Windpower: The promise and the challenge

Minnesota is around the ninth windiest state in the country. While there is more to wind power than just the wind, our state can boast a number of favorable conditions.

There is good reason for anyone to choose wind power over other renewable technologies when possible; wind power emits no pollutants or greenhouse gasses during electricity generation. There are environmental impacts from building and transporting wind turbines, but these impacts are certainly no greater than any negative effects of other renewable technologies. While many people worry about turbine interference with avian migration patterns, studies show that bird collision levels are negligible when quantified. It seems, then, that Minnesota is on the right track. Wind power already provides 4.6% of the energy for our state, second only to Iowa but still below our full potential.

The most efficient way to harness wind power on a large scale is through wind farms, or concentrated groups of large wind turbines. In order to benefit from economies of scale, these farms should be big enough to generate at least 20 megawatts of energy, and 50 MW wind farms are not uncommon. Although such utility-scale wind farms require about 60 acres per megawatt of generating capacity, only about five percent of that area is actually occupied by turbines. The other ninety-five percent can be put to use for farming or ranching. In fact, “in California, Minnesota, Texas, and elsewhere, wind energy provides rural landowners and farmers with a supplementary source of income through…arrangements with wind power developers.” The need to make such arrangements is one reason establishing a wind farm can be a complex undertaking.

While wind farms can be built in eighteen months to two years, it only takes about six months to actually install the turbines. The rest of the time is likely to be spent obtaining construction permits, navigating zoning laws and measuring the area’s wind flows. Site selection is a delicate matter and requires working with (or around) local regulations that are designed to protect a range of environmental and social interests including wildlife health and noise levels for local communities. Considerations like turbine interference with airplane routes are also important. Additionally, before building a wind farm, the developer must identify a utility willing to purchase (and able to access) the electricity generated. Wind power can deliver a significant amount of electricity to existing power grids, but due to its high variability it cannot stand alone.

Wind power is unique in its dependence on a highly variable system: the weather. As the American Wind Energy Association explains, “utilities must maintain enough power plant capacity to meet expected customer electricity demand at all times, plus an additional reserve margin.” The three main interconnected power networks that operate in the United States, and the smaller “control areas” that comprise these networks, adhere to strict standards for maintaining a minimal frequency and a minimal backup capacity at all times. Thus, utilities prefer to buy power from conventional energy sources that can deliver consistently on-demand. But as long as wind contributes only about ten percent of the electricity to a power system in any given hour, the flexibility built into the system can easily cover for its variability. If wind power contributes ten to twenty percent of the energy for a system, the application of wind forecasting and other careful management techniques can keep it running smoothly. Only once a system relies on wind for more than twenty percent of its electricity does its overall variability increase enough to demand significant additional expenditure for regulatory equipment. Thus, the goal is to maximize the use of wind power in conjunction with energy sources able to ensure system stability.