On August 8th, Tropical Storm Iselle struck Hawaii. As the storm made its way across the Big Island, wind speeds dropped to about 50 miles per hour. Julio, a second tropical cyclone that was forecasted to hit Hawaii, eventually diverted and posed no threat to the islands. As expected, Hawaii’s wind farms were able to withstand the storm’s strengths. Wind farm operators prepared for the storm and experienced only minimal downtime. While the island had prepared for Iselle as a hurricane, the storm struck the island as a tropical storm with wind speeds less than 73 miles per hour.
Crystal Kua, Director of External Affairs in Hawai’i for FirstWind, noted:
“Our wind turbines are located in areas that were not significantly impacted by either storm. We made the necessary preparations in anticipation of hurricane force winds and the turbines performed well with no problems under the minimal storm conditions that did come our way.” FirstWind has developed, owns or operates approximately 150 megawatts of wind energy capacity in Hawaii.
Kevin Gillespie, Director of Plant Operations at Sempra, noted that their wind farm, Auwahi Wind, did lose its grid connection. In 2011, a similar situation occurred after Hurricane Irene struck the east coast of the United States and caused widespread grid outages. When a local grid failure occurs, wind turbines automatically shut off to protect the turbines and transmission technicians. After the grid is restored, wind turbines can be turned back on.
As chronicled previously on this blog, wind turbines are designed to withstand extreme weather. The risks of a catastrophic weather event are fairly well known and can be planned for, to an extent. Wind turbines are generally expected to survive up to a Category 3 hurricane. Wind turbines are designed to have a lifespan of 20-25 years (although some wind turbines constructed in the 1980s are still in operation today). Wind farm developers and insurance issuers take into consideration the statistical likely risk of a loss associated with a hurricane over the wind farm’s lifetime. Similar to homeowners insurance, if the risk of destruction by hurricane or some other natural disaster is high, insurance premiums increase. For a wind farm, if total costs (including insurance costs) are uneconomic, then it is likely that wind farm will not be constructed. Since 1950, no hurricane (a tropical cyclone with wind speeds of over 74 miles per hour) has struck Hawaii, suggesting hurricane insurance costs are a minor contributor to overall wind farm costs in Hawaii.
Iselle (2014) now joins the ranks of Irene (2011) and Sandy (2012) as case studies showing that wind turbines can withstand tropical storms and hurricanes. It’s been a while since the United States has been hit by a Category 3 hurricane, or higher. Let’s hope that trend continues.