With current technology, offshore wind turbines can range from 12 MW to 14 MW. GE Renewable Energy is developing a 14 MW turbine with a 220-meter rotor, 107-meter blade, and 260 meters high.
A wind turbine functions like a very slow-motion fan, but in reverse. Instead of applying electricity to turn the blades and produce wind, a turbine uses wind to turn the blades, which are connected to a generator in the nacelle.The generator converts the mechanical rotation into electrical energy, which is then fed into the grid.
All wind turbines operate in the same basic manner. As the wind blows, it flows over the airfoil-shaped blades of wind turbines, causing the turbine blades to spin. The blades are connected to a drive shaft that turns an electric generator to produce electricity. The newest wind turbines are technologically advanced and include engineering and mechanical innovations to help maximize efficiency and increase the production of electricity. For more information about wind turbine technology, see NREL’s “Wind Energy Basics: How Wind Turbines Work“.
According to the National Renewable Energy Laboratory’s Annual Technology Baseline, a commonly-used tool in the power generation sector to forecast electricity prices across technologies, the cost of offshore wind is anticipated to be competitive with gas generation by 2030 – the year by which North Carolina has committed to generating 2.8-gigawatts of offshore wind through Governor Cooper’s Executive Order 218.
Depending on the wind speed, offshore turbine blades will turn one revolution about every 4 to 8 seconds, or a rate of about 8 to 16 RPM.
The Energy Policy Act of 2005 (EPAct) authorized the Bureau of Ocean Energy Management (BOEM) to issue leases, easements and rights of way to allow for renewable energy development on the Outer Continental Shelf (OCS).
BOEM’s renewable energy program occurs in four distinct phases: planning, leasing, site assessment, and construction and operations. BOEM engages key stakeholders throughout this process, as early communication with interested and potentially affected parties is critical to managing potential conflicts.
When turbines are taken out of service, they are processed through one of three ways–repurposing, recycling, or disposal. This largely depends on the materials the component is made of but can also be affected by local and state regulations, market demand, costs, and the availability of recycling infrastructure.
Between 85%-95% of wind turbine components are able to be recycled, with the composite blades being the hardest component to recycle. Offshore wind developers, turbine component manufacturers, and the federal government are contributing to research to eliminate waste and create a “circular economy” for the industry.
In the U.S., much progress is being made in the recycling of blades at scale in order to process a sudden influx of old blades that were replaced by newer models or during decommissioning.
Projects will be decommissioned and wind turbines will be responsibly removed once an installed project reaches the end of its useful life. The permits required to build offshore wind projects establish a plan and funding mechanism for decommissioning.
A typical wind turbine will repay its carbon footprint in less than six months , and it will generate emission-free electricity for the remainder of its 20 to 30-year lifespan.
Both onshore and offshore turbines have built-in mechanisms to lock or feather the blades (reduce the surface area that is pointing into the wind) when wind speeds are excessive. These mechanisms have proven successful in the U.S.’s first offshore wind farm in Block Island, RI.
The US Coast Guard has publicly stated that they have no intention of limiting navigational and fishing access to the foundations of turbines in State or Federal waters.
BOEM provides several public comment periods for the public to provide input during the regulatory process. So far, offshore wind has received positive feedback from fishermen in the North East because turbines create artificial reef structures that enhance biodiversity of fish and filter feeders, enhancing the recreational and commercial fishing industries.
A seven-year-long study, the first of its kind in the United States, titled, “Demersal fish and invertebrate catches relative to construction and operation of North America’s first offshore wind farm,” was published in the ICES Journal of Marine Science on March 29, 2022. The researchers found that there was no significant negative effect on fish that live near the bottom of the sea – demersal fish – and invertebrate populations during Block Island’s construction and operation.
11 states along the east coast (Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, Delaware, Maryland, Virginia, and North Carolina) have joined the Fisheries Mitigation Project. This project serves as a common framework across east coast states to anticipate and avoid impacts on fisheries and provide financial compensation for any acquired economic impact related to offshore wind development.
Offshore wind activity presents a low risk to marine mammals, including whales. Best management practices to reduce ship strikes, noise pollution, and species specific impacts during construction, operation and maintenance, and decommissioning of wind energy areas are part of a dynamic research and monitoring process that developers must follow.
The military has a well-established and rigorous process for ensuring that wind development occurs in a manner that is compatible with military operations. The Department of Defense (DoD) Siting Clearinghouse examines and analyzes each proposed wind farm, and includes participation from all five military branches.
Federal law allows DoD to raise concerns if a proposed energy project, individually or on a cumulative basis, may adversely impact military readiness or operations.
Researchers who analyzed AirBnB rental data before and after construction of the Block Island Wind Farm have found that, contrary to some concerns, the turbines have been linked with increased tourism on the island.
“During July and August following construction of the turbines, AirBnB rentals in Block Island experienced, on average, a 19 percent increase in occupancy rates and a $3490 increase in monthly revenue compared to those in Narragansett, Westerly and Nantucket.” Learn more here.
In the case of wind power, most carbon emissions are nearly all front-loaded. That contrasts with fossil-fueled electric power plants, where emissions occur continuously as coal and natural gas are combusted
Wind power has a carbon footprint 99% less than coal-fired power plants, 98% less than natural gas, and a surprise 75% less than solar.
Additionally, wind turbines average just 11 grams of CO2 emission per kilowatthour of electricity generated. That compares with 44 g/kwh for solar, 450 g for natural gas, and a whopping 1,000 g for coal. Read more.