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points by sandworm101 17 hours ago | 0 comments

I am still a fan of centrifugal systems. The lifecycle costs of a spinning mass seem more manageable than the complexities of chemical batteries. The mass of a block of concrete and steal isn't going to degrade over time. And bearings/motors are such mature tech that they can last decades, even a century without replacement.

[–] rexskimmer 12 hours ago

> And bearings/motors are such mature tech that they can last decades, even a century without replacement.

This is not true at all for bearings in large industrial systems under constant load. As the mass scales up, the systems become exponentially more sensitive to vibrations from wear of the mechanical parts. Even magnetic bearings max out at about 20 years.

Flywheel systems are more complicated and expensive than simple chemical batteries. Cost also scales much more than batteries as you increase the energy storage. They are also less efficient over time due to friction even with magnetic bearings.

[–] nixon_why69 17 hours ago

If you're going mechanical, why not pumped water storage instead? Nothing has to spin super fast and hydro has a lot of maturity.

(From a guy who got burned buying stock in a centrifugal system as my first "wicked smaht" investment as a 22yo).

[–] stefs 16 hours ago

there are areas where almost all options for pumped hydro are already developed and there's little room for expansion. additionally, the heat waves from the climate catastrophe affects pumped hydro negatively (evaporation and higher water temperature).

[–] tpm 15 hours ago

Evaporation can be solved by covering the reservoirs, so the water can't evaporate. Geography is the real issue. Costs to build possibly too.

[–] grumbelbart2 17 hours ago

Mostly because we already used all suitable places. It also has a huge environmental impact, large upfront costs that you can only spend in bulk, permissions, lawsuits, protests from the local population and so forth.

[–] sandworm101 17 hours ago

Hydro is limited by geography. It cannot scale in the same way. Rather than giant spinning masses at central locations, current thinking is more about smaller masses scattered throughout a grid. There are even a few studies on whether existing air conditioner/heat pump compressors could contribute.

[–] mixdup 11 hours ago

I think geographic dispersion of batteries is going to be a big plus. If the "battery" is a giant lake or a big plant with a spinning mass, the power has to be transmitted from that facility to the end user over the grid

Putting a ton of smaller chemical batteries at distribution substations means when the grid is at the peak, you can cover that peak without transmitting that power over the transmission system. Putting the battery near the consumer will take a big load off of the transmission system which as much of a bottleneck as the lack of generating facilities

[–] rgarrett88 17 hours ago

Maintenance on high energy movement hasn't exactly had a great track record either.

[–] detourdog 14 hours ago

There was a giant flywheel company near me about 20 years ago. Maybe it's still there. They had one incident where a flywheel broke.

https://beaconpower.com/stephentown-new-york/

[–] angry_octet 17 hours ago

There's a very long waiting list for new synchronous condensers, almost 5 years from order to delivery.

[–] toomuchtodo 17 hours ago

Batteries can serve the same function, while also providing energy arb and additional grid services, so I'm somewhat curious how log the market for syncons continues to exist.

[–] sandworm101 16 hours ago

Batteries (and their associated HV switching gear) are slow to react and have very limited lifespans, on the order of a few years. That's why your washing machine uses a capacitor to start its motor rather than a battery. Even capacitors are not as reactive as an already spinning mass.

[–] sanderjd 16 hours ago

How are you defining "slow" in this comment?

My understanding is that batteries are demonstrating longer useful lifetimes than was anticipated.

Ultimately I think diversity in technologies is the best policy, but difficult to set up the incentives to achieve it.

[–] toomuchtodo 16 hours ago

Both assertions are false. Batteries react within milliseconds [1], and last 10-20 years (depending on chemistry and cycling, lithium at the shorter end, sodium and flow at the longer end) [2] [3] [4]. Australia had to reconfigure its ancillary services market due to how fast battery storage reacts, for example (proven out with the Hornsdale Power Reserve).

Please update priors to current state of the art.

[1] https://www.eia.gov/todayinenergy/detail.php?id=50176

- The most common cited use case for batteries is frequency response. Frequency response is a service that maintains grid frequency as close to 60 hertz (Hz) as reasonably possible. Deviations below 60 Hz can lead to protective generator trips that result in a subsequent decline in system stability. Batteries are particularly well suited for frequency regulation because their output does not require any startup time and batteries can quickly absorb surges. At the end of 2020, 885 MW of battery storage capacity (59% of total utility-scale battery capacity) cited frequency response as a use case.

[2] Smith, J. et al. "Lithium - ion battery degradation mechanisms and mitigation strategies for utility - scale energy storage". Journal of Energy Storage, 2020.

[3] Brown, A. "Lead - acid battery performance and lifespan in utility - scale applications". Power Systems Research, 2018.

[4] Green, C. et al. "Flow batteries for long - term utility - scale energy storage: A review". Energy and Environmental Science, 2019.

[–] adrianN 15 hours ago

Siemens is making a lot of money selling inertial stabilizers. There is ongoing research on how to stabilize grids in the face of decreasing inertial frequency stabilization.

[–] toomuchtodo 14 hours ago

Do you have any resources you can share on how this compares to synthetic inertia battery storage and renewables inverters can provide? I am interested!

[–] jabart 13 hours ago

If the washing machine is using an induction moter, the capacitor is for creating the conditions for it to self-start on a single phase system. Three-phase induction motors don't need this.

[–] BenjiWiebe 3 hours ago

And in fact, a lot of washing machines these days use a 3 phase motor. BLDC and a controller.

[–] _blk 17 hours ago

Yup. Esp. when space is available. But thet benefit heavily from low pressure environments though so it's not just an arm and a mass in a fence.