I bet these aren't cheap...

....but they are neat, and from my home state:

http://www.beaconpower.com/products/EnergyStorageSystems/docs/BHE6_specs.pdf

http://www.corporate-ir.net/ireye/ir_site.zhtml?ticker=bcon&script=410&layout=-6&item_id=737839

...as usual they want to sell primarily to power companies, so I wouldn't expect a household-appropriate offering. Can't blame them for following the money to nice big bulk purchases, I suppose. Since you do have to dig a hole to plop it in, I could see where they wouldn't want to get too tangled up in individual unit sales.

:)

They do look interesting, however. I'm looking for a low-maintenance low-demand power system.

Mindless of me, I apologize.

(I wish people would stop using PDF so much, too.)

I actually bought stock in them a few years ago. I note with disappointment that I have not become rich. But they aren't out of biz yet, either :-)

I thought they would be a good fit for home solar installations, as an alternative to chemical batteries. The fact that they go in the ground is a plus. No wasted space for big battery banks, and low maintenance.

At least one of their models would actually be a good size for a home installation. It stores a few kilowatt-hours of electricity. But I don't think the current price is conducive for a residential buyer.

...visiting their site a year or so ago and them still being in the "we have a few working models" stage. To see them in ALPHA/BETA deployment is a good sign. I'd hang on to that stock; it's probably going to wake up over the next year or so.

(I really have to learn how to go about trading stocks someday... sigh... how mundane.)

Can you believe I give out that kind of advice for free??

The main piece of advice I have about stocks: keep thorough records! When the time comes that you sell, you have to establish cost-basis, and for that you need to know every purchase you made: how many shares, and what you paid for them. It also helps to have a record of every stock-split and stock-merge.

Like a cretin, I threw away some purchase records on a stock once, and you wouldn't believe what a nightmare it is to try and restore those kind of records. Often, you just can't. You end up estimating, and hoping that the IRS doesn't take issue with it. According to my accountant, this happens rather frequently, so the IRS has some flexibility about it, but I can tell you it's infinitely easier to just keep the records.

There are some corrolaries to this: The fewer purchases you make, the easier it is to keep records, and compute cost-basis. Schemes like frequent re-investment of dividends, etc, will make cost-basis a stone bitch to compute.

There are probably books out there that explain the basics. I'd recommend reading one or two of them. I pretty much jumped into it without knowing what I was doing, and the various legalities, rules, etc, are more complicated than the basic theory.

I'm not sure it's been worth the trouble. Unless I get rich.

told me if I think it's a nightmare for me, think what a nightmare it is for the IRS.

Millions of ignorant rubes like me getting sucked into the stock-market game. "Woo hoo! How hard can it be?"

Tulip futures, anyone?

I just happened to be on morningstar's front page and noticed Beacon as one of the most active today :-)

Of course, my net career performance is still healthily negative, but I'm moving back toward zero :-)

Also how long do they keep spinning without drawing or inputting power?

Their loss due to friction is low, but I don't know the specs. Stuff like that adds to the cost, of course, but it also increases the lifetime of the equipment, since there are no physical bearings to wear out.

But to give you an idea The 6kWh unit supplies at 2kw, so it takes 3 hours to drain off all the energy in it with a load. These are clearly intended as battery equivalents.

Flywheel shrapnel is a scary thing.

These devices are an alternative to big lead-acid batteries which are often a pain in the butt to maintain.

Someone would buy this because they could put it in the ground and forget it about it. With any luck, it will still be working after they retire.

The average guy has to go to Sears and buy golf cart or wheelchair batteries.