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Store Your Own Juice
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 when prices are "low"? Does it have a hardcoded database that will be inaccurate in a few months, or does it observe-and-compare prices?
Why even bother offering a home product at $10k?
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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
Wow! This must be a PERSONAL letter, just for me!
Here in NH, our power company, PSNH.com, is overburden by its customer base. Lately they have been doing free energy audits to locate places people are losing money on heating and cooling. Both my residence, a 200 year old mill building, and my employer, a large interoperability lab, were audited by PSNH for heating and cooling, and in the case of the lab, other weird places we waste power. At my residence, they paid 80% of the replacement costs for new windows, in an effort to avoid new infrastructure. They simply can't afford to build anything new that generates power. And the overages that they have to supply all come from Canada, which costs them enough that it isn't worth it for them. So I would have to suspect that they would love it if people in their customer base were to install these, as it would just put their peak output down and give them some breathing room. I have to admit I don't know what it's like elsewhere in the world, but maybe some other people would share too.
slashdot: where everyone yells sarcastic metaphors to themselves to understand the issue
It's worse than that. My former roommate used to work for a company that built high-tech meters that would report use, outages, etc. in near-real-time and, conversely, the spot rates could be reported back to the meter.
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.
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"You are not remembered for doing what is expected of you." - Atul Chitnis
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.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
I work at a company which manages the power grid for all or parts of thirteen states. This device would work to even out the load curve. I know the dispatchers in the control room wouldn't mind a flatter load curve during traditionally high load periods. That said, I don't see this being very useful for single family homes at the price points mentioned. Multi-tenant units could benefit if they would be willing to aggregate their metering.
Besides the cost, I see this being a huge benefit to reducing power load on the grid. I suppose the real question is, why don't power companies do this further up the pipe, at the generating stations?
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.
I scanned through the article, but didn't see this mentioned:
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.
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=usfor 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).
Maybe the technology doesn't scale well?
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.
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This is nothing big -- the Swiss have been doing it for years. They simply buy power off the French grid at night from the nuclear plants, and then use it to pipe water up a mountain. Once the peak hits, they let it down to power hydroelectric plants, selling energy back to the French -- for profit.
;)
Clever bastards those swiss
DYWYPI?