How Electricity Gets from the Wind Farm to Your House
The United States can be divided into five regions (Northeast, Southeast, Midwest, Southwest, and West) based on different structures for the electric industry. Each region relies on different fuel mixes to produce electricity, depending on price and the availability of supply in the areas (for an illustration of this, see the Edison Electric Institute map). No single fuel is likely to provide the energy to meet all of our nation’s electricity demands, and diverse fuel mixes help to ensure affordable and reliable electricity. Wind energy plays a valuable role in these fuel mixes.
How is electricity distributed? The high-voltage transmission system that carries electricity to the utility that serves your house is operated by a Regional Transmission Organization (RTO)/Independent System Operator (ISO) or the utility company itself, depending on which region you live in. Some regions operate without RTOs or ISOs, such as states in the Southeast and the West. Regional energy markets like ISOs/RTOs are beneficial for wind energy development because they provide large integrated markets and tend to have operating characteristics that are favorable for integrating wind energy onto the power system.
An initiative by the Advanced Energy Economy provides resources and information to help make the complex electric industry market structure in the U.S. and in each state accessible to a broader audience.
The following links offer more information about RTOs/ISOs:
No discussion of electricity grids and wind integration is complete without mentioning transmission. The United States has an aging, inadequate transmission infrastructure, and it continues to be a significant barrier to wind energy development in the country. For example, at the end of 2011, nearly 200,000 MW of proposed wind capacity had applied for interconnection to the grid but had not yet been connected, with the inadequacy of the grid being a critical barrier for many of these projects. Often areas with the best wind resources are far from population centers with the largest loads. For instance, the “Saudi Arabia of Wind,” the Midwest region from the Dakotas to Texas with a tremendous wind energy resource, has very little transmission capacity. Improving the U.S. power grid would benefit consumers by improving electric reliability, providing access to lower cost sources of energy, and improving the efficiency of the power system, generating enough savings to pay for the cost of the transmission investment.
Regional transmission planning and cost allocation processes must incorporate evaluations of the transmission required for the anticipated development of new power plants. Generation companies are reluctant to commit to a new generation project unless available transmission is guaranteed, but transmission developers are reluctant to make a move until they are certain that new generation resources will be built. In addition, in many regions policy structures are not in place to pay for large-scale transmission investments that would benefit broad regions. The 20% Wind Energy by 2030 scenario would require a different way of thinking about transmission planning and cost allocation. Collaboration on a shared plan across a large geographic area would yield major economies of scale and regional benefits.
Wind Resources in Your Region
Wind energy can be produced anywhere the wind blows with a strong and consistent force. Windier locations produce more energy, which lowers the cost of producing electricity.
The 2008 U.S. Department of Energy 20% Wind Energy by 2030 scenario identified enough cost-effective wind energy resources to meet the electricity needs of the U.S. more than a dozen times over. Importantly, moderate to excellent wind resources are found in most regions of the United States. However, the most useable wind resources are found in the Plains states.
The wind resource maps from the Energy Department’s WINDExchange initiative can help you determine whether the wind resource in your area is adequate for wind power.
80-Meter Wind Resource Maps
The U.S. map shows the predicted mean annual wind speeds at 80-m height (at a spatial resolution of 2.5 km that is interpolated to a finer scale). Areas with annual average wind speeds around 6.5 m/s and greater at 80-m height are generally considered to have suitable wind resource for wind development.
Reliability of Wind in Your Region
Large amounts of wind energy are already being reliably and cost-effectively integrated with the grid in the U.S. and around the world. In 2010, the Texas grid obtained 7.8% of its electricity from wind energy, with wind energy providing more than 25% of the grid’s electricity at one point. Roughly 20% of the electricity produced in Iowa now comes from wind energy, and at one point in 2011 Xcel Energy’s utility system in Colorado obtained more that 55% of its electricity from wind energy, all without any reliability problems. Similarly, European countries like Germany, Spain, Portugal, Denmark, and Ireland now obtain 10% to 25% of their electricity from wind energy, and studies indicate that much higher levels can be achieved with no negative impact on reliability.
How is this possible? A large part of the answer is that grid operators are already very good at dealing with variability and uncertainty on the power system. Factories turning large electrical equipment on and off and millions of people changing their use of air conditioning and electric heating as the weather changes cause large and often unpredictable changes in the demand for electricity. Similarly, large changes in electrical supply occur fairly frequently when large conventional power plants experience sudden outages due to mechanical or electrical failures and must go offline instantaneously. The loss of a large power plant can happen at any time, forcing grid operators to have 1,000 megawatts (enough for a large city) or more of reserve generation standing by 24/7, ready to activate at a moment’s notice if needed.
Dealing with unexpected changes in supply and demand is a continual and highly sophisticated balancing act. Grid operators often deal with these changes by changing the output of power plants, in many cases hydroelectric dams or natural gas power plants that can store their fuel behind a dam or in a pipeline. In other cases, the grid operator may purchase or sell power to a neighboring region or it may use demand response resources–large electricity users like factories that have agreed to change their electricity use in exchange for payment.
In contrast to the large, abrupt, and often unpredictable changes in electricity demand and in conventional generator output, wind output changes tend to be gradual and predictable. When wind turbines are spread over large areas, it typically takes an hour or more for a significant change in wind output to occur. In addition, wind energy forecasters can now predict what wind output will be hours and days in advance with a high level of accuracy and confidence, thanks to the use of advanced computers, weather models, and trained meteorologists.
It is also important to keep in mind that much of the variability of wind energy is canceled out by opposite changes in supply and demand caused by other sources of variability. Just as the odds are very high that the additional demand caused by my turning my lights on will be offset by someone else turning his TV off, many increases in wind output will be offset by people turning appliances on and vice versa. In fact, one of the main reasons we built a power grid in the first place more than 100 years ago was so that different sources of variability could cancel each other out.
The fact that changes in wind output are slower and predictable has important implications for the cost and emissions associated with integrating wind. Slower changes can be dealt with through the use of non-spinning reserves–power plants that are not operating but are standing by ready to provide power within 30 minutes or so. Since non-spinning reserves are not operating, there is no fuel use associated with them standing by, ready to operate. As a result, there is little to no emissions impact from having these reserves, and the cost of these non-spinning reserves is typically a few percent of the cost of the fast-response and higher-emitting spinning reserves that are needed to accommodate sudden changes like the loss of a large fossil or nuclear power plant.
The American Wind Energy Association
AWEA maintains data for the wind industry by and publishes state-specific information.
Regional Energy, National Solutions is a nonpartisan report that argues that the United States can enact a long-term strategy to achieve climate stability, economic prosperity, and energy security by using the unique assets of each region of the country and choosing smart places for investment in multiple forms of energy and fuel. The new report responds to a recent vision laid out by the American Petroleum Institute, which suggested clean energy be put on the back burner in favor of aggressive oil and gas drilling, both on shore and off, and coal mining. In contrast, offshore wind is an ideal technology that could contribute substantially to the sustained, long-term energy demands of the Atlantic Coast states. According to the report, developing just 54 gigawatts of offshore wind in Atlantic waters would generate $200 billion in economic activity and create 43,000 permanent, well-paid technical jobs, in addition to displacing the annual output of 52 coal-fired power plants.
Governors’ Wind Energy Coalition
The Governors’ Wind Energy Coalition is a bipartisan group of U.S. governors who are dedicated to the development of the nation’s wind energy resources to meet America’s domestic energy demands in an environmentally responsible manner—while reducing the nation’s dependence on imported energy sources and stimulating state and national economic development. Through its multi-state coordinated efforts, the Coalition undertakes initiatives designed to encourage sound policy and legislation for the development and distribution of wind-generated energy; to communicate and demonstrate the value and benefits of wind energy to consumers, energy companies and policy makers; to create an environment of support for those who wish to develop responsible wind energy resources; and to make investments in infrastructure to support expansion of wind energy across the United States.
Current Coalition members include:
Arkansas, California, Colorado, Delaware, Hawaii, Illinois, Iowa, Kansas, Kentucky, Maryland,Massachusetts, Michigan, Minnesota, Montana, New Mexico, New York, North Dakota, Oklahoma,Oregon, Pennsylvania, Rhode Island, South Dakota, and Washington.
For more information about the Coalition or to identify the representative from your state, visit the Governors Wind Energy Coalition website.
National Renewable Energy Laboratory
Status of Regional Wind Integration Studies (presentation; PDF 776 KB). (2007).
Photo by Bill Dickinson