Another thing we're good at: Wind
Wind is becoming a big business in farm country -- and it has nothing to do with the current political season.
Utility companies and farmers are erecting wind turbines by the hundreds in the upper Midwest and Great Plains, an area that's been called the Saudi Arabia of wind power because of its flat, open terrain and steady stiff winds. Take all the states from North Dakota down to the Texas panhandle, and the states that touch them, and you've defined the geography of this wind superpower.
At a meeting last week in Story county in central Iowa, farmers came to learn about wind energy and the giant wind farms that are being built by utility companies seeking renewable "green" energy sources. Extension service organizers had thought 50 people might attend, but were surprised with triple that number. Farmers there have a special reason to be interested, with a new wind farm under construction by Florida Power and Light in their county.
Here are a few of the facts that Bill Haman from the Iowa Energy Center told the group.
- Wind itself is a byproduct of solar energy as the uneven heating and cooling of the earth's atmosphere creates pressure gradients. About two percent of solar energy that strikes the earth is converted to wind.
- You get more power from cold wind at lower elevations. Both of those things cause the air to be more dense, giving the power boost.
- Winds tend to be slower in the summer, when the air is warmer and packs less punch. Unfortunately, these summer "dog days" of wind power come at a time when electricity use peaks for air conditioner use. Since the power companies can't count on power from the wind when they need it the most, wind-generated electricity has a lower value to them compared to their coal- or gas-fired plants.
- Most turbines you see spinning in farm fields have three long blades. While it might seem that more blades would harvest more wind power, that's not true. As the blades move through the air, they leave a wind cavity that has to be refilled for the next blade. Three blades take best advantage of this cavity refill.
- You need a minimum of seven-mile-per-hour winds to operate most turbines. In Iowa, the year-around average wind speed at 160 feet above the ground is about 15 mph. It averages three to four mph faster in the winter and spring compared to the summer. Winds in far northwest Iowa average about 17 mph, compared to about 14 mph in the southeast part of that state.
- A little extra wind means a lot. As the wind goes from a steady seven mph to 10 mph, the power output generated by a wind turbine triples. Go from 15 mph to 17, and you get a 46% power bump.
- North Dakota should be the wind capital of the U.S. as it gets the steadiest, strongest winds coming off the western mountain ranges. A few years ago, it was calculated that if North Dakota could harvest all the wind power moving over it, and transmit it to where it's needed, it could provide 36% of all the electric power needs of the entire country. Unfortunately, the infrastructure and transmission lines to move that much power don't exist. And the cost to build it is prohibitive -- up to $1 million per mile. That's why most new wind farms are being built in states farther south and east, where the power grid is in place.