Meeting the Multiple-Source Feedstock Challenge
It has long been understood that commercially available, large-scale gasifiers are an imperfect fit for biomass conversion. In the past, fuel sourcing, preparation, and feed problems—combined with unique ash properties and tar production—made it very challenging to reliably operate a large gasifier on renewable sources. Is this still true today?
Researchers at the Energy & Environmental Research Center are not convinced, and they are gathering the data to make their case.
A multifaceted team of engineers and scientists at the EERC is performing tests to demonstrate that there are near-term opportunities for large-scale biomass gasification. The team is focused on testing the performance of coal and biomass blends in systems that mimic commercially available gasifiers. The testing at EERC is in support of the Connecticut Center for Advanced Technology’s efforts to identify alternative sources of liquid fuels for military applications. To date, several pilot-scale test campaigns have been completed at EERC that demonstrate the ability to gasify various sources of biomass blended with various ranks of coal. The testing is in support of CCAT’s work for the U.S. government to help identify potential alternative sources of liquid fuels that have an equal or better carbon footprint than traditional liquids.
By developing systems that can produce alternative liquid fuels and power, the U.S. military sees the potential for improved energy security, competitive fuel costs, increased efficiency, and environmental sustainability. Cofeeding biomass with coal and utilizing CO2 capture technologies will allow CO2 emissions from these advanced energy technologies to be minimized.
When CCAT originally set out to develop this project, one of the main goals was to ensure that the technologies being considered were near-term and supported commercially. To meet these goals, CCAT put together a highly qualified team, in addition to EERC, that includes the U.S. DOE, Arcadis/Malcom Pirnie, Avetec Inc., and world-renowned experts in gasification technologies.
EERC is working with the CCAT team to develop the key data needed to prove reliability and availability by performing coal and biomass gasification test runs in the EERC’s pilot-scale transport reactor integrated gasifier (TRIG) and a small, pilot-scale entrained-flow gasifier. The TRIG technology is currently being installed commercially as part of the Kemper County (Miss.) energy facility, a 582-megawatt integrated gasification combined-cycle facility. Hundreds of entrained-flow gasifiers are operating at commercial scale around the world today, and the technology is supported by large companies such as Shell, Siemens, and General Electric, to name a few. The team believes that the focus on commercially available systems is of critical importance.
Because commercial systems are very large and would require vast amounts of biomass, the team believes that coal-biomass blends up to a maximum of 30 percent by weight represent the highest blend ratio that would be fed to the gasifier. In addition, to ensure that the blending requirements could be met year round, the team is developing data on various sources of biomass that include wood, corn stover, switchgrass, and other opportunity feedstocks that could be sourced around the globe.
Each of these sources of fuel has unique challenges and opportunities based on the basic properties of the biomass. The pilot-scale testing has shown promise that these fuels can be operated reliably in commercial gasifier designs if the physical and chemical properties of the material are understood prior to injecting into the gasifier.
This project, and the technical and economic information it generates, could help open doors for real-world conversion of coal and biomass to liquid fuels. This may help improve investor confidence and bring advanced technologies one step closer to the commercial marketplace. The testing at the EERC is expected to continue through the end of the year.
Author: Joshua J. Stanislowski
Research Manager, EERC