&E and MCE the utility can't even manage to tell me my current rate-- determining from my bills requires solving a linear system in three unknowns, requiring three bills. And the rates change quarterly, so I can only determine the rates at the moment they no longer apply. The rate scheme also has various non-linearities such that my total rate depends on my overall usage over the year and as a result my true marginal rate is unknowable at any given time. I dunno how rates are supposed to incentivize behavior when they're so opaque.
So I like to imagine a future with smart electrical panels and appliances where their behavior can be rate shaped in realtime, ... but then I encounter the actual behavior of the PUC and utilities and a future with demand shaped by economics seems distant indeed.
And that is not even accounting for the fact that right now only a small proportion of total energy use is transmitted electrically, which means that with future energy generation becoming greener being strongly tied to having more solar/wind (which is also electrical), there will anyway have to be a massive increase in grid capacity.
> Currently, clean energy is the dominant form of energy in many countries already (e.g. Europe, China, parts of the US)
Just not true. Yes, some countries are (Iceland is one of the few) but most European countries are far from what you claim. Maybe you meant energy transmitted as electricity instead of all energy.
See https://ec.europa.eu/eurostat/statistics-explained/index.php...
Quote: > In 2019, renewable energy represented 19.7 % of energy consumed in the EU-27, only 0.3 % short of the 2020 target of 20 %.
> The share of energy from renewable sources used in transport activities in the EU-27 reached 8.9 % in 2019.
We actually also do have self created gravity-based systems, where we also do the work by ourself, to have a energy storage on demand:
https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...
They work reliable and with big capacity since the very beginning of electricity. The only problem is ... scale. You cannot just build them where you want them. You need rivers and height differences.
Unless you create such systems completely artificial and there are plans to do so, but that will be very expensive.
edit: here is a paper (in german) discussing such possibilities, to create a artificial pumped-storage out of the remains of surface mining
https://epub.wupperinst.org/frontdoor/deliver/index/docId/72...
edit 2:
and my opinion is, that I am not a fan of complicated solutions, like the originial solution from the article seems to be, which is also stated as "The technology is still “incredibly immature”
There are solutions to make batteries without rare elements. They just don't reach the energy density of lithium based ones, but that is not really a problem, when you have them stationary.
So if you could scale up production of these and in the end, have a big battery in every home/factory connected to the grid - you would have a stable grid without any need for gas- or coal powered backup.
The suiss folks are gaming the west European energy market this way.
When the French produce too much nuclear energy, the German have leftover and stop buying it 100%w Price go down.
Swiss buy it cheap and pump water in their dam system with it.
Inevitably, the french grid align and produce a bit less. Price goes up slightly.
That when the suiss comes out, release the water into a turbine system and sell the energy for a higher price that what they bought it for to German, French and Italian grid.
I can’t even be mad at them. They have the perfect setup. But you need the Swiss alp and climate to do what they are doing. And being freaking Swiss.
Source/Context from a Swiss news paper : le temps, in French
They describe that « system » and apparently it’s being disturb in recent years with the evolution of the German market.
https://www.letemps.ch/economie/barrages-suisses-vendre-esto...
You buy cheap when you have storage and sell expensive when demand goes up. Pretty much how the market should work?
This way there is incentive to balance it out (by creating storage) - and in this case stabilize the grid.
When the grid would become more flexible, so even homeowners can do this with their solar panels and big batteries - then this should be net gain for everyone, no?
Unless gaming it, with big money, destabilises it. So some safeguards probably should remain.
That sounds great. They are first, but as we deploy more renewables, we'll need much more cases like this.
How much of a swing in pricing are we talking about here? Because that storage mechanism is maybe 80% efficient. So the price swing would have to be at least that big to break even. And in that case, if they are helping to smooth out swings in demand that are that large... Sounds like they're providing a valuable service.
https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...
EDIT: Keep in mind that electricity is entirely fungible. This is no different than the Swiss turning on a power plant when prices are higher. Except it would probably be too expensive to have a power plant just sitting there idle when the price isn't "high enough".
This is exactly what is done, and pretty much inevitably must be done - grids need spare capacity that can be relied on to spin up rapidly when demanded, that's usually done by gas turbine plants.
Does it? If you use iron instead then we only need to know that it has eight times the density of water. Multiplying a volume by eight is not a lot; it's only twice the size in length, width, and depth.
So let's imagine replacing a typical hydroelectric power station [0] with a 'gravicity' system. Supposing the same depth you need a system of about one third of its length and its width and then fill it to the brim with iron. And of course do not forget to install cranes that are able to lift this iron to another space about 200m lower and back up.
By the way, for concrete blocks it would only be a volume factor of 2.5, which would mean about 36% more in length, width and height.
All in all, the amount of space that can possibly be gained with these systems seems pretty minimal to me.
[0] https://en.wikipedia.org/wiki/Taum_Sauk_Hydroelectric_Power_...
Edit: care to explain the downvotes?
The most immediate need for energy storage is frequency regulation, and short hours-long dips in power output. If we can solve that we can scale renewables very far.
For days-long dips in power output, it's probably better to keep some gas power plants on stand-by. I think many areas of the world has enough of them to handle these needs already. To make it sustainable, they could be switched to using renewables fuels, like hydrogen or ammonia made from electricity. We're going to need a shit-ton of those kinds of fuels for trucks, ships and airplanes anyway, so setting aside some of it for backup power wouldn't be a huge problem.
For seasonal variations, I think trash burning power plants is a reasonable solution. Sweden and Norway has some of them, and they also provide heating to nearby homes. I mean, yeah: first of all we should reduce, reuse and recycle. But eventually our trash become unrecyclable, and burning it seems to be the best option. Modern facilities seems to be able to extract almost all harmful compounds from the waste then. There are also experiments with carbon capture from these plants, which in a fully renewable world could make them carbon-negative, and become one of several tools to help reduce CO2 in the atmosphere again over time.
And of course, nuclear would be a great help. If it can be made cheap enough again, it can be used for seasonal variations. But we're still going to need renewables. So we still need energy storage for frequency regulations and minute/hours-long dips in energy output. Nuclear power plants are NOT a good solution for that.
Keep in mind this will only get worse as heating demand is switched from natgas to electricity.
It won't be until our power storage is far more beefed up that we'll shut those down, and that will take years.
It will take years before this is potentially a problem and by that time we'll likely have gone through a few cold snaps.
Europe tries to be at a forefront of green energy. No sun/wind is a real issue there, not just an edge case.
We have a long trip to get there, so why worry about a once in 3/5 year event? We wouldn't go a year without fossil fuels and say "Ok, that was it! Demolish all the plants right now!"
Keep in mind the UK already has about 30GW of solar and wind potential nameplate capacity. Your suggestion would result in a requirement of 700GW of solar and wind to be installed. On windy and sunny days would result in probably 350GW of generation, at least 300GW more than we need.
Some investment in long distance power transmission would go a long way towards smoothing out the grid.
If Israel can build natural gas pipelines to Italy, I think we can handle a subsea electrical cable.
You don't want all your eggs in one basket, but this seems like a poor excuse for having zero eggs at all.
We cannot guarantee that the UK will be at peace with every county between them and the Sahara forever. Hosting the power line would grant significant political or military leverage.
It's a big upfront investment, but it could be much cheaper than storage at scale.
I think ultimately you want power transmission stretching from the UK to Japan so as the sun moves the power generation continues.
I imagine it will happen one day, because it would seem to make so much sense, but this is something governments could make happen a lot sooner if they put their mind to it.
We’ve been designing around super cheap on-demand energy for a while now, but we did manage before that.
Burying it is a form of CO2 sequestration. Burning it just releases it into the atmosphere.
You are only looking one half of the problem. Wind power in the UK has a power factor of about 35%. What that means is to meet the average demand from the UK electricity grid we'd need not install 3 times as much Wind Power as the demand. This is borne out in the current figures, we have some 25GW installed wind power for an average of about 6GW supplied. If we have enough renewables to meet the demand on average, a windy day across the UK is going to result in a glut of power.
If we don't have ways of storing that modestly efficiently then our only choice will be to take turbines out of service, increasing the overall cost.
This is just false. Every wind turbine I've ever seen uses 50 square feet on a farm or cattle ranch.
Not once have I seen a wind farm where the land underneath isn't still used for it's previous purpose.
And at least in US we have enough farmland to power entire US with wind.
And that's not counting rapidly growing offshore wind power. Which uses no land at all
The only meaningful comparison is material used vs solar. Once these things are built they use near zero resources. For everything else you have to keep mining shitloads of material forever.
How much coal do we have to mine for coal plants? How many gas wells and pipelines for gas plants? What about transport? How much does it take to mine and process all the uranium into fissile isotopes for nuclear?
With wind and solar you plop the thing in a field and get years, maybe decades of energy with no input.
I'm convinced that all these land use and building materials costs studies are just FUD funded by the fossil fuel industry.
Coal and gas plants use many times their weight in materials for a lifetime of operation. Nuclear probably does too because the massive waste involve in uranium refining.
What do you suggest as a greener power source than wind?
Unlike solar?
A coal plant is a 1000MW machinery. A wind turbine is in the order of 10MW. Also, turbines have a very low capacity factor so you have to double them to guarantee their output and combine them with storage. So it's 1 coal plant vs 200 turbines at the very least.
And have you been close to a big coal plant? They're massive. A coal plant probably used more land than 200 turbines and unlike turbines the land is unusable.
Coal plants use many times their mass in coal during their lifetime. If you're looking at total materials needed over the lifetime of the plant, I wouldn't be surprised if coal was 100X higher than 200 turbines.
With solar and wind, you put it up and you're done. No more inputs. It chills in the field.
With coal and gas you're feeding shit tons of material into it every day. And you always need more, for the life of the plant.
It's bonkers you think the amount of steel and concrete that go into a turbine are anywhere close to comparing to the raw materials other power sources consume.
Turbines require steel and concrete. So does every other building above 5 floors
It looks like:
- Hydropower + Bioenergy -> 100 gCO2eq kWh−1
- Traditional fossil fuels -> 78–110 gCO2eq kWh−1
- Nuclear, Wind and Solar -> 3.5–12 gCO2eq kWh−1
So it appears fossil fuels take ten times more energy to run over a lifetime. Less than I expected but still bad
If they are going to use wind why not pump water up from the Columbia River up to the top of the surrounding hills? Use the potential energy at least.
Essentially all buildable sites have already been built, and there's a growing awareness some existing damns need to come down. The Gorge is not some great untapped resource for pumped storage that people were too distracted by wind power to discover.
Windows, cars, and pet cats kill multitudes more birds than windmills
Hydro plants do use wind to bank energy. Either by shutting down and banking water when the wind is blowing, or even running the pumps in reverse.
I agree with you that energy storage is a big problem with wind. It is with solar too. But we can get near 50% wind and solar before it becomes a problem since much more energy is used during the day.
Dams also have a finite lifetime, something nobody really talks about. They silt up over 50-100 years until they're completely full. This is a bigger problem in places like China with turbid water but happens everywhere eventually. The sun will shine and wind will blown till long after we're gone but dam sites will be gone eventually.
If it's way too expensive (and there's no obvious way to reduce costs), then scalability is irrelevant, which is probably why people are fixated on it. We need both scalability and price to be favorable.
Maybe all we need is to have massive overcapacity of renewables - if we have 10x more solar than we need, even the most cloudy day will still provide power.
All of this is essentially ways to create hydroelectric plants without the water. If we can find a way to create more of them without massive disruption it'd probably be the most effective.
We need to find a solution that isn't just based on good wishes.
There are about 10E7 active oil wells in the US.
https://www.eia.gov/petroleum/wells/
There are 10E8 private water wells in the US.
https://www.epa.gov/privatewells
So 10E6 sounds practicable and, as discussed previously, may be a significant overestimate of actual need. Suspect 50 year life cycle costs and various environmental and political externalities would be substantially lower for gravity-based solutions. But who knows?
Concrete requirements? About 10E10 tons of concrete are consumed worldwide each year.
https://concretehelper.com/concrete-facts/
Again, 10E6 doesn’t look so big, but might involve some engineering cleverness.
But 10E6 big, capital intensive, fairly generic things can justify a lot of engineering cleverness in that one generic design. Geotech would need a lot of thought.
This sounds amazing. It's like the repetitive, seemingly-pointless behavior you see in the background in videogames...
Not sure if this is the same one I read about, but it's the same concept: https://energyvault.com/
These guys “solve” the wind and control problem by digging a 300m deep pipe for the weights.
He seems to think Energy Vault is an alternative to pumped hydro, which it is absolutely not. They're not solving the same problem.
Pumped hydro is best suited for regulating power over days/weeks. You do not want to use it to do frequency regulation or regulate power fluctuations over hours/days. In fact, in Norway, where there's a whole lot of hydropower, and now an increasing amount of wind power, they're considering putting battery storage inside hydro power plants. This may seem really stupid until you understand that constantly regulating the output of a hydro power plant up and down wears down all the parts of the power plant much faster, and can cause issues for life in the river downstream. So it actually makes a lot of sense, since the hydro power plant has a good grid connection and may have some spare areas for batteries.
Batteries and solutions like Energy Vault are primarily intended for frequency regulation and short term storage, and that covers most of what's needed to help balance renewables in most areas.
There's a bunch of other serious flaws in his reasoning too, such as thinking that a marketing-material picture of Energy Vault next to wind turbines means that they actually propose putting Energy Vault towers right next to wind turbines, rather than just an illustration that the Energy Vault helps regulate output from renewables.
Quick back-of-the-napkin calculation: Car batteries come in at less than $100/KWh. They're good for at least 1000 cycles at 80% capacity. That gives us at least 0.8MWh for a 100$ investment.
It's very, very unlikely that initial construction of the site and operational costs more than triple that price.
$367 of LI batteries at year X is $171 of LI batteries at year X+5 and $86 at year X+10, so it's important to look at what the X is in their study. And of course, we should consider that chemical battery costs are expected to decrease in the near future, while the cost well-established mechanical components would stay stable.
Bias: I participated in their crowdfunding campaign.
> For a 25-year project, he estimates that Gravitricity would cost $171 for each megawatt-hour. Jessika Trancik, an energy storage researcher at the Massachusetts Institute of Technology, says that number is aspirational and still needs to be supported with field data. But Schmidt’s calculation of the lifetime cost per megawatt-hour for lithium-ion batteries, $367, is more than twice as much. Flow batteries, a promising grid-scale technology that stores charge in large tanks of liquid electrolyte, come in at $274 per megawatt-hour
What is the $/MWh cost associated with mining for, recycling, and disposing of battery components? What about the third order effects of centralizing control over the fuel source within only a handful of countries[0]? What's the $/MWh of the political shifts?
I can't safely make assumptions about why you personally stopped reading after cost came up, but it seems to be a common reaction at this point. "Show me the money!" tends to end most conversations about energy these days.
0: https://unctad.org/news/demand-raw-materials-electric-car-ba...
I can rephrase to say that the comparator function for money has an ideological bent. It rewards the externalization of costs
In order to compare two actions, you need to normalize their consequences to make them comparable. This is a fundamental requirement of making decisions. 'Money' is simply the unit we choose to do that in our complex society. We can call it utility points or something else, if you want, but it's still the same abstract object.
There's so much bullshit in mainstream energy analysis; there's too much incentive. Energy is central to civilization - what we use, where and how we get it, how we use it, how much of it there is and when we can use it - change any of those variables, change the shape of the entire civilization.
Yet the conversation around energy technologies is entirely dominated by dollar cost. This obfuscates so much, and lends a false equivalence to pricing/market/financial mechanisms - it implies that if something can be sold cheaply (low price) then it can be produced/extracted cheaply (low cost).
We are quite capable of, and actively involved in, stealing from our futures (high cost) in order to achieve low prices in the present. The economic externalities of our energy usage don't go away - by definition, that which is finite and we use now to do this, cannot be used later to do that.
That energy we'll one day need to feed ourselves, and heat our homes, and supply our medicines and materials? We're using it, right now, to make a shitload of disposable, toxic, plastic shit. Junk nobody needs that we'll convince them they want anyway.
And why are we doing this mad, insane, thing? Because we're convinced it doesn't matter, we're convinced the price of energy will always be low. We're convinced we're not the ones paying the costs.
Apologies for going full doomer on y'all. https://pics.onsizzle.com/oh-i-made-myself-sad-me-irl-242092...
We should limit it's use to making medicines and materials instead of burning it to heat our homes and propel our cars.
Not only does the latter consume a lot more fossil fuels, it does so by dumping a lot more CO2 into the atmosphere. Plastics consume 14% of global petroleum production today [1].
We could ban all the "disposable, toxic plastic shit" tomorrow (and I agree that we should find ways to create a less disposable culture) and we would still have a huge CO2 problem caused by fossil fuel powered space heating, transportation and electricity production.
1. https://e360.yale.edu/features/the-plastics-pipeline-a-surge...
A chemical battery is rather compact, imagine how much stuff you need to build a gravitational mega-structure.
A fraction of the cost of the batteries, naturally.
> What about the third order effects of centralizing control over the fuel source within only a handful of countries[0]?
The lead in car batteries is one of the most recycled materials on the plant. Your link is talking about lithium, not lead. Lithium-ion batteries only make sense in portable applications like cell phones and electric vehicles where weight is a major consideration. In stationary applications, heavier batteries like lead-acid are infinitely more practical.
This is ridiculous.
I'm charging right now my EV from a 14 kWh 16S LFP pack which costed me $1400 tax paid and delivered.
LFP properly managed will do minimum 3000 cycles, so that's 42 MWh for $1400 which gives $34 per MWh out of the battery.
Note: 5kW 48V inverter cost $500.
https://pubs.rsc.org/en/content/articlelanding/2021/EE/D0EE0...
Re-examining rates of lithium-ion battery technology improvement and cost decline
Wow, that's amazing. But why are home battery systems still so expensive? I see system prices in the range of $700 to $1200 per kWh. Even on aliexpress, it's minimum $550/kWh. Is the inverter so expensive?
I found the vendor by following:
https://www.youtube.com/channel/UCoj6RxIAQq8kmJme-5dnN0Q
DIY Solar Power with Will Prowse
It's also important to remember that capacity will be reduced gradually. After 25 years both the energy storage capacity and power output of batteries will be seriously reduced, while the gravity-based system will most likely still be at full capacity.
I still think the estimate may be too high. Especially taking into account that these systems will compete in the future at a time where battery costs will be lower. But it might still make sense to build gravity based systems for a while to make sure all the lithium we mine goes to batteries for transportation.
Which is why vertical glaciers are so tempting. Its just ice, you pile it up, in large columns, with a puddle of water beneath. Energy is extracted by warming the water and taking part of the pressure to a turbine.
Energy is added by pumping and freezing water on top, while the extracted heat is stored in a side tank for later usage. Insulation against heat prevents energy loss for longer times. Four T-beams hold up the freezing machinery on top. Storage grows with demand. If the ice starts to deform, added carbon-flakes, can increase tensile strength. Pressure in the pool is kept via onion-seals
Maybe the efficiency can be improved upon with a small-scale 'gravity battery', but water has massive advantages when it comes to scaling it up, as well as being able to combine it with traditional hydro, where nature moves much of the water for you.
I've often wondered what scale of a system would be required to power a fully off the grid home at say 30kwh/ day, for say, 6 days? I'm imagining a tank based system with two tanks where the fluid is effectively just exchanged (so one doesn't have to account for the environmental impacts of a dam or for losses due to evaporation)..
After some googling: https://www.edie.net/library/Using-pumps-as-turbines-to-gene...
That is LESS than 1 kWh of energy storage.
I hope it's not the one on the picture otherwise their cost estimates are way off and two orders of magnitude larger than current lithium batteries, even taking into account battery replacement.
Another problem would be the ever-lowering price of batteries comparing unfavorably against this good old tech with stable or raising costs (human costs tend to rise over time)
I'm also curious if anyone's seen a good comparison to hydro/dam based gravity batteries? Or even to the gimmicky sounding electric train based ones I've read about before?
My understanding is that anything near or past 90% efficiency gets very hard to achieve, but perhaps there are special cases where this isn't true?
Finally, I'm also curious how these compare to flywheels, which offer a similar style of energy storage, but with rotational potential instead of gravitational.
Storage is clearly one of the largest barriers to large scale adoption of many renewable sources of power we have. And, chemical batteries raise a lot of valid concerns in terms of safety and environmental impact.
You're digging for the foundation anyway, maybe maybe the marginal cost to dig a few meters deeper is worth it. You're building with a crane anyway, maybe the marginal cost to build a steel frame tower on the roof is worth it. It's certainly not a mine shaft, but perhaps better than nothing.
To make a comparison, there is a human-scaled variant of the concept in the GravityLight by Deciwatt. The concept is clever, it involves lifting a bag of rocks to get a bit of light for 20 minutes. But if you run the numbers, it is tiny. As the name of the company suggests, the generator outputs 0.1W, enough to power a 15lm LED. For 20 minutes you need to lift a 12.5kg bag 1.8m. That's around 0.03 Wh per lift. By comparison, a good 18650 battery is around 13 Wh, about 400x more.
As a niche product, GravityLight is not a bad idea, but it is telling that their new product, NowLight operates the same way, but they replaced the bag of rocks by... a 18650 battery.
Back to the topic, it looks like that "drop a weight in a mine shaft" idea does worse than what you can do with a single Tesla car, which have more energy storage and more power at the wheels. Plus, it is cheaper and you get a whole car with it.
Liquid metal batteries will be better than gravity storage IMHO.
https://www.youtube.com/watch?v=NiRrvxjrJ1U
First commercial scale system is going live in 2021 so we shall see how it works out.
So applying first charge must heat it to melting temperature but then it's working.
Then when you discharge it, electron flow cause heating again. So if it is constant use it just works.
But looking at the size of the project, I have a hard time believing this is viable.
We use pumped hydro because water is basically free and it is infinitely scalable depending on geography. Meanwhile the proposed system is limited by the size and existence of mineshafts. In other words this is a dead end.
Energy vaults is impractical but it at least tried to solve the scalability problem by taking advantage of the fact that the energy storage grows quadratically with the length of the crane arm. Assuming it is possible to actually build that system in a sealed tower to protect it from the elements (wind makes the control problem almost impossible). Given a large enough energy vaults system there will be a point where its advantages massively outweigh its downsides.
Going one step further, you could carve out a large cylinder of rock out of the landscape [0]. By using wiresaws you will only need to cut the surface area of the cylinder out. At this point your material costs are approaching 0. The only challenge is sealing the walls of the hole and sealing the walls of the cylinder to turn the system into a giant hydraulic cylinder. Storage scales with the fourth power of the radius. Considering the theoretical performance of a gravity storage system anything that is below r^2 scaling is just laughable, which is why the mineshaft idea will ultimately fail.
[0] http://eduard-heindl.de/energy-storage/energy-storage-system...
A european household uses approx 3500 kwh/year; americans use upwards of 10000 kwh/year.
Clearly such a slab of concrete will comfortably allow buffering an entire day's worth of power, and then some.
Edit: fuck me I'm dumb. Off by a factor 1000. 39 watthour in that cube, not 39 kWh. Ignore everything I said.
[0] https://www.google.com/search?q=2400+kg+*+10+m+%2F+s%5E2+*+6...
I know not every where is suitable for reservoirs but this seems pretty obvious. Run renewable to pump the water up hills, all the 'battery' components of the tech are well established. You're creating additional benefit by storing potentially potable water. It seems like the tech for water storage/ transport/ regeneration to electricity is all pretty well figured out. I'm thinking some place like the Columbia gorge where there is high capacity for wind and for hydro.
https://en.m.wikipedia.org/wiki/Flywheel_energy_storage
It isn't practical and much more complicated than the other alternatives mentioned
With electromagnetic, we are barely capable of scraping a bit of energy from the surface without the device self-destructing. Even in superconductors, only a fraction of electrons whizzes around and even high-energy plasma is a mixture of both charges.
One and only minor problem is how we prevent the 2.7 GWh energy storage, which is 1E9 m^3 aka one cubic kilometer inflatable container, not rupturing or raising up.
But otherwise ingenious nicht wahr?
This is basically the same as pumped water storage, but instead of immense amount of water you can pump between very large reservoirs, you’re limited to one solid weight that’s too light to store nontrivial amount of energy, but heavy enough to be significant problem from engineering perspective. It just doesn’t make practical sense.
It's still basically piss-stakes: the largest wind turbine right now (14MWe Haliade-X) has 765t sitting on top of a 150m tower, so let's say you keep the 150m tower, rejigger it so it can move a 765t weight up and down the shaft without crumpling, and add your weight (a lead weight 4m in diameter and 5.4m tall), how much energy does that store?
250kWh, 2.5 teslas, or a medium-large electric bus battery.
And it's not like you can add that to a working turbine: the tower was set up for 765t not 1500, and you need space for the crane.
A stick of butter and an 2-tonne truck at 216 km/h both "contain" about 1 kilowatt-hour of energy.
The butter could maybe burn your house down but the truck could easily kill a couple of dozen unprotected humans in a fraction of a second.
I grew up in one such city, there were "covered holes" everywhere.
This is so amazing I'm just jittering over here. So what are big shafts filled with before they are shafts? Dirt! What do plants need to grow? Dirt! So what you do is ... wow this is great ... what you do is you take the dirt out, then you make this big battery thing a stack of dirt shelves that go up and down and while they are going up and down they also grow plants in the dirt.
So now you have a big field of these dirt stacks going up and down and in the middle you have a big farmers market. Money from dirt two ways. God how is this not already a thing.
Problems solved. Done.
[1] http://thescienceexplorer.com/universe/how-gravity-changes-t...
I was under the impression that this is an effect of force generally, nothing to do with gravity in specific.
It's not. Once something has fallen down, it can't fall down again.
To draw energy from the gravitational attraction of 2 bodies, you must first separate them. That consumes energy.
On second thought, I suppose tidal energy fills the bill. Extracting that energy is really exploiting the Moon's motion, using gravity as the "conduit". Not strictly perpetual, but essentially so for our needs.
I don't think Maxwell's Demon is 100% solved.
Tidal energy could play into it, some underwater tides deep in the ocean are insanely strong.
To generate power you need gravity to move something downwards, releasing the potential energy. And when that thing hits the bottom of the shaft you've used up all the potential every that was stored in it.
We understand most things about it
> It's a perpetual energy source right in front of us,
No it's not. It's a good way to store energy but in no way is a source.
> and can barely offer a basic explanation as to what powers it
It's not something that has power. It's a consequence of entropy.
> It even impacts time itself
You sound surprised by this? Given relativity it would be more surprising if it didn't.
Science is basically a stream of updated realizations that the previous "known" things were actually wrong.
Excuse me, I'm off to build a battery out of a bank of leaf springs.
In a classical mechanics sense - yes. But the waves were detected just couple years ago.
However, they were predicted in 1916 as part of Einstein's Relativity work: https://en.wikipedia.org/wiki/Gravitational_wave
They are the types that would ridicule Christopher Columbus for even considering the notion that the Earth wasn't flat...then after proven wrong go around telling people they had a strong feeling the Earth wasn't flat.