Optimizing Renewable Energy

In well over half of the United States, legislatures have required that an increasing percentage of electric power be generated by renewables. The legislation has been supported by a coalition of three parties: environmentalists who want to reduce greenhouse gas and other pollution, advocates of green jobs, and energy independence groups.

Professor Jay Apt has developed an extensive body of work demonstrating that it matters how renewable resources are integrated into the U.S. electricity grid. Renewables, including wind and solar, are variable and intermittent sources. Nonetheless, the electricity grid must provide reliable electricity on demand, 24 hours a day. Recently, Apt and his colleagues published a summary of their research over the past five years pertaining to this important issue titled, “Smart Integration of Variable and Intermittent Renewables,” that clearly demonstrates the value of a quantitative approach to analyzing integration.

For instance, wind-generated electricity presents variability on every time scale from seconds to days, and this variability must somehow be accommodated as wind is incorporated into the electric grid. Apt’s research demonstrates the utility of using a Tepper School strength in frequency domain analysis to see how many and what types of firm generation are required in these instances. Limited quantities of wind power can be successfully integrated by using the current generation and demand-side response mix, but as deployment of this variable resource increases, the resulting variability will be a bit more costly to mitigate. Public discourse that addresses the issues surrounding the cost of compensation needed would be a significant contribution to large-scale deployment of renewables.

Every generation of technology has good and bad points. Jay Apt and the researchers at the Tepper School and Carnegie Mellon Electricity Industry Center are on the leading edge of quantifying how to utilize new technologies to best advantage when integrating large-scale renewable electricity.

Editors note: This research summary was prepared by W. Michael Griffin, co-director and executive director of CMU's Green Design Institute and assistant research professor, Engineering and Public Policy and Tepper School of Business.

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Faculty & Research

Professor Jay Apt

“Smart Integration of Variable and Intermittent Renewables"

Carnegie Mellon Electricity Industry Center