Alternative Fuels

Alternative aviation fuels are receiving considerable attention from researchers and policy makers alike, as a potential means to reduce greenhouse gas emissions while increasing and diversifying fuel supplies. Moreover, alternative jet fuels are generally superior to petroleum-based fuels in terms of their impacts on air quality when combusted. However, the production of alternative aviation fuels may come at a cost. For example, bio-based fuel production could compete with food production; increased agricultural activity could strain freshwater reservoirs and pollute rivers and oceans. Fuel production may be prohibitively expensive if the biomass yield is insufficient, biomass availability limited, or the conversion technology inefficient or capital-intensive. It could induce alterations in land use, which can increase CO2 emissions associated with fuel production if, for example, carbon-sinks such as forests are cleared for cropland.

Alternative jet fuels’ greenhouse gas impact must be comprehensively assessed because greenhouse gas emissions differ between pathways and feedstocks, and not all candidate fuels decrease greenhouse gas emissions on a well-to-wake, or lifecycle, basis. The overall sustainability impact of alternative fuels must be addressed using a multicriteria approach that considers technical, environmental, and economic aspects.

The Laboratory for Aviation and the Environment )LAE) conducts multidisciplinary research addressing alternative fuel’s technical, environmental, and economic feasibility. This research seeks to understand the societal benefits and costs of pursuing various fuel options. LAE has extensive knowledge in greenhouse gas emissions and water usage life-cycle analysis, and has developed techno-economic models for evaluating alternative fuel production costs. We conduct tradeoff analysis among metrics and feedstock-to-fuel-pathways, and assess economy-wide implications of biofuel mandates and goals.

In addition to researching options drop-in fuel production options, we are investigating mid- to long-term alternative fuel options. Such options pose technical challenges in aircraft design and fuel infrastructure. LAE works in collaboration with our sponsors and cost-share partners, which include federal agencies, fuel producers, aircraft manufacturers, and academic institutions.

LAE’s output is multifaceted. We create and foster knowledge on the full costs and benefits of pursuing alternative fuel options using a comprehensive set of metrics. We develop tools for fuel producers, airlines, and policy makers to assess fuel sustainability. Our jet fuel lifecycle greenhouse gas analysis framework and results are included in the GREET (Greenhouse Gases, Regulated Emissions and Energy Use in transportation) lifecycle tool, which is maintained by Argonne National Laboratory and is the benchmark for U.S. transportation fuel lifecycle analysis. The U.S. Environmental Protection Agency has used our techno-economic process flow simulations for hydroprocessed esters and fatty acids (HEFA) fuel in its ruling on the eligibility of HEFA fuel under the Renewable Fuels standard. We advise federal agencies on compliance of feedstock-to-fuel options under Section 526 of the Energy Independence and Security Act, which prohibits those agencies from procuring alternative fuels if the lifecycle GHG emissions are higher than those of fuel from conventional petroleum. We support aircraft manufacturers in determining the technical feasibility of engineering solutions to accommodate non-drop-in fuels. Through this work, LAE is doing much to mitigate aviation’s environmental impact.