Siting Issues
Where are the best wind energy resources in New England?
New England has a number of sites with wind speeds strong enough to generate electricity at a commercial scale. Most of these locations are on mountain ridges, along shorelines, and off shore. Because most of the region is densely developed and many of these areas are valued for competing uses, much of the potentially usable wind resources in New England is unlikely to be developed.
Commercial wind power projects using large turbines generally require mean wind speeds of at least 7 meters/second. Click here1 to see a wind map of New England prepared by AWS Truewind (a private contractor) for MTC, the Connecticut Clean Energy Fund, and Northeast Utilities. When you select a state on the New England Wind Map you will see a pull-down menu at the top of the screen to choose a height for wind speed information. Wind speeds at a height of 70 meters are applicable for siting large-scale turbines.
All of the commercial wind energy projects currently operating, permitted, or under construction in New England are located on land. Operating projects range in size from less than 1 megawatt to 42 megawatts. Click here2 for a map showing these facilities.
Where are the best offshore wind resources in New England?
Wind is an economically and technically viable resource for power generation along New England’s coast and offshore. Commercial wind power projects using large turbines generally require mean wind speeds of at least 7 meters/second. Click here3 to see a wind map of New England prepared by AWS Truewind (a private contractor) for MTC, the Connecticut Clean Energy Fund, and Northeast Utilities. When you select a state on the New England Wind Map you will see a pull-down menu at the top of the screen to choose a height for wind speed information. Wind speeds at a height of 70 meters are applicable for siting large-scale turbines.
To be suitable for commercial-scale development, offshore wind areas also need to be in areas where turbines can be installed and maintained safely, and should be located near load centers and regional transmission lines. Click here4 to see enhanced wind maps of Massachusetts and New England that show water depths and the proximity of onshore electric transmission lines. As these maps show, many coastal New England areas with strong winds are in ocean waters more than 50 feet deep. Current offshore wind turbine towers are not typically able to withstand wave stresses in waters deeper than approximately 50 to 60 feet. Coastal New England areas with significant wind resources and water depths of 50 feet or less are generally 1-2 miles from shore, with larger areas in Nantucket Sound, Buzzards Bay, and near the southern coasts of Nantucket and Martha’s Vineyard.
Could a wind farm comparable in size to Cape Wind be built elsewhere in New England, either on land or offshore?
No land-based sites in New England offer conditions as good as the proposed Cape Wind site (including high-class wind energy resources, sufficient surplus electric transmission capacity, and enough open space to build a wind farm of this size). In its 2004 draft EIS, the Army Corps of Engineers evaluated eight land-based sites in Massachusetts, Connecticut, Vermont, and Maine, and nine offshore sites in Rhode Island, Massachusetts, and Maine as potential alternative locations for a wind farm with a capacity of 200-1,500 megawatts. The only large land site with adequate wind resources and transmission was the Massachusetts Military Reservation/Otis Airforce Base, which is an active-duty military facility. Table 3-4 of the U.S. Army Corps of Engineers' Draft Environmental Statement (ACE DEIS)5 summarizes these land alternatives.
The Corps also evaluated alternate offshore sites for a wind farm comparable to Cape Wind, but at most of those locations water depths or wave heights were too large to make a project using current turbines feasible. Current technology for offshore wind turbines is designed to operate in shallow waters (mean low water depths less than 50 feet and extreme storm wave (ESW) heights less than 20 feet. Nearly all of the alternative offshore sites evaluated had water depths greater than 50 feet and/or ESW heights over 20 feet. Many also had other constraints, such as locations within important navigation areas or in areas with inadequate transmission capacity. Table 3-5 of the ACE DEIS6 compares these offshore alternatives, and Section 3.47 contains the Corps’ review of these alternative land and offshore sites.
The Corps conducted a more detailed analysis of four sites that came close to meeting the screening criteria, one onshore (Massachusetts Military Reservation) and three offshore in Massachusetts state waters. Each of these options had the potential for significant impacts on marine and avian species or involved technical challenges such as placing turbines in waters more than 100 feet deep. Section 3.4.3 of the ACE DEIS contains the Corps’ detailed discussion of these sites, and Table 3.57 compares the alternatives.8
Will offshore wind projects in shallow waters advance work on siting wind farms in deep waters?
According to the National Renewable Energy Laboratory, maximizing the benefits from offshore wind energy in the United States will eventually require developing wind farms in waters up to several thousand feet deep. Technologies for wind energy generation at these depths are probably a decade or more from commercialization. Constructing wind farms in shallow waters will provide insights into many technical, environmental, and regulatory issues that are also applicable to deepwater wind generation, in the same way that offshore oil and gas drilling in shallow waters fostered the development of technologies for drilling in thousands of feet of water today. This can help New England develop the infrastructure and capabilities for subsequent deepwater projects.
The Northeast coast (New England and the mid-Atlantic states) is an attractive region for developing offshore wind energy in shallow waters because slightly more than half of the nation’s identified offshore wind energy potential lies here, and water depths increase gradually with distance from shore. In other areas such as the U.S. West Coast, water depths increase sharply close to shore, so there is not the same potential to move from wind farms in shallow waters to deeper waters in the same region. MTC’s Framework for Offshore Wind Energy Development in the United States contains more information about U.S. offshore wind energy resources,9 as does a more detailed paper on offshore wind energy published by the National Renewable Energy Laboratory in 2006.10
1http://truewind.teamcamelot.com/ne/
2http://www.eere.energy.gov/windandhydro/windpoweringamerica/ne_projects.asp
3http://truewind.teamcamelot.com/ne/
4http://www.masstech.org/renewableenergy/Community_Wind/wind_maps.htm
5http://www.nae.usace.army.mil/projects/ma/ccwf/deis.htm, table 3-4
6http://www.nae.usace.army.mil/projects/ma/ccwf/deis.htm, table 3-5
7http://www.nae.usace.army.mil/projects/ma/ccwf/deis.htm, Section 3.4
8http://www.nae.usace.army.mil/projects/ma/ccwf/deis.htm, Section 3.4.3 and table 3.57