Source: Eastern Wind Integration and Transmission Study. Prepared by EnerNex Corporation: February 2011

 

The quotation, in the graphic above, is taken from page 28 of the 2011 Executive Summary of the Eastern Wind Integration and Transmission Study. In full;

"With large balancing areas and fully developed regional markets, the cost of integration for all scenarios is about $5 (US$ 2009) per megawatt-hour (MWh) of wind, or about $0.005 per kilowatt-hour (kWh) of electricity used by customers."

The Eastern Renewable Generation Integration Study (ERGIS) is a follow-on study to the Eastern Wind Integration and Transmission Study, the Western Wind and Solar Integration Study Phase 1, and other analyses. It is a multi-year U.S. Department of Energy-funded research project designed to simulate operations of the largest power system in the world with high penetrations (up to 30 percent) of wind and solar generation.

The final results from ERGIS, released in August 2016, are here - alternatively here's a great summary by David Roberts of Vox.