Production of products with favourable GHG emission reductions from cellulosic feedstocks

摘要

The present invention provides a process for producing one or more products for use as a transportation or heating fuel. In various embodiments the process comprises treating a cellulosic feedstock in one or more processing steps that release extractives from the feedstock. A solids-liquid separation is subsequently conducted on the process stream comprising the extractives and solids. An aqueous stream comprising one or more of the extractives may be fed to an anaerobic digester to produce crude biogas from which one or more impurities may optionally be removed. In various embodiments the process further comprises providing a solids stream to a thermal process. A product produced or derived from the thermal process may displace a product made from fossil fuel. One or more products obtained or derived from at least one of the foregoing process steps are provided for use as a transportation or heating fuel. In various embodiments the process enables advantaged fuel credit generation.

主权项

1. A process for producing a transportation fuel comprising the steps of:
(i) pretreating a cellulosic feedstock in one or more processing steps that release extractives comprising at least acetic acid, acetate, or a combination thereof from the feedstock; (ii) conducting a solids-liquid separation on a process stream comprising the extractives and solids, thereby producing an aqueous stream comprising soluble extractives and a solids stream comprising insoluble components; (iii) feeding at least a portion of the aqueous stream comprising the soluble extractives to an anaerobic digester to produce crude biogas; (iv) removing at least 80 weight % of carbon dioxide present in the crude biogas to produce purified biogas; (v) providing an inorganic salt-containing liquid stream originating from the anaerobic digester and introducing at least a portion of the inorganic salt-containing liquid stream to (a) the anaerobic digester; (b) a stage upstream of the anaerobic digester and downstream of step (i); or (c) a combination thereof, wherein the at least a portion of the inorganic salt-containing liquid stream is not subject to water removal to produce a concentrated salt stream prior to the introducing; (vi) purging a stream comprising inorganic salt from said inorganic salt-containing liquid stream and subjecting the purged stream to a water removal step; (vii) providing solids from at least one stream selected from the solids stream comprising the insoluble components and a second solids stream comprising insoluble components to a thermal process to produce an energy product; (viii) introducing the purified biogas produced in step (iv) to a pipeline for transporting methane and causing withdrawal of an amount of methane from at least one of the pipeline and a connected pipeline; (ix) providing one or more products obtained or derived from step (viii) for use as a transportation fuel; and (x) generating or causing the generation of a renewable fuel credit wherein the inorganic salt-containing liquid stream introduced in step (v) comprises a fraction of the inorganic salt-containing liquid stream originating from the anaerobic digester effective to reduce overall GHG emissions relative to a comparative process wherein the complete inorganic salt-containing stream is subject to water removal and biogas yielded by the comparative process is used for generating internal heat and electricity rather than as a transportation fuel.