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, and energy facility projects. Her expert witness, business consulting, and arbitration services have involved industry restructuring, market analyses, regulatory policies for renewables and energy efficiency, transmission planning, siting and cost-allocation, wholesale and retail market design, contract disputes, resource planning, resource procurement analysis, market monitoring, and asset valuations. In addition, Dr. Tierney’s work has covered regional transmission organizations, siting of generation and transmission facilities and natural gas pipeline projects, natural gas markets, electric system reliability, and environmental policy and regulation. A former Assistant Secretary for Policy at the U.S. Department of Energy and state public utility commissioner, she is chairman of the board of the Energy Foundation and a member of the National Commission on Energy Policy and the Secretary of Energy's Advisory Board. She has published widely and frequently speaks at industry conferences.