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Comment by burntrelish1273 | Hacker News Reader

FYI: 129 MWh would be about 1300 42U-style racks for batteries alone.

Source: there's a guy in socal (Jehu Garcia) building a reclaimed peaker 1 MWh pack in about 10 racks from used batteries and equipment (50 kW 480VAC inverter) on the cheap in order to store energy off-peak (plus possibly charge using solar) and use it at peak supplemented by grid power. This is how manufacturing and other heavy industry / large electrical consumers can save money right now in US day-of-use billed grid systems.

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Jehu Garcia's Youtube videos are definitely worth checking out, the guy is doing cool things with 18650 lithium ion cells. He converted a VW bus into an electric vehicle. My main takeaway after watching his videos and others in the same vein is that lithium ion battery packs are the gasoline of the 21st century.

You can build 18650 packs for electric bikes, scooters, boats etc... or build your own Power Wall type home electric energy storage.

The costs of these cells coming out of China have gotten down to $1 each in some cases of excess inventory...

I'm going to look myself, but do you have any links about the 18650 packs?

Edit:cheapest aliexpress ones i see are about usd$2.00 each. That's not bad though.

Check ebay, packs from hover boards that got recalled are available.

The cost can be $1 a cell, a pack might have 20. Each cell might be 10-12 watt hours. It takes 3 cells to produce 12 volts.

Indeed. I hadn't actually reviewed ebay for electronics things for a couple of years, because any of the products I used to see there were significantly more expensive than anything I could get from aliexpress. It looks like, at least in this instance, that has turned around. I could even see individual 18650 cells for $1.

Great stuff.

He's trending hard, took me a few seconds to realize he was the 18650 dude I watch every week on youtube.

I'd love to emulate his work.

ecobot ! assemble !

HBPowerWall is also good. Australian guy with a 40KwH wall made from old laptop batteries. Lots of good content.

I had this idea 10 years go to use flywheels to buy cheap power and re-sell it during peak demand. Day vs night pricing will quickly normalize.

There are a few experimental installations of these around. I don't believe they are viable for larger scale storage, but fit smaller scale they seem competitive.

I think it's the other way around. Fly wheels can be extremely dangerous. It is really only large scale that they could be competitively safe.

Wouldn't some kind of gravity-based storage be cheaper/safer? Just lift some huge weights with excess energy, lock it in place, and then let gravity pull it down to reclaim it.

Both are back in sight these days.

Australian Synchrotron is already using three giant flywheels as an UPS, here is a short presentation. I am sure that you will be able to find enough information to determine if doing this would be feasible on a commercial scale.

http://www-conf.slac.stanford.edu/wao2012/talks/Thu_Aug9/McG...

Flywheel systems are currently sold for short-term power interruptions in datacenters: outage -> flywheel power -> diesel generator

Most datacenters use batteries instead.

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