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36 votes
Accepted

Why is there no spring based energy storage?

Because springs have low energy density When storing energy, especially in a residential setting, you want to be able to store a lot of energy, or not take up too much space. To store a reasonable ...
LShaver's user avatar
  • 11.9k
11 votes

Domestic flywheel energy storage: how close are we?

Lets check the pros and cons on flywheel energy storage and whether those apply to domestic use (source): Compared with other ways to store electricity, FES systems have long lifetimes (lasting ...
Ghanima's user avatar
  • 496
10 votes

Domestic flywheel energy storage: how close are we?

Domestic flywheels are unlikely to happen for 3 reasons: They must be heavy to store significant energy. If you need a crane to install one at your house it’s never going to be super cheap, even with ...
Ian 909's user avatar
  • 101
9 votes

Why is there no spring based energy storage?

This is a question that I've heard several times, though it is the first time I've seen it here. The main problem is, I think, efficiency. Firstly, though, not long ago, when I was a child (OK, quite ...
M Juckes's user avatar
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8 votes

Why is there no spring based energy storage?

You can easily calculate the maximum strain energy in a material by considering the maximum stress (for metal: yield stress) and stiffness (Young's Modulus). The maximum strain energy in a material ...
Sanchises's user avatar
  • 181
7 votes

Domestic flywheel energy storage: how close are we?

We were looking into flywheel UPSes for my company and I read up on this a bit. Of note in recent developments: Instead of traditional bearings, they're using magnetic bearings to mostly eliminate ...
Dave's user avatar
  • 71
6 votes
Accepted

What is the most economical and convenient house battery type?

Lithium-Ion electric car batteries would do the job, but they are too expensive and I am not sure about their lifetime. A pack of ordinary lead acid car batteries seems to be a more affordable ...
juhist's user avatar
  • 5,099
6 votes

Is Tesla Powerwall a good investment?

No it is not. Your calculations of 13year ROI is based on the assumption that charging the power wall is free during the day time. It is not. Depending on your locale, either you need to factor in ...
Aron's user avatar
  • 380
5 votes

What's the average efficiency of pumped hydroelectric energy storage facilities?

In this question about rooftop hydro I covered the efficiency question almost as an aside. I can't find an actual plant with efficiency over 80%, only claims that that might be possible. The average ...
Móż's user avatar
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4 votes
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Is there enough total Lithium in the Earth's crust to make sufficient grid storage to meet total global Winter energy demand?

TL/DR Yes, but it is meaningless. The meaningless is well covered by juhist's answer. Lithium in the earths crust: Estimates for the Earth's crustal content range from 20 to 70 ppm by weight. Middle =...
User65535's user avatar
  • 386
4 votes
Accepted

What are the most viable options for long-duration storage of large amounts of energy?

With renewables being in large part weather-dependent, the issue of energy storage is slowly moving to the center stage of the incipient net-zero economy. I agree. Lithium ion batteries are kinda ...
juhist's user avatar
  • 5,099
4 votes

Why is there no spring based energy storage?

There is - it just doesn't use metal springs Metal springs have numerous failure modes. In tension, they only remain "springs" for a certain point, after which they simply become wires/rods ...
Graham's user avatar
  • 141
4 votes

Why is there no spring based energy storage?

Not only is the energy density of such systems low, as other posts explained - stored energy that will be released as mechanical energy immediately in case the storage system fails has been shown to ...
rackandboneman's user avatar
3 votes
Accepted

Are there any good diy examples of home level STES or BTES

STES (Seasonal Thermal Energy Storage) is, in most cases, too expensive to really be practical because of the huge quantity of the storage medium needed to supply the seasonal demand. Typically, you ...
Gannet's user avatar
  • 161
3 votes

Water electrolysis for storing energy

China, Japan, and South Korea are buying hydrogen that is either made using renewable electricity or that has the carbon from production then captured. Hydrogen is easier to ship and store in the form ...
S Spring's user avatar
  • 302
3 votes
Accepted

Why is the usage factor for utility-scale storage declining in the U.S.?

Usage factor is declining because the average duration of batteries on the grid is increasing Inspired by the report that M Juckes shared, I dug into the data source for utility-scale batteries: Table ...
LShaver's user avatar
  • 11.9k
3 votes
Accepted

Is it possible to harvest energy from the storm?

Your idea is interesting but would fail in the real world for a number of reasons: The energy embodied in even a moderate storm is staggering. No amount of "Stormbuoys" could make even a dent on a ...
Tim's user avatar
  • 2,844
3 votes

What alternatives to batteries exist to store solar energy at home?

I've been doing quite a bit of reading and other research in the area of using solar for hot water tanks. There are quite a few Youtube videos by people who have been using PV (Photo Voltaic solar ...
Donny Bowers's user avatar
3 votes

What's the average efficiency of pumped hydroelectric energy storage facilities?

Energy Storage Association cites round trip efficiencies above 80% http://energystorage.org/energy-storage/technologies/pumped-hydroelectric-storage As for the evaporation question. I don't know of ...
William Rimmer's user avatar
2 votes

What alternatives to batteries exist to store solar energy at home?

Adding Power-to-(natural-)Gas, since no one mentioned it yet: By now, it's also possible to transform the energy from solar panels not only to hydrogen, but further into methane, 'the main component ...
dasWesen's user avatar
  • 186
2 votes

Domestic flywheel energy storage: how close are we?

My knee jerk reaction: From what I know of mechanical systems, anything mechanical introduces losses due to friction in the form of heat, sound, and vibration. How would you even begin to use the ...
MountainClimberi's user avatar
2 votes

Domestic flywheel energy storage: how close are we?

I was only able to find one residential flywheel energy storage system for sale as of right now. It has a low (but manageable) power output and is priced competitively. Unit Specs: Power: 3kW | Energy:...
Brian C's user avatar
  • 21
2 votes

Domestic flywheel energy storage: how close are we?

TL:DR: They extend the life of expensive UPS batteries by absorbing the transients. Example: Hosptial with an MRI Engery surge on start up with UPS graciously assisting. The MRI fires up 10 times a ...
Mike's user avatar
  • 21
2 votes

Energy storage idea: Pumped hydroelectric storage in ocean using difference in salt content

It may be technically feasible. But in reality, for places that do desalination, it's never going to be economical, because there's already an easier way to do things. Storage on the grid is useful ...
410 gone's user avatar
  • 14.7k
2 votes

Why is the usage factor for utility-scale storage declining in the U.S.?

The operating costs of using a battery once it has been installed are generally low. In fact, they appear to be too low to report on: the recent "Battery Storage in the United States: An Update ...
M Juckes's user avatar
  • 1,021
2 votes

Is there enough total Lithium in the Earth's crust to make sufficient grid storage to meet total global Winter energy demand?

No there isn't, but we don't need lithium for that. The lithium reserves are barely adequate to make all cars electric. They are not adequate for grid energy storage. We need about 500 hours worth of ...
juhist's user avatar
  • 5,099
1 vote

Are there any good diy examples of home level STES or BTES

I have done this sort of, in reverse. I'm a tree farmer. I get seedlings and to extend the time I can plant them I have made a cold room. This is a 12x12 foot room with 4" fiberglass + 12" ...
Sherwood Botsford's user avatar
1 vote

Energy storage idea: Pumped hydroelectric storage in ocean using difference in salt content

The article you linked says that the salt content of the seawater released by the desalinization plant is increased by 20%, not that the effluent is 20% salt. This means that normal 3.5% salt seawater ...
kingledion's user avatar
  • 1,077
1 vote

Energy storage idea: Pumped hydroelectric storage in ocean using difference in salt content

This all seems highly inefficient. Your one calculation based om m*g*h is meaningless, g is not 9.8 here. You have to displace the sea water which is almost as dense as the saltier water you want to ...
Martin Maat's user avatar
1 vote

Domestic flywheel energy storage: how close are we?

TL;DR - Because of how flywheel energy storage scales it is unlikely that significant efforts will be made to develop the technology for home use. This is similar to the case for windmills, where ...
LShaver's user avatar
  • 11.9k

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