Bigger wind turbines and towers are just part of what the United States needs to more effectively use wind energy in all 50 states.
That was the basic thrust of a future wind energy call to arms report called “Enabling Wind Power nationwide” issued this week by the Department of Energy which details new technology that can reach higher into the sky to capture more energy and more powerful turbines to generate more gigawatts.
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“Technological advancements, such as taller wind turbine towers of 110 and 140 meters and larger rotors—currently under development by the Energy Department and its private sector partners—can more efficiently capture the stronger and more consistent wind resources typically found at greater heights above ground level, compared with the average 80 meter wind turbine towers installed in 39 states today,” the DOE stated.
New technologies could also help use wind energy from US regions such as the Southeast which would represent an additional 700,000 square miles—or about one-fifth of the United States—bringing the total area of technical wind potential to 1.8 million square miles, the agency stated.
“As of 2015, installed wind power is a significant contributor to the nation’s electricity generation portfolio, with more than 65 gigawatts (GW) installed across 39 states supplying 4.9% of the nation’s electricity demand in 2014 . The technical potential for land-based wind energy for the contiguous United States is estimated to be 12,000 GW of generating capacity at 100-meter hub height -- assuming a net capacity factor of at least 26%; and the technical potential for offshore wind energy is estimated to be 4,150 GW, the DOE stated. These resources combined are greater than 10 times current total U.S. electricity consumption.
In the report detailing its plans, the DOE outlined key topics, including:
Towers: The United States has vast wind resources across all 50 states. Continued advancements in turbine technology–including those that enable higher hub heights, larger rotors, and improved energy capture --can access the stronger and more consistent wind resources typically found at greater heights above ground level. They also enable wind to be a true nationwide economic resource. Developed by the Energy Department and industry partners, these technological wonders stand 110 to 140 meters tall in “hub height” (calculated at the center of the rotor), up to 1 ½ times the height of the Statue of Liberty. The cost of wind turbine towers increases rapidly with increasing height, creating a trade-off between tower cost and the value of added energy production. Many taller tower concepts are either commercial products or have been demonstrated at full-scale, but are not yet widely deployed in the United States due to unfavorable economics, the DOE stated.
Turbines: Based on an advanced turbine concept and assuming hub heights of 110 meters (which are already in wide commercial deployment in Germany and other European countries), the technical potential for wind deployment is estimated to grow to 4.3 million square kilometers, a 54% increase compared to current technology with 80-m hub heights. By pursuing hub heights of 140 m, the technical potential for wind deployment is estimated to grow to 4.6 million square kilometers, a 67% increase compared to current technology with 80-m hub heights, the DOE stated.
Locations: Improvements in siting practices have contributed to the deployment of 65 GW) in cumulative installed wind capacity (as of 2014). Pursuing more moderate resource quality sites can and should be done in coordination with the broad stakeholder community for wind to coexist with the environment and federal and state agency missions, the DOE stated. Visual impact is an important issue to public acceptance and permitting of wind power development. Siting wind plants to minimize visual impacts to high-value scenic resources is a challenge for land management agencies across the United States.
Birds and bees: Anything that would increase the size and height of wind towers would likely have more of an impact on bats and birds. For example, the DOE said: “Dedicated research is needed to understand the biological and ecological factors related to potential interactions between Bald Eagles and wind, improve the ability of regulators and developers to predict risk to Bald Eagles at particular sites, and assess potential mitigation measures.”
Big trucks, little roads: Transporting long, wide wind turbine blades is difficult due to turns, narrow passages, and overhead obstructions on U.S. roads and railways, with the length of blade that can be transported over roadways generally limited to between 53m and 62 m. Transportation of large diameter tower sections encounters similar difficulties, with diameters limited to 4.3 m to 4.6 m, far below the optimum diameter for the taller towers discussed in this report. Tower concepts such as sectional-component-based assembly and in-field assembly, can reduce the transportation challenges for wind turbine rotor blades as well.
Big cranes: Hoisting wind turbine nacelles onto taller towers requires the largest crane capacity of all wind turbine components to install due to the lift height onto the tower and mass of the nacelle, and issues associated with transporting and hoisting heavier drivetrains onto taller towers is expected to become increasingly important as these systems grow in size. Dual crane lifts, commonly used in Europe, present one opportunity among many to address this issue, the DOE said.
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