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Research reduces cost; increases wind generated electricity production
06 July 2005
The following article appears in the June 2005 issue of the State Department's electronic journal, titled Protecting the Environment: Thirty Years of U.S. Progress.
Wind Power Today
By Robert Thresher, director of the National Wind Technology Center at the U.S. Department of Energy�s National Renewable Energy Laboratory
The U.S. Department of Energy (DOE) has worked with the U.S. wind energy industry for more than 30 years to turn yesterday�s dream for a clean, renewable energy source into today�s most viable renewable energy technology.
Wind power�the technology of using wind to generate electricity�is the fastest-growing new source of electricity worldwide. Wind energy is produced by massive three-bladed wind turbines that sit atop tall towers and work like fans in reverse. Rather than using electricity to make wind, turbines use wind to make electricity.
Wind turns the blades and the blades spin a shaft that is connected through a set of gears to drive an electrical generator. Large-scale turbines for utilities can generate from 750 kilowatts (a kilowatt is 1,000 watts) to 1.5 megawatts (a megawatt is 1 million watts). Homes, telecommunications stations, and water pumps use single small turbines of less than 100 kilowatts as an energy source, particularly in remote areas where there is no utility service.
In wind plants or wind farms, groups of turbines are linked together to generate electricity for the utility grid. The electricity is sent through transmission and distribution lines to consumers.
Since 1980, research and testing sponsored by the DOE Wind Program has helped reduce the cost of wind energy from 80 cents (current dollars) per kilowatt hour to between 4 and 6 cents per kilowatt hour today.
One goal of the Wind Program is to further reduce the cost of utility-scale wind energy production to 3 cents per kilowatt hour at land-based, low-wind-speed sites and 5 cents per kilowatt hour for offshore (ocean) sites. A low-wind-speed site is one where the annual average wind speed measured 10 meters above the ground is 13 miles per hour.
To accomplish this and other goals, two of DOE's main research laboratories, the National Renewable Energy Laboratory (NREL) in Colorado and Sandia National Laboratories in New Mexico, work with industry partners and university researchers nationwide to further advance wind energy technologies. Each laboratory has unique skills and capabilities to meet industry needs.
NREL's National Wind Technology Center (NWTC) is the lead research facility for the wind program. NWTC conducts research and supports industry partners in design and review analysis, component development, systems and controls analysis, testing, utility integration, technical assistance, and more. Sandia conducts research in advanced manufacturing, component reliability, aerodynamics, structural analysis, material fatigue, and control systems.
Thanks to such research and development, global wind energy capacity has increased 10-fold in the last 10 years—from 3.5 gigawatts (a gigawatt is 1 billion watts) in 1994 to nearly 50 gigawatts by the end of 2004. In the United States, wind energy capacity tripled, from 1,600 megawatts in 1994 to more than 6,700 megawatts by the end of 2004—enough to serve more than 1.6 million households.
In 2005, because of a federal production tax credit renewed by Congress in 2004, the U.S. wind energy industry is poised for record growth. The tax credit provides a 1.9-cent per kilowatt hour credit for eligible technologies for the first 10 years of production. Some wind industry experts predict that wind technology installations for 2005 will add more than 2,000 megawatts of capacity because of the tax advantage provided by this law.
The wind industry has grown phenomenally in the past decade thanks to supporting government policies, and the work of DOE Wind Program researchers in collaboration with industry partners to develop innovative cost-reducing technologies, cultivate market growth, and identify new wind energy applications.
Developing Cost-Reducing Technologies
Work conducted under DOE Wind Program projects from 1994 to 2004 produced innovative designs, larger turbines, and efficiencies that have led to dramatic cost reductions. Although this drop in cost is impressive, electricity produced by wind energy is not yet fully competitive with that produced by fossil fuels. Researchers believe that further technology improvements will be needed to reduce the cost of electricity from wind another 30 percent for it to become fully competitive with conventional fuel-consuming electricity generation technologies.
Cultivating Market Growth
To cultivate market growth by increasing acceptance of wind technology around the country, DOE’s Wind Powering America (WPA) team works with industry partners to provide state support, develop utility partnerships, conduct outreach, and develop innovative market mechanisms to support the use of large- and small-scale wind systems.
The WPA strategy for increasing acceptance of wind technology includes extensive information activities to better inform various publics about the benefits of this technology. In 2004, WPA team members staffed exhibits at 36 events in 20 states and distributed 43,000 copies of WPA publications to state wind working groups and at various events. The number of visitors to the Wind Powering America Web site (http://www.windpoweringamerica.gov) continues to grow.
Through such efforts, the WPA seeks to increase the use of wind energy in the United States with the goal that at least 30 states have 100 megawatts of wind capacity by 2010.
New Wind Energy Applications
Decades of work conducted through public-private partnerships have moved wind energy from yesterday’s dream to today’s reality.
To ensure continued industry growth in 2005 and beyond, the Wind Program is exploring innovative applications that will open new markets. The applications include installing wind turbines offshore in shallow and deep water, using wind energy to produce fresh water, and developing new technologies that will help wind work in synergy with other renewable energy technologies like hydropower.
Offshore and Deep-Water Development
Offshore wind turbines, now in the early stages of development, are more expensive and harder to install and maintain than turbines on land. Offshore turbines must be designed to survive the offshore wind and wave loading of severe storms, and protected from the corrosive marine environment.
Some advantages of offshore installation are that turbines can be made bigger than those onshore to produce more power per turbine, and the ocean location provides greatly increased wind speeds and less turbulence. Offshore installations also reduce land-use and could ease aesthetic concerns, if the turbines are located far from shore and out of sight.
Recent studies show that there are significant offshore wind resources in regions of the United States near major urban areas in the mid-Atlantic and northeast. In Europe, offshore wind turbines produce about 600 megawatts, but no turbines have yet been installed in waters deeper than 20 meters.
For offshore turbines in shallow water (less than 30 meters), European turbine manufacturers have adopted conventional land-based turbine designs and placed them on concrete bases or steel monopiles driven into the seabed. An offshore substation collects the energy and boosts the voltage, and then a buried undersea cable carries the power to shore, where another substation provides a further voltage increase for transmission to utilities for distribution to customers.
A large amount of potential U.S. offshore wind resources are in waters deeper than the current technology limit of about 30 meters, as developed in Europe for the Baltic Sea. Monopile foundations driven into the seabed are less suitable for the deeper waters off U.S. coasts. To produce cost-effective wind energy in deep water, floating platform technologies developed by the oil and gas industries need to be adapted and scaled for application to wind energy and new lower-cost anchoring methods developed. The ultimate vision for this new offshore wind technology would be to build the turbines and the supporting platform in a shore-based dry dock with local labor, tow the floating turbine to its place on the sea, drop anchor, and plug in to the power cable to shore.
The Wind Program is evaluating several floating platform concepts for offshore wind turbines for cost-effective electricity generation in water 50-200 meters deep. The program is also negotiating a partnership agreement with a domestic company to develop the first U.S. multi-megawatt wind turbine prototypes designed specifically for shallow-water offshore use.
Wind and Water
The Wind Program is investigating how wind and water can work together to provide a more stable supply of electricity and fresh water. The scarcity of fresh water is a growing global problem. According to the United Nations, the world’s burgeoning population will need billions more cubic meters of fresh water per day by 2025. The current global desalination capacity is an estimated 28 million cubic meters per day.
An important solution to water scarcity is desalination of abundant ocean salt water, but desalination is a highly energy-intensive technology and is not cost effective in most areas. Among all the desalination process technologies, reverse osmosis has the highest electrical energy efficiency, at 3-8 kilowatt hours per cubic meter of water.
Reverse osmosis is a method of producing pure water by forcing salt water through a semipermeable membrane (which allows some molecules through but not others) that salts cannot pass through.
Even with the high efficiency of reverse osmosis, energy accounts for about 40 percent of the total desalinated water cost. From a cost and environmental point of view, inexpensive and clean alternative power sources are needed for a low-cost desalination solution.
Wind power is the most promising and least expensive renewable power source but, because of its variable nature—because wind doesn’t always blow—researchers must determine the effects it will have on desalination systems and their operation.
In 2004, the Wind Program funded a conceptual design study for an integrated wind energy and desalination system. The project is exploring wind and desalination concepts, identifying technical issues, exploring the feasibility of alternative concepts, and evaluating their economic viability.
To provide a stable supply of electricity to the utility grid, the Wind Program is conducting research into the potential benefits of combining wind and hydropower (or waterpower), which harnesses the energy of moving or falling water.
As part of that effort, the United States helped form a working group of the International Energy Agency (IEA) whose participants will focus on integrating wind and hydropower systems (the IEA Research, Development and Demonstration Wind Annex XXIV).
The annex will exchange information and conduct cooperative research into the generation, transmission, and economics of integrating wind and hydropower systems. The annex held its first meeting at the Hoover Dam in Nevada in 2005.
The U.S. Department of Energy’s Program to make clean and sustainable wind energy cost effective for several market applications has made significant progress in recent years and is on a steady course to further significant improvements. Sound and sustainable development of this renewable energy resource is a key element of the U.S. strategy to reduce national reliance on carbon-based fuels and reduce the production of greenhouse gas emissions.
(Distributed by the Bureau of International Information Programs, U.S. Department of State. Web site: http://usinfo.state.gov)
