Source: The AutoChannel.com | Stephanie G Seay, ORNL | November 26, 2019
A technology developed at the U.S. Department of Energy’s Oak Ridge National Laboratory and scaled up by Vertimass LLC to convert ethanol into fuels suitable for aviation, shipping and other heavy-duty applications can be price-competitive with conventional fuels while retaining the sustainability benefits of bio-based ethanol, according to a new analysis.
The analysis, published in Proceedings of the National Academy of Sciences, showed that this single-step process for converting wet ethanol vapor could produce blendstocks at $2/gigajoule (GJ) today and $1.44/GJ in the future as the process is refined, including operating and annualized capital costs. Thus, the blendstock would be competitive with conventional jet fuel produced from oil at historically high prices of about $100/barrel. At $60/barrel oil, the use of existing renewable fuel incentives result in price parity, the analysis found.
The conversion makes use of a type of catalyst called a zeolite, which directly produces longer hydrocarbon chains from the original alcohol, in this case ethanol, replacing a traditional multi-step process with one that uses less energy and is highly efficient.
“The robustness of the catalyst enables direct conversion of wet ethanol, which greatly simplifies the process, reduces the cost of ethanol purification and makes hydrocarbon blendstock production costs competitive based on the analysis,” said Zhenglong Li, staff scientist for biomass catalysis at ORNL and a collaborator on the project.
Advanced biofuels hold promise as clean-burning, carbon-neutral renewable energy sources. The goal is to create advanced liquid biofuels that can take advantage of existing pipeline delivery infrastructure and can be used in existing or advanced engines without loss of performance. The fuels are particularly attractive to help reduce net carbon emissions in heavy-duty engines such as those in aircraft, ships and large commercial vehicles where electrification is challenging.
Given current standards, the advanced biofuel could be blended at 20% with petroleum-derived jet fuel and somewhat higher for gasoline, subject to certification and verification.
Meanwhile, a life-cycle analysis of the conversion process found that its greenhouse gas emissions profile is similar to that for the ethanol fed to the process.
“Our scientists constantly push the boundaries of what’s possible to deliver breakthroughs for clean energy,” said Moe Khaleel, associate laboratory director for Energy and Environmental Sciences at ORNL. “The conversion of ethanol into hydrocarbon blendstocks takes advantage of an abundant domestic energy resource while supporting the development of thriving American bioeconomies.”
Refinements by Vertimass to the original, lab-scale process include the development of cheaper forms of the catalyst, as well as more than doubling the liquid fuel yield, the paper noted.
The paper details the refinements as well as results from analyses by Argonne National Laboratory, the National Renewable Energy Laboratory, Vertimass, and ORNL in collaboration with Dartmouth, the Federal Aviation Administration, Boeing, Pennsylvania State University, University of California-Riverside, Imperial College of London, the Brazilian Bioethanol Science and Technology Laboratory, and the Brazilian Center for Research in Energy and Materials.