Carbon Sequestration Pilot Program Results: Estimated Land Available for Carbon Sequestrationin the National Highway System

The Federal Highway Administration (FHWA) established the Carbon Sequestration Pilot Program (CSPP) in 2008 to assess whether a roadside carbon sequestration effort through modified maintenance and management practices is appropriate and feasible for state Departments of Transportation (DOTs) when balanced against ecological and economic uncertainties. CSPP findings are expected to inform DOTs that may be considering the implications of future climate change legislation or that independently want to evaluate the cost effectiveness of using National Highway System (NHS) right of way (ROW) to generate revenue from the sale of carbon credits, offset their own emissions, or meet statewide greenhouse gas emissions objectives. The project team used data from Minnesota and several other states to estimate the amount of unpaved NHS ROW available for carbon sequestration—marking the first time that a rigorous study has been conducted to quantify the amount of state DOT-managed soft estate acreage. In the first of two analytical approaches used, ROW widths at random locations in nine states were manually measured on property maps to provide a distribution of common ROW dimensions and observed vegetation types. A subsequent geographic information system (GIS) analysis of 1,000 random locations nationwide provided insight into the types of land cover in close proximity to the NHS. Results indicate that there are approximately 5.05 million acres in the NHS nationwide, with a likely range of 1.4 to 8.7 million acres. Roughly 68 percent, or 3.4 million acres, is unpaved. Evidence shows that the land cover has undergone little change since 1992. The project team estimates the NHS ROW has approximately 91 million metric tons (MMT) of carbon currently sequestered in vegetation and is currently sequestering approximately 3.6 MMT of carbon per year, or 1.06 metric tons of carbon per acre per year. This equals the annual carbon dioxide emissions of approximately 2.6 million passenger cars. At its carbon equilibrium, the entire NHS ROW is estimated to be able to sequester between 425 and 680 MMT of carbon. Using a hypothetical carbon price of $20 per metric ton, this equates to a total potential value of $8.5 to $14 billion nationwide.