This blog was written by Simon Mahan, former Energy Policy Manager at the Southern Alliance for Clean Energy.Guest Blog | August 25, 2017
Hurricane Harvey is projected to become the first Category 3 hurricane to hit the U.S. since 2005. That year, it was Hurricanes Dennis, Katrina, and Rita that wreaked havoc across the Gulf Coast. In anticipation of Hurricane Harvey, oil platforms in the gulf are evacuating. The South Texas Nuclear Generating Station between Corpus Christi and Galveston, is preparing. Ports and some major power plants along the Texas coast are beginning to brace for Hurricane Harvey. All energy infrastructure along the path of Harvey will be affected, including wind farms.
Several large wind farms may be in the line of sight for Hurricane Harvey. Wind projects including Harbor Wind (9 megawatts, MW), Papalote Creek I (180 MW), and Papalote Creek II (200 MW), Baffin (188 MW), Penascal I (202 MW), Penascal II (201 MW), Pattern Gulf (283 MW), Magic Valley (203 MW), Los Vientos Wind 1A (200 MW) and 1B (202 MW) and Cameron 1 (165 MW) may see hurricane force winds.
To date, no wind farm in the United States has been destroyed by a hurricane. Neither Hurricane Iselle (Hawaii, 2014), Hurricane Sandy (New Jersey, 2012), nor Hurricane Irene (Delaware, 2011) harmed wind farms. Wind farms in hurricane-prone coastal zones are frequently designed to withstand hurricane-force winds, up to level Category 3 hurricanes. For self preservation purposes, wind turbines automatically shut down when wind speeds reach excessive levels. Hurricane Harvey is slated to become a Category 3 storm, and may test the limits of turbine engineering.
Wind turbines are designed specifically to harness the wind but they are also designed to withstand it. Modern wind turbines utilize several techniques to reduce the likelihood of harm. Active techniques require action by the turbine or operator to protect a turbine. These techniques are used to stop turbines and halt electric generation in extreme weather conditions and so technicians can perform regular maintenance. Passive techniques are built-in and require no additional activity to protect a turbine. The following list is a non-exhaustive list of active and passive techniques to reduce turbine damage:
- Turbine brakes – Most turbines are installed with turbine breaks that automatically engage if winds reach a certain speed – usually around 55 miles per hour. At the rated speed, the turbine brakes are applied and the rotor stops spinning.
- Blade feathering – Wind turbine blades can be tilted (feathered) remotely by an operator or automatically so instead of harnessing strong winds, wind is allowed to slip past the blades.
- Active yaw systems – Large turbines have active yaw systems that require a small motor that moves the nacelle (or gearbox, where the generator is housed) to point directly into the wind. By pointing directly into the wind, turbine aerodynamics allow wind to flow past the blades easily.
- Heavy monopole towers – Monopole towers can reach up to 100 meters in height and are meant to hold nacelles and blades that can weigh several tons. Thicker monopoles constructed with more steel and internal structures can support more weight and withstand stronger environmental forces.
- Strong foundations – For onshore wind turbines, most large scale turbines have a foundation pad constructed from concrete. These foundation pads are usually buried several feet deep to help anchor the turbine to the ground.
Having a wind farm situated near the coast does have its benefits. A natural phenomenon in the coastal zone called the “Sea Breeze Effect” ensures wind power production in the late summertime afternoons – when utility power demand tends to be very high. The Sea Breeze Effect is why beach-goers will frequently experience a rushing wind in late summertime afternoons.
Texas’ grid operator, the Electric Reliability Council of Texas (ERCOT) will forecast Harvey’s effects on wind farm power generation, and will do its best to manage the power system during this highly dangerous storm.
Stay tuned for a post-storm recap.
Stay safe, everyone.
Special thanks to Justin Sharp at Sharply Focused LLC for his contributions to this post.