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Posted on 11/23/2007 6:28:19 AM PST by Uncledave
ScienceDaily (Nov. 21, 2007) — Wind power, long considered to be as fickle as wind itself, can be groomed to become a steady, dependable source of electricity and delivered at a lower cost than at present, according to scientists at Stanford University.
The key is connecting wind farms throughout a given geographic area with transmission lines, thus combining the electric outputs of the farms into one powerful energy source. The findings are published in the November issue of the American Meteorological Society's Journal of Applied Meteorology and Climatology.
Wind is the world's fastest growing electric energy source, according to the study's authors, Cristina Archer and Mark Jacobson. However, because wind is intermittent, it is not used to supply baseload electric power today. Baseload power is the amount of steady and reliable electric power that is constantly being produced, typically by power plants, regardless of the electricity demand. But interconnecting wind farms with a transmission grid reduces the power swings caused by wind variability and makes a significant portion of it just as consistent a power source as a coal power plant.
"This study implies that, if interconnected wind is used on a large scale, a third or more of its energy can be used for reliable electric power, and the remaining intermittent portion can be used for transportation, allowing wind to solve energy, climate and air pollution problems simultaneously," said Archer, the study's lead author and a consulting assistant professor in Stanford's Department of Civil and Environmental Engineering and research associate in the Department of Global Ecology of the Carnegie Institution.
It's a bit like having a bunch of hamsters generating your power, each in a separate cage with a treadmill. At any given time, some hamsters will be sleeping or eating and some will be running on their treadmill. If you have only one hamster, the treadmill is either turning or it isn't, so the power's either on or off. With two hamsters, the odds are better that one will be on a treadmill at any given point in time and your chances of running, say, your blender, go up. Get enough hamsters together and the odds are pretty good that at least a few will always be on the treadmill, cranking out the kilowatts.
The combined output of all the hamsters will vary, depending on how many are on treadmills at any one time, but there will be a certain level of power that is always being generated, even as different hamsters hop on or off their individual treadmills. That's the reliable baseload power. The connected wind farms would operate the same way. "The idea is that, while wind speed could be calm at a given location, it could be gusty at others. By linking these locations together we can smooth out the differences and substantially improve the overall performance," Archer said.
As one might expect, not all locations make sense for wind farms. Only locations with strong winds are economically competitive. In their study, Archer and Jacobson, a professor of civil and environmental engineering at Stanford, evaluated 19 sites in the Midwestern United States, with annual average wind speeds greater than 6.9 meters per second at a height of 80 meters above ground, the hub height of modern wind turbines. Modern turbines are 80-100 meters high, approximately the height of a 30-story building, and their blades are 70 meters long or more.
The researchers used hourly wind data, collected and quality-controlled by the National Weather Service, for the entire year of 2000 from the 19 sites in the Midwestern United States. They found that an average of 33 percent and a maximum of 47 percent of yearly-averaged wind power from interconnected farms can be used as reliable, baseload electric power. These percentages would hold true for any array of 10 or more wind farms, provided it met the minimum wind speed and turbine height criteria used in the study.
Another benefit of connecting multiple wind farms is reducing the total distance that all the power has to travel from the multiple points of origin to the destination point. Interconnecting multiple wind farms to a common point and then connecting that point to a far-away city reduces the cost of transmission.
It's the same as having lots of streams and creeks join together to form a river that flows out to sea, rather than having each creek flow all the way to the coast by carving out its own little channel.
Another type of cost saving also results when the power combines to flow in a single transmission line. Explains Archer: Suppose a power company wanted to bring power from several independent farms--each with a maximum capacity of, say, 1,500 kilowatts (kW) --from the Midwest to California. Each farm would need a short transmission line of 1,500 kW brought to a common point in the Midwest. Then they would need a larger transmission line between the common point and California--typically with a total capacity of 1,500 kW multiplied by the number of independent farms connected.
However, with geographically dispersed farms, it is unlikely that they would simultaneously be experiencing strong enough winds to each produce their 1,500kW maximum output at the same time. Thus, the capacity of the long-distance transmission line could be reduced significantly with only a small loss in overall delivered power. The more wind farms connected to the common point in the Midwest, the greater the reduction in long-distance transmission capacity that is possible.
"Due to the high cost of long-distance transmission, a 20 percent reduction in transmission capacity with little delivered power loss would notably reduce the cost of wind energy," added Archer, who calculated the decrease in delivered power to be only about 1.6 percent. With only one farm, a 20 percent reduction in long-distance transmission capacity would decrease delivered power by 9.8 percent--not a 20 percent reduction, because the farm is not producing its maximum possible output all the time.
Archer said that if the United States and other countries each started to organize the siting and interconnection of new wind farms based on a master plan, the power supply could be smoothed out and transmission requirements could be reduced, decreasing the cost of wind energy. This could result in the large-scale market penetration of wind energy--already the most inexpensive clean renewable electric power source--which could contribute significantly to an eventual solution to global warming, as well as reducing deaths from urban air pollution.
Adapted from materials provided by American Meteorological Society.
Large-scale wind developers are seeing this, such as FPL which owns and operates thousands of wind turbines around the country. Between the geographic dispersion and modern wind forecasting techniques, they're able to predict total wind energy output across their portfolio remarkably accurately. More wind turbines only reduces intermittency risk.
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How about setting up your own home wind turbine to make yourself more self relient?
I am planning to start next spring to set up our own system, and with solar as well, to become more self relient & tell my local electric co. to shove off!
Every time I turn around they keep raising my rates, for various reasons, and I hate that!
Here on the left coast, we have Interstate 5, which runs from the Mexican border all the way north to the Canadian border. Not far from me is a section called the “Grapevine” which has an approx. 10 - 11 mile downgrade of 6 - 8%.
Many 10’s of thousands of trucks per day come down this hill. They are required to run no more than 35 mph due to the steepness. There are truck escape ramps also.
It would sure be nice if someone could capture the energy required to keep these trucks going slow down this hill.
Regenerative breaking
Think IRS tax credit.... Think Form 3800 Line h, think Form 8835 section A
This is why I was planning on both solar & wind, and it is a multi year project to finish. I figure 3-5 years to do so.
I am not worried about the possible payback, I just want to be more self reliant. We live in a semi-rural area and I worry about power outages [when that happens we loose just about everything, [ie water,lights,computer,tv ect...], and with 2 kids [1 with down syndrome] things can be a little hetic without power.
A series of transmission lines connecting all these states would mean that the wind only had to be blowing against 40% of these windmills at any time to meet 100% of the elctrical needs.
Since the Texas power grid is connected to both the East and West Power grid electricity generated in Nebraska can be sent to Maine, Florida, Oregon or California!!!
Excess electricity could be stored in batteries, (a Michigan Utility pumps water uphill into a storage lake and when more electrity is needed the floodgates are opened, water runs down hill and the pumps polarity is changed and they generate electricity.), a battery stores energy and kinetic energy can be stored by pumping it up jill to become potential energy.
“...wind is intermittent,”
...except on the High Plains of Texas, where it is pretty well constant. The use of windmills for power generation there and the next huge wind farm planned along the coast of Texas will prove to be almost as profitable as the oil/gas business has been.
Recovering it when she runs downhill?
She fell, remember?
Yeah, Ive looked at wind, and most small turbines require high (15 mph+) steady wind to put out anything meaningful. I just can't justify it on a residential scale at this point when the same investment in more solar panels would generate far more power over the year.
She came down with $2.50
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There are two locations for wind farms that I consider ideal:
Cape Cod.
Wherever Gore is speaking.
Jill Wagner--a bunch of potential energy!
If the wind farms are on the grids and the grids are already interconnected wouldn’t this be an already accomplished task?
GM is doing this for its big pickup trucks coming soon to your local dealer. Hybrid setups should have standard regenerative braking.
Yeah, the headline misses the point of the study as I pointed out in post #1. The story is how managine a portfolio of wind farms takes out much of the variability in forecasting power production.
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