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Batteries To Store Wind Energy
Roland Piquepaille writes "Scientific American reports that Xcel Energy, a Minneapolis-based utility company, has started to test a new technology to store wind energy in batteries. The company is currently trying it in a 1,100 megawatt facility of wind turbines in Southern Minnesota. The company started this effort because 'the wind doesn't always blow and, even worse, it often blows strongest when people aren't using much electricity, like late at night.' It has received a $1 million grant from Minnesota's Renewable Development Fund and the energy plant should be operational (PDF) in the first quarter of 2009. If this project is successful, the utility expects to deploy many more energy plants before 2020 to avoid more polluting energy sources."
i believe some dams release water through the turbines during peak times, then pump it back up off peak at night with excess cheap electricity ready for the next day, is that not a reasonable form of energy storage? i imagine a similar level of energy storage in anything recognisable as a battery would be insanely expensive and/or involve alot of toxic chemicals
I don't know if this is feasible but I've always thought that a mechanical solution would be better. Use the excess energy to lift a huge weight like the weights on a pendulum clock. When the wind dies down, just let the weight power a generator. Assuming concrete is reasonably environmentally friendly this would be a pretty clean solution.
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They do that. It's called Pumped-storage hydroelectricity.
I remember that flywheels were considered for electric cars as well.
Some of the issues I remember off hand were:
1. Specialized materials needed to build flywheels that are small, yet heavy enough to keep spinning for a long enough time after being "charged"
2. Getting the energy IN the flywheels in the first place - it takes more energy to get them spinning than what you draw from them.
3. Given the high velocities - what will happen when they fly apart? Also, the gyroscopic effects they generate while spinning.
4. The heavy mounts needed to safely position them negated any advantages through increased weight.
I don't know if any of these apply to stationary flywheels built into power plants though...
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Selling a few million plug-in hybrids should help quite a bit.
It would be even better if those cars were on the Internet so they could talk to the power company. For instance if I tell my car to be charged by 8am the next day, it could negotiate with the power company to draw power whenever it is cheapest.
I remember that flywheels were considered for electric cars as well.
Some of the issues I remember off hand were:
1. Specialized materials needed to build flywheels that are small, yet heavy enough to keep spinning for a long enough time after being "charged"
2. Getting the energy IN the flywheels in the first place - it takes more energy to get them spinning than what you draw from them.
3. Given the high velocities - what will happen when they fly apart? Also, the gyroscopic effects they generate while spinning.
4. The heavy mounts needed to safely position them negated any advantages through increased weight.
I don't know if any of these apply to stationary flywheels built into power plants though...
They don't apply for a power plant:
As a sailor, I'm sure your maritime experience is vast. But... do you happen to know where Minnesota is? You might want to check a map... XD
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Flywheels are attractive for short-term peak power delivery. They have low failure rates and easy fault detection (if the wheel is intact and spinning at the required speed, you know how much energy is available).
For long term loads (hours) flywheels aren't competitive with lead-acid batteries, let alone more exotic types such as the NaS battery the article describes. For example, the Active Power CSDC-500 flywheel storage system supplies 50kW for 138 seconds = 1.92kWhr. The cabinet is 78" x 54" x 34" and it weighs just over 3 tons. Four long-term loads, a system with two 12V 100Ahr VRLA batteries would be 14" x 14" x 10" and weigh 140 lb.
A flywheel based system has nowhere near the energy density of a battery storage system. Peak power density is the flywheel's forte.
I am so sick of science writers who mess up the story because they don't understand the units of energy and power.
The article says the batteries store 7 megawatt hours. Fine.
Then it goes on to say "meaning the 20 batteries are capable of delivering roughly one megawatt of electricity almost instantaneously" WTF does that mean? Power, measured in megawatts is by definition an instantaneous unit. What's with "almost instantaneous". Also, the rate of discharge of a battery MW is unrelated to its storage capacity MWh, so the entire meaning of the sentence makes no sense.
Then the article says, "Over 100 megawatts of this technology [is] deployed throughout the world," Huh? Battery capacity is measured in megawatt-hours, not megawatts.
Then the article says, "costing roughly $3 million per megawatt" same thing. Battery cost must be proportional to megawatt-hours, not megawatts.
I suspect that their idea is to make a battery with 24 megawatt-hours of capacity able to deliver 1 megawatt of power uniformly for 24 hours, then say so.
Shame on Sciam writers and double shame on Sciam editors for not mastering such basic units in an article about energy.
How about a little economics. The article mentions two understandable numbers, an 11 MW wind plant, and 7 MWh of battery capacity. The combination of the two, allowing for wind variations during the day believably deliver 1 MW continuously to the grid. That's 24 MWh per day.
Now the batteries cost $3 million, and the wind generators cost $22 million. Total $25 million to deliver 1 MW of base load. That's $25 billion per GW.
The peak generating capacity of North America is about 750 GW. Let's say 250 GW when levelized to base load. Therefore, to supply 100% of that with wind and batteries would cost roughly $6.2 trillion dollars. Now Al Gore says, "No problem. We can do that in just 10 years." WTF is he thinking?
Even if we did spend $6.2 T, there will still be periods where not much wind blows for large regions for many weeks at a time. I live where it's cold, and I know that when it hits -30F, the wind is almost always still and the sky dark, and that it can stay like that for a couple of weeks. We therefore, need to double or triple the $6.2T plus more for transmission, to provide backup power sources, plus the means of delivering the energy over large distances.
Wind and solar are wonderful for up to 15-1-20% of the total grid generation and the cost of construction and operations dominate. More than that, and reliability and deliverability of the electric supply become dominant in the economic equation.
If it spins horizontally, won't it be fighting the rotation of the earth... always turning a corner so to speak. So we build a bunch of them, then the Global Slowing crowd forms and someone makes a movie no one is ever allowed to spin anything without permission from the Rotational Protection Agency... Leave them up on edge and let the chips fall where they may.
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Hydrogen is a PAIN.
Hydrogen embrittlement makes storage and transportation a problem as does it's low density.
If you are going to make hydrogen you might as well take the next step and convert it to NH4 and use it for fertilizer or CH4 and use it for fuel. NH4 will also work as a fuel if you want. Both would work in a fuel cell or a gas turbine.
Of course Nuclear doesn't have these problems and if they would allow fuel reprocessing the storage problem would go away as well. As to safty modern western reactors have a great record. And any one that brings up the C word is just spreading FUD since it that disaster would never have been allowed to have been built in the US.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
No, I ran the numbers on this a couple years back. The amount of energy you can store in a fly-wheel is limited by the (tensile) strength to weight ratio of the materials you are using. They could never be as inexpensive as chemical batteries (unless you use carbon nanotubes or something like that that doesn't exist). Also, they have moving parts, while batteries have no moving parts. To me that means batteries are a more elegant solution.