Dr. Tierney is an expert on energy policy and economics, specializing in the electric and gas industries. She has consulted to companies, governments, non-profits, and other organizations on energy markets, economic and environmental regulation and strategy, energy and renewables policy, and energy facility projects.

A former Assistant Secretary for Policy at the U.S. Department of Energy, she is chairman of the board of the Energy Foundation and a co-chair of the National Commission on Energy Policy. She has published widely and frequently speaks at industry conferences.

In Massachusetts, Dr. Tierney was previously Secretary of Environmental Affairs, Chair of the Board of the Massachusetts Water Resources Agency, Commissioner of the Massachusetts Department of Public Utilities, and executive director of the Massachusetts Energy Facilities Siting Council. Dr. Tierney has a Ph.D. in Regional Planning from Cornell. Her dissertation: Congressional policy making on energy policy issues.