Great question! One of the most important challenges of bringing offshore wind power to land is the cable installation near land and routing of the cable to a station, where it supplies synchronized power directly to the grid. In addition to avoiding critical benthic habitats in the water, the path must avoid sea turtle nesting grounds and seabird habitats which are both close to shore. The installation can also be timed so as not to interfere with the seasonal migration and nesting of these animals. Directional drilling techniques that allow the cable to be routed completely underground can provide some flexibility with regard to the station placement, although cost then becomes an important consideration since it is a more expensive technique and the cable itself is expensive.
During operation, electrical cables produce heat that is a concern for sea turtles since nest temperature is critical for their embryonic development. Proper cable burial depth (normally 1-2 m ¹) and placement can guarantee the temperature change is insignificant at the surface and far from nesting sites. Artificial lighting is also a concern for turtle hatchlings because it has been shown to affect their sense of direction ². Therefore lighting at the power station should be minimized and designed to avoid shining light near sea turtle nesting sites.

¹ Sharples, M., 2011. Offshore Electrical Cable Burial for Wind Farms: State of The Art, Standards and Guidance & Acceptable Burial Depths, Separation Distances and Sand Wave Effect. Bureau of Ocean Energy Management, Regulation & Enforcement-Department of the Interior; Washington, DC.
² Salmon, M. (2003). “Artificial night lighting and sea turtles.” Biologist 50(4).

Thank you very much for taking the time to watch our video and for your questions. We are advocating for a tiered approach to the environmental assessment that will allow us to assess the direct (e.g., mortality from collision) and indirect (e.g., displacement from habitat degradation) risk of offshore wind energy developments to marine ecosystems and to wildlife utilizing the aerosphere (i.e., birds and bats). During the first tier, we will use statistically-robust at-sea and aerial surveys to determine the presence of marine organisms within the development area and surrounding marine habitat as well as a selected control habitat areas that displays similar biophysical characteristics (e.g., water depth). In addition to recording presence of avian species and marine mammals, a camera system would also be deployed at stations along transects to characterize the marine habitat. In the second tier of our assessment, we would use these data as well as other existing work and expert opinion to identify those species that may be most vulnerable to offshore wind energy development.

After identifying these species of concern, we will complete more focused studies that will help us determine if and how these species are affected by the offshore wind energy development. Tier three studies would include completing statistical analyses of post-construction aerial and at-sea survey data to evaluate shifts in the distribution of marine organisms and habitats. In addition to this survey work, we would deploy location tags on marine birds and mammals to determine fine-scale movement within and around the offshore development area. We would also complete studies at breeding bird colonies that would allow us to put these at-sea data within the overall context of breeding bird reproductive biology. Specifically, such integrated work would allow us to assess if marine birds are having to exert additional energy to forage (as indicated by location tag tracks) in response to the offshore wind energy project, and if such additional energy expenditures in turn cause declines in reproductive biology parameters (e.g., adult and chick body condition, productivity success). Overall, we feel strongly that this three-tiered approach will allow us to efficiently assess and identify potential adverse effects and then eventually develop a management plan to avoid, minimize, and mitigate the potential adverse effects of offshore wind energy development on marine ecosystems.

Thank you, William.
Catherine

Thanks for the questions! Within this tropical marine ecosystem, two primary marine habitats of concern are seagrass beds and coral reefs. Offshore wind energy development, and specifically the construction process, has the potential to disturb these sensitive habitats that support marine fish, birds, mammals, and benthic species. To measure these potential effects, we will use multiple methods. First, we will use existing state and federal marine habitat distribution data to assess general habitat distributions and use focused video and still-camera surveys to characterize and map marine habitat composition in areas of potential impacts. This pre-construction work will be used to site wind turbines, cable paths and landfall sites and avoid potential detrimental effects on seagrass and corals, as well as critical terrestrial habitats. Second, we will analyze pre- and post-construction video and still-camera surveys to evaluate any changes in benthic habitat composition as measured by percent cover of dominant taxa groups (e.g., coral, seagrass, sand). These video and still-camera methods, which both use a defined quadrat grid, facilitate quantifying such changes because they are able to consistently and accurately measure key parameters such as percent cover of major taxa groups or density of key benthic species.

Regarding the costs of foundations for offshore wind turbines, they depend mostly on water depth. The benthic habitat of the area between Puerto Rico and Culebra is diverse, but much of the proposed wind farm area falls into an ideal range that is too deep for coral and seagrass to grow (since they depend on photosynthesis for energy), but still shallow enough for a normally priced offshore wind farm. The distance to shore for this case study is less than 12 miles, and so it is a typical distance for an offshore wind farm (see for example Windpark Egmond aan Zee or Nysted Wind Farm). “Micrositing”, that is, determining the specific location of each turbine within the farm, becomes very important here, because there are a number of “patch reefs” in the area that need to be avoided. One big question that has not been answered is how large an area is needed around the turbines to limit the effect on nearby coral, as small changes in turbidity and insolation on the surface of the water can have impacts. Further studies may be needed to quantify these effects.

In general terms, the desire to move offshore is driven both by land resource issues and the higher speed and smoother wind that occurs offshore ¹. The resources offshore normally result in a higher capacity factor for wind farm installations, meaning they can produce and sell more energy than their equivalent onshore counterparts. This trade-off between distance offshore and energy production must be balanced to determine an acceptable cost for the project that can produce energy for a community at a good rate. Puerto Rico and other islands are specially positioned to benefit from offshore wind despite its cost relative to onshore wind because of the high costs they already pay for fossil fuel energy.

¹ Musial, W., Ram, B. Large-scale Offshore Wind Power in the United States: Executive Summary. NREL/TP-500-49229

Thank you for your question. While on Culebra this past March we conducted a preliminary survey of island residents and tourists (n=62). While the survey group was small, and recruitment was random, we did gather a wide range of informative responses to our six open-ended questions from a diverse mix of respondents. From these surveys, we carried out some initial statistical analysis of public attitudes about renewable energy on Culebra. We found strong concern for environmental conservation and general openness to renewable energy development among Culebra residents, though they were suspicious of wind power, in particular, largely due to a recent proposal by an outside developer to construct turbines above a popular beach (which is the economic lifeblood of the island). This plan, understandably, generated a massive public outcry and created suspicion about the intentions of developers.

We would like to follow up on this initial survey with a more thorough and scientific survey of public attitudes toward wind power both on Culebra and the eastern coast of the main island. We would develop a more sophisticated survey instrument and recruitment techniques. The end goal would be not only to paint a picture of attitudes in Puerto Rico, but to also compare those attitudes with similar surveys that have been conducted in the northeastern U.S.

I hope that you get a chance to do a more scientific survey. As you point out, wind power is very controversial in Culebra and generally in Puerto Rico. Everybody wants renewable energy, as long as it is NIMBY.

Thanks Alan! We agree that stakeholder engagement is a critical component of these projects. The Caribbean region is home to a widely diverse set of stakeholders with sensitive socio-economic characteristics. Some of the challenges include defining and identifying who the key stakeholders are for particular projects and how to manage a dialogue with different stakeholder groups that often have competing interests and differing views. The findings of our research suggest that deliberate and ongoing stakeholder engagement throughout project development is essential in mitigating conflicts, such as those between competing marine resource users. The process should be built upon trust using facilitators perceived to be neutral and allow for stakeholders to define the process, goals, and concerns, while ensuring stakeholders have the power to actually influence decisions ¹. Maintaining transparency by providing scientific studies to stakeholders is also a key factor. These are highlighted in a set of best practices we currently developing in more detail.

Specific to the Puerto Rico project, we have met with a variety of different stakeholders that include developers, environmental regulators, economic development officials, and local residents at various levels. We hope to build on our existing relationships in Puerto Rico, and develop connections with other important stakeholders, such as the state power authority and citizens’ conservation groups as the project moves forward.

¹ Rhode Island Ocean Special Area Management Plan. 2010. Rhode Island Coastal Resources Management Council, Volume 1.

Gracias María!

Hi Bryan,
Very good question. Hurricanes are a topic of much research in the wind engineering community. During hurricane force winds, the wind turbine would stop spinning, and turn the blades to produce the least amount of force on the structure. However, in very strong hurricanes, there may still be enough forces from the wind and waves to cause damage to the blades and tower. Engineers at UMass and other research universities are trying to create models to predict and prevent this damage, but there is still quite a bit of work needed in this area, and the lack of real life data is a big problem for this research. Hopefully we will have a better answer than that in a few years!

What will be the expected maximum wind speed that it will resist? Very strong hurricanes dont happen that often, if it can resist at least a category 2 hurricane this project will be bigger that it already looks!!

Hi Bryan,

For more information on the current design standards for offshore wind turbines, including the loading cases, I would refer you to the IEC 61400-3 standard, and in addition this presentation by our professor Dr. Manwell: http://windenergyigert.umass.edu/seminar/intern...

Wind turbines are normally designed for 20 years and so the likeliness of a hurricane coupled with the probability of wind and wave occurence and location with respect to the wind farm require more information and research than we (or the standards) can present at this point.

thank you!