The National Academies of Sciences, Engineering, and Medicine Transportation Research Board has released a new report on the air quality impacts of sustainable alternative jet fuel (SAJF) emissions.

SAJFs are synthetically made fuels intended to reduce carbon emissions in commercial aviation. They can be used within the existing US fuel distribution system without making engine modifications. To date, five different SAJF fuel production pathways have been defined by the aviation industry as safe for use in commercial aircraft, and more are under review.

One of the main purposes for airlines to use SAJFs is to reduce pollutants, such as those listed in the Clean Air Act. These include carbon monoxide, sulfur dioxide, nitrogen oxide, particulate matter (soot), unburnt hydrocarbons and hazardous air pollutants.

The State of the Industry Report on Air Quality Emissions from Sustainable Alternative Jet Fuels distils the emissions data from 51 reports of SAJF quantitative emissions analyses.

Its data summary shows that when blended with conventional jet fuels defined by ASTM international standards, SAJFs:

  • Significantly reduce sulfur dioxide and particulate matter
  • Generally reduce carbon monoxide and unburnt hydrocarbon emissions
  • Minimally reduce or have no effect on nitrogen oxide emissions

Based on projected growth of the aviation industry, other drivers for the use of alternative jet fuels include domestic energy security, diversity of fuel supplies, less fuel price volatility, lower long-term fuel cost and  job creation, according to the US Department of Energy.

Laying the groundwork

“This state of the industry report is the first review of its kind,” says Dr. Philip D. Whitefield, chair and professor of chemistry and director of the Center for Research in Energy and Environment (CREE), S&T’s lead investigator. “It lays the groundwork to define the environmental impact of SAJF emissions on air quality in and around airports throughout the world and gives them the information they need to start determining strategies for switching to alternative jet fuels.”

 He added: “Until this report, these reductions had not been well-defined…All evidence suggests that the use of SAJFs will substantiate reductions in pollutants emissions.”

The report’s content comes from projects sponsored by federal agencies, the aviation industry and academia, Whitefield notes.

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