At the end of 2018, the US had only 30 megawatts of wind-power capacity offshore. But projects in various stages of development totaled an estimated 23,735 megawatts. Offshore wind could, therefore, grow by 79,016% by 2030.

Offshore wind has the capacity to be the most efficient power source of anything but nuclear power. And whatever technical hurdles remain, they don’t compare to the problem of dealing with nuclear waste. The Vineyard Windfarm project will come online at about the same time yet another nuclear power plant shuts down.

It takes years for stars in entertainment to become an “overnight success.” Offshore wind has languished behind other kinds of renewable energy for a long time. Will it soon become an overnight success?

The wind along coastal waters in the US can potentially generate 7,200 terawatt-hours of electricity every year. One terawatt-hour is one trillion watts per hour. Now, one watt of power isn’t much. Your electric bill is measured in kilowatt hours, or 1,000 watts per hour. The “kilo” prefix means 10³; tera means 10¹².

So 7,200 terawatt-hours is an unimaginably vast amount of energy. Converting only one percent of it to electricity would power nearly 6.5 million homes. Converting all of it would almost double our current annual consumption of electricity.

The US has abundant offshore wind resources. Development of offshore wind power offers many environmental and economic advantages. It will increase the diversity of energy sources and decrease greenhouse gas emissions from energy generation.

Obstacles to the development of offshore wind farms

The eyesore factor

A negative visual impact has been a major drawback, however. The wind industry depends on horizontal axis wind turbines (HAWTs). The taller the turbine, the more efficiently it works. So they have grown taller than skyscrapers.

Ugly wind turbines can destroy the natural beauty of our coastlands. Why lower property values and destroy the tourism industry to generate electricity?

In the early 21^stcentury, Senator Edward Kennedy and the Koch brothers agreed about one thing. They opposed the Cape Wind wind farm proposed to be built in Nantucket Sound. After sixteen years of litigation, the developers abandoned the project. All the required turbines would have been overwhelmingly visible not only from the Kennedys’ and Kochs’ homes but from any of the popular tourist destinations that encircled the sound.

At the time, wind turbine technology could only work in shallow waters close to shore. Available undersea cables weren’t long enough to reach the shore from deeper in the ocean. That hardly mattered. No one knew how to build deep-water turbines, or at least, not economically.

Fortunately, technology now allows offshore wind farms to be built three miles or more out to sea. Past that distance, the curvature of the earth makes anything at sea level invisible. Of course, people can still see HAWTs that rise several hundred feet above the ocean’s surface. Each mile of distance lessens their visibility.

In recent years, big oil has become heavily involved in offshore wind power. It has long experience with floating platforms for its drilling rigs. That expertise provides obvious advantages for offshore wind farms. Without the need to anchor turbine masts to the ground, wind farms can be built farther out to sea.

Hurricanes

We all know the devastation hurricanes can cause when they make landfall. Onshore wind farms hardly noticed Hurricane Harvey in 2017. But how will offshore windfarms fare?

The larger the turbine, the more it can withstand strong winds. According to today’s standards, an offshore wind turbine must be able to withstand a 155-mph gust of wind for three seconds.

Current turbine design calls for them to survive category 2 hurricanes. Hardly anything can withstand a category 5 hurricane, although most oil rigs in the Gulf of Mexico survived Hurricane Katrina.

A hurricane’s worst winds occur near the eye. The chances of truly catastrophic winds hitting any given turbine are small enough that it makes no sense to design for protection against them.

Large enough offshore wind farms could even potentially lessen the impact of hurricanes once they reach the shore. It would rain harder nearest the turbines. The winds passing over the turbines would decrease, much as they decrease after landfall. Therefore, the storm would inflict less wind and rain upon landfall that it would without the windfarms.

The development of offshore wind farms in the US

The first offshore wind farm in America, Deepwater Wind, went live late in 2016. It has five turbines and replaces the diesel generators that used to provide electricity for resorts on Block Island, Rhode Island.

A larger project called Vineyard Wind is scheduled to begin operation in 2022. It will have 84 turbines 14 miles south of Martha’s Vineyard.

Maryland’s Public Service Commission has recently approved a wind farm to be built no less than 17 miles from Ocean City.

Right now, fifteen leases have been approved for development on the East Coast, with more proposed both on the East Coast, West Coast, and Hawaii. The southern-most existing offshore wind lease is located off Kitty Hawk on North Carolina’s Outer Banks. Developers are exploring the possibility of leases farther south.

Vineyard Winds will use turbines that rise almost 650 feet above sea level. That’s just a little taller than the General Electric Building in New York, which has  50 floors.

Those 9.5-megawatt turbines will have a rotor with a diameter of 174 meters. That’s big. But last year General Electric announced plans to build a 12-megawatt turbine with a 220-meter rotor.

These truly gigantic rotors perform better in the strong and steady winds that exist offshore than earlier, smaller ones. Their bearings and gearboxes last longer. Fixing a broken off-shore turbine is very expensive. These behemoths will break down less frequently.

Some challenges still remain. Finding places to bring those long cables onshore can be tricky. The “not in my backyard” syndrome works against more than landfills! The fishing industry fears being shut out from traditional fishing grounds. Some environmentalists worry about the effect of the sound of building the platforms on whales and dolphins.

But being able to build mammoth wind turbines in the ocean and out of sight seems like a greater challenge than those.

Sources:

5 stats about offshore wind power that will blow you away / Maxx Chatsko, Motley Fool. September 4, 2018
Hurricanes no deterrent for Avangrid, offshore wind industry / Business Network for Offshore Wind. September 24, 2018
Offshore wind farms are spinning up in the US—at last / Eric Niler, Wired. April 14, 2019
What to know about the visual impact of offshore windfarms / Paul Dvorak, Windpower Engineering. June 14, 2018

Photo credits:
Block Island windfarm. Both are US Department of Energy photos, public domain
Great Yarmouth-angler and offshore wind farm. © Copyright Chris Downer and licensed for reuse under this Creative Commons Licence
Floating offshore wind turbine. Public domain from Wikimedia Commons
Middelgrunden. Public domain from Wikimedia Commons