The first offshore wind farm in the US will become operational by the end of 2016

The project is called Block Island Wind Farm and will supply electric power to 17,000 households

The project is called Block Island Wind Farm and will supply electric power to 17,000 households

There are approximately 2,500 wind turbines spinning in the ocean off the coast of Europe today, but none yet in the United States. This is going to change soon, as the construction of the Block Island Wind Farm, roughly 6 km (4 miles) off the coast of Block Island, in Rhode Island, has entered its final stage. Installation of the five 6MW-turbine towers, blades and nacelles was scheduled to begin in early August and according to the (project’s) developer Deepwater Wind, it remains on-schedule to be fully constructed this summer and commissioned this fall. Commissioning will be undertaken by GE (General Electric Renewable Energy), Deepwater Wind’s partner in this project. The wind farm has an expected total capacity of 30 MW and will produce 125 GWh of electricity per year, enough to cover the needs of 17,000 households. 'It’s go time,' said Deepwater Wind CEO Jeffrey Grybowski. 'We’re ready to bring this historic project across the finish line. This is sure to be a momentous summer – not just for this project, but also for the start of a new American industry.' 

Operational Challenges

Although close to completion, the project’s designing and building had to overcome great difficulties, such as the prospects of hurricanes and tropical storms, freezing winters and corrosive salty winds. The wind turbines have blades more than 75 m (250 ft) long, meaning that the tips will be more than 150 m (500 ft) apart. ‘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. That means wind conditions above may not be the same as below (sometimes, the winds can be steadily 10 miles per hour faster at the top than at the bottom). For these times, the wind turbine is set to lock the blade’s rotors so that they do not spin too fast or chaotically. ‘If we reach some level of wind which is not acceptable, then we stop the machine and it is put in standby’, says GE Renewable Energy project director Eric Crucerey. This is also the setup for when temperatures dip below -10°C (14°F). But even when in hibernation, the turbines could get knocked down by the winds, mainly due to the large surface area of each of their blades. To address that, a narrow foundation of 60 m (200 feet) below each turbine has been dug and each is anchored directly to the seabed. Also, according to Crucerey, the insides of the turbines are pressurized, forcing out any bits of wind or salt that might try to break the wind farm up from within.

More off-shore in the US

The Department of Energy (DOE) estimates that about 80 % of the country’s power demand comes from coastal states, and since 2012 it encourages and financially supports offshore wind energy projects so that coastal city-dwellers get their power from closer to home.

Apart from Block Island, Deepwater Wind has proposed to construct another, larger offshore wind plant in the US, again in the East Coast, called Deepwater One South Fork. Its 15 turbines will be able to generate 90 MW of power to be delivered directly to East Hampton. At the end of last year, the American Wind Energy Association (AWEA) had identified 11 offshore wind energy projects under active development. The U.S. DOE says there are more than 20 projects in various stages of development with a potential of about 15 GW, based on current leases. Most of them are located on the East Coast, especially in New England, but there is also a project under development in the West, where the company Trident Winds has just started working on a floating wind farm off the coast of California. However, even if all the current projects move forward given the cost and regulatory barriers, the U.S. will continue to be a laggard in offshore wind, taking into account that the global cumulative offshore wind capacity reached 12,000 MW in 2015.

Source: Global Wind Energy Council

The U.S. DOE estimates there are more than 20 projects in various stages of development with a potential of about 15 GW, based on current leases.

By 2020, the U.S. Department of Energy expects about 10% of U.S. electricity demand will be served by wind, but only a sliver of that will be offshore.