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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 amount of energy with a steel spring, you need a large spring (or a lot of small springs). The 2014 paper "Benefits and challenges of mechanical spring ...


9

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 a few decades ago, but in living memory), energy storage in springs was a common way of powering clocks and watches. Energy stored in weights was used for ...


8

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 is then E = 0.5 x yield stress ^ 2 / Young's Modulus. If you take high quality steel with a yield stress of 1000MPa and a typical Young's modulus of 200GPa, you ...


5

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 solution but I don't know if they are stable under high power demands. You'll reget your choice if you select lead acid instead of lithium ion. Any lead acid battery ...


4

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 friction. To be able to suspend the flywheel on magnets, that requires a lower weight/mass. To counter the lower weight/mass, you have to replace that with ...


4

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 be extremely dangerous in practice. Even the example of a wind-up clock shows it - if you disassembled a fully wound old school alarm clock the wrong way, there ...


3

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 (which also have a Young's modulus, but in a different way). In compression, they also only remain "springs" until the coils touch, at which point ...


3

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 of ammonia-gas. Then ammonia-gas can be converted back into hydrogen with only the release of nitrogen. The electric powerplants in Japan are just burning the ...


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