With funding from the U.S. Department of Energy’s Bioenergy Technologies Office (BETO), Oak Ridge National Laboratory (ORNL) evaluated the performance of several key materials used in biofuel production, processing, storage, and transportation systems. Rubber components and sealants are often exposed to chemically complex biofuel intermediates, which can cause materials to swell and affect the overall performance and service life of the product. Selection of materials that resist these effects is, therefore, a critical element for ensuring the long-term economic viability of biomass processing systems. ORNL’s recently released study provides the necessary data to help the fueling infrastructure community produce safe and reliable biofuel production and delivery systems. Advanced biofuels company Butamax also provided funding for this project.

The production of biomass-derived, infrastructure-compatible transportation fuels can be accomplished through many different routes. One of the more efficient pathways is a process called fast pyrolysis, during which biomass is rapidly heated to temperatures of 400°C to 650°C in an oxygen-starved environment. This rapid thermal treatment breaks down the tough, rigid cellular structure of plant material, turning it into a vapor that is then condensed down into a dark brown liquid called “bio-oil.” Before this bio-oil can be converted into a fuel or used in a refinery, it must undergo upgrading. This is due in large part to the reactivity and water content of the raw bio-oil. 

Considering that these chemical properties may affect the long-term performance of materials used in bio-oil processing systems, ORNL examined the compatibility of six different elastomers and used the results to provide guidance on proper seal material selection. They determined that both silicone and a rubber called styrene butadiene performed well after long-term exposure to bio-oil. These two materials are also among the least expensive of those tested, potentially improving the economics associated with advanced biofuel production.

Bio-oil derived by fast pyrolysis of biomass represents a potentially significant source of hydrocarbon transportation fuels. As this technology continues to scale up, the production costs will need to be comparable with those for petroleum production. ORNL’s compatibility studies are helping to ensure implementation of these technologies is not limited because of materials issues. 

Oak Ridge National Laboratory is one of eleven Energy Department national laboratories that conduct bioenergy research. This project is part of BETO’s Conversion Research and Development Program, which develops viable technologies for converting biomass feedstocks into cost-competitive biofuels and bioproducts through biological and chemical processes.