Christoph Wollersheim

Water consumption footprint and land requirements of large-scale alternative diesel and jet fuel production.

Middle distillate (MD) transportation fuels, including diesel and jet fuel, make up almost 30% of liquid fuel consumption in the United States. Alternative drop-in MD and biodiesel could potentially reduce dependence on crude oil and the greenhouse gas intensity of transportation. However, the water and land resource requirements of these novel fuel production technologies must be better understood. This analysis quantifies the lifecycle green and blue water consumption footprints of producing: MD from conventional crude oil; Fischer-Tropsch MD from natural gas and coal; fermentation and advanced fermentation MD from biomass; and hydroprocessed esters and fatty acids MD and biodiesel from oilseed crops, throughout the contiguous United States. We find that FT MD and alternative MD derived from rainfed biomass have lifecycle blue water consumption footprints of 1.6 to 20.1 Lwater/LMD, comparable to conventional MD, which ranges between 4.1 and 7.4 Lwater/LMD. Alternative MD derived from irrigated biomass has a lifecycle blue water consumption footprint potentially several orders of magnitude larger, between 2.7 and 22 600 Lwater/LMD. Alternative MD derived from biomass has a lifecycle green water consumption footprint between 1.1 and 19 200 Lwater/LMD. Results are disaggregated to characterize the relationship between geo-spatial location and lifecycle water consumption footprint. We also quantify the trade-offs between blue water consumption footprint and areal MD productivity, which ranges from 490 to 4200 LMD/ha, under assumptions of rainfed and irrigated biomass cultivation. Finally, we show that if biomass cultivation for alternative MD is irrigated, the ratio of the increase in areal MD productivity to the increase in blue water consumption footprint is a function of geo-spatial location and feedstock-to-fuel production pathway.

The Impact of Fuel Price on Airline Fuel Efficiency and Operations

Jet fuel prices have increased significantly during the past decade, resulting in fuel cost becoming airlines’ primary operating cost. Given the relevance of the air transport system for the economy, it is important that industry and policy makers are informed of past changes and likely future impacts driven by increased fuel prices. The prominence of this issue for policy makers is highlighted by the FAA Modernization and Reform Act of 2012, which explicitly required the execution of a fuel price impact study. Moreover, future market-based carbon constraint policies may further increase the effective price of jet fuel. Understanding the operational impact of fuel price increase may inform such policies. This analysis found that fuel price increase after 2004 is correlated to airline fuel efficiency improvement. Although fuel efficiency gains from new, more fuel efficient, aircraft appear to be limited between 2004 and 2010, data analysis and interviews provide evidence for a number of operational changes, such as cruise speed reduction, which may have led to improved airline fuel efficiency. It was found that increasing fuel price may have reduced short stage length traffic. However, there appears to be little impact on network structure and airport connectivity. Simulation of a number of future fuel price scenarios indicate that increasing fuel price would reduce the rate of growth of airline operations, but total operations would continue to grow through to 2025. Simulation results also demonstrate an important link between GDP and fuel price in relation to airline operations. GDP growth can increase fuel price, but also dampen the impact on airlines of fuel price increase, relative to a reduced GDP growth scenario. A key finding of this paper is that increased fuel price appears to lead to improved airline fuel efficiency, but slow investment in new aircraft in the short term.