The purpose of this project is to systematically identify and examine possible long-term ecological and environmental effects from the production of hydrogen from various energy sources based on the DOE hydrogen production strategy and the use of that hydrogen in transportation and power applications. From these analyses, a comprehensive impact assessment will be developed to provide reliable estimates of hydrogen leakage rates to the environment and criteria pollutants emitted from the distributed and central-scale hydrogen systems that might be deployed in the future. The project will involve modeling, data analysis and field experiments. Specific objectives include analyses to address the following: