Wind Energy

Wind is the world’s fastest growing source of energy. It is harnessed by tapping the kinetic energy of flowing air—wind—to create mechanical energy. Historically, this mechanical energy was used directly for grinding grain and other purposes; current technologies convert it into electricity for either on-site or off-site use.

Hundreds of windmills once dotted Cape & Islands landscapes. The mechanical energy supplied by the rotating paddles of these early machines pumped water, processed food, and powered saltworks and other early industries. Antique windmills and replicas may be seen today, evoking the region’s historical reliance on this abundant resource.

Wind energy’s current renaissance is fueled by modern turbines. These high-technology machines transform the mechanical energy of rotating blades into zero-emissions electricity. Many countries—particularly in Europe—are developing wind resources to meet growing demands for power while reducing reliance on fossil fuels and meeting commitments to reduce greenhouse gas and pollutant emissions. Wind generating capacity in the United States has substantially increased over the last few years, but it still supplies only a small fraction of the country's overall needs.

Cape Cod, Martha’s Vineyard, and Nantucket are blessed with onshore and offshore wind energy resources that are among the best in the continental United States. Numerous wind projects have been proposed or are being considered by homeowners, institutions, businesses, and municipalities. A few small-scale turbines are up and running, while the first large-scale, land-based unit was installed at Massachusetts Maritime Academy in spring 2006.

Click on the links below for more information on wind energy in the Cape & Islands region. Issues and activities specific to municipal wind projects are described on this website's Community Wind page.

Technology Overview
Benefits
Barriers & Issues
Applications & Sizing
Cost-Performance Characteristics & Siting Considerations
Resource Description
Local Projects
- Cape Cod
- Martha’s Vineyard
- Nantucket
- Offshore
Baseline Information Resources

Technology Overview
Wind energy is derived from the sun, which heats the Earth’s atmosphere and surface. Different air masses, land surfaces, and water bodies absorb and release this heat at varying rates. This creates circulation in the atmosphere. These natural movements of air include the jet stream at the continental scale and onshore and offshore breezes at the local scale.

Today’s wind turbines harness the kinetic energy of this flowing air and then transform mechanical energy into electricity—flowing electrons. Over the past 25 years, major advances in turbine technology have made this process ever more efficient, making wind energy a cost-competitive option for a growing number of applications.

Most modern turbines include four primary components: the rotor and nacelle are located atop the tower, while electronics are distributed throughout this highly engineered system. The rotor includes a central hub and, in most cases, three lightweight blades that are also known as airfoils. The rotor spins as air flows over the blades, rotating faster as wind speeds increase. This spinning motion drives the shaft of an electric generator, which is typically located in the nacelle. The generator converts the rotational (mechanical) energy into electricity.

Control systems and other electronics monitor, manage, and optimize system operations to maximize power generation under varying wind conditions. Electrical cables carry green electrons from the nacelle toward the base of the tower, where they are connected to a power delivery circuit via electronic devices of varying complexity.

Benefits
Wind turbines tap a locally available energy source to generate green electrons without depleting natural resources. The clear environmental advantages of wind power are complemented by numerous economic and social benefits. These benefits are listed below and characterized in more detail on MTC’s Clean Energy website.

Barriers & Issues
Use of wind power is constrained by many factors that can be addressed on a site-specific basis. Others are being addressed through the development of enlightened public policy and advanced science and technology. General barriers and real and imagined issues are listed below and characterized in more detail on MTC’s Clean Energy website. Specific challenges relating to municipal wind projects are described on this website's Community Wind page.

A small-scale, consumer-side turbine helps power the resource-conscious endeavors of the South Mountain Co. on Martha’s Vineyard. (Photo source: South Mountain Co.)

Wind energy can be used in diverse applications because systems may be sized to meet site-specific needs. Commercially available turbines range in rated capacity from 0.25 kW—little more than a small fan that generates rather than uses electricity—all the way up to 4.5 MW—a large and very visible machine. When operating at full power, the smallest and the largest wind generators can power a few light bulbs and thousands of homes, respectively.

Wind turbines can be deployed individually, in small clusters, and in large-scale arrangements known as wind farms or wind parks. Three types of uses exist:

Consumer-side (behind-the-meter) applications: The wind generation, typically one turbine, is located on the customer’s side of the electric meter. Electricity is used to meet on-site requirements, and excess electricity may be fed to the power grid for sale and delivery to others. Turbines installed at Cape Cod Tech in Harwich and Upper Cape Tech and the Massachusetts Maritime Academy in Bourne fit this description. Many local towns are pursuing this type of installation, as are Cape Cod Community College, Woods Hole Research Center, and other organizations.

Supply-side applications: The wind generation—from one to several to hundreds of turbines—connects directly to the grid on the utility’s side of the electric meter. Electricity is fed onto the power network for sale and delivery to consumers. The Cape Wind project proposed for Nantucket Sound may be the most prominent supply-side installation in the region, but other applications are being explored.

Off-grid applications: The wind generation is tied to a localized circuit that does not connect to the power grid. Electricity is used to meet on-site requirements. Off-grid applications often include solar photovoltaic and/or battery storage systems to supply electricity when the wind is not blowing.

Wind turbines may also be classified by scale, with rated capacity increasing with rotor diameter and hub height. Present-day technology may be divided into three broad size ranges, briefly characterized below:

• Residential and small commercial: rated capacity below 30 kW, rotor diameter of 1 to 13 m (4 to 43 ft), hub height of 18 to 37 m (60 to 120 ft), used in consumer-side and off-grid applications.
• Commercial: rated capacity between 30 and 500 kW, rotor diameter of 13 to 30 m (43 to 100 ft), hub height of 35 to 50 m (115 to 164 ft), used in consumer- and supply-side applications.
• Industrial: rated capacity between 0.5 and 4.5 MW, rotor diameter of 30 m to more than 100 m (100 ft to more than 325 ft), hub height of 50 m to more than 80 m (164 to 260 ft), generally used in supply-side applications or behind-the-meter settings by consumers with significant electricity demands.

Community-scale wind projects may include one or a couple large turbines with rated capacity of about 1.5 MW or less.

The actual power output of a turbine is generally much lower than rated capacity because the wind does not blow consistently. A capacity factor of 25 to 40% is typical. A turbine rated at 1 MW with a 30% capacity factor could produce anywhere from 0 to 1 MW on an instantaneous basis, but its annually averaged output would be 0.3 MW. The table shows the influence of capacity factor on actual output—and on the number of homes served by an individual turbine (assuming an average home consumes about 6,000 kWh/yr).

Cost-Performance Characteristics & Siting Considerations
Wind turbines are priced based on rated capacity, which is a measure of electricity generation under ideal conditions. In the real world, the wind blows intermittently, at varying speeds. Average wind velocity at hub height is the main determinant of actual capacity, and it is the primary measure used to determine whether a turbine or collection of turbines sited in a specific location will generate sufficient electricity to justify installation. In general, an average wind speed at hub height of at least 6.5 m/s (14.5 mph) is required for commercial viability.

The power available from wind is proportional to the cube of its speed, which means that twice as much wind produces eight times as much electricity. This relationship has three important implications: (1) at low wind speeds, little power can be generated; (2) even small increases in average speed correspond to a significant increase in the amount of electricity produced; and (3) there is much more energy available in locations with high wind velocities.

Wind speed generally increases with fetch (the distance over which the wind blows), which explains why the best wind resources are generally located on plains, on ridges and mountaintops, and in coastal and offshore environments. Wind speed also generally increases with height, which explains why today’s turbines are positioned atop tall towers.

Other key siting considerations include

• Proximity: In supply-side applications, a wind installation must be sited near existing power lines that can handle additional capacity. In consumer-side or off-grid applications, turbines must be sited near electrical loads. Building new transmission capacity or lengthy interconnections to loads can be prohibitively expensive.
  
  
• Accessibility: A site must be accessible, via roads or other means, to allow wind turbine installation and maintenance.

Resource Description
Cape Cod, Martha’s Vineyard, and Nantucket are eastward extensions of the continental United States. Temperature differentials between these landmasses and surrounding water bodies, combined with the general westerly flow of passing weather systems, create an abundance of wind throughout the region. Some of the best wind resources in the nation may be found in both onshore and offshore locations.

Detailed wind resource maps for the Cape & Islands region are available. All of these maps are derived from work conducted by TrueWind Solutions and AWS Scientific under funding provided by MTC, Connecticut Clean Energy Fund, and Northeast Utilities Service Company. Maps of onshore and offshore wind resources, transmission lines, ocean depth, and other features for the Cape & Islands region, the state, and New England are available via the link below:

• MTC Wind Resource Maps

More detailed maps of wind energy resources, open space, and other landscape features for Cape & Islands communities and other towns in Massachusetts are available from the MTC Community Wind Atlas. These maps facilitate initial analysis of siting possibilities for land-based wind projects in local communities.

Site-specific wind resource data are available for several locations in the Cape & Islands region. These data were collected by the Renewable Energy Research Laboratory at the University of Massachusetts with funding from the MTC and the Massachusetts Department of Energy Resources. Click here to access data characterizing the wind resource in Nantucket Sound (Bishop & Clerks Lighthouse), Bourne, Eastham, Falmouth, Nantucket, Orleans, Yarmouth, and other locations.

Local Projects
Cape & Islands homeowners, businesses, institutions, and municipalities are evaluating consumer-side installations of modern wind turbines. Potential supply-side applications include land-based installations of commercial- and industrial-scale units as well as the proposed Cape Wind project, which would deploy some of the largest turbines in the world in Nantucket Sound. Wind energy development activities in local communities and offshore environments are detailed below. This information is based on media reports and other sources.

Harwich—Cape Cod's first grid-connected turbine, a 1.7-kW unit, began operation in June 2005 at Cape Cod Regional Technical High School. It was installed through a hands-on training session involving Cape & Islands Self-Reliance, Clean Energy Design, and other local organizations. In its initial 6 months of spinning, the turbine generated more than 1300 kWh, no pollution or greenhouse gases, lots of attention, and valuable learning opportunities. Nearby homeowners liked its looks so much they are pursuing the town's first residential installation under a new town bylaw.

Depot Development LLC is seeking to install a 20-kW turbine at its facility in North Harwich, with a goal of having the first privately owned commercial wind project on the Cape.

Sandwich—A Bishop Path homeowner looking for relief from skyrocketing electricity bills is attempting to site two small turbines on 30-foot towers on one small lot, generating consternation from neighbors and concern from renewable energy advocates interested in quality installations. The project has been delayed due to permitting issues; as of February 2007, the town is working to develop a bylaw for residential wind projects.

Truro—The Highlands Center at the Cape Cod National Seashore is pursuing a wind project incorporating anywhere from one to three large-scale turbines. A 50-m meteorological tower installed on a former helipad in the southeast region of the Center is scheduled to begin monitoring wind conditions in spring 2006.

Martha’s Vineyard: Detailed status information on municipal wind projects is available here; other wind energy development activities in local communities and offshore environments are listed below. Click here to submit updated information on these or other projects.

Oak Bluffs—A 2.5-kW turbine began spinning in October 2006 at the shop of Against the Grain Cabinetmakers.

West Tisbury—South Mountain Co. installed a 10-kW turbine in fall 2004, the island's first grid-connected machine. This resource-conscious architecture and building company installed the turbine with the intent of meeting more than 50% of electricity needs at its shop.

• Cape Wind Associates (developer)
• U.S. Minerals Management Service (project information page for lead federal review agency)
• U.S. Army Corps of Engineers (project information page for former lead federal review agency)
• Cape Wind Draft Environmental Impact Statement (document prepared for the Corps of Engineers and additional federal, state, and regional review agencies, reporting results of studies funded by the developer)
• Cape & Islands Offshore Wind Stakeholder Process (fact-finding process organized by Massachusetts Technology Collaborative)
• Alliance to Protect Nantucket Sound (lead opponent)
• Clean Power Now (lead proponent)
• WindStop (rabid local opponent)
• Cape Cod Times (fair and balanced local coverage, with strong editorial slant in opposition)
• Cape Cod Today (more fair and balanced local coverage, with strong editorial slant in support)

For information on the Buzzards Bay project, visit the following links:

• South Coast Offshore Wind Project (developer's site)
• Proposed Wind Farms in Buzzards Bay, Buzzards Bay National Estuary Program

Brief information is available here on the local sites in federal and state waters identified by Winergy LLC.

The U.S. Minerals Management Service is heading up U.S. efforts to develop a framework for siting and permitting offshore energy projects in federal waters. In addition, MTC, in partnership with the U.S. Department of Energy, GE Wind, and others, is coordinating the Offshore Wind Collaborative (OWC). This group focuses on technical, political, economic, environmental, and societal barriers to the development of U.S. wind resources in deepwater and far-offshore environments, where energy levels are higher and aesthetic concerns are reduced or eliminated. The goal is to establish "over the horizon" wind farms in U.S. waters as a cost-competitive electricity supply option.

1. "Community Wind" - Cape & Islands Energy Information Clearinghouse: detailed background and status information on municipal projects in local communities
   
   
2. American Wind Energy Association: overview and detailed information on basic concepts, economics, policy issues, environmental impacts and benefits, and other topics

Wind Energy Fact Sheets

Wind Web Tutorial

3. Cape Cod Commission/Cape Light Compact: model bylaw for regulation of land-based wind installations and report addressing basic concepts, project economics, environmental considerations, and industry status

   Model Bylaw

Assessment of Distributed Generation

4. Massachusetts Department of Energy Resources: guide for installation of small wind systems

Small Wind Electric Systems: A Massachusetts Consumers Guide

5. Massachusetts Technology Collaborative: background information and updates on MTC-funded initiatives

Clean Energy Information: Wind Energy

Community Wind Collaborative

Offshore Wind Collaborative

6. University of Massachusetts Renewable Energy Research Laboratory: fact sheets addressing key issues related to the development of community-scale projects in Massachusetts

Community Wind Fact Sheet Series

7. Windmill World: images and historical information on windmills in the Cape & Islands region

Last updated 11.08.06