Status of Hydrogen Production Pathways - Comparison of Energy Efficiencies, Fossil Fuel Use, Greenhouse Gas Emissions, and Costs

A benefit of hydrogen as an energy carrier is that is can be produced from a diverse set of energy resources by means of a variety of process technologies. Energy resources include fossil, renewable, and nuclear energy; while process technologies include thermochemical, electrochemical, photolytic, and biological processes. We used the analytical tools H2A and GREET to evaluate several hydrogen production pathways in terms of energy efficiency, greenhouse gas emissions, and cost. We evaluated central and distributed production facilities, the distinction being the quantity of hydrogen produced (in kilograms or gasoline gallon equivalents (gge) of hydrogen per day). For relatively immature production pathways, we assessed the state of technology. Critical technical barriers that must be overcome to realize the potential of these technologies are discussed.