A coal and biomass mixture could be a boost for the jet fuel industry, researchers said.
Overall, research “showed potentially highly effective alternative fuel resources that can end the current debate,” according to a project report. Objectives of the study, conducted by the U.S. Defense Logistics Agency and the Connecticut Center for Advanced Technology, included the investigation, through analyses and testing of the use of domestic coal and biomass mixtures to make liquid fuel (CBTL), with a focus on gasification.
The project team executed gasification testing and analyses of 150 coal-biomass feedstock tests, performing them at five different partner and facility locations.
All CO2 footprint projections of alternative jet fuel made from solid feedstocks tested were below the petroleum baseline for blended jet fuel (50 percent alternative fuel plus 50 percent petroleum-based fuel), thereby satisfying Section 526, according to the report.
Other major findings included:
• When coal was the sole feedstock, the CO2 footprint was the largest and required the most capture.
• Increasing percentages of biomass in the solid feed generally resulted in lower CO2 footprints and smaller amounts of required capture.
• Torrefied wood offers advantages in blending with coal and lowering the CO2 footprint for the CBTL plant.
• Municipal solid waste and biomass (considered to be “nuisance plants” in areas where they are abundant) may be economically feasible for use as feedstocks.
• Feedstock preparation and feed system design are critical to the successful development of a large-scale CBTL project.
• Electricity generation and CO2 displacement credits from CBTL are significant contributors to lower GHG emissions. At a ratio of 30 percent biomass, emissions were 38 to 62 percent below the baseline; with 10 percent biomass, 13 to 33 percent below the baseline; and with no biomass, 2 to 18 percent below the baseline.
On economic findings, the study found that on the rough order of magnitude, cost estimates using the techno-economic model for a 50,000 barrel-per-day CBTL plant with an entrained flow gasifier or transport gasifier showed average required selling price (RSP) of jet fuel ranged from approximately $134 to $170 per barrel, on a crude oil equivalent basis. Instances where coal was the sole feedstock resulted in the lowest RSP; increasing the percentages of raw biomass in the solid feed generally resulted in a higher RSP. Using torrefied rather than raw biomass resulted in a lower RSP, according to the report.
The project team concluded that blending various grades of coal with biomass presents a credible approach for reducing carbon dioxide emissions and producing alternative jet fuel.