Alternative seals for alternative fuels

When considering seal compatibility, switching an aircraft from traditional jet fuel to a synthetic fuel presents an interesting technical challenge that has both financial and practical considerations, especially for aircraft that are already in service.

There are basically two alternative fuels under consideration in the aviation industry: those synthesized using the Fischer-Tropsch process, and biojet, which is made by biological processes.

With F-T fuels, coal, natural gas, or other carbon feedstock is converted directly into a liquid fuel. This is a proven chemical process, although not an inexpensive one. The most common method of producing biojet involves extracting oil from certain strains of algae and chemically processing it into a liquid fuel. This process has not yet been developed on a commercial scale, so full-scale production costs are not yet known. Unlike F-T-derived fuels, biojet is renewable and offers a low net carbon footprint.