Greenhouse Gas Emissions from the Construction, Manufacturing, Operation, and Maintenance of U.S. Distribution Infrastructure for Petroleum and Biofuels

To meet greenhouse gas (GHG) emissions for the transportation sector, the United States is expected to expand infrastructure for producing and distributing lignocellulosic biofuels over the next decade. To compare the life-cycle GHG footprint of biofuels to the petroleum baseline, emissions associated with feedstock and fuel handling, storage, and transportation must be included. U.S.-specific life-cycle GHG emission factors were developed for each major distribution chain activity by applying a hybrid life-cycle assessment methodology to the construction, manufacturing, operation and maintenance of each component. A projection was then made for the fleet of infrastructure components necessary to distribute 21 billion gal. (79.5 billion L) of ethanol derived entirely from Miscanthus grass for comparison to the baseline petroleum system. Owing to geographic, physical, and chemical properties of biomass and alcohols, the distribution system for Miscanthus-based ethanol is more capital- and energy-intensive than petroleum per unit of fuel energy delivered and was estimated to be over five times more GHG-intensive than petroleum (i.e., 17—18 versus 3.2 g CO2-e/MJ of consumed fuel, ignoring feedstock production and conversion). Lower life-cycle emissions could be attained by employing more efficient and durable equipment and vehicles; reducing material losses; minimizing feedstock delivery, biofuel delivery, and consumer refueling errand distances; and producing more energy-dense biofuels than ethanol.