PNNL reaches major milestone in the demonstration of biocrude conversion into renewable diesel
Type of post: NEWS.
A large-scale demonstration converting biocrude to renewable diesel fuel has passed a significant test, operating for more than 2,000 hours continuously without losing effectiveness. Scientists and engineers led by the U.S. Department of Energy’s Pacific Northwest National Laboratory (PNNL) conducted the research to show that the process is robust enough to handle many kinds of raw material without failing.
Press release: “Biocrude Passes the 2,000-hour Catalyst Stability Test”, 25/03/2021.
Figure 1. Basic flow diagram of the whole process (Illustration by Michael Perkins, PNNL)
The initial step in the process is called hydrothermal liquefaction. Wet wastes from sewage treatment and discarded food can provide the raw materials for this innovative process, which converts and concentrates carbon-containing molecules into a liquid biocrude. Just as crude oil from petroleum sources must be refined to be used in vehicles, this biocrude needs to be refined into biofuel, undergoing a hydrotreating process.
The demo project took place at the Bioproducts, Sciences, and Engineering Laboratory on the Richland campus of Washington State University Tri-Cities. For 83 days, a constant flow of biocrude was fed into the reactor. The hydrotreating process introduces hydrogen into a catalytic process that removes sulfur and nitrogen contaminants found in biocrude, generating a combustible end-product of long-chain alkanes, the fuel used in vehicle engines.
The research showed that essentially any biocrude, regardless of wet-waste sources, could be used in the process and the catalyst remained robust during the entire run. While this is just a first step in demonstrating robustness, it is an important step. For the industry to consider investing in this technology, these kinds of demonstrations that show durability and flexibility of the process are needed.
Knowing that transporting biocrude to a treatment facility could be costly, modelers are looking at areas where rural and urban waste could be gathered from various sources in local hubs. For example, they are assessing the resources available within a 50-mile radius of Detroit. There, the sources of potential biocrude feedstock could include food waste, sewage sludge and cooking oil waste. In areas where food waste could be collected and diverted from landfills, much as recycling is currently collected, a processing plant could be up to 10 times larger than in rural areas and provide significant progress toward cost and emission-reduction targets for biofuels.
The next steps for the research team include gathering more sources of biocrude from various waste streams and analyzing the biofuel output for quality. In a new collaboration. PNNL will partner with a commercial waste management company to evaluate waste from many sources. Ultimately, the project will result in a database, which could help decide how facilities can scale up economically.
