Store Your Own Juice 415
sfeinstein writes "Power companies using dynamic pricing models to charge more for electricity during hours of peak usage is nothing new. Now, however, one company has decided to take advantage of this by using technology to buy (and store) capacity when rates are low and use that capacity when rates are at their highest." From the article: "The device, called GridPoint Protect, is the size of a small file cabinet and connects to the circuitbreaker panel. (The company also offers a lower-capacity version designed for homes, which costs $10,000.) A built-in computer powered by a Pentium chip will make intelligent purchase decisions, buying when prices are low, then storing the electricity for later use. That will make it possible to run your company during the workday with cheaper electricity that you purchased at 3 A.M."
How does it know? (Score:5, Interesting)
Re:With intel inside (Score:3, Interesting)
Assuming it cuts my electric bill to nothing, the $10000 home model will pay for itself in...just under 25 years.
No thanks.
Why bother? Pump power BACK into the grid instead (Score:5, Interesting)
Besides, people should be thinking about generating their own power and pumping the surplus back into the grid, running their meters backwards (a legally protected action in most states) at a cost to the power company.
These are called intertie systems, and power companies are federally mandated to allow them:
http://www.google.com/search?hl=en&q=solar+intert
I wonder how that'd work up here (Score:5, Interesting)
Great, now please talk to me about those gel cells (Score:3, Interesting)
Not exactly a friendly way to deal with things. A better usage of the money would be to put up some solar panels and do a little cogen.
Re:With intel inside (Score:2, Interesting)
End result - a more fragile power net for everyone.
This post brought to you by the law of unintended consequences - just like almost everything else in life.
Re:Mass Usage issue? (Score:5, Interesting)
Now imagine what happens when big industrial users start up and shut down based on spot pricing. Demand increases -> rates increase -> plants shut down -> demand drops -> rates drop -> plants start up.... Rinse, lather, repeat.
Each customer will have different profiles of price sensitivity, startup/shutdown delays, costs of production pauses and such. It's impossible to quick start/stop a refinery or chemical plant, hard to switch your manufacturing plant on and off, but if your building air conditioning uses an ice storage system (make ice when rates are cheap, melt it when costs are high) then you can flip on and off pretty much at will.
Managing the effect on the grid turns out to be a difficult problem.
But at $10,000/home, this thing isn't going into mass usage.
just saw this a Universal Studios Orlando (Score:3, Interesting)
I also read that the NYC subways were testing flywheels for breaking energy storage. The flywheels are to be located at the stations, this way the trains didn't have to carry the flywheels.
It is way past time we made flywheels do more work.
Won't compete with PV (Score:3, Interesting)
If I had $10,000 to throw at the problem I'd install $10,000 of photovoltaics. No batteries, just run the meter backwards during the day when power is needed most anyway. And I'd be contributing to production not just shifting my consumption.
Re:With intel inside (Score:2, Interesting)
Ah, how I remember the rolling blackouts. Our plant diesel generator would kick in shortly after we got a phone call telling us it was us on the next blackout.
Yes, I do live in California and I was working in San Jose when it was happening. You could tell the president of the US didn't give a rat's ass about the technology sector.
Re:Mass Usage issue? (Score:5, Interesting)
The more energy you're pushing through the transmission lines at once, the higher the line-losses, so that works in your favor.
Electricity would be cheaper if plants could be kept running at a constant level all day and night. When you have to build a couple power-plants that only need to be operated during peak demand, that's wastes a lot of money.
It's entirely possible that this is something which will only work in a distributed fashion, and can't be centralized very well. Again, line-losses may be a factor.
Re:How does it know? (Score:5, Interesting)
?
This device would be easy on the grid (Score:3, Interesting)
Re:Storing juice? (Score:4, Interesting)
They do -- but batteries don't scale well into the megawatts or gigawatts, so they have to do things like fill water-reservoirs high in the mountains during the night and drain the water through a turbine-generator during the peak time. There are lots of other ways to do this, but none of them are trivial.
Power storage technology? (Score:4, Interesting)
What kind of power storage technology is used for the $10k "filing cabinet" model? How much capacity does it have? What's the round-trip efficiency?
If it uses batteries, what is the lifetime of the batteries? Many battery technologies have a severely limited charge-discharge cycle lifetime.
I answered some of my questions from Gridpoint's site:
- Gridpoint sells these in 7kw and 10kw capacity
- Price is between $9k and $19k MSRP. The 7kw model is likely the $9k model
- The batteries are VRLA (Valve Regulated Lead Acid)
- Rated capacity is 10 hours at 1kW AC Avg Load. That's 1000/120 ~= 8A load, about half of a single 15A household circuit. This unit isn't rated high enough to run a typical hair dryer.
I couldn't find details on what kind of lifetime to expect out of the batteries.
Re:Well, there's a good chance he's right (Score:2, Interesting)
I did the same thing for an automated welder in the 80's. You would enter the weld type code on a keypad and it displayed various status on an LCD, adjusted the feed rate for autofed welding rod and flow-rate of the gasses, had a temp sensor and even auto-ignited.
68HC05 @ ~2MHz (IIRC), no o/s or kernel, about 50 k of ram.
The OP's sentiment is right.
Cringely's essay from years ago (Score:2, Interesting)
I wonder if there are appropriate points in the traditional power grid system where power-storage systems could be used to buffer enough stuff over 24 hours to solve this problem. Gigantic flywheels [wikipedia.org] near your block, poised to clobber through the neighborhood, anyone? I suppose this problem has already been studied. [wikipedia.org]
Re:Nice idea, but the cost... (Score:5, Interesting)
I went to their home page and downloaded the pdf.
Here's the deal - BATTERIES NOT INCLUDED!!!
The ten grand buys you a switch. That's it. A switch controlled by a computer, and an inverter. You still need to buy batteries (that will give you a grand total of 1 kw for 10 hours, so forget about running more than a couple of computers off this).
They're trying to sell you on buying a bunch of solar cells (NOTE - NOT INCLUDED IN THE PRICE EITHER) that you connect to the switch, and depending on their output, you either suck off the sun or the power grid.
Their big marketing scam - TAX CREDIT of $500 - $2500 for Solar Power Systems.
In other words, you can do this yourself with off-the-shelf parts - buy one of these http://www.apcc.com/resource/include/techspec_inde x.cfm?base_sku=SU5000UXINET&tab=features&ISOCountr yCode=us [apcc.com]for under 2 grand, and with the other 8 grand, buy a sh*tload of batteries for it, and you're ahead of the game cost-wise. Heck, buy two, phase-lock them, and you can run your washer and electric dryer at the same time - something you can't do with their $10,000 system (which is really a lot more after you add the batteries).
Must not scale well. (Score:4, Interesting)
I'm not sure exactly myself, but it's not so wildly out-of-the-box an idea that nobody can have thought of it before. I assume there's something wrong with the economics of doing it at the generating station. Maybe it has to do with going down from typical generation voltages to something that can be stored and then back up again? (That would be the problem using batteries...) Other large-scale forms of energy storage, things that could store real MWh's, might be impractical.
Actually, when you think about how hydroelectric power plants work, they do this already: they build water up behind the dam when demand is low, then open the gates further and produce more energy when demand is high. I know it's not the kind of "storage" we're talking about here, but most power plants have some form of output regulation; it seems like the power companies are probably trying to match demand as closely as they can, from their "top down" perspective, but can only get so close.
By putting small storage devices out at the edge, close to the points of consumption and where voltages are low, you might get a lot more effect than taking the same amount of storage and putting it all upstream.
Re:How does it know? (Score:3, Interesting)
A better option for the near future (Score:3, Interesting)
Nothing big. (Score:5, Interesting)
Clever bastards those swiss
Re:Savings? (and battery costs) (Score:1, Interesting)
Energy storage is a bank of "gel cells" (valve-regulated lead acid batteries). The bank is rated 310Ahr at 48V, which would sell for about US $1000-$1500 (based on 12 each 12V, 105Ahr batteries at $80-$125 each). The system capacity is 10kWhr. With proper charging and care, battery manufacturers claim they will last 700-1000 cycles at 70% depth-of-discharge; call that 2-3 years of daily use. So that's 7000-10000kWhr before buying a new battery bank. You will pay $0.10 to $0.20 per kWhr just for replacement batteries, excluding installation labor and disposal fees for the old ones. This is in addition to the costs of system inefficiencies that others have noted. If your peak/off-peak differential is less than the amortized battery replacement cost, you never break even--even if the unit is free and 100% efficient.
The article's claim of $375/month savings (15% of $2500) is not likely to occur for one 10kWhr unit. Thirty daily cycles would be 300kWhr per month, requiring peak/off-peak savings of $1.25/kWhr above and beyond the cost of internal power losses and battery replacement.
There are good reasons for using battery energy storage: avoiding down-time and having power at off-grid locations are two major ones. But actual cost savings are rare. The off-peak price discount seldom will pay for battery replacement and system power losses.
Posted anonymously, for professional reasons (I need to keep my job!)