An AG reader has suggested that the efficiency of BTL (Biomass To Liquid fuels) clearly could be enhanced, if two or more fuels were produced simultaneously from the feedstock. It is similar to and a somewhat simpler approach than “a modest proposal” previously proposed by Engineer-Poet.
While there has been considerable study about co-generation, i.e., converting biomass, especially agricultural, lumber and municipal solid waste to heat and power, there remain areas for further development.
“Here is one example, though I’m sure there are more.” The suggestion is the pyrolysis of biomass (either waste biomass or dedicated energy crop biomass), specifically, application of the Best Energies process to yield Syngas.
Note: Lignocellulosic biomass is composed of cellulose and hemicellulose, and lignin. The carbohydrate polymers (cellulose and hemicelluloses) are tightly bound to the lignin, by hydrogen and covalent bonds. Biomass comes in many different types, which may be grouped into four main categories: 1) wood residues, including sawmill and paper mill discards, 2) municipal paper waste, 3) agricultural residues, including corn stover (stalks and straw) and sugarcane bagasse, and 4) dedicated energy crops, which are mostly composed of tall, woody grasses.
Biomass Feedstock for Slow Pyrolysis
Of course, first and foremost, is production of Syngas. The AG reader promotes a specific process, the Best Energies process, which takes a portion of the Syngas product for further drying of the biomass and then carbonization.
The remaining Syngas is processed into liquid fuel. The AG reader suggests DME (Di Methyl Ether), a.k.a., ETBE (Ethyl Tert Butyl Ether). This blog previously noted that Penn State researchers have suggested the production of DME by means of a similar process.
A byproduct from the Best Energies process is char, which becomes feedstock for production of the second fuel, specifically, the application of the Great Point Energy process, to convert the char to methane.
Entrained flow gasification technology can make use of many different types of coal, petroleum coke, several sewage and industrial sludges, oils, slurries, liquid production wastes and biomass. The coal industry strongly advocates these gasification technologies, even when they can use feedstock other than coal, since a high minimum throughput of many tons per day is required to be cost effective. It even will work with bitumen, a.k.a., tar sands, thus, a process endorsed by Big Oil. What Emperor Fossil wants…
Jim Fraser reports that Great Point is a Boston-area start-up with a low-cost process for converting coal into pipeline-grade natural gas.
The process [takes place] in one single, efficient reactor by moving the catalysts into the gasifier itself. The key is a proprietary, recyclable catalyst developed in house with help from gasification and catalysis experts at Southern Illinois University, the University of Toronto, and the University of Tennessee, among others. The catalyst lowers the amount of heat required to gasify coal and simultaneously transforms the gasified coal into methane.
In fact, the heat released in the syngas-to-methane step is sufficient to sustain the gasification, eliminating the need to fire up the reactions with purified oxygen. "It’s perfectly heat balanced," says CEO Andrew Perlman.
In the AG reader’s example, heat from Great Point Energy process is used to reduce the amount of Syngas needed for 1) drying the biomass and 2) driving the pyrolysis. Integrating the processes thereby improves efficiency. “The result is the thermally efficient production of two, CO2-neutral fuels from a single biomass source.