The renewable energy sector continues growing as more people and companies turn toward the cost-effective and environmentally friendly alternatives to fossil fuels. Wind energy accounts for roughly 4.1% of the United States’ overall electricity generation. As of September 2014, the current installed wind capacity in the U.S. reached 62 GW. Thinking about making the switch? To get you started, we’ve done the research and answered a few FAQs associated with wind power.
What are a few advantages and challenges of using wind generated power?
Wind is caused by the sun unevenly heating the atmosphere, the earth’s rotation, and surface irregularities. Therefore, as long as the sun shines, wind will blow, making it a sustainable energy source. Of course, wind is also a clean energy source. Unlike fossil fuels such as coal, wind turbines emit no CO2 or pollutants such as methane, nitrous acid, or other greenhouse gases.
Another plus: it is one of the lowest-priced renewable energies on the market. On average, wind generated power costs between $0.04 and $0.06 per kWh. Solar power costs an average of $0.12 to $0.30 per kWh.
Although wind power’s price per kWh is cost-competitive, its high initial investment costs pose a financial challenge for developers. Sites deemed suitable for wind farm development are often far away from the cities – load centers. Thus, transmission lines must be built to bring the electricity into the city, further driving up development and construction costs.
Turbines have their own set of challenges, including noise and aesthetic concerns, along with reports of a few bird deaths. However, advances in technology and better siting practices are solving or minimizing many of these problems. Lastly, wind is a variable source so it does not yet generate the base load, and a cost-effective wind energy storage system has yet to be developed.
How are wind farms developed?
The first step in wind project development is identifying a site with sufficiently strong winds such as those in the Great Plains, a region running north-south and just about in the middle of the United States. AWEA lists North Dakota, Texas, Kansas, South Dakota, Montana, Nebraska and Wyoming as the top 10 best states for wind energy. All are in the Great Plains.
Accessibility to transmission lines and a ready market are also contributing factors when selecting a site. Following an initial assessment, the developer conducts a thorough investigation of the site, collects meteorological data for at least a year, considers environmental and community impacts, and researches siting and permitting. Because most wind farms are built on private land, the developer and landowner must come to a lease agreement before construction begins. The developer then contracts with a local utility to supply the electricity produced, purchases and install the turbines, and hires a construction company to build the facility. Upon completion, the wind farm is often sold to an independent operator, although some utilities own and operate the wind farm directly. In some instances, the developer also owns the wind farm and, in rare situations, turbine OEMs develop and own the project, as well as manufacture the turbines. This was the case with Acciona Energy’s EcoGrove, Pioneer Grove, Red Hills, and other wind projects. Gamesa Energy also used this model for its Pocahontas Prairie, Sandy Ridge, and Allegheny Ridge 1 projects.
How are wind turbines classified?
Wind turbines are generally divided into a few categories: utility-scale offshore and offshore, and small wind.
Utility-scale wind features turbines larger than 100 kW, although most range from 850 kW to 2.5 MW and more with tower heights ranging from 130 to 400 ft. Rotor diameters range 170 to 310 ft. Electricity is delivered to the power grid and distributed to customers through electric utilities.
In Europe, offshore wind farms are typically erected in shallow, coastal waters with depths ranging 15 to 90 ft, with turbines mounted on platforms anchored to the ocean floor. Several new technologies are emerging for floating platforms, permitting development further off the coast and in deeper waters.
Electricity generated by the offshore turbines is transmitted through underwater cables buried beneath the seabed to a collector station. From there, one line connects to the power grid onshore.
To capitalize on the stronger, more consistent winds at sea, most offshore turbines carry nameplate ratings from 2 to 6 MW, and more soon, easily doubling that of many onshore turbines. What’s more, tower heights typically exceed 200 ft and rotor diameters range from 250 to 420 ft. Turbines intended for offshore duty are also built to withstand corrosion, storm waves, hurricane winds, and other environmental challenges.
Small Wind, also known as distributed wind, uses turbines with nameplate ratings of 100 kW or less to directly power individual homes or businesses. Small wind systems can operate either on or off-grid. Grid-connected systems operate in conjunction with a local utility. When wind power is available, the local turbine provides it. When wind subsides, the utility makes up the difference. Conversely, when the turbines produce more energy than needed, the excess can be sent or sold to the utility.
A small wind system not connected to the grid is referred to as a stand-alone system. These are viable options in remote locations where it could cost upwards of $50,000 to extend a power line to the grid. However, this option requires additional equipment, such as batteries, a converter, and a charge controller to govern the power used the home or business.
By Michelle DiFrangia, Assistant Editor
Filed Under: News