October 23, 2019

Wind Turbine Repowering

Do you have your permits?
Wind repower blog

Repowering older wind turbines has become an attractive option for wind project owners as they seek to capitalize on production tax credits and optimize energy production from existing assets. Equipment technology has improved over the years making modern machines more efficient and reliable to operate.  Generally, repowering involves exchanging existing turbine components such as blades, hubs, gear boxes, and other electrical components.

On the face of it, these would seemingly be minor upgrades that can be accomplished in short order with a modest amount of planning and preparation. In reality, repowering requires careful consideration of many issues to ensure success.

Considerations for Repowering Projects

Environmental permitting

Often overlooked is the importance of evaluating various aspects of environmental permitting. Adding longer blades to existing turbine towers increases the overall height and rotor diameters, which can change original permitting assumptions for a number of parameters. 

For instance many counties, and some states, have required turbine setback distances to public roads, occupied residences, and non-participating properties be written into zoning codes. It is imperative that these are carefully evaluated using the new blade lengths to ensure compliance, or to identify areas that are not in compliance and might require waivers or no-objection letters from landowners.

Noise and shadow studies

While new turbine technologies are often quieter, the longer blades tend to change assumptions regarding how blade shadows are cast on the landscape, particularly in relation to occupied homes and buildings. Noise and shadow studies should be repeated using the proposed component characteristics to ensure the repowered turbines are within acceptable shadow hours and noise levels as determined by local or state requirements. Increased blade lengths may also affect previously issued FAA permits and assumptions surrounding telecommunications avoidance.

Construction permits

Dismantling old components and installing new equipment requires use of large construction cranes. While environmental impacts from these cranes are usually temporary, consideration should be given to permits or approvals that might be required. 

For instance, crossing jurisdictional watercourses will likely require a permit from the U.S. Army Corps of Engineers, and installing temporary culverts in floodplains may require a permit from local authorities. Other considerations include the potential for disturbing sensitive plant communities, wetlands, threatened and/or endangered species and cultural resources. These issues should be thoroughly vetted within the proposed crane path corridors prior to construction.

Road Use Agreements

Finally, local authorities will likely require the execution of a Road Use Agreement to cover potential damages and repairs to local roadways. RUAs generally require evaluation of delivery routes, pre-construction road condition surveys, and financial sureties. Local roadway access permits will also likely be required.  

Westwood's multi-disciplined approach makes us uniquely positioned to address the myriad of permitting challenges facing owners wishing to repower their wind projects. Westwood’s team of professionals can evaluate your repower project and facilitate acquiring the permits and approvals necessary to keep your project moving forward. Having assisted clients on over 600 US wind projects in 40 states since 1997, there is a good chance we were involved with the original design of a project that has reached its repower stage!

Contact the Westwood team to learn more about your potential repowering needs.

Keep Reading