Wind Project Development and Lifespan
The process of developing a utility-scale wind farm varies greatly depending on the site and scale of the project. This section is intended to give a general overview of the steps involved from the community perspective and an outlook on the impacts over the course of the project’s lifespan.
The first step of the development process is site selection. Developers identify suitable sites for wind turbines based on a number of factors which contribute to the project’s profitability and general feasibility.
The principle site selection factor is the quality of the wind resource. Although turbines can operate at lower speeds, a general guideline used by developers is that sites become economically viable with an average wind speed of 5 meters per second (~11 mph). Before committing to land agreements at a particular site, developers typically erect meteorological towers and gather wind and weather data for several months or even years to ensure sufficient wind resources exist.
Another factor with an impact on the economic feasibility of a potential site is the distance to high voltage transmission lines. Connecting to the grid can be very costly and it is the responsibility of the developer to build any new transmission lines needed to connect the turbines to the grid. In order to minimize capital costs developers build wind facilities as near as possible to existing transmission. Additionally, land availability is a key issue for developers. Acquiring the use rights to large areas of land can be difficult and expensive, so determining the potential for securing these rights is an early stage in the site selection process.
Land use agreements
Once a high potential, economically feasible site has been identified by developers, the next phase is acquiring land rights. Generally, wind facilities are constructed on publicly or privately owned land that is leased by the project owner for a period of 20 to 50 years. A typical wind turbine lifespan is approximately 20 to 30 years. If the developer and landowners enter an agreement for a longer period, it may cover multiple project cycles. In this case, the developer would operate the turbines for their full lifespan and then replace them with new turbines at the same location and continue operation. Wind project developers are much more likely to lease land, rather than purchase it, in order to avoid an additional expense for an already capital-intensive project. Also, many land uses, such as agriculture, can continue despite the presence of the turbines.
Once a developer has identified an ideal site and has acquired land use rights and determined a viable wind resource is present, the next stage is permitting. Depending on the size of the project, its location, and the surrounding landscape, there will be a variety of permits from the different levels of government that must be acquired prior to construction. The American Wind Energy Association provides a thorough account of potential permitting authorities in its Wind Energy Siting Handbook.
Federal agencies engaged in the permitting process as permitting or consulting agencies include the Federal Aviation Administration, the US Army Corps of Engineers, the US Fish and Wildlife Service, Environmental Protection Agency and the Bureau of Ocean Energy Management (for offshore wind).
State and local permitting
There is currently no state-wide wind permitting rule in North Carolina so the majority of permitting happens at the local level. Any electricity generating facility larger than two megawatts must obtain a certificate of public convenience and necessity from the North Carolina Utilities Commission, as required under the N.C. General Statutes §62-110.1(a). Local authorities can require various permits depending on zoning and land use regulations. Generally, communities can influence the future development of any wind power facilities by issuing a wind ordinance. For more information on local wind ordinances in North Carolina, see the Responsible Community Integration page.
Once the permitting process is complete, the wind facility construction will begin. The duration and complexity of the construction of the project, as with other phases of the process, depends largely on its scope and location, though it can typically be completed in under a year. In most cases, the first step will be to build or update roads to the site. Wind turbine construction requires large equipment such as bulldozers, flat bed trucks, and large cranes – all of which in turn require adequate roads. Once suitable roads are in place, depending on the area, land may need to be prepared for concrete foundations to be poured for the turbine towers. This will be followed by the digging of trenches for the underground electrical and communication cables. Finally, the towers will be raised and the nacelles and rotors will be mounted.
As the electricity is generated, it must be fed into the grid so it can be delivered to consumers. The interconnection process varies depending on the scale of the generation. For small residential systems, the turbine can be connected directly to the distribution system and the electricity is sold to the utility company through net-metering. Net-metering is a system by which the electricity generated offsets consumption and the customer’s utility bill is reduced appropriately. The North Carolina Utilities Commission requires the investor owned utilities in the state to offer net-metering for systems up to 1 MW.
At the utility scale, interconnection can be a complicated and expensive process, depending on the project’s size. Large projects have a power substation that then connects the project to the larger electric grid through high voltage transmission lines. In some cases, the distribution or transmission lines need to be upgraded to increase capacity in order to accommodate the new generation from the wind farm.
Operation and maintenance
After the initial wind facility construction, there are minimal operation and maintenance (O&M) requirements to keep the turbines running. An average wind turbine requires about 40 hours of routine maintenance per year. Small wind farms may not have full time O&M crews at all, whereas larger facilities will typically have a two person crew for every 20-30 turbines.
Repowering or Decommissioning
When the turbines reach the end of their lifespan (typically 20-30 years), the site will either be ‘repowered’ with new turbines or the project will be decommissioned. Decommissioning includes removing all equipment and other evidence of the project. This includes turbines, towers, foundations, above- and underground cables, O&M buildings, and possibly roads. There may be other site restoration requirements of the developer, depending on the permits issued or individual land agreements. This could include replanting any vegetation that was cleared for roads, turbines, or O&M buildings. Most decommissioning requirements are included within land use agreements. However, local governments may include supplementary requirements within the local wind ordinance.
 National Wind Coordinating Committee. Permitting of Wind Energy Facilities. 2002. p. 12 http://www.nationalwind.org/publications/siting/permitting2002.pdf