Wind could replace coal and natural gas for 20 to 30 percent of the electricity used in the eastern two-thirds of the United States by 2024, according to a study released Wednesday by the Energy Department.
But doing so would require a reorganization of the power grid and a significant increase in costs. And it would have only a modest impact on cutting emissions linked to global warming, the study found.
The Energy Department under President Obama has been a proponent of renewable energy, and the study tackles one of the biggest questions involving wind energy: How much can the power system use and still remain stable, given that the amount of electricity generated by wind turbines is as fickle as the breeze?
The answer, according to the study, is that heavy reliance on wind energy is “technically feasible” but will require significant expansion of the power grid.
That expansion would require spending about $93 billion in today’s dollars, according to David Corbus, a senior engineer at the National Renewable Energy Laboratory, which supervised the study. He said that sum, large as it is on its face, was “really, really small compared to other major costs” in the power system.
A bigger obstacle is how to overcome a political impasse over building power lines, and how to find, and finance, sites for 10 times more generating capacity. The study did not address those questions.
Adding wind gets progressively more difficult as the amount used rises because of wind’s intermittent nature and the need for back-up power generation, according to the study. Without a better grid, the system would often waste large amounts of wind power because at many times during the year, the power grid would not be able to handle the amount of power that wind turbines were putting out.
But the amount of wasted wind energy, and the amount of backup needed, would decline as grid connections got better, the study said. A better grid, Mr. Corbus said, would also lead to fewer blackouts.
The conclusions are hypothetical, because almost all planning for power lines in North America is based on local considerations, not those half a continent away. Critical to enlarging the use of renewable energy, according to the study, is a better planning approach that takes account of the whole country’s needs.
The study covers the Eastern Interconnection, which delivers electricity to about 70 percent of the United States population. It covers North America from Halifax to New Orleans, and from Miami to Fargo, N.D. A parallel study for west of the Rockies is under way; the third North American grid covers most of Texas, which is already heavily dependent on wind.
While it is based on engineering, the study wades into a dispute between grid operators and energy producers in the Great Plains and those in the East, especially New York and New England.
Midwestern companies want to blanket parts of the Great Plains with windmills. They argue that the region could produce about 25 percent more power than comparable sites in the East because of stronger winds.
But the Eastern interests say that they can build turbines offshore, where wind is steady and predictable and distances to big cities are short. The governors of 10 eastern states entered the argument on May 4, 2009, sending a letter to Congress asking that no special provisions be made to build additional power lines to bring Midwestern energy to the East, because that would preclude wind farm development in their states.
The new study, conducted by the EnerNex Corporation, of Knoxville, Tenn., is the first major effort to compare those assertions. It found that in the “reference” case, with new windmills being built to satisfy state-by-state requirements for renewable energy, total yearly electricity costs in the Eastern Interconnection would be about $125 billion (in today’s dollars) in 2024. That would bring wind’s share to about 6 percent of electricity. Building windmills in the Midwest to get to 20 percent, with matching transmission lines, would raise that to about $140 billion, and building offshore would bring costs of about $150 billion.
Thomas Rumsey, a spokesman for the New York Independent System Operator, the grid operator, said that building a better transmission system to the West would be a pathway for bringing in more coal energy, as well as wind energy. New York, he said, would focus on better connections to Quebec, which has hydroelectric power and the potential for significant wind generation.
Regardless of where the windmills are built, the projected global warming benefits are modest: a drop of about 4.5 percent in emissions, at best. If no additional wind machines are built, carbon emissions will rise.