Building in Rhode Island isn’t easy. Hurricanes and tropical storms barrel through its quaint coastline towns, interrupting perfect summer weekends. Freezing winters bring blizzards that can shut down the entire state. And every season features corrosive salty winds, biting at the coast as if sent by a Britain still seething at the first American colony to declare independence.
But one company sees the state’s incessant wind as a utility. Deepwater Wind has partnered with General Electric Renewable Energy to build the first offshore wind farm in the United States, off the coast of Block Island. Hooked up to the grid by the end of 2016, the system could supply 90 percent of the tourist destination's power within the next few years. But it hasn’t been easy. Designing and building spinning fans hundreds of feet tall that stay sutured to the ocean floor in the face of currents and wicked winds has taken almost three years of work.
The blades on Deepwater Wind’s turbines, which have been arriving at Block Island over the last month, will be almost 250 feet long. That means the top and the bottom of the rotors will be separated by 500 feet or more. Anything covering that much area will have to deal with widely variable wind conditions, says Cristina Archer, a professor at the University of Delaware who studies offshore wind farms. Sometimes the wind will be the same speed across the whole turbine, but that speed will change dramatically over the course of the day. Other times, the winds can be steadily 10 miles per hour faster at the top than at the bottom.1
To help protect the turbines’ machinery and electronics, engineers can lock their rotors to keep them from spinning too fast or chaotically. “If we reach some level of wind which is not acceptable,” says GE Renewable Energy project director Eric Crucerey, “then we stop the machine and the machine is put in standby.” The same happens if it gets too cold, he says. The turbines can keep working down to 14 degrees Fahrenheit; below that, they’ll go into hibernation.
But stopping the rotors doesn’t stop the wind. The surface area of each blade is about the same as a football field, so there’s a lot of air hitting the turbine and trying to topple it. To stay steady, turbines are anchored to the seafloor and to a narrow foundation dug 200 feet underground. That anchoring, with help from very strong building materials with a corrosion-resistant coating, make the turbines stable enough to hold their own against wind and storms. Crucerey says that the insides of the turbines are also pressurized, forcing out any bits of wind or salt that might try to break the wind farm up from within.
After they’re done at Block Island, Deepwater Wind will push even farther out to sea with a larger wind farm called Deepwater ONE, which will provide 30 times the power of the Block Island Wind Farm (assuming they both go online without a hitch). It's not the only company trying to build wind farms off American shores, either. The Department of Energy estimates that about 80 percent of the country’s power demand comes from coastal states, and it’s pledged up to $40 million to help coastal city-dwellers get their power from closer to home.
And there are plenty of available locations. “The East Coast is actually pretty much all amazing” for offshore wind farms, says Archer---especially in New England, where projects in New Jersey and Virginia are currently in development.
The West is also no sleeper. One of the projects funded by the Department of Energy is a floating wind farm company in Oregon, and a different company called Trident Winds has just started working on a wind farm off the coast of California’s Morro Bay. It’s projected to supply about 20 times the power of the Block Island Wind Farm.
There’s no one-size-fits-all solution to replacing fossil fuels with renewable energy. But the coming generation of offshore wind farms are positioned to play a large role in the power used in coastal regions around the United States. In 1775, Rhode Island led the charge to independence. In 2016, it’s leading the way to independence from fossil fuels.
1UPDATE 1:15 pm EST 7/28/16: This post has been corrected to state the accurate difference in wind speed between the top and bottom of a turbine.
