Renewable Energy from the Wind

Aerial photo of a wind farm in Hawai‘i. Seven white wind turbines are scattered near and far. The dark blue ocean is in the distance with whitecaps on the waves. A bank of clouds is rolling in above the ocean out in the distance. The wind turbines are surrounded by green grass and a brown, dirt road weaving in between them. A few trees are interspersed on the outskirts of the photo.

This 10.5-megawatt wind farm, located on the northern tip of Hawai‘i at Upolu Point near Hawi on the Big Island, takes full advantage of winds that blow 70% of the time.

The sun's heat drives the winds, whose energy is captured with wind turbines. People have been harnessing the wind's energy for hundreds of years, mainly for agricultural uses, such as pumping water and grinding grain. Today, the windmill's modern equivalent—a wind turbine—uses the wind's energy to generate electricity.

Wind Energy Basics

Wind turbines, like windmills, are mounted on a tower to capture the most energy. At 100 feet (30 meters) or more aboveground, they can take advantage of the faster and less turbulent wind. Turbines catch the wind's energy with their propeller-like blades. Usually, two or three blades are mounted on a shaft to form a rotor.

A blade acts much like an airplane wing. When the wind blows, a pocket of low-pressure air forms on the downwind side of the blade. The low-pressure air pocket then pulls the blade toward it, causing the rotor to turn. This is called lift. The force of the lift is actually much stronger than the wind's force against the front side of the blade, which is called drag. The combination of lift and drag causes the rotor to spin like a propeller, and the turning shaft spins a generator to make electricity.

A photo of an ancient Hawai‘ian sailing canoe with a crew dressed in traditional Polynesian garb, including headpieces and flowing robes. In the foreground is the large orange canoe with two furled sails, their masts secured by rigging. The boat is sailing on an indigo sea. In the background are puffy orange, yellow, purple and white clouds against a blue evening sky.

The wind was an important resource for ancient Hawai‘ians, who relied on the trade winds to sail their canoes.

Wind Energy in Hawai‘i

Wind is plentiful on Hawai‘i's islands. In the past, ancient Hawai‘ians depended on the trade winds to sail their canoes. And for the people of Hawai‘i today, the wind holds tremendous potential as a clean, renewable energy source. Wind turbines can be used as stand-alone applications, or they can be connected to a utility power grid or even combined with a photovoltaic (solar cell) system. For utility-scale (megawatt-sized) sources of wind energy, a large number of wind turbines are usually built close together to form a wind plant. A growing number of utility providers use wind plants to supply power to their customers. In Hawai‘i, wind farms are already supplying electricity to consumers on Maui and the Big Island, and plans are under way to install wind turbines on Lana‘i, Moloka‘i, and O‘ahu.

Stand-alone wind turbines are typically used for water pumping or communications. However, homeowners, farmers, and ranchers in windy areas can also use wind turbines as a way to reduce their electric bills.

Small wind systems also have potential as distributed energy resources. Distributed energy resources refer to a variety of small modular, power-generating technologies that can be combined to improve the operation of the electricity-delivery system. Learn more about distributed energy resources on the National Renewable Energy Laboratory (NREL) Web site.

Map of the Hawai‘ian islands and wind power classes. If you have a disability and need assistance with the wind map, please e-mail the Webmaster.

This map of Hawai‘i shows the wind resource at 50 meters. On the DOE Web site, you can view a larger version or download a printable map (PDF 1.9 MB) Download Adobe Reader.

Map of the Hawai‘ian islands showing wind power density. If you have a disability and need assistance with the wind map, please e-mail the Webmaster.

This map of Hawai‘i shows the wind power density at 50 meters. Download the printable map (PDF 1.8 MB). Download Adobe Reader.

The U.S. Department of Energy's (DOE) Wind Program and NREL have published a wind resource map for the state of Hawai‘i. The map shows wind speed estimates at 50 meters above the ground and depicts the resource that could be used for utility-scale wind development. Future plans are to provide wind speed estimates at 30 meters, which are useful for identifying small wind turbine opportunities.

As a renewable resource, wind is classified according to wind power classes, which are based on typical wind speeds. These classes range from Class 1 (the lowest) to Class 7 (the highest). In general, at 50 meters, Class 4 or higher can be useful for generating wind power with large turbines. Class 4 and above are considered good resources. Particular locations in the Class 3 areas could have higher wind power class values at 80 meters than shown on the 50-meter map because of possible high wind shear. Given the advances in technology, a number of locations in the Class 3 areas may be suitable for utility-scale wind development.

This map indicates that Hawai‘i has wind resources consistent with utility-scale production. Good-to-excellent wind resource areas are fairly evenly distributed throughout the islands. The largest contiguous areas are located on the western parts of Moloka‘i and Lana‘i, on the western and southern shores of Maui and Kahoolawe, and on the northern and southern tips of Hawai‘i. There are also localized high-wind resource areas on the islands of Kaua‘i and O‘ahu.

Additional Wind Energy Information