September 11, 2005

Some data on blade failure and throw

At the 2004 California Wind Energy Collaborative Forum (click the title of this post for proceedings, both PowerPoint PDFs and audio MP3s), Scott Larwood of the California Wind Energy Collaborative, University of California, Davis, presented "Permitting setbacks for wind turbines and the blade throw hazard."

His research concludes that a reasonable expectation for blade failure is 1 per 100 turbines per year. Thus setbacks in consideration of blade or fragment throw are indeed important to establish.

His calculations (or his reporting of a Danish study) establishes, first of all, how far a blade or fragment could be thrown at tip speeds at and above the normal operation maximum, expressed as multiples of the total turbine height, using data for 1.5–2.0-MW turbines. At the normal maximum, a blade could be thrown to a distance almost 1.5 times the turbine height and a hazardous fragment over 3.5 times. At twice the normal tip speed, a complete blade could be thrown over 2.5 times the turbine height and a hazardous fragment almost 6.5 times. The maximum fragment distance is 6.5 times the turbine height.

Second, Larwood calculates blade and fragment thrown as a function of turbine height, finding that as height increases, the absolute distance they might be thrown increases, but as a multiple of turbine height it decreases. For example, a 50-m (164-ft) turbine (height to blade tip) could throw a whole blade about 120 m (2.4 × ht) and a fragment over 250 m (5 × ht); a 100-m (328-ft) turbine could throw a blade about 125 m (1.25 × ht) and a fragment about 375 m (3.75 × ht).

Larwood does not recommend specific setbacks, presumably because they involve other considerations as well, such as noise, high voltage, and visual intrusion.

On another note, he cites the distance the turbines should be from each other for minimal wind interference: three rotor diameters when aligned perpendicular to the wind and 10 rotor diameters when parallel to the wind. Thus, the GE 1.5-MW turbine, with a 70.5-m rotor span, requires 37-123 acres per tower. Each Vestas V90 1.8-MW turbine, with a 90-m rotor, requires 60-200 acres.

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September 10, 2005

Local zoning for wind turbines

The Ludington (Mich.) Daily News reported yesterday on a new ordinance in Hamlin Township governing the construction of wind turbine towers. It seems like good clear zoning.
The ordinance ... allows individual wind energy conversion systems (WECS) in all parts of the township, such that the power is only generated for non-commercial purposes with a rated capacity of 300 kilowatts or less.

Setbacks for the individual systems must be, at a minimum, twice the height of the total structure (tower and blade combined) on all sides of the site boundary. The generated noise of the WECS cannot be more than 5 decibels above the ambient noise at the site of any neigboring dwelling.

The ordinance limits commercial, industrial-sized wind energy generating stations to agriculturally-zoned and industrial areas. They must adhere to the same restrictions as the non-commerical turbines.

Also, the commercial wind turbines, among many things must be surfaced in a uniform, neutral, non-reflective color; have signage to warn of high voltage and other dangers; be equipped with both a manual and an automatic braking device capable of stopping the turbine operation in high winds; and adhere to guidelines set forth by the U.S. Fish and Wildlife Service "Guideline to Avoid and Minimize Wildlife Impacts from Wind Turbines."
As the leader of the research team that drafted the ordinance pointed out, variances are possible to loosen the restrictions but not to tighten them, so they need to be tight to start with.

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September 9, 2005

Paper tiger vs. hard facts

To the editor:

The Bennington Banner (editorial, Sept. 8) appears to think that those who oppose industrial wind power plants on the ridgelines prefer nuclear radiation, coal smoke, and mercury poisoning. They have created a paper tiger and missed the real argument.

Most opponents would readily accept the need for large wind turbines if in fact they reduced the use of nuclear and fossil fuels. Their argument, based on the experience of Denmark and Germany and research elsewhere, is that they don't -- certainly not to any degree that justifies industrializing the ridgelines.

The Banner cites Searsburg as supplying electricity for 2,000 homes. Actually, Searsburg produces an annual average (11,000 MWh) equivalent to that used by less than 1,500 Vermont homes (average 7.5 MWh/year). According to a study sponsored by the Department of Energy, however, almost 40% of the time the turbines are not producing any power at all. That study also reveals that power drawn from the grid by the turbines themselves is not metered and the actual net production is unknown. The bottom line is that it would take an awful lot of turbines to make even a dent in our need for more reliable sources.

To equal the electricity we use from Vermont Yankee (almost 2 million MWh/yr) would require 700 MW of wind turbines, or about 390 of the 1.8-MW 400-feet-high models now being proposed. That probably exceeds even the Banner's opinion of how much more development we should tolerate.

That figure is based on the industry's own self-projections. Based on the actual experience of Searsburg, more than 1,100 MW of wind turbines would be needed.

But because of the cubic relation of energy output to wind speed, two-thirds of the time the turbines would be producing at a rate below their already low average. More than a third of the time, as we have learned at Searsburg, they would not be producing at all. That is, fossil-fueled plants and Vermont Yankee would still be needed to provide electricity when we need it.

To point this out is not to prefer nuclear and fossil fuels, as the Banner implies. Most of us would love to see renewables instead. But we have come to realize that wind power will not significantly reduce our need for "dirty" power any more than taking a walk in the morning will reduce the amount of gas I use to drive to the grocery store in the afternoon.

September 7, 2005

Gas vs. wind

From the Miller (S.D.) Press, "Wind power development faces many challenges," Sept. 6, 2005: '"When the wind isn't blowing, it's not serving anyone," [Ron Rebenitsch of Basin Electric Power Cooperative] commented. "I think wind will become a partner with gas energy," meaning when the wind isn't producing, the gas will take up the slack.'

And Renewable Energy Access, "Wind, Natural Gas Hybrid Project Moves Ahead," Aug. 3, 2005, described an 108-MW wind facility proposed off the coast of Cumbria (U.K.) with its own back-up 98-MW natural gas–powered generator.

As noted previously, many advocates of industrial wind power argue that it will help stabilize or offset rising natural gas prices. (Natural gas is used to generate about 15% of the electricity in the U.S.) It has been frequently noted recently that wind power is now economically competitive with natural gas.

The use of natural gas has increased because it is so much cleaner than coal, which still provides over 50% of the electricity in the U.S. (Oil is not a significant source, providing only 2.4%; nuclear fission provides over 20%.) Now it appears that industrial wind power will only displace natural gas.

At best, expansion of industrial wind will fuel an expansion of natural gas, necessary to provide quickly responsive back-up to the unpredictably variable wind production. Increased use of natural gas may then further reduce the use of coal. The presence of wind turbines, with their fluctuating production, however, would require the gas plants to run less efficiently and with more pollution (and more expensively) than if they could run steadily. Obviously, rather than mitigating the demand for gas, wind turbines will be increasing it.

But rather than contributing to an albeit imperfect system of reduced emissions, wind power will be reducing the positive effects of natural gas vs. coal. If new gas plants are going to built anyway, it would be better if wind turbines weren't.

Summary: Wind power requires gas power back-up but reduces its efficiency, thus increasing the emissions of the cleanest fossil-fuel alternative to coal.

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September 6, 2005

Wind behind expansion of coal power

This just in:

“Wind energy in Germany is still backed up by coal. For every 1 megawatt of wind capacity, German power companies will install 0.6 megawatts of coal generation as a backup source, said [Bernhard] Hartmann [a vice president at global management consulting firm AT Kearney].”

--Interfax China, Sept. 6, 2005

That is to say, wind power is actually driving an expansion of coal plant.

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September 4, 2005

Confusion

Christine Vanderlan, Global Warming Program Director for Environmental Advocates of New York, Albany, writes in today's Elmira (N.Y.) Star-Gazette ("More renewable energy offsets natural gas hikes," letter), citing the Union of Concerned Scientists, that "increasing the use of wind, solar and other renewable sources for electricity production would help solve the problem of rising natural gas prices."

But the goal of using renewable energy is to move away from coal first, not natural gas which is a much cleaner fossil fuel. So much for the kids with asthma (let alone the dire predictions of global warming) -- these environmental advocates just want to keep their energy cheap! Welcome to the house of mirrors.

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September 1, 2005

Stupidity

The alarming rise in gasoline prices in the U.S. (still a fraction of what they are in most of the world) is addling people's brains. At least two recent news articles have cited gas prices as a reason to support building giant wind turbines, as if an erratic supply of expensive electricity will help power your car or heat your home. (It won't even help you keep the lights on!)

As gas skyrockets, Lenox considers alternatives, The Advocate (North Adams, Mass.), Sept. 1, 2005:
Town Manager Gregory Federspiel is alerting residents to a possible reduction in services this winter with the prospect of oil and natural gas shortages and sky-high prices. ...

Federspiel said that this is the time for people to start talking seriously about alternatives to fossil fuel energy such as wind towers and solar panels.
Regular gas in Harwich is $3.50 a gallon already, Sept. 1, 2005:
At noon today the gas station on Main Street (Route 39 at Bank St.) in Harwich Center posted a price for regular gas at $3.50.

Ironically the station in the West End of Hyannis nearest Ted Kennedy's home is charging the same, and some Boston suburbs now pay over $4 a gallon while pundits predict we'll be paying $6 a gallon within weeks if not days.

The national web site which audits gas prices around the country shows the lowest and highest prices locally in the last 24 hours. That site reveals a jump of $1 a gallon in one day!

It is finally time for our Senior United States Senator to change his mind about whether he will tolerate a renewable energy wind farm on the distant horizon in front of his waterfront home.
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