Wind Turbines

Wind turbines—like windmills—are mounted on a tower to capture the most energy. At 100 feet or more aboveground, they can take advantage of the faster and less turbulent wind. Turbines catch the wind's energy with their propeller-like blades. Two or three blades are usually mounted on a shaft to form a rotor.

A blade acts much like an airplane wing. When the wind blows, a pocket of low-pressure air forms on the downwind side of the blade. The low-pressure air pocket then pulls the blade toward it, causing the rotor to turn. This is called lift. The force of the lift is actually much stronger than the wind's force against the front side of the blade, which is called drag. The combination of lift and drag causes the rotor to spin like a propeller, and the turning shaft spins a generator to make electricity.

Land-Based Wind Energy

Wind turbines can be used as stand-alone applications; or connected to a utility power grid; or combined with a photovoltaic (solar cell) system. For utility-scale (megawatt-sized) sources of wind energy, a large number of wind turbines are usually built close together to form a wind plant, also referred to as a wind farm. Several electricity providers today use wind plants to supply power to their customers.

Wind Projects

To develop a wind project, developers must obtain legal rights to the land on which the wind turbines will be placed. These rights may be in the form of a purchase of the land; a lease of the land; or easement to use the land.

The process of securing these rights for a wind energy project may begin with an option agreement—an exclusive right to conduct due diligence on the available wind resources, property conditions, and energy market until the developer is ready to move forward with project development.

The most common land agreement for a wind energy project is a lease. Leases allow the developer to spread the payments over the life of the project to minimize upfront costs. And since the wind project facilities occupy only a small portion of the land, landowners can continue existing land uses, while adding an additional revenue source with a wind energy lease.

A utility company (utility) will often require that the utility or the developer own the land where a utility-owned substation will be located. If the project includes construction of a new utility-owned substation, the developer or the utility will usually negotiate a purchase agreement directly with a landowner.

In Minnesota, wind turbines are regulated by a combination of state statutes, local ordinances, and federal laws. The Minnesota Public Utilities Commission (PUC) oversees the siting and permitting of large wind energy conversion systems (LWECS), which are wind projects with a capacity of 5 megawatts or more. Developers of LWECS must obtain a site permit from the PUC before construction can begin. For smaller wind projects, local governments have authority over the permitting process. Developers must secure legal rights to the land, typically through leases or easements, and may start with an option agreement to assess the suitability of the site. Landowners can benefit from additional revenue by leasing their land for wind projects while maintaining their existing land use. When a utility-owned substation is part of the project, the utility or developer often purchases the land directly from the landowner. Minnesota supports wind energy development as part of its renewable energy goals and provides guidelines to ensure safe and responsible development of wind energy resources.