Could a Long Island Offshore Windfarm Disrupt Weather Radars?

Above, A marks the spot of a wind farm in central Wisconsin that is disrupting weather radars, making forecasting all the more challenging. Image source: Google Maps.

Saw a great article in the Milwaukee Journal Sentinel recently about a large wind farm disrupting weather radar capabilities in central Wisconsin. We’ve talked a lot about the benefits of wind power, especially in rural areas, to generating clean electricity. Here is a demonstrated negative consequence of large wind farm installations.

The National Weather Service has issued a new kind of warning because of a Dodge County wind farm that is disrupting the agency's ability to monitor storms in southeastern Wisconsin.

The wind farm's giant turbines - each as wide as a football field and as tall as a 20-story building - are sending false storm signals to the government's weather radar system.

Weather service officials say they see no significant public safety threat, although they say the wind farm has caused radar interference and could confuse some storm watchers.

Meteorologist Marc Kavinsky said the approaching summer storm season will be the federal agency's first opportunity to gauge the wind farm's full impact.
"It'll be interesting," he said. "I'm hoping the effects will be minimal."
Located just outside the Dodge County community of Iron Ridge, the wind farm includes 36 turbines that began operating over the past few months, generating electricity for several surrounding communities.

The farm is about 30 miles north of the National Weather Service office in Sullivan, which provides radar coverage and severe weather alerts across a 125-mile radius that includes all of southeastern Wisconsin.

The meteorologist, Marc Kavinsky, who was quoted in the article has a great website demonstrating the effects of these tremendous blades on Doppler radar returns.

His key implications of the wind farms on radar returns were:

• Thunderstorm or winter storm characteristics could be masked or misinterpreted, reducing warning effectiveness in the vicinity of the wind farm.

• False signatures contaminating Doppler velocity data in the vicinity of the wind energy facility could reduce forecaster's situational awareness, particularly
during hazardous/severe weather events.

• False precipitation estimates could negatively impact flash-flood warning effectiveness.

To summarize the above, the false returns negatively affect the weather services’ ability to forecast for severe events, like thunderstorms, tornadoes and flooding rains. While this would be a major concern in the Midwest where severe weather associated with thunderstorms is common, how important would it be here in the New York region? Let’s try to anticipate the effects of a wind farm 10 miles off of the south coast of Long Island, as has previously been proposed.


The figure above shows how topography coupled with an extremely high wind farm affects weather radards. Source: National Weather Service.

The figure above shows why the wind farm in Wisconsin is so effective in disrupting the radar signals. The radar beam is tilted up, generally in the neighborhood of 0.5 to 3.5 degrees, and in this case the beam intersects the windfarm because the terrain is sloping upward along the beam path. If the ground was flat, the windfarm would go undetected by radar. How would this work in the New York region?

The NWS Doppler radar that serves the New York region is sited on Brookhaven National Lab on Long Island. A conservative estimate of the height of the Doppler radar is 250 feet above mean sea level. Using Google earth software I calculated the distance from the radar to Fire Island on the south shore of Long Island to be about 8.6 miles. Plan for the windfarm had it to be placed about 12 miles off shore, so let’s estimate the closest possible distance between windfarms and the Doppler radar to be 20 miles (even though in the planning stage the windfarm was located futher west, increasing the distance between radar and windfarm). Next step, figure out the height of the proposed windfarm. Taking the extreme of a 20 story windfarm at 15 feet a story, we come up with a height of 300 feet. With the lowest angle (0.5) of the radar, 20 miles away the beam would be about 528’ above where it started and with the highest angle (3.5) it would be 3696’ above the ground where it started. If you ignore radar beam broadening and throw in a ground elevation of somewhere near 250’ the beam would be 775’ to 4000’ above sea level by the time it reached the windfarm.

Bottom line, a wind farm 20 miles away from the Doppler Radar would require a height of at least 775’ to interfere with Doppler radars offshore in the New York region. While wind farm interference is a problem given the complicated topography of central Wisconsin, it will likely be not be an issue with an offshore farm in the New York region.

Big Turbines in the Big Apple

Okay, today’s post will be much shorter than yesterday’s…that was too much text for any mere mortal to enjoy.

Big Turbines in the Big Apple?
Yesterday we discussed why large, industry standard 1.5 mega Watt turbines would not work in New York City. Today we’ll talk about a proposal to have large, industry standard 1.5 mega Watt turbines in New York City. As we discussed yesterday wind turbines need a lot of space. They are massive structures. They create noise not suitable for residential locals, and they can throw ice chunks great distances. Where in New York City is there space enough for giant wind turbines? Answer according to the New York Times: the United States largest landfill; Fresh Kills in Staten Island.

Having spent decades persuading the city to close the giant Fresh Kills landfill, Staten Island officials are now arguing that the vast site would be the perfect home for the energy-creating windmills that Mayor Michael R. Bloomberg has proposed as a way to make New York City more sustainable.

Wow turning what the Staten Island Borough President refers to as “one of the country’s worst ecological nightmares” into New York City’s first wind farm would be quite an environmental coup. Unlike the failed Long Island offshore windfarm, this endeavor may be economically viable (much of the cost with the Long Island had to do with construction and maintenance of an offshore site, a land based construction would be much more economical.) Lost in the Times article is that the project is just part of a major rehabilitation process for the landfill, including the creation of large areas of parkland and nature preserves.

A question arises, will the public have access to parts of the park where the wind turbines are located? Short term exposure to the noise generated by the turbines is not a serious concern, so long as care is taken during icy periods to avoid ice throw, hopefully the public will have full access to the region.

Will Small Turbines Work?
A second article in the Times discusses the utility of smaller turbines, the type that Mayor Bloomberg proposes to deploy across the city on rooftops, bridges and other structures. Do these small turbines produce enough energy for their expense?

These tiny turbines generate so little electricity that some energy experts are not sure the economics will ever make sense.
By contrast, the turbines being installed at wind farms are getting ever larger and more powerful, lowering the unit cost of electricity to the point that they are becoming competitive with electricity generated from natural gas.
The spread of the big turbines and a general fascination with all things green are helping to spur interest in rooftop microturbines, creating a movement somewhere on the border between a hobby and an environmental fashion statement.

The article seems to insinuate that at present the cost of instillation is not made up by the meager energy produced. Instead instillation is being driven by a desire to be green or be trendy. The article attempts to differentiate between smaller stand alone wind turbines and roof based, small turbines, noting that the smaller yet independent wind turbines do indeed produce enough energy to pay for themselves, whereas the roof based ones do not.

One assumes that technology will at some point overcome the technological and manufacturing challenges and produce inexpensive rooftop turbines. But the article notes that there are some major concerns with the urban wind environment in general.

But many experts caution that rooftops, while abundant, are usually poor places to harness the breeze. Not only are cities less windy than the countryside, but the air is choppier because of trees and the variation in heights in buildings. Turbulence can wear down a turbine and make it operate less efficiently. This is particularly problematic for houses with pitched roofs.

New York is a winder environment than most cities (windier in fact than the so called “Windy City” of Chicago), but the presence of sky scrapers does introduce a frictional drag decreasing the wind speed. The building induced turbulence is not a problem that technology will solve any time soon.

So the city faces major technological challenges to its desire to harness wind power upon rooftops. Only time and technology will show if this ambitious project is feasible.

Concerns About Wind Power in an Urban Enviroment

(Aside: Thanks to everyone who has e-mailed me about Science Debate 2008. I am planning on writing a few posts about how this years crop of politicians have performed on issues relating to the environment in October. Until then, you can stop e-mailing me about this :-).)

Avid reader, master strategist and all around great guy Chris John noted this concern about implementing wind power in an urban environment:

If an art exhibit (Olaf Eliasson's [sp] waterfalls) under the Brooklyn Bridge almost killed two kayakers, I dread to think of the mess we're going to have to clean up from wind turbines.

So lets take a few minutes to address wind power, and to think about how well suited it would be for a major urban region like New York City.

A couple of years ago I was lucky enough to win the Evan R. Liblit Scholarship. I was honored to be chosen as the Evan R. Liblit Scholar, since Mr. Liblit was an environmental hero, championing the cause of recycling and responsible waste management on Long Island during the 1980’s and 1990’s. (People are so passionate about Evan Liblit, that they are even willing to row the length of the Yukon River to raise awareness and money). As part of the Scholarship I was to attend the New York State Solid Waste and Recycling Conference in Lake George. Admittedly, I wasn’t particularly excited about this – who wanted to spend a week learning about garbage? But my talk was well received, which was great and I got to see a presentation session on Wind Power in New York State, the content of which has stuck with me ever since.

As it turns out, wind power is becoming a big business in many parts of New York State, especially those regions that abut the Great Lakes. The regions downwind of the Great Lakes are (as we discussed before) in a region with great wind power potential, and also are suffering from a still stagnant economy that began its decline in the late 1980’s. As such many municipalities are investigating whether allowing utility companies to construct wind turbines on farmland and other open terrain would be beneficial to the communities. I can’t recall this with much certainty, but I do recall someone citing at the conference the example of a small town that had reduced its school and property taxes to zero by contracting with a major utility.

To me, one of the most surprising aspects of the wind power craze in Central and Western New York State, was the degree to which lawyers needed to be involved in the process. Here I will try to speak as simply as possible to avoid displaying my legal ignorance (much like Sarah Palin should avoid speaking in public about polar bears, global warming and ANWAR – ZING!). Small rural municipalities were very much so dependant upon two firms (one in Albany one in Buffalo) to draft complicated lease agreements with utilities as well as to craft appropriate zoning regulation that protected the health and welfare of residents along with allowing for economically reasonable utilization of wind energy. This process is much more involved than you think, due to the impacts of ice throw and noise pollution generated by wind turbines (actually it is so complicated that there is a legal blog dedicated to issues regarding wind power).

Ice Throw

Ice throw occurs when wind turbine blades become coated in ice, generally from freezing rain or from freezing fog. As winds pick up after the storm, the blades begin to rotate and in the process the ice that has accumulated on the blade can be thrown over large distances. The figure to the right, taken from this non-peered reviewed source, shows the distance ice can be hurled. Along the ordinate (x-axis) is shown the width of the turbine blades in meters. The y-axis shows the distance that ice chunks have been thrown. The color of the dots show the mass of the hurled ice chunks. Smaller chunks of ice have been shown to be thrown lengths in excess of three football fields. Larger chunks of ice, coming in at about 1kg or 2.2 lbs have been shown to be thrown 25m! Well take those results with a grain of salt, since they don’t come from a peer reviewed source, but none the less it is evident that wind turbines cannot be sited in densely populated regions, or even in regions with large amounts of infrastructure. It doesn’t need to be said, but obviously chunks of ice flying off of 50 story buildings in Manhattan would probably be frowned upon by local residents.

It should be noted that by my recollection, none of the speakers at the conference considered ice throw to be a major issue. They noted that technology was improving, reducing the capacity of ice to be thrown and that the amount of ice accumulation was relatively small in general and limited to short periods of the year. They also pointed out the lack of observed injuries related to ice throw, suggesting that either this is not a serious issue or that people have done a good job citing turbines.

Noise Pollution
A second major concern that requires the attention of zoners, is that of noise generation. Turbines when operational generate a low frequency humming noise. Although not altogether an unpleasant sound, the volume (which gets higher as the turbines speed up) accumulated over time can injure local residents long term hearing.

Here is a video of a large industrial wind farm, documenting the noise that the giant turbines make:



The amount of noise will vary based on the design of each turbine, the wind speed and local topography. Each community needs to assess how much noise each turbine in their town is expected to put out, and make zoning regulations that make sense for local resident’s health. In the case of New York City, it is unclear whether or not a wind turbine would produce noise in excess of the current noise levels. Massive wind turbines, like those shown on the above video are also not possible in an urban environment. One imagines that a smaller turbine built for rooftop use would have a much smaller noise impact.

Aesthetic impacts
The visual presence of wind turbines is thought to have a potential negative aesthetic impact. This is true in many pristine environments, but in other environments some folks actually enjoy the way the wind turbines look. I wish I had a reference to back this up, but I heard once that in Europe property values of locations with wind turbines.

In the case of the Long Island Windpark, concerns over property value were paramount. Additionally folks were very worried about the impact of wind turbines on the view from regional beaches and tourism.

Bird deaths
To be frank, I think that this issue is overstated. The number of birds killed by feral cats at Stony Brook University outnumbers the total number of birds killed by wind turbines in all of New York State I would guess. This issue seems to be something of an “ecco-myth” and probably stems back to antiquated technology. Some new wind turbines come equipped with “whistles” that emit sound on a wavelength that birds can hear (humans however cannot hear the sound) and find annoying.

Birds have a large number of threats to their well being to be sure, high tension wires, high rise buildings, automobiles, domesticated invasive species – I’m not so sure that wind turbines are of the order of impacts as the previously listed problems.

Yikes this post is getting long, probably past the point that anyone is still reading. So let me conclude with a wildcard. Everything we have been discussing so far has pertained to the traditional wind turbine. Colossal, gigantic, tall, massive – these are all adjectives that could be used to describe the turbines. These are not the sorts of turbines that would be practical in New York City.

Rohit Aggarwala, the director of the city’s Office of Long-Term Planning and Sustainability, said that turbines on buildings would likely be much smaller than offshore ones. Several companies are experimenting with models that look like eggbeaters, which the Bloomberg administration says could be integrated into the spires atop the city’s tall buildings. “”You can make them so small that people think they are part of the design,” Mr. Aggarwala said. “If rooftop wind can make it anywhere, this is a great city,” he said. “We have a lot of tall buildings.”

Such new turbines would have to be designed to not produce any icethrow, and regardless of the size of the particles or how far they are thrown, ice chunks falling from sky scrapers would not be acceptable. Noise concerns must be taken into account, but I’m not entirely confident that wind turbines would be appreciably louder than air conditioner units currently housed on many rooftops, nor would they be louder than the ambient city noise levels. Bird kill in New York City may be a serious problem as many birds congregate on city rooftops. Furthermore, birds in New York City are notoriously stupid and their termination may be a blessing in disguise…just kidding.

New York: Alternative Energy Capital of the World?

Great article in the New York Times yesterday about how New York City aims to provide renewable energy to the city in the next few years.

In a plan that would drastically remake New York City’s skyline and shores, Mayor Michael R. Bloomberg is seeking to put wind turbines on the city’s bridges and skyscrapers and in its waters as part of a wide-ranging push to develop renewable energy.

….

“When it comes to producing clean power, we’re determined to make New York the No. 1 city in the nation,” Mr. Bloomberg said as he outlined his plans in a speech Tuesday night in Las Vegas, where a major conference on alternative energy is under way.

Sounds good. My initial response to this news is that even though this plan may never see the light of day, it’s great that New Yorkers are hearing that alternative energies can be generated in their backyards. It’s important that New Yorkers put their money where their mouth is, and try to develop energy sources locally, rather than importing energy from California and Arizona. Mayor Bloomberg agrees:

“In New York,” he said in his speech, “we don’t think of alternative power as something that we just import from other parts of the nation.”

Oh but Mr. Bloomberg good sir, I’m afraid we do. A similar project, although smaller in scope, was proposed off the south shore of Long Island. It was rejected handily by Long Islanders mostly due to cost considerations (i.e. it would be really expensive per watt of energy produced), but there was also sizeable objections to obscurations to the view off of Jones Beach.

So what makes the mayor so confident that building wind turbines off of Queens and on top of the George Washington Bridge will not face similar challenges?

Rohit Aggarwala, the director of the city’s Office of Long-Term Planning and Sustainability, said that turbines on buildings would likely be much smaller than offshore ones. Several companies are experimenting with models that look like eggbeaters, which the Bloomberg administration says could be integrated into the spires atop the city’s tall buildings. “”You can make them so small that people think they are part of the design,” Mr. Aggarwala said.
“If rooftop wind can make it anywhere, this is a great city,” he said. “We have a lot of tall buildings.”

Well it’s a start I guess. Certainly less visible turbines would be easier for New Yorkers. who are quite proud of their skyline, to accept.



But if New York State has any source of alternative energies, it is wind power. As the figure above shows, the waters off of Long Island and Lake Ontario are considered to be near the highest classification of wind power. Likewise on shore, the Southern Tier, Tug Hill Plateau and nearly all lands downwind of the Great Lakes are good spots for wind turbines as well (not shown).



Contrast that with solar energy. As you can tell from this figure (taken from this fantastic textbook by Botkin and Keller), New York State as a whole ranks very poor in terms of potential solar energy. Of course any one who’s lived here for a winter could tell you that just as easily without a fancy picture -- but none the less solar energy as a future power source in New York will be dependent upon technological advances.

New York City has long done well in thinking ahead of environmental problems and Bloomberg’s administration has been no exception (in fact Mayor Bloomberg has espoused some rather progressive environmental views, at other points during his tenure.). New York City has adopted an aggressive policy of purchasing and preserving land surrounding their extensive reservoir system in an attempt to control water quality. As a result, the city is saving money long term by avoiding the high costs of energy and chemicals for water purification. As an affective bonus this land is preserved from development and adds to the impressive quantity of land preserved in the Catskill State Preserve. But the achievements in the Catskills would be dwarfed by the prospect of the United States largest city developing alternative energies enough to power itself.