WIND IN A BOTTLE: From flywheels to batteries, companies are developing ways to store energy from renewable sources.
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Wind farms typically generate most of their energy at night, when most electricity demand is lowest. So a lot of that "green" energy is wasted.
So the big question is: How do you bottle that power for air conditioners and other appliances that are busiest during the day?
There are many companies moving to fill the energy gap. Using federal loan guarantees and $4 billion in "smart grid" stimulus cash, they are working on utility-scale storage units that they hope will help balance intermittent renewable sources like wind and solar and let electric grid operators match power supplies with demand.
Among the leaders is a Massachusetts company that plans to use hundreds of "flywheels" to store 20 megawatts of electricity, enough to power 200 homes for a day. Beacon Power Corp. is working with a $43 million federal loan guarantee for its $69 million storage project in Stephentown, N.Y., which is scheduled to break ground by year's end.
The plant would store cheap "off peak" electricity in 2,500-pound flywheels that turn faster than the speed of sound. When the electricity prices rise -- or when winds die -- energy can be withdrawn from the wheels and sold to the grid at a premium rate.
"It will signal a dramatic shift to a cleaner, more sustainable method of providing frequency regulation on the grid," Beacon CEO Bill Capp told the GridWeek conference in Washington last week.
Utilities today use combinations of hydropower and natural gas to "firm up" intermittent power sources, but hydropower has spatial limitations and natural gas can be expensive and polluting. Yet the need for reliable backup power will grow as states require utilities to use more renewable energy and the cost of carbon-based power rises in the face of expected climate regulations.
"There's a natural affinity between storage and renewables," said Rich Kalisch, senior director of technology initiatives at Midwest Independent Transmission System Operator, which manages nearly 100,000 miles of transmission lines in 13 states.
The nonprofit group currently manages 6,600 megawatts of wind power -- about 4 percent of its total generation -- but has about 54,000 megawatts of wind projects in development. Operators warn that those projects could threaten reliability.
"We are very concerned," Kalisch said.
Demonstration projects
Still, recognizing a need for energy storage is one thing, but proving that storage technologies can work is another.
One of the largest U.S. demonstrations of battery-based storage uses sodium-sulfur, or NaS, batteries manufactured by Japan's NGK Insulators. American Electric Power Co. Inc. has installed 7 megawatts of the bus-sized batteries to ease congestion on its transmission lines, and it has an additional 4 megawatts under development.
Meanwhile, Xcel Energy Inc. is testing a 1-megawatt NaS battery to manage its wind power in Minnesota.
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17 Comments
Add Comment"to store 20 megawatts of electricity, enough to power 200 homes for a day".
Reply | Report Abuse | Link to thissome editor should be embarassed at this sloppiness.
either 2o megawatts is enough to power 200 homes or it isn't - powering them for a day makes no sense. is the amount of power used by the homes increasing sharply or something? get your units straight. watts are units of power.
Additional unit confusion. Speed is distance per unit of time. The speed of sound (and is it in air, water, metal?) is usually feet per second. Rotation is events per unit time. The flywheels rotate at x revolutions per minute. No connection to "speed" as in the "speed of sound".
Reply | Report Abuse | Link to thisI think the speed must be outer edge of the flywheel going in a circle. It travels the circumference of the circle in an amount of time. The part I question, is that most wind power is generated at night. The wind is convection currents driven by the sun. I have enjoyed for years watersking at dusk or dawn when the wind driven waves wane and the water is smooth.
Reply | Report Abuse | Link to thisI also do not understand the contention that wind will generate most of it's power at night. Where I live (Midwest) it is nearly always calm between dusk and dawn in the absence of a storm.
Reply | Report Abuse | Link to thisI think it is misinformation which I have seen in relation to electric cars and using wind energy to charge them at night. I would like to see some justification of this claim.
This article was "reprinted" from a politically oriented group.
Reply | Report Abuse | Link to thisThat is why the article is so scientifically inaccurate. It was written to advance a cause.
I read Scientific American for science news and information, not political point of views. Whats going on here? Maybe I'll cancel my subscription. Does anyone concur?
SA has been nothing but an environmentalist propaganda rag for years.
Reply | Report Abuse | Link to thisI think the efficiency of flywheel storage can be increased substantially if the air friction can be removed by creating a vacuum around the flywheels.
Reply | Report Abuse | Link to thisWith a spinning disk you can measure it's surface feet per second.For storage,the storing of air pressure wins hands down for start up cost,and it might be used as a clean,and safe way to transport energy.What ever happened to the development of superconducting battery's?This seems me to be the best all methods.Imagine driving coast to coast,or flying around the world without refueling,and having such a device in each home, would elimitnate the need of large scale facility's,and dangers of attack that they pose. In events that cause power outage's like earthquakes,ice storms, blizards,and other disasters, people would still have power.
Reply | Report Abuse | Link to thisdduff617 wrote
Reply | Report Abuse | Link to thisto store 20 megawatts of electricity, enough to power 200 homes for a day".
either 2o megawatts is enough to power 200 homes or it isn't - powering them for a day makes no sense. is the amount of power used by the homes increasing sharply or something? get your units straight. watts are units of power.
JD You should read a little better yourself. 20MW is enough for 20k homes how you are thinking about it or about 1000 home on a per day basis if they average 1kw/hr YMMV. How many kwhrs/day do you use? I use 4-11 kwhrs but I'm way below average use. Most use about 15-25kwhrs/day.
The article is riddled with errors and assumptions like when wind blows. That depends on location, season. For instants here on the east coast of Fla the wind average is rather light but most comes during the heat of the day, just when it's needed most thus no storage needed. Same with solar in most places power comes at peak power needs. And the facts are this power is far more valuable than other steady or intermittent power.
The storage problem only becomes a problem with big wind farms. If many more wide spread home units were used, they would average out, thus again no storage needed. Since they need no land, transmission lines, overhead or stockholders cost and homeowner save x's the $/kwhr, home size units are 2-3x's more cost effective. Same goes for solar.
Lead batteries store power at under $100/kwhr so 1/3 the price of flywheels though I do like flywheels, just they have their place smoothing out power surges.
NG is not expensive.
I can go one but this article isn't worth much of anything.
Wind Power at night can soon be used charging the batteries in our new plug-in Hybrid Cars. Solar cells can then help feed the airconditioners when it is sunny and hot. Saving energy is another important "source" but there seems to be less motivation yet from traditional energy suppliers to "sell" that stuff?
Reply | Report Abuse | Link to thisdduff617 -
Reply | Report Abuse | Link to this"some editor should be embarassed at this sloppiness."
"either 2o megawatts is enough to power 200 homes or it isn't - powering them for a day makes no sense. is the amount of power used by the homes increasing sharply or something? get your units straight. watts are units of power."
You're right, the authors screwed up the units.
"Among the leaders is a Massachusetts company that plans to use hundreds of "flywheels" to store 20 megawatts of electricity, enough to power 200 homes for a day."
In fact, according to the white paper, the 20 MW flywheel plant can output 20 MW for only <b>15 minutes</b>:
http://www.beaconpower.com/files/SEM_20MW.pdf
So the capacity is thus 5 MWh (megawatt*hours). Extended over a 24 hour period, this is just 200 kW, which roughly agrees with the "200 houses" figure.
watts are units of energy
Reply | Report Abuse | Link to thiswatt hours are units of power
kw=energy
kwh=power
Don't disgrace the sanctity of science Solomon.
uvdiv - Thanks for the link and info. You'd think an article in a Science mag would have provided that.
Reply | Report Abuse | Link to thisAs far as whether the wind blow more at night or during the day, it depends on location. But electricity use is less at night, so if the wind does blow at night, the energy that could be generated is often wasted.
And local windmills at people's houses don't make energy sense - the small ones take more energy to produce than they'll generate over their lifetime. The reason the industry is going to ever bigger windmills is the economic and energy payoff is better the bigger they get.
Rooftop solar is different - that does make sense.
>and why was it/is it again that the storage of hydrogen/electrolysis using extra peak enrgy by solar &/or wind isn't possible ?
Reply | Report Abuse | Link to thisH2 is not eff at under 40% at best. Vs batteries or flywheels that are 90-98% eff and lower cost/unit of energy.
Reply | Report Abuse | Link to thisI think the science and research behind energy saving from wind farms is interesting. I've often wondered if a <a href="http://caenergyconsultants.com">HERS rater</a> would show that wind power is energy-efficient. I would be surprised if it wasn't.
Reply | Report Abuse | Link to thisI think the science and research behind energy saving from wind farms is interesting. I've often wondered if a <a href="http://caenergyconsultants.com">HERS rater</a> would show that wind power is energy-efficient. I would be surprised if it wasn't.
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