Environmental and economic assessment of alternative transportation fuels

• Main Author: Withers, Mitch Russell
• Other Authors: Steven R.H. Barrett.
• Format: Others
• Language: English
• Published: Massachusetts Institute of Technology 2014
• Subjects: Aeronautics and Astronautics.
• Online Access: http://hdl.handle.net/1721.1/90808

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2014. === Cataloged from PDF version of thesis. === Includes bibliographical references (pages 56-63). === Alternative fuels have the potential to mitigate transportation's impact on the environment and enhance energy security. In this work, we investigate two alternative fuels: liquefied natural gas (LNG) as an aviation fuel, and middle distillate fuel derived from woody biomass for use in aviation or road transport. The use of LNG as a supplemental aircraft fuel is considered in the context of the Lockheed Martin C- 1 30H and C-130J transport aircraft. We estimate the cost of retrofitting these aircraft to use LNG and the savings from reduced fuel expenses. We evaluate the societal impacts of LNG within a cost-benefit framework, taking into account resource consumption, human health impacts related to air quality, and climate damage. We find that aircraft operators can save up to 14% on fuel expenses (retrofit costs included) by employing LNG retrofits, with a 95% confidence interval of 2-23%. Society can also benefit by 12% (3-20%) from LNG use as a result of improved surface air quality, lower resource consumption, and climate neutrality relative to conventional fuel. These results are highly dependent on fuel prices, the quantity and cost of the LNG retrofits, and the frequency and length of missions. Woody biomass harvested from old-growth forests produces a large carbon debt when used as a feedstock for transportation fuel. Managed forests are an attractive alternative for inexpensive biomass production with the potential to reduce this carbon debt. We study the effect of forest management practices on the carbon debt payback time resulting from harvesting woody biomass from managed forests for middle distillate fuel production. We also calculate the breakeven time in terms of radiative forcing, temperature change, and economic damages. We find that biofuels produced over a period of 30 years have higher CO 2 emissions than fossil fuels for 59 years, higher radiative forcing for 42 years, higher temperature change for 48 years, and higher cumulative discounted (1-2%) economic damages for more than 100 years. These damages never break even at discount rates above 2%. Payback times can be reduced by increasing the age at which biomass is harvested. When biofuel production is sustained indefinitely, greater climate benefits are achieved over the next 100 years by instead producing long-lived wood products like lumber. === by Mitch Russell Withers. === S.M.