Dr. Paulina Jaramillo
Assistant Research Professor,
Department of Engineering
and Public Policy,
Carnegie Mellon University


Executive Director,
RenewElec Project

Previous life cycle assessment (LCA) studies using limited system boundaries have attempted to quantify the benefit of offsetting coal use. However, these studies do not consider the operations of the power grid and how changes to the operations of individual power plants will affect the system. In this study, simplified economic dispatch models (representing existing power plants in a given region) and historical load data are used to determine how natural gas and coal utilization will change short-term in response to changes in natural gas prices and the retirement of coal power plants. The associated changes in fuel mix, life cycle GHG emissions, and sulfur and nitrogen oxides are reported. Results indicate that the change in air emissions are lower than suggested by life cycle assessment studies. In addition, while net reductions of SO2 and NOx occur in the systems analyzed, some counties will likely see increases in the damage costs associated with these emissions. This study shows that traditional life cycle studies overestimate the benefits of fuel switching and that incorporating the operations of energy systems is needed to properly capture these benefits.