Reducing Pollution from Aviation and Ocean Shipping

International aviation and ocean shipping are significant and potentially fast growing sources of greenhouse gas emissions. Both sectors also contribute to poor local and regional air quality. This thesis analyzes three interventions aimed at reducing air emissions from airplanes and ships. The first is the use of tugs, or an electric motor embedded in the landing gear, to propel the aircraft on the ground. If airlines were to tow all large narrowbody aircraft on domestic service from the gate to the edge of the runway before take off at 41 of the 50 busiest airports in the U.S., CO2 emissions would fall by 0.5 million tonnes annually. In addition, the switch would produce $150 million in annual air quality benefits from reduced emissions of particulate matter, hydrocarbons and the oxides of nitrogen. Using embedded electric motors to taxi large narrowbody aircraft would cut CO2 emissions by nearly 2 million tonnes per year. The second intervention is the market based mechanism, designed to cap CO2 emissions from international aviation at 2020 levels, currently being designed at ICAO. An analysis of an early draft of this mechanism suggests that it would require airlines to offset an average of 270 million tonnes in CO2 emissions during each of the years between 2021 and 2035 when it will be active. The analysis suggests that the current proposal is complex, and poorly specified. We recommend that the mechanism be made much simpler: for example, by simply determining an airline’s offset obligations on the basis of its carbon footprint in that year. Finally, we study the costs and benefits of a more widespread use of grid electricity to energize berthed vessels. We use mixed-integer linear programming to identify combinations of ports and vessels where using shore power would produce the greatest benefit to society. We conclude that the practice could reduce CO2 emissions by 0.2 million tonnes per year and yield air quality improvements worth $80-200 million per year at no net cost to society.