A 2008 analysis of wind speeds, infrastructure capacity, and government regulations estimated that the United States could generate 20 percent of its electricity from wind energy by 2030.
The new analysis, released on Wednesday, concluded that wind power could supply as much as 30 percent of the area east of the Great Plains, known as the U.S. Eastern Interconnection, by 2024 if transmission infrastructure expands significantly.
The energy department's National Renewable Energy Laboratory (NREL) envisioned three 20-percent scenarios. The first would rely on energy from remote, windy regions. The second would rely on operations closer to areas with higher populations and include some offshore wind. Both would increase annual energy costs by an estimated $15 billion more than current projections, while avoiding greenhouse gas emissions, water use, and fuel consumption.
A third 20-percent scenario would include 'aggressive' offshore wind development and greater amounts of wind energy near the eastern population centers, costing some $30 billion more each year.
'As you go eastward, the transmission costs go down but the capital cost of offshore wind goes up,' said David Corbus, an NREL senior engineer who monitored the study, which EnerNex Corporation, an electric power research firm, prepared.
A fourth NREL scenario increases the wind energy mix to 30 percent by combining high-speed wind farms in the Midwest with larger wind operations offshore. As with the other scenarios, the United States would buy less fossil fuel, but costs savings would be outweighed by the higher costs of installing, operating, and maintaining wind plants. The scenario would cost an additional $50 billion each year.
Before the financial crisis, the United States surpassed Germany in wind energy production and cumulative wind power generating capacity, with more than 25,000 megawatts in operation, or nearly 2 percent of net U.S. electricity generation, at the end of 2008.
The study's cost scenarios all assume continued growth of energy demand. However, the United States holds vast energy efficiency opportunities that could slow increases in energy demand, notes the Worldwatch Institute's latest report, Renewable Revolution: Low-Carbon Energy by 2030.
The American Council for an Energy-Efficient Economy estimates that energy efficiency has met 75 percent of new demand for energy services since 1970, and the Rocky Mountain Institute found that bridging the gap between the most and the least energy-efficient states could avoid 30 percent of national electricity consumption. The global consulting firm McKinsey & Company found that $520 billion invested in energy efficiency in the United States could reduce projected energy demand 23 percent by 2020.
Speaking at a Worldwatch Institute-hosted side event in Copenhagen last month, Dan Reicher, director of climate and energy initiatives at Google.org, compared changes to U.S. energy infrastructure to retrofitting a house: the house must first be modified to use energy as efficiently as possible, and then an appropriately sized renewable energy system can be put in place.
The main obstacle to the higher wind energy scenarios is transmission infrastructure. Sufficient power lines do not reach the Midwest and offshore regions where the highest wind speed sites are located. Grid expansion would represent less than 15 percent of the total electricity costs, the NREL study notes, but regional operators would need to overcome several siting and certification hurdles.
States and local organizations, including environmental groups, have opposed large transmission projects due to their location near neighborhoods or natural habitats, even though such projects would facilitate greater renewable energy use. 'Everybody loves wind, but nobody likes looking ahead to see a wire,' Corbus said.
Unless new transmission lines are built soon, already congested transmission lines will become further constrained, which may lead several wind operators to shut down their facilities. Transmission lines are also essential to balance the natural variability inherent in wind generation, especially if constructed using more efficient 'smart grid' technology.
While smart grid technology could help the aging grid structure evolve into a system that facilitates the integration of larger amounts of wind and other renewable power, it could also improve the operational security of the grid. It is, however, the transmission grid construction that requires the most time. Corbus estimates that 1,000 miles (1,600 kilometers) of transmission lines require, on average, seven years to build, while 500 megawatts of wind power could become operational in two years.