Thursday, April 9, 2009

Blow Me

Humans have been harnessing the wind’s power with windmills since probably before the ninth century A.D., when we humans built our first windmill to grind grain for making beer. That's not true, but it certainly is a more noble cause than making flour. The new “green” push and all of the economic incentives put forward by the government have made harnessing the wind’s power more attractive as of late. Wind power is currently being touted as the cornerstone of the sustainable energy future of the U.S. because it is cheap; provides jobs and revenue; and doesn’t cause pollution, generate hazardous wastes, or deplete natural the fuel is free. Wind lobbyists and environmentalists would have you believe that all you have to do is throw up a couple of benign and beautiful wind turbines and not only will we become energy independent, but we will be saving the planet to boot. “Hurry! Hurry! Hurry! Step right up ladies and gents! Be the first in your lovely little community to capture that magical ether and turn it into free energy! It’s true! Wind in a bottle! You can take it home today for the low, low price of 1000$/kW!” As usual after rubbing the shine off of the subject it turns out that things are a bit more complex.

In America today all across the countryside a silent debate is raging in community halls about large-scale wind turbine installations and their benefits, with the lobbyists, environmentalists, and turbine corporations on one side of the fence while property owners sit predictably confused on the other. My curiosity about this subject was peaked by a proposed installation of 151 commercial-scale wind turbines in the sleepy Illinois farming community where Daniel P. Daniel was borned and raised. The press release can be found here. So, I decided to spend a little time trying to figure out what the real deal is with these wind turbine farms. After some extensive research I think I’ve been able to flush out what the actual pros and cons of large-scale wind farms turn out to be.

First, some background information. Much of the confusion and concern over these industrial-scale turbine installations is simply a lack of information about how they work and why they even exist in the first place. The primary reason for their existence is to defray some of the pollution caused by power generation from coal. In the U.S. over 50% of our energy comes from burning coal. Two-thirds of sulfur oxides, 40% of carbon dioxide, 1/3 of mercury and 22% of nitrogen oxides (the brown cloud gas) that are emitted in the U.S. annually come from these plants. In order to meet our energy demands the U.S. burns over 1 billion tons of coal every year (total) in about 500 coal-fired power plants that have an average energy output of 667 megawatts (MW). That’s around three tons of coal per person every year. If you ignore external costs (air pollution, water pollution, health effects, hazardous wastes, and environmental destruction from mining) coal power is cheap, costing less than one cent/kWh. As a reference, wind energy costs 3-6 cents/kWh and solar photovoltaic power costs 14-25 cents/kWh. If you do factor in those external costs, wind power becomes an economic contender which is one reason that it remains an attractive alternative to coal.

About 26,274 megawatts of wind power capacity are currently installed in the U.S. (January 2009), generating over 66 billion kilowatt-hours of electricity annually. That’s as much electricity as about 6.2 million average American households use each year. Considering there are about 117 million households in the U.S. (not to mention business and industrial use), we might as well be pissing in the wind, but you’ve got to start somewhere. Right? In order to displace the energy produced by one average-size coal-fired power plant a wind farm would need about 445 1.5MW wind turbines. In actuality there would have to be close to double that many since turbine capacity is 20-40% of the nominal rating due to variable wind speeds. The capacity is calculated as: actual amount of power produced over time / power that would have been produced if turbine operated at maximum output 100% of the time. So, a turbine that is designed for constant 12mph winds will operate at a lower capacity if the winds die down even if the blades are still turning 60-90% of the time. If the winds speed up then it operates at a higher capacity. The capacity for coal-fired plants is generally 40-80%, but that is usually a function of equipment reliability whereas turbine capacity is mostly a factor of economical turbine design.

Two factors determine how much power a turbine will put out: turbine size and wind speed. As far as turbine size goes, if you double the rotor diameter, you will end up with an area that is four times larger (two squared). This means that you also get four times as much power output (potentially) from the rotor. Utility-scale wind turbines for land-based wind farms come in various sizes, with rotor diameters ranging from about 165-300 feet, and with towers of roughly the same size. Offshore turbine designs will have larger rotors (some have a 360 foot rotor diameter) since it is easier to transport large rotor blades by ship than it is by land. The power available in the wind is proportional to the cube of its velocity, which means that doubling the wind speed increases the available power by a factor of eight (two cubed). Thus, a turbine operating at a site with an average wind speed of 12mph could generate about 1/3 more electricity than one at an 11mph site, because the cube of 12 (1,768) is 1/3 larger than the cube of 11 (1,331). So, what seems like a small difference in wind speed means a large difference in available energy. It follows that there is little energy to be harvested at low wind speeds (6mph winds contain less than 1/8 of the energy of 12mph winds). Not surprisingly, most utility-scale wind farms are placed in areas where the average wind speed is ~13mph. Still with me?

And, obviously, when there is no wind or even low wind the turbines will not spin at all, so they will not generate any power. This brings up an interesting dilemma regarding wind power. With an intermittent and unpredictable fuel source, electricity generation will be intermittent as well. Without some form of energy storage (which does not currently exist) there must be backup power generation. In most instances traditional power plants with capacities equal to 90% of the installed wind power capacity must be permanently on line in order to guarantee power supply at all times. I suppose this is not necessarily bad since we already have the power plants in place, and wind energy is essentially free. However, it does mean that wind power will never be able to completely displace all of our conventional power plants unless some technological battery or energy storage innovation happens in the future.

Wind plants typically cost around $1,000/kW of installed capacity, and they generally pay themselves off after five years of operation. The lifespan of a modern industrial turbine is approximately 20 years. These turbines are designed to work for some 120,000 hours of operation throughout their design lifetime of 20 years. That’s only about 30 times longer than an average automobile engine, and the maintenance costs are in the one cent/kWh range over the lifetime of the machine. They are pretty impressive pieces of equipment. Do they fail? Yes, and when they do it is sometimes spectacular. However, I think the failures are so noticeable because these machines are large and generally running in the non-industrial countryside where the most spectacular failure that is usually seen is Uncle Billy running over a lawn gnome in his riding lawnmower. I think it is important to mention here that not one single member of the public and only a handful of maintenance staff have been killed or injured in a turbine accident. If you compare that to the current power plant (including coal and uranium mining) safety record in the U.S…well let’s be nice and say it’s better.

O.K., I’ve run through a lot of information pretty fast, but I think I’ve hit most of the important facts about wind power generation. Now I’m going to dig a little into the most prevalent arguments for and against these large wind farm installations. I’ll start with the one that seems to be the most prevalent: wind turbines are large and unattractive. Sorry, but "wind turbines are big and scary" is not a good argument against the technology. Hmmm…What else are big and ugly? Buildings, radio towers, cookie-cutter houses, strip malls, and Rosie O’Donnell, maybe? Nobody seems to be too worried about those crashing to the ground or ruining the pastoral view. Well, except Rosie. OSHA had to shut down The View because Rosie wasn’t rigged properly, and they were afraid she might collapse on the studio audience. Anyway, a 1.5MW turbine (the size proposed in the DeKalb farm) would have blades that are approximately 105 feet long with an overall height of ~300-400 feet. The diameter of the swept circle is around the same size as the wingspan of a 747. Admittedly, they are a bit intimidating, but they are safely designed and massively over-engineered. I can understand the argument if the wind farm was proposed in an area of extraordinary beauty (rim of the Grand Canyon, covering the Black Hills, in front of the Statue of Liberty), but in the Midwest the extraordinary geographical feature is…the horizon. Let’s be honest here, anything taller than eye-level blocks the view.

Another argument against turbines is that they kill birds. This one is true. Wind turbines account for around one bird death out of every 10,000 birds that are killed each year in the U.S. That’s .0001%. I know. The horror. The…horror. It’s virtually a slaughter. We should halt all wind power production (which helps the environment, generates jobs, and creates revenue) until this issue is resolved. Or maybe not. ~60% of bird deaths come from collisions with buildings and radio towers. They just fly smack into them. Guess what the second-leading cause of death for birds in the U.S. is. It’s your fekking cats, Jaggoff. Ten percent of the birds that die for anthropogenic reasons in the U.S. are killed by domestic cats. So, before we shut down one turbine we should declare open season on those useless felines. It would help the environment, create recreational opportunities and bolster the faltering cat-skin hat trade. There’s no downside, really.

A third argument against wind power is that it is inefficient. I touched on this one a bit earlier. An average U.S. household uses about 10,655 kWh of electricity each year. One MW of wind energy can generate from 2.4 - 3 million kWh annually. Which means that a MW of wind generates about as much electricity as 225 to 300 average households use. Assume that a 1.5MW turbine can generate 1.8 million kWh of power if it operates at 40% capacity. That’s enough power to run 150 homes. Quick quiz: How many 1.5MW turbines would it take to meet the power needs of, say, the Chicagoland area (pop. 9.5 million)? Did you get 20? WRONG! It’s somewhere in the vicinity of 24,300 turbines, and that’s not counting industrial electric use or businesses. But remember, wind is free and the turbines are relatively inexpensive. So the efficiency argument is really just a mathematical one, since wind power is only intended to be a supplementary power source. As a reference, only about 15% of the energy from the fuel you put in your car’s gas tank gets used to move you down the road (unless you drive a hybrid or electric vehicle). 20-40% for wind power isn’t looking too bad now, eh?

The next argument is valid, but it does have a solution. One item that must be considered when determining the site placement of these turbines is the noise. To be fair, as far as massive pieces of machinery are concerned wind turbines are pretty quiet. You can stand probably beneath one and have a normal conversation...depending on who you are. I’ve heard the sound compared to a flowing river, leaves rustling in the breeze, vehicles traveling down the highway, a gas fireplace running in a living room, the HVAC at your office, etc. However, to me they sound very similar to a slow fetal heartbeat, and it’s that cyclical nature of the noise that I would find particularly annoying. Background white noise can cause all sorts of problems, after all the military does use it to confuse and flush out entrenched combatants. One problem with the noise is that turbines are generally sited in areas where the background noise is near zero. People move to the countryside to get away from noise. Also, these machines run around 90% of the time, day and night, and no amount of complaining to anyone will help after the turbine is installed.

A similar issue with a similar solution is what is called shadow flicker. As the turbine blades spin they create a strobe effect with their shadows that is particularly annoying. If you can imagine a 400 foot hand alternatively covering and uncovering the sun every two seconds or so then you will get the picture. As with the noise issue, the issue with shadow flicker can be resolved with proper placement of the units. Congress tasked the Congressional Research Service to prepare a report on wind power in the U.S., and their recommendation was for a minimum setback of 2640 feet (1/2 mile) to minimize noise and shadow flicker complaints. I’ve also seen the approximation of 10 rotor diameters which is close to ½ mile. The proposed setbacks for the DeKalb wind farm are not posted for obvious corporate B.S. reasons. I will guarantee that they are not ½ mile. Here’s a map of the proposed site. They do say that they will offer $1000/year to anyone that lives within ¾ mile of a turbine. I wonder why they chose ¾ mile? Because they know that even ¾ mile probably isn’t enough separation. As of this writing wind turbine corporations are lobbying congress to eliminate any setback standards for turbines. Typical. I would not want to live within one mile of these things, particularly since as a property owner I would have no recourse for complaint because the turbine owners make property owners sign pretty nasty contracts. So, in my mind we run into a bit of a problem here. The turbines should probably be placed as far as possible from dwellings, but there aren’t too many places you can stick them where there are no houses around for two miles and there is enough infrastructure available to make them functional. As always, it’s the property owners’ responsibility to ensure that what they propose to do on their land doesn’t adversely affect their neighbors, because the turbine corporations certainly don’t give one rat’s ass.

O.K., one more issue, and I’ll let you go. In order to install these massive structures roads must be built that can handle the trucks that haul in the large blades. Also, trenches must be dug to connect the turbines to the power infrastructure. This may be obvious, but I think it comes as a surprise to many when they see their land being broken up to accommodate the heavy equipment. Again, probably just a little awareness of this will go a long way.

So what do you think? Are wind-fueled power plants the panacea that they are touted to be or are they just more corporate greenwashing? My opinion is that they are a little of both, actually. I think at best we are putting a windy green hat on a coal puking monster, but wind farm maintenance and installation costs are low, the fuel cost is zero, and they can be decommissioned safely and cheaply. A 50-MW wind farm can be completed in 18 months to two years, which is much better than the 10-20 years it takes to commission a modern coal or nuclear facility. The main drawback is one of quality of life for people that live near the turbines. The companies that install and maintain the turbines offer some economic incentives to people that are inconvenienced, but I believe that it is imperative that property owners obtain appropriate legal counsel before they agree to sign anything. And a little education on the subject goes a long way, but that’s why you keep Daniel P. around, right?

Thanks, again to Witmo for the article suggestion, and as always if there is anything that you are curious about, just let me know.

Some pertinent wind-power links:


Anonymous said...

oh ,come on it took you all that time to talk about the wind farm. i think i fell a sleep half way through,just kidding. i fell if we have to give up a little space to put these in go for it, if they would let me i would put it in my back yard . good research,im all for it.... jewels

The Hippy said...

Not in my back passage. I like the out at sea idea though, can we just run with that? Oh wait, how does electricity get from Puget Sound to Colorado? Anyone..?