The U.S. Department of Energy's National Renewable Energy Laboratory today released a major study of the technical, operational, and economic issues facing the integration of large amounts of wind energy into the power system.

The bottom line is: The existing grid serving most of the United States east of the Rockies would need a multi-billion dollar upgrade before it could handle even 20% wind-generated power.

The DOE's Eastern Wind Integration and Transmission Study (EWITS) evaluates the impacts of wind energy penetration into the power system through 2024. The study encompasses the majority of the utilities in the Eastern Interconnection, one of the two major alternating current (AC) power grids in North America. The Eastern Interconnection reaches from Central Canada eastward to the Atlantic coast (excluding Québec), South to Florida, and back West to the foot of the Rockies (excluding most of Texas).

About a year ago, a Joint Coordinated System Plan study group concluded that a 20-percent wind energy scenario would “require 15,000 miles of new extra-high voltage lines, at an estimated cost of $80 billion, in addition to $1.1 trillion in total generation capital costs by 2024.”

The new DOE study increases those numbers to 22,000 miles of new transmissions lines at a cost of $90 billion. But it argues that the $90 billion cost for transmission upgrades is only a small percentage of the total cost to build the wind generation capacity.

The new study also cautions that wind farms must be spread out geographically so they will not account for a large percentage of power generation at any given point in the grid. According to the new DOE study, "increasing the geographic diversity of wind power projects in a given operating pool generally makes the aggregated wind power output more predictable and less variable, while also reducing the variation in load and increasing the number of generation assets that can be committed and dispatched."

Other highlights from the new DOE study include:

• There are no fundamental technical barriers to the integration of 20% wind energy into the electrical system, but transmission planning and system operation policy and market development need to continue to evolve in order for these penetration levels to be achieved;

• Without transmission enhancements, substantial curtailment of wind generation would be required for all of the 20% wind penetration scenarios;

• Although the costs of aggressive expansion of the existing grid are significant, they make up a relatively small piece of the total annual power system costs in any of the scenarios studied;

• Wind generation displaces carbon-based fuels, directly reducing carbon dioxide emissions. Emissions continue to decline as more wind generation is added to the energy supply; and

• Reduced expenditures on fossil fuel costs more than pay for the increased costs of transmission in all wind scenarios.
  

For more information about incorporating increasing amounts of wind energy into the power system while maintaining reliable grid operations, see the DOE's Wind and Hydropower Technologies Program's Renewable Systems Interconnection web site.

John Howley
Orlando, Florida