Biogenic materials, including agricultural residue or other organic waste, hold a considerable amount of energy density in the form of carbon and hydrogen, but efficiently processing these solid materials to harvest energy can pose challenges. The Modular Conversion TechnologyTM (MCT) developed by Kore Infrastructure (Los Angeles, Calif.; www.koreinfrastructure.com) employs slow pyrolysis in a continuous plug-flow process in the absence of oxygen to convert biomass into a biogas mixture and solid carbon. “We are heating a continuous flow of biogenic feedstocks using slow pyrolysis to upwards of 1,000°F over about 45 to 60 minutes. This combination of temperature plus time volatizes nearly every chemical component except the inorganic ash and fixed carbon,” explains Kore senior technical advisor Joe Zuback.
At the beginning of the process (diagram), solid feedstock is reduced in size to around 1-in. in diameter, as needed. It is then fed continuously through two air-lock valves into an upper retort (a large-diameter pipe outfitted with a slow-speed augur to push the feed through). Once the feedstock passes through the first retort, it is dropped into a similar lower retort, exiting again through two air-lock valves that prevent oxygen from entering. Heating gas enters below the lower retort and flows in the interstitial space between retorts in the opposite direction of feedstock flow. “The two horizontal retorts in series are positioned vertically to maximize heat-exchange area in the smallest equipment footprint,” mentions Zuback. For the pyrolysis heat source, Kore’s process can use combusted gas, stack gas or air heated with waste heat. Heat can also be provided by combustion of a portion of the produced biogas, which could also be used for onsite power generation.
Kore has operated a 1-ton/h pyrolyzer over a two-year period for a project in Los Angeles sponsored by Southern California Natural Gas and the South Coast Air Quality Management District. The company has also begun work to deploy its technology at a landfill operated by Waste Management, Inc. (Houston; www.wm.com) in Lancaster, Calif. to process large solid material leftover from composting operations, as well as demolition wood and other organic waste. “Landfill diversion in California now is being mandated by law, and we think that will expand to other regions. Our MCT is sized small enough to be co-located at a landfill to support the environmental services industry to divert organics and upgrade them for clean energy use, whether it’s clean power or hydrogen or renewable natural gas,” notes Cornelius Shields, Kore’s founder and CEO. Next on the horizon for Kore are installations in the cement industry for producing a renewable coal alternative, and for handling waste in the forestry industry.