By far the most efficient grid "battery" to reconcile fluctuations in demand & supply is to have a realtime price for electricity. Water heaters, for example, can be equipped with an internet device (at last, a reason for an internet connected water heater!) to monitor the price of electricity and shut off the heater during price spikes.
Some "batteries":
1. hot water heater
2. HVAC system
3. EV charging
4. Some lights (like yard lights) can be dimmed or shut off during rate spikes
5. Same for street lighting
6. Computers can switch to low power mode
7. Refrigerators
8. Dryers
This is far better than the "rolling blackout" bureaucratic solution.
Note that the pump price of gas varies daily. This is the market reconciling constantly shifting supply & demand, and it works great.
I work for an oil and gas company and I’m working on a project to turn our pumps on and off based on spot price, since we pay wholesale 15-minute price for electricity. There’s a huge untapped benefit to aligning incentives between electricity consumers and producers.
2. Utilities were obliged by law to provide whatever electricity consumers demanded at that rate
This meant that utilities had no choice but pay whatever Enron demanded and resell to consumers at a massive loss. This ridiculous catastrophe was entirely a construction of the electric regulatory framework.
It doesn't have any resemblance to what I proposed. What I propose is more akin to how gas pump prices vary every day. Note that there are no laws setting the price or distribution of gas. When there were (back in the 70's) the result was LOOOONG gas lines. The Enron fiasco and the gas line fiasco are prime examples of what happens when government tries to centrally plan pricing and distribution.
Not really: the Enron fiasco happened because the government reduced its involvement, deregulating the power grid, and gave actors like Enron, Duke Energy and others the ability to manipulate the market, causing prices to swing wildly. California saw an 800% increase in wholesale energy prices. You object that the retail rates were set by law. But consumers could not handle that 800% increase; most people can't handle an unexpected expense of a few hundred dollars. Utilities weren't obliged to provide power when things went to hell, they imposed rolling blackouts. They had to.
With gasoline, you can wait and shop around; if a station tries to gouge you you can see if you can get a lower price down the block. The power grid has to be balanced on a continuous basis, and if it's out of balance, the grid operator has to obtain power immediately.
The power grid requires careful management. Call that "regulation" if you like, but it isn't optional.
California did indeed deregulate wholesale electricity prices, but not consumer prices. Rolling blackouts are a form of rationing, rationing results from shortages, and shortages are the result of price fixing by by the government.
Note that Reagan's first act as President was to repeal all oil and gas price and distribution controls, and the gas lines evaporated literally overnight. Yes, I was there and remember it :-) We've had a number of oil crises since, but no gas lines.
> But consumers could not handle that 800% increase; most people can't handle an unexpected expense of a few hundred dollars
Many places that enable spot price electricity contacts for consumers have other kinds of contacts available too. Consumers who choose spot do it if they trust it's on average a win. There are also hybrid models where there is a price ceiling or other hedge.
“Any market reform, government initiative intended to reduce red tape and promote market forces will have the ultimate effect of increasing the total number of regulations, the total amount of paperwork, and the total number of bureaucrats the government employs.” — David Graeber
The carbon lobby pummeled us with propaganda about how renewables "weren't ready" until batteries were good enough to fill in the gaps once they started becoming price competitive.
Ironically they were the ones who set up think tanks that preached putting faith in the market to solve our problems for us - at least until they started getting undercut.
My previous firm (in Australia) attempted to do this for commercial buildings by monitoring the 5 minute wholesale electricity price from the National Electricity Market [0]. We installed current meters on each circuit in the buiding, HVAC, lighting etc. then were able to estimate cost savings for a given 30 or 15 minute period if that circuit was shut off. We even tried to estimate the savings if HVAC was e.g. reduced by 1 degree C in the building for a given time of day, occupancy, and weather conditions by using 1-2 years of 15-30 min resolution historical energy usage data for that building.
> The Power Partner Program is a community-wide coordination of air conditioning usage that allows Austin Energy to manage energy use during peak summer days when it matters the most.
> During a Power Partner event Austin Energy will adjust the temperature setting on your Internet-connected thermostat. Temperature adjustments up to four degrees reduce usage when the energy and cost savings are needed the most community-wide, yet do not significantly impact comfort.
It's not market-based in the way you're talking about (real-time price being pushed through to the consumer), but it may be market-based in a different way. The same page goes on to say it "helps lower the overall cost of electricity in the community". So I assume the utility uses it to reduce how much electricity it has to buy at peak prices.
It's a clumsy attempt to emulate what a market does. One telltale aspect of its clumsiness is the elastic use is confined to the A/C (I listed other avenues). A market based solution would use price, and let the consumer find the best way to adapt to it.
Another complicated bit of clumsy silliness is cap-and-trade. The straightforward way is just tax the carbon.
I had something similar offered by Duke Energy. They credited like $10/mo to be able to turn my AC off whenever they felt like it. It was terrible. You know when i want my AC the most? When its hot. And that is exactly when it would be disabled. That thing got removed within days.
There is already a very successful company here in Sweden, that is doing exactly that.
They do even much more than what you describe like providing electricity realtime from the best supplier depending on various factors like price and climate friendliness in a given time.
That's good. This can be objectively determined with things like a tax on emitted pollution, which goes into the price of electricity provided, and then the utility can simply buy the cheapest.
Supply and demand is great, but calling it “battery” is a huuuge stretch. Batteries manage supply, pricing helps manage demand. You need both.
Gas prices at the pump is pretty bad example. Varying electricity prices are build on shifting demand by few hours. Gas prices are unpredictable and you cannot really shift demand much, and prices swings can last years.
Modulating demand by modulating the price won't solve the entire problem, but I bet it could reduce the size of needed grid batteries by a huge margin.
> calling it “battery”
I did put it in scare quotes, because although it is not an actual battery because it does not store/release charge, it serves the purpose of one.
There's a bacteria called Legionella that thrives between 60 and 120 degrees Fahrenheit. To prevent it from growing in the hot water supply, most water heaters shoot for 140 and then achieve cooler temperatures by mixing in cold water at the faucet.
Your plan could still work, but I think that the water heater is its best target, and that much of the savings goes away once you factor in that constraint.
I think that there are many opportunities to improve by thinking along those lines though. For instance, I always thought it was weird that the grocery store I worked at ran the refrigerator compressors even when it was cold outside.
For killing off the legionellas it's sufficent to heat the water tank to 140 once a week. The exact time could of course be chosen according to the currrent energy price.
Water should be heated using heat pump or other more efficient system. Also most of hot water is used in washing, you can recover a lot of that waste water heat back.
I had the same idea. Startup name is strata.energy. Pool pump s are another good one for your list. No one cares when the pump runs, just that it runs.
Literally decades ago we had a simple version of this. I think it was only for our pool pump...maybe the water heater. My understanding is my parents got some sort of fixed discount if the power company had the ability to periodically cut power. I'm not sure how the signal was sent, but I remember an electrician pointing out the wires. It was probably a small box next to the breaker.
In countries where big industry is gone the main demands become consumers, and so it becomes consumer loads on the grid that need to change to adapt to supply. That's more complicated than a few big industrial users being paid to turn off equipment.
There's many more stakeholders to coordinate.
There used to be an electricity tariff in the UK called Economy7 which was a simplistic version of this. Valid during night hours, you could, eg, recharge storage heaters with it, for release during the day.
Not sure if it is still available.
Edit: it is, but requires special meters at the premises.
Man. This smells of techie overkill. The utility can make an announcement via radio or broadcast or sms to let you know if the supply is under pressure. Then switch off non essential appliances normally.
I live in a country with a struggling national power grid as people have come online faster than the utility could service old and build new powerstations. The blackouts or load shedding are not as frequent as a decade ago but we've learned to live energy cheap.
Peak and off-peak pricing already exists in many places. Power consumption naturally fluctuates pretty wildly. It is very difficult to make any large scale system that is highly efficient at both 100% capacity and 50% capacity.
I don't know how efficient a houseful of IOTs can be, but I don't want one.
Second question: what's to keep my neighbor(s) from ignoring efficiency in favor of demand. So I'm doing without lights while they party on. (Please don't say regulations.)
> I don't know how efficient a houseful of IOTs can be
The Nest thermostats come to mind.
> what's to keep my neighbor(s) from ignoring efficiency in favor of demand
He gets to pay the price for it. It's the same thing that prevents him from buying fuel guzzling cars. (Note that sales of guzzlers inversely track pump gas prices.)
Price fixing by the government has the perverse effect of continually causing demand to outstrip supply - rolling blackouts, shortages, rationing, etc.
Heating water with electricity is the literally last thing we should do. That is, once clean electric energy is cheap, we can do it. But we are not there yet. Hence we should at least use heat pumps or similar technology.
Heat pump is heating water with electricity... And it’s not the last thing we should do, it’s economical today if you live in a mild climate. I installed one in my house a year ago. The initial cost was ~$500 over a similar gas water heater but it qualified for a $1000 rebate making it cheaper than a gas unit. Cost of heating is less than I used to pay for an old gas water heater. It might not make sense in a region with cold winters, but in a moderate region they make a lot of sense.
In a heat pump, the heat does not come from the electricity but from an environmental source. The electricity moves and compresses but does not heat anything.
Your usage of dollars indicates you live in the US. I hate to tell you but your definition of "economic" is probably not sustainable. Your price of electricity would probably double or even triple when switching to (cheap) renewables.
> Your price of electricity would probably double or even triple when switching to (cheap) renewables.
Finally someone who recognized that renewables are a magnitude more expensive instead of the usual "muh, renewables are cheaper!" fallacy. Look at the typical price per kWh in Germany (around 32ct/kWh) and tell me again how that is cheap...
I was talking with someone recently and they recently bought a new electric water heater. I asked why they didn't go with a heat pump option, and they said the dealer told them that heat pump water heaters are basically a "robbing Peter to pay Paul" situation where you end up taking heat you would have added to your house and putting it in your water instead.
I guess in warm climates / seasons that is probably a net benefit, but I've noticed our electric co-op also promotes highly-insulated electric water heaters instead of heat pump water heaters.
Not sure what I think of it all. We have an electric water heater and at first I was grumpy about the relative cost to run relative to natural gas, but I've come to terms with it. It's about the simplest device possible, and that has some value I think.
A conventional heater can, at best, use 100% of the energy to heat both the water and the house.
A heat pump would use some of that energy to capture some more from a heat source (outside air, or geothermal, ground temperature). It gets less efficient as the heat source becomes cooler, so it might not be such a good idea in very cold climates. Theoretically, though, it shouldn't get lower than 100%, and efficiencies can reach 300% pretty easily.
I read about 270% at -4°C (25°F). 1 watt of electricity in, 2.7 watts of heat out, not bad. The same graph reads about 480% at 18°C(65°F), and 150% at -20°C (-5°F). I know that gas heat pumps exist as well, and some systems are hybrid, so it sounds like a no brainer to me. On the flip side, they can be quite expensive, so do your calculations relative to the temperature history, and hourly electricity hours. It would be more efficient to heat when the air is warmer during the day (assuming air pump), and combine that with a well-insulated house.
Solar (thermal or electric) is pretty interesting too, I wonder what kind of efficiency one can get with photovoltaic + heat pump (photovoltaic is more versatile, being more useful during summer).
I think GP is talking about heat pump water heaters that are working between the air in the room where heater is installed and the hot water. Very different from what you are suggesting. It could still make sense if it is installed in a room with lots of waste heat, e.g. next to a clothes dryer and other appliances.
> I think GP is talking about heat pump water heaters that are working between the air in the room where heater is installed and the hot water.
Correct. Every heat pump water heater I've ever seen has the heat pump directly on top of the water tank. It's possible they make ones that tie into an external heat pump, but I've never seen one.
The trouble with water heaters is you want hot water year round. Heat pumps are pretty ineffective once you get down close to freezing. So having an exterior air source heat pump would only make sense for maybe half the year in a lot of locations.
Generally utility rooms in houses have a decent amount of waste heat anyway from being near the furnace, so it probably does work out decently a lot of the time.
My in-laws have a heat pump water heater and it makes their basement noticeably colder in the summer, which is pretty nice.
To counter that point, high-end tumble dryers are universally built with a heat pump that is all located inside the same room (it's even in the same device).
It's because they are cooling air to dehumidify it (the drying part), then they pump the heat back into the same air to circulate back into the wet clothes.
This is because a bunch of the units on the market source their heat from directly around the water heater (likely a conditioned area of your house). They have options for ducts to dump the cold air they generate outside during the winter, but this doesn't help as you then need to draw in outside air to make up the pressure differential (otherwise good luck opening doors).
Units that have the radiator/compressor outside are 3-5x the price, and are hard to find.
The way the parent comment is worded, he is actually advocating for not doing activities like running hot water heaters during peak load times.
I know many utilities in my area have a program you can sign up for where they will cycle through the registered AC units to balance out peak load in the summer. I'm not entirely sure how they manage that, I suppose they have to have some sort of sensor switch they install in your circuit.
> you can sign up for where they will cycle through the registered AC units to balance out peak load in the summer
This is inefficiently attempting to solve the problem in the same way while trying to maintain that flat electric rate. We need to get past the idea that electric rates must be flat.
> We need to get past the idea that electric rates must be flat.
I'm not aware of anyone that does minute to minute electricity pricing, but I know for many utilities you can sign up for alternate price schedules that have different rates based on the time of day.
I would guess as much as anything it's a metering issue.
price schedules that have different rates based on the time of day.
That's better than 24/7 flat, but is not a solution for dealing with spikes in demand or fluctuations in supply. Minute-by-minute spot pricing is the solution for that. With the ubiquity of the internet, and low cost for IoT, it's feasible, practical, efficient, and effective.
How does this work? Where I'm at (Iowa) your electric provider is determined by where you live. As far as I know, you have one company that provides electric to your home. You don't have the option of picking someone else.
Based on the website it looks like Griddy is something you can just sign up for and then your bill will be routed through them somehow? How does that work? Who maintains the infrastructure?
The common term for this is “regulated electricity market” vs “deregulated electricity market”.
By your description it sounds you guys in Iowa have a regulated market. There you have a vertically integrated electric utility company who does everything from generation to line maintenance and billing with oversight from a public regulator.
In a deregulated electric market you have separate generator companies who sell wholesale electricity to retail energy suppliers who sell it on to end customers. Transmission companies maintain the grid infrastructure and they are paid by the other participants for this service. This scheme when it works right can result in more competition and thus better efficiencies.
Meanwhile, there are hot water heaters in use everywhere. That isn't going to change anytime soon. Besides, in many places during peak solar there isn't anyplace to dump the electricity. Electric hot water heaters can take care of that problem, as water will stay hot in one for a couple days (I know from experience).
> Heating water with electricity is the literally last thing we should do.
Would you consider electric showers an exception? They only heat whatever water you're using. I've lived in houses with no hot water in the taps for months, but could still take a hot shower whenever.
I think it was a reference to the way we get electricity.
Burn gas at the plant to heat water to run steam through turbine to get electricity ... and then use electricity to heat water again? Just use gas at the end point.
Getting heat from fuel (or sun) is easy and efficient. Converting it to electricity isn't.
If electricity comes from a non-fossil-fuel source - it is even more expensive/valuable.
Something that doesn't often get brought up in these energy "storage" discussions is the potential for duty cycling existing generation to time shift the duck curve. Eg. California (large solar generation) shares a grid with Washington and British Columbia (large hydro generation). When the sun is shining, hydro reservoirs can be filling, as solar is meeting the demand. When the sun goes down, hydro facilities can duty cycle on and drain the overhead. This requires some flexibility in reservoir levels, as well as the ability to stop/re-spin turbines on a daily cadence. But you eliminate all of the efficiency losses with schemes such as pumped storage (though gain some transmission losses due to the increase length of geographic arbitrage).
The same opportunity exists on the East-West axis. The sun is still shining in California after its set on the East coast.
What you're describing sounds a lot like open-loop pumped storage [1]. You don't hear about it much because it's already quite common and has been for decades. There's something like 22GW of capacity in the US alone.
It was my understanding that this is more of a seasonal thing than on a day to day basis. That is, during the summer, southern California uses a large amount of electricity for climate control, and so power is transferred along the Pacific DC intertie in a north -> south direction.
In the winter, electricity usage in the north is devoted to heating, whereas in the south temperatures are mild. The result is that power is moved back up the intertie from south -> north. In the spring, snowpack melt refills the reservoirs in the hydroelectric system, allowing it to be ready to provide power to the south again once temperatures start to climb.
Its my understanding that some hydro facilities do this. One issue I can think of is the losses of transmitting that much electricity from 1 area to another (1000s of miles away). the losses of transport coupled with the losses of "storage" and "generation" make it more expensive. I don't know the actual costs, just ideas I think about.
Not so much with ultra-high-voltage lines. China has been doing it for years because of the really long distances between electricity production and consumption.
This is true - but pumped hydro has limitations on where it can be built, meaning it becomes constrained on transmission. So, in theory it is super awesome, but in practice you need to include the cost of many years of litigation to navigate the balkanized US system for permitting power lines. Not to say it's not a good option in many cases, just to say that it's not a panacea.
Somewhat related: I cannot plug The Energy Transition Show (https://xenetwork.org/ets/) podcast enough on subjects like this. It's the only podcast I pay for. Each episode the guest will be some PhD or similar in whatever the subject is, always super in-depth. Highly recommended.
What’s most cost efficient for the duck curve at scale is single axis tracking solar systems. The added cost produces ~zero extra power at noon and significantly more power at sunrise and sunset. It doesn’t completely remove the issue, but you get about 80% of max capacity for about 90 minutes more in the morning and evening.
Density is lower, but daily kWh of solar power per acre stays surprisingly close. In effect flat solar panels are shading each other to some degree for most of the day. Density therefore becomes just another trade off.
Anyway, as long distance transmission is cheap panels are generally on the cheapest land you can find, often sub 1,000$ per acre. This makes minor differences in density largely meaningless. The added spacing also reduces the local environmental impact as plants can grow around the panels which can significantly reduce dust. They also make better use of limited PV manufacturing capacity.
That said, if you’re actually space limited for whatever reason, flat panels win.
as a counterpoint, nearly every grid-attached power storage system I've seen has been almost entirely described/discussed in terms of "useful for renewable power", i.e. the duck curve. though it doesn't often get mentioned by name.
the exceptions are either A) they also mention how e.g. nuclear power is very limited in its ability to change output at all, so it's also useful for day/night power imbalance in general, or B) they target short-term spikes and dips to e.g. allow gas/coal time to adjust.
> Pumped storage is by far the largest-capacity form of grid energy storage available, and, as of 2020, the United States Department of Energy Global Energy Storage Database reports that PSH accounts for around 95% of all active tracked storage installations worldwide, with a total installed throughput capacity of over 181 GW, of which about 29 GW are in the United States, and a total installed storage capacity of over 1.6 TWh, of which about 250 GWh are in the United States.
Soo many different better options. As a member of the energy storage industry I give this a hard pass, this is also old news, costly and not multi functional. Pumped storage makes sense in some specific cases.
Look to lithium ion for short time high cycle/fast response, vanadium flow for long duration (expensive currently, large sites), hydrogen potentially and fascinating long duration start up out of Massachusetts (forget the name right now). More tech will come down the pipeline soon.
Compressed air possibly but hasn’t really progress much over its existence so far (geological restraints too). My two cents
The new thing I read there was the use of old abandoned mine shafts, providing up to 1km of vertical distance with a 5000 tonne mass. There are a lot of abandoned mine shafts. Does it work?
The grid-nerd term for rapid-response capacity delivery is "frequency control ancillary services." It's a real problem in times of heavy load. If a local grid's frequency drops below nominal (60Hz US, 50Hz elsewhere) the regional grid has to disconnect. So without rapid-release stored energy a power generating org has to fire up extra capacity and keep it running to cover transients.
Old missile silos might be interesting. But most of them are far from population centers.
Pumped storage is still great given the right geography. Northfield Mountain has been running flawlessly for almost half a century, storing about 9 GwH. https://en.wikipedia.org/wiki/Northfield_Mountain_(hydroelec... But it takes about ten minutes to spool up. And the fish and boaters in the nearby Connecticut River definitely notice it.
When the frequency of the generator is not tied to a mechanical property of it (like the spin of a turbine) - e.g. when the source is solar panels and the AC is produced via an inverter circuit, what are the remaining frequency-related issues?
I imagine with solar the generator can pretty much pick any frequency it wants, it should not be influenced by load, it could simply stay in sync with the grid no matter what, is that right?
The problem with inverters is that they have no inertia to impart on the grid. When you have a gigantic spinning turbine, the amount of power it takes to change its speed is immense. This has huge implications for grid stability when we are talking about renewables.
Frequency is really the "adaptation parameter" of the grid, rather than voltage. For fast frequency response, the requirement is to "push" the frequency faster by outputting more energy.
Imagine being in a team of people pushing a car along a road at a steady speed (frequency). One of your colleagues trips over and stops pushing. You then can't maintain the speed without putting in more effort.
Most cheaper solar panel inverters are synced to the grid and require the external 60hz wave to output power, resulting in solar panels that will not provide energy without being connected to the grid.
Just do the math. Total amount of energy they store is no more than a TEU container worth of lithium batteries, or few dozens of modern flywheels, or hundred so of plain steel ones.
Yeah all of them are questionable. The only one that has even a tiny chance of succeeding is the piston idea. You don't have to pay for the weight and you only have to cut the circumference of the piston out.
The piston idea has a problem. Rock isn't like that. Natural rock does not often come as one big solid piece. It's more like a pile of boulders of different sizes. There are cracks, underground water, rubble, etc.
Does no one do fundamentals at school anymore, water is around the same density as concrete (~2.4 times smaller) except you can just use a simple pump.
The reason they use concrete in these designs is because if they used water people would say it's stupid. That's literally the reason. It's the same for mineshafts. These concepts are introduced to confuse you.
"But pumped hydro requires some very specific geography—two big reservoirs of water"
So does concrete. Expect you are building the geography and it'll be around the same size if it stores around the same energy.
Seems a bit limited and expensive. Pumping water uphill when there's a surplus seems like a no brainer, doubly so when you are already using hydro and hydro production is already tied into the grid. Seems like pretty much the only way to cost effectively bank substantial amounts of energy for 6 months.
It's good but not perfect. Dams require a reservoir, which takes land out of use and changes the flow dynamics of a river. It can interrupt wildlife patterns both up and downstream. It introduces some risks of dam failure, and decommissioning a dam requires careful management of built up sediment. Flooded organic matter anaerobically produces methane.
It also requires significant space and particular configurations (must be on a river, must be in a hilly or mountainous area, etc.) It also isn't necessarily scalable -- how many more dams can we build?
You can build a crane and blocks or drill a big hole in lots and lots of places.
So yes, pumped hydro is better than fossil fuels. But also it's not something we can consider to be the ultimate solution to the issue of storage. By all means, let's use it (and we do use it today), but not stop there.
It seems like using hydro as a demand-smoother changes the aspect of how much damming you need to do. Instead of having to construct a massive reservoir to provide constant power if the hydro is only intended to provide peaking or off-demand power then it seems like the reservoir could be much smaller - and conversely less environmentally impactful.
Once you've committed to a dam, much of the environmental damage is baked in, whether small or large. And dams have huge environmental impacts across the entire river system.
They still have their place. There is a pumped hydro system here in the Bay Area (San Luis Reservoir) that is coupled to a hydro station, and produces power when it drains back in to the aqueducts. It's primary purpose is water capture and distribution, not power storage, but it does both.
Dams are expensive and have significant side effects. However the duty cycle on a dam is pretty low (they rarely run the turbines at 100%). So there's substantial additional capacity that could be had by pumping water upstream whenever there is a surplus of power.
I am not sure that this form of storage is comparable to a traditional dam. The fact that blocks of matter need to be physically moved by a crane severely limits the total capacity of the system. The most dense metals are only about 20x as dense as water, so we are not talking about a huge volume of water. The equivalent mass of water can be stored in a tank - no dam required and moved through a pipe - no river required.
Paying for 20 denser material is usually more expensive than just "buying" 20 times as much material. Gravity storage will always be a scaling problem because you would rather have 1000 times the material than 20 time the density. Doing something as nonsensical as using a mine shaft whose size is fixed is not going to work out.
The crane system could work out in theory if you make the crane arms 200m or longer. The covered surface area grows much faster than the length of the crane arm. In practice it's an engineering nightmare.
The piston idea has the benefit that you just use a wire saw and cut out a circle. The primary challenge is building what is basically the largest seal on the planet. The pressure itself is not a problem but the sheer size is.
Compared to hydrogen, reflow batteries, compressed air, heat storage, etc gravity energy storage is extremely questionable unless it's pumped hydro.
The piston idea seems like a appealing design requiring minimal new technology. The plant is the same as existing pumped hydro plant, the weight can come from the native rock.
Using a rolling membrane for the seal is discussed at
These ideas are cute but they lack interest from major players.
In Europe it seems the big players are betting big on hydrogen. The EU is looking to convert all gas pipelines to be hydrogen proof and for new pipelines to also be hydrogen proof. I know Japan is also very bullish on hydrogen infrastructure.
With regards to energy storage, it seems to me the solutions that are most likely to be widely adopted are: batteries, pumped hydro, and hydrogen and the many synthetic hydrocarbons that can be obtained from it. Besides that, improvements to the energy grid can be made to eliminate the need to store as much energy in the first place.
Were we stand in 2021 is that policy is already on the books and funds being distributed for these projects. So hydrogen ready pipelines are definitely getting built. Whether they will prove useful remains to be seen.
About 10-15 years ago my sister's highschool classmate tried to fund a startup to build mechanisms that would store energy by towing buoys down to the bottom of the ocean. I can't find it on the web now, though.
It's an interesting idea compared to other gravity storage solutions because
- It's the volume of the buoy rather than the mass that's important
- It could be colocated with and hooked up to offshore wind farms to smooth their generation
- You don't need to build a super-tall crane or elevated reservoir (but you do have to assemble the thing at the bottom of the ocean which sounds hard)
I haven't heard anything about it in ages so it must have turned out not to be practical.
Why would you need to assemble anything at the bottom of the ocean? Couldn't you set it up above then drop it with the cables attached, assuming it's heavy enough?
You wouldn't necessarily need to even drop much more than a mass that weighs more than twice the buoyant force of the buoy with a block to redirect the cable, then have a floating platform that's more buoyant than the sinking buoy.
Seems like they'd do it on the edge of a natural cliff to avoid having to build a tower, or maintain an abandoned mineshaft. There aren't big cliffs everywhere, obviously, but where there are, seems like an economical option.
Cliffs tend to move a bit, falling slowly over time. There may be more stable cliffs to use, but the ones near where I grew up on the coast have a fairly steady fall rate (a new cm/year).
Yeah, don't do the math on their outrageous claims. Excavating a hole in the ground that's 150m across and 1000m deep represents a monstrous up-front investment of energy. Not to mention the small matter of their 8-megaton piston costing half a billion dollars.
This article surprised me since funding came from Softbank and not the state government as most does IIRC.
Where I see the problem with all these forms of energy storage is that there is no one efficient approach (yet!) and innovation will come mostly from government funding, so governments decide what they see as the best opportunity.
This seems like its pretty much hit-or-miss and betting on the wrong thing will arguably speed up the development of it but at the same time, we might end up at a point we could have reached quicker and cheaper had we used a different technology.
I think putting tanks in the bottom of abandoned mineshafts, and filling them through positive displacement pump/motors is the way to go. You get energy as the water goes down, and use it to pump the water back up. The costs are the mine, and the maintenance required to keep the lift working, and the whole thing from collapsing... and two tanks / pools.. one at the bottom, one at the top, piping between the two, and a positive displacement pump, with a motor/generator.
There is a reason no one has tried it. What you are proposing would be very expensive. You have to transport the water to them. The large tanks (eg. 10M litres) require ongoing maintenance. You must make sure they don't leak, evaporate too much, make sure the ground in both places won't settle, worry about seismology, etc.
Apparently storing energy in concrete blocks has no advantage over water, but brings in a lot of drawbacks (mostly the whole structure being exposed to weather).
Energy Density of Gravity storage is too small to work with smaller installations. Investment is high.
The future of renewable energy is obviously Solar PV, with Wind and other offsetting to some extent, but Solar is predictable, cheap to build and easy to maintain.
I really wish there was more thrust into carbon capture and conversion to fuel with Solar power.
There are a bunch of other technologies as well. Huge flywheels [1], which are supposed to be used for very responsive power needs (i.e. grid stabilisation), trains loaded with weights which get pulled up a mountain and released [2], redox-flow batteries and so on.
The zoning commission runs at the town/country level, so even if you don't have HOA busybodies you still need to get the permits. The law is usually worded such that if you're doing something abnormal you don't get a "there is no rule that says a dog can't play baseball" loophole, you instead have to bring it up before the county council and justify the project.
Usually when you see compressed air storage solutions they're talking about plugging up an old mineshaft or cave and pumping air in.
Doing it under water would seem to have some advantages, like a less catastrophic failure condition and having a ready place to sink all of the heat. Downside is that the water would cool the air much more effectively than solid rock so you lose efficiency.
Are there any combination solar, hydro, fracking/oil plants? I'm joking but not entirely. Not sure how much water would fit in an oil field but it seems like a natural reservoir one could use.
The trick would probably be getting your energy back after you've pumped the old oilfield full of water. Most oil fields aren't gushers, especially after they've had most of the oil sucked out of them.
A lot of these storage technologies have been around for a long time (I have a "Nature" magazine from the 60s that discusses storing excess energy as wind in salt mines and in lakes. This was the 60!).
What people underestimate is just how much energy we need to store. Lakes won't do it and neither will salt mines. Gravity certainly won't do it. We need to think much BIGGER.
I always had the feeling that with electricity consumption, smaller is better. What if we all add a few blocks in our corridor which would be lift up during the night and bring back energy during the day? This would get the curve plane and we can follow its usage closely, wanted to reduce our own bill...
But isn't that efficiency directly depending of the system itself? I mean the performance of the dynamo which would create the electricity when the weight goes down
An AA battery holds about 4 watt hours of energy, or 14.4 kilojoule. Dividing by 9.81 m/s^2 times 1 meter, yields about 1.5 metric tons. Not quite 360, but still quite a lot.
As an alternative to storage working with large industrial users to adjust their electricity demand in real time can help mitigate some supply/demand imbalances.
This solution competes against short term storage, (typically tens of minutes, up to hours). Flywheels are commonly used and efficient energy storage for short term.
Pumped hydro mentioned in the article is good for long term storage > weeks, months, even seasonal.
Use solar/wind to crack water into hydrogen and oxygen. Compress it to liquefy it. Store this in some temporary storage tanks.
Then when you want to make electricity, pipe the hydrogen and oxygen into a fuel cell. Then electricity and pure drinking water comes out.
Then you can bottle the pure drinking water and sell it locally for an additional profit.
I haven’t analyzed the cost for all the technology and infrastructure. But this idea seems mechanically simpler than the gravity brick idea. Additionally, you can transport the LH and LOX, to other areas if necessary.
Hydrogen works despite the inefficiency because there is an existing gas infrastructure ready to be converted. If we had to build everything from scratch we would be desperate for other solutions.
Quite a while ago, I thought up of what I though would be a simple system that has a net positive energy output (it already sounds ridiculous, I know, but I just can't see what concept I am missing) that follows this principle. I finally have a relevant article I can share it with here on Hacker News!
The gist of the system is as follows:
1. let a hanging weight freefall under gravity to spin a generator. (via a pulley connected to a chain drive or gears etc)
2. The power generated by the generator is stored in a battery
3. The weight is pulled up very slowly back to its drop position using a DC motor that uses power from the battery (the DC motor could be actually the generator itself but likely a specially tuned one for slow lifting will be better)
4. Repeat. The system lifting / reset process requires less energy than the energy produced by the drop, so there will slowly be a net buildup of charge in the battery.
Super simple numbers example:
PE of a 100kg mass falling 2m:
PE = (100kg)(9.8m/s2)(2m) = 1960 J
The mass falls at a near g acceleration - I know it won't be exactly g because of the moments of inertia of the generator and generating drive apparatus - but it would be quite close to g. At this acceleration the mass falls for ~0.63s, so the theoretical max power we can hope to extract using the generator is:
P = W / t = 1960 J / 0.63s = ~3000 W
Even if we consider a horrible electric generator with only 50% efficiency (just to be even more conservative and fair, and to capture any losses we've forgotten), we should hope we can get at least 1500 W from the drop.
The "trick" of mine is mentioned in that very slow "reset time" for the weight. That is, use a DC motor to pull the weight up, but give it a long time to do so. In this way, the power used to lift the weight back up to its dropping point is much less than what was produced by letting the weight fall and spin the generator.
Using the same numbers from the example above, if we let the lift time be, say 20 minutes (=1200s) and since we know the W of the lift is the same as the drop PE, then the power needed to lift the weight back to its original drop point is:
P = 1960 J / 1200s = 1.63 W
That means we produced about 1500 W (even with our crappy 50% efficiency generator), and only need ~2 W to reset the system. Assuming you put a nice battery between the generator and the dc motor - you get a net positive storage of energy over time.
Does anybody see any glaring issues with such a system and my analysis? I know when anything in physics appears to be a free lunch, something must be wrong. (Though if you consider these long 'cycle' times, it isn't really a free lunch)
Perhaps I don't understand exactly how DC motors / generators really draw or produce power in the real world - Physics 101 was a long time ago for me :)
The trick to my proposed system, which systems like those in that of the linked article don't do, is my slow reset time. Obviously not feasible for massive applications or load balancing, but a net power storer nonetheless.
You need 1.63 W for 1200 seconds (i.e. 1960 J, assuming no losses) to reset the system. I.e. the same energy you already got out.
If this worked, you could get free energy from any sort of gearing system - e.g. you could put a fly-wheel on your bicycle and power all your up-hill trips from the downhill legs of the same size by switching gears at the right time.
Step 4 contradicts basic physics. What you are doing wrong is that you are confusing power with energy. If you lift the weight slowly you need less power because for the same work (= energy) done you can do it in twice the time. But using less power over longer periods of time will result in the same energy consumption.
You seem to be comparing power differences and not taking into account that your battery would run out of energy in just the second attempt at lifting your mass to full height (assuming no other power inputs to the battery besides the falling mass generator).
Some "batteries":
1. hot water heater
2. HVAC system
3. EV charging
4. Some lights (like yard lights) can be dimmed or shut off during rate spikes
5. Same for street lighting
6. Computers can switch to low power mode
7. Refrigerators
8. Dryers
This is far better than the "rolling blackout" bureaucratic solution.
Note that the pump price of gas varies daily. This is the market reconciling constantly shifting supply & demand, and it works great.