Wind power seems to be the future, so here's all about wind power

With the price of energy high, the future seems to be about wind power, the most promising of the energy generation technologies. So, it's about time I learned more about it. Here's what I found out.

The new US Farm Bill does subsidize wind power generation at "2 cents per kilowatt hour of electricity produced," or "$4.5 billion over 10 years." This was enough to get 3,100 turbines installed in 34 states in 2007. These 3,100 turbines are the larger turbines, not like these home models. However, homeowners can rake in federal and state incentives, loans and tax credits for installing small wind generators.

The wind farm subsidy is far less than the $3.57 billion ethanol producers receive each year. However, the ethanol subsidy has been reduced a little in 2008. However, a new subsidy of $1.01 per gallon has been introduced "for production of cellulosic ethanol, made from non-edible products like wood chips." Anyway, I did the math,and Farmers Should Be Wind Farming, Not Making Moonshine for Cars.

In my travels lately, I came across a very tall wind farm, taller than the many I've seen before. Even though these were on land, these seemed to the monstrous-sized wind turbines that I thought were only used for off-shore sites. The height of the towers made me wonder why that was necessary. Wouldn't several smaller towers be just as effective and less costly? The reasons for larger wind turbines are many, which I'll explain below.

One reason the wind turbines were larger is probably because I just came across a newer installation. In 1981 the wind turbines were 10 meters across. Each year they kept getting larger, and in 2000 the wind turbine rotors were 71 meters in diameter. The largest wind turbines, made in northern Germany, have 650-foot tall towers and produce 5 and 6KW (see picture of nacelle and rotor at link). 80 meter rotors that produce 10KW are being designed in America.

One reason for larger turbines is economies of scale. Each assembly involves friction, so one assembly with a large rotor provides more efficiency. Similarly, the fewer blades the better. One or two would be best, but those configurations are unstable. Three is stable, and more blades than three would be less efficient. So most rotors are three-bladed.

The higher the tower, the faster the wind is. However, the gain is not as much as one might think. Some scientist named Rayleigh figured out wind power generation , and provided formulas that everyone uses. One of his formulas states that if the wind speed is 9.8 mph at 10 meters, it is 12.5 mph at 50 meters. This small increase in average wind speed makes a lot of difference though. For instance, the same wind turbine mounted at 30 meters can produce 60 percent more power than when lowered to 10 meters. Also, the increased height means a correspondingly larger blade can be installed. Many blades now sweep more than a football field in area. The larger blades allow more kilowatts to be generated, too. For instance, a ten meter rotor can only generate 45 KW, whereas a 71 meter rotor can generate 1,650 KW.

Wind Farm Locations
Wind farm locations are listed on the Web. The Great Lakes provide excellent wind for off shore wind farms. One such farm is located 15 KM from the short on Lake Ontario here.

It seems that the Southeast of the US is the big loser when it comes to wind power, and the northern US, the Great Plains and the West are the big winners:

US wind potential map. Map sure to select the
wind turbine hub height (60, 80 or 100 meters)

Historically, the Southeast was not as inhabited as the North because the weather is so hot and sticky, and the area is subject to hurricanes. However, before WWII many rivers in the Southeast were dammed to create electricity, and after WWII air conditioning came of age. Air conditioners made the Southwest and Southeast more inhabitable, so more people moved south. Now, however, wind charts show that the Southeast does not have as much potential for wind generation.

The Southwest as a similar history. Hydroelectric dams were built before WWII on the Colorado River and other rivers out West. Still, stifling heat kept the Southwest sparcely populated until after WWII, but then the air conditioner came of age. Plentiful hydroelectric power supplies built LA and Las Vegas with all their lights and air conditioners.

In the Southwest, California's Central Valley does not have much wind power generation potential, but long distance electrical wires could be stretched to wind turbines placed in the distant mountains up and down the entire West Coast.

Now one wonders whether Wind Patterns will mean the Great Plains and the northern US will again be popular, and the populations centers will shift away from the Southwest and Southeast, reversing the shift to the South since WWII.

Parts of a Wind Turbine

HowStuffWorks has a lot of information and videos on wind power, especially if one searches on "wind power." Unlike old flat blade windmills that rely on wind pushing the blades to the side as it goes by, the blades of wind turbines are a mix between an airplane wing and a propeller. Instead of the lift pulling the wing of an airplane upward, on the wind turbine the blade is pulled to the side (diagram). The blades spin as fast as 75 meters per second, or 164 miles per hour.

Wind turbines usually have a braking system in the hub so that in case the wind speed gets too high (above 25 mph), centrifugal forces don't tear apart the rotor. Here is a YouTube of a Dutch wind turbine breaking up because its braking system failed. The larger turbines can control the pitch of the blades relative to the wind to reduce lift as much as possible. Newer blades have tips that rotate to catch the wind, and act as a brake.

Here is a series of 65 pictures of six wind turbines in Minnesota being constructed from the ground up--with explanations. Here is a graphic with the parts labeled. Here's a video of a wind turbine being built in Minnesota.

The nacelle is the housing for the wind turbine's generator and related electrical equipment. Here's a picture of inside the Nacelle of a wind turbine. Here's a picture of inside of turbine tower looking up. The nacelle turns on the turbine tower. The technical term for this twisting or rotation is to yaw, or yawing.

Storing Wind Energy For Peak Demand

Since solar plants produce power only during the day, some solar plants store heated fluid in insulated underground tanks. Then during peak demand when the price of electricity is highest, the heat is released from the tanks to generate electricity.

Wind farms could store the energy in any number of ways, including heating liquid for use later, and electrolysis of water and then burning the hydrogen to run generators when needed. I've read that some wind farms run air compressors that sent air down into old mines that often are entirely filled with ground water. The air compresses the ground water squeezing some of it out of the mines. The compressed air is released to run generators when the demand for electricity warrants, and the price per unit of electricity is higher.

Storing wind power at night for use during the day is not necessary in most places, and might not be necessary in the future anywhere. First, wind power often provides only a minor percentage of the electricity needed in an area. Thus, when the wind is blowing, the coal and natural gas plants could shut down so wind could power the whole system. Of course, shutting down a nuclear plant is not an option since the rods stay hot so long. Second, in many areas the wind blows mostly at night, and other places during the daytime. If houses were heated during the winter with electricity, they would need the most electricity at night when it's coldest. Thus, the wind farm would be a good match for that need. Also, starting in 2010, plug-in hybrids like the Chevrolet Volt and Toyota Prius (the non-hybrid plug-in version) are supposed to become popular since they will cost much less to run than gasoline-powered vehicles.

By the way, fuel-cells are not the the solution since they only change the mode of energy production from internal combustion to flameless chemical reactions. The fuel-cell can consume hydrogen, hydrocarbons and alcohol, but any vehicle run on these fuels is much more expensive to operate per mile than plug-in electrical cars.

Compressed-air cars are not a better solution either due to their poor energy-to-weight ratio. That's because compressed air is heavy and doesn't store that much energy, and it takes strong, expensive, heavy tanks to store it. A liter of gasoline stores 34,000 kilojoules of energy. To store the same amount of energy using compressed air takes a 176-liter tank pressurized to 30 MPa (300 Bar). The air weighs 80 kilograms just by itself. The tanks that store the compressed air might be as heavy as the air they hold, so add another 80 kilograms. Thus, the total weight to store one liter of gasoline's worth of energy would be 160 kilograms. Meanwhile, a lithium-ion battery that holds the energy equivalent to one liter of gasoline would weigh only 57 kilograms, less than half the weight of the compressed air option! Moreover, nanotechology is improving battery storage continually.

Hydrogen has a much better energy-to-weight ratio than compressed air. By weight, liquid hydrogen only has one-tenth the energy of gasoline, so ten hydrogen tankers would be needed to transport the equivalent of one gasoline tanker. Hydrogen-powered cars are still much more expensive per mile than gasoline-burning and plug-in electric cars, and also the necessary refueling infrastructure is prohibitively expensive. Hydrogen is very reactive and very cold, so the pipelines, tankers and tanks necessary to store and transport it are expensive.

If the price of electricity were lower at night, millions of people would use timers to set their cars, lawnmowers, snow blowers, etc., to recharge at night. Thus, the wind farms would not need to store the energy themselves, but millions of people would be storing the energy for them. The effect of plug-ins hitting the streets around the world will immediately lower the price of gasoline since a small drop in the demand affects a big price drop, and vice versa as we all know too well.

related links:
Wind power FAQ

Wind Power History in the US FAQ

UK to get 40% of electricty from off-shore wind farms by 2020

Oil baron Pickens Plan, as seen on TV, July 2008