Processes, systems, and methods for producing combustible gas from wet biomass are provided. In one aspect, for example, a process for generating a combustible gas from a wet biomass in a closed system is provided. Such a process may include growing a wet biomass in a growth chamber, moving at least a portion of the wet biomass to a reactor, heating the portion of the wet biomass under high pressure in the reactor to gasify the wet biomass into a total gas component, separating the gasified component into a liquid component, a non-combustible gas component, and a combustible gas component, and introducing the liquid component and non-combustible gas component containing carbon dioxide into the growth chamber to stimulate new wet biomass growth.

A combined hydrothermal liquefaction (HTL) and catalytic hydrothermal gasification (CHG) system and process are described that convert various biomass-containing sources into separable bio-oils and aqueous effluents that contain residual organics. Bio-oils may be converted to useful bio-based fuels and other chemical feedstocks. Residual organics in HTL aqueous effluents may be gasified and converted into medium-BTU product gases and directly used for process heating or to provide energy.

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.

The description describes the integration of a gas fermentation process with a gasification process whereby effluent from the gas fermentation process is recycled to the gasification process. The one or more effluents which can be recycled include a stream comprising microbial biomass, a product stream comprising at least a portion of the at least one fermentation product, a by-product stream comprising fusel oil, and a waste water stream comprising microbial biomass. The stream comprising biomass can be dried before it is passed to the gasification zone. At least a portion of the waste water stream can be passed to the gasification process where one use is to replace at least a portion of the process water. The waste water stream can be further processed to produce a clarified water stream and a biogas stream comprising methane either or both of which can be passed to the gasification process.

The disclosure provides for the separation and combustion of at least one hydrocarbon, oxygenate, sulfur compound, and or nitrogen compound, from industrial gas or gasification derived syngas to generate steam. A gasification process and a gas fermentation process may be integrated using tail gas from the fermentation process for the flame to combust tar and other compounds from the syngas generated by a gasification process. Integration may be achieved by removing tar and other compounds from industrial gas or gasification derived syngas using an adsorbent and regenerating the adsorbent using tail gas from the gas fermentation process. Tail gas enriched with the desorbed tar and other compounds may be used to generate steam in a steam boiler and the steam may be used for a variety of purposes including power generation to power, for example, a compressor of the gas fermentation process.

The description describes the integration of a gas fermentation process with a gasification process whereby effluent from the gas fermentation process is recycled to the gasification process. The one or more effluents which can be recycled include a stream comprising microbial biomass, a product stream comprising at least a portion of the at least one fermentation product, a by-product stream comprising fusel oil, and a waste water stream comprising microbial biomass. The stream comprising biomass can be dried before it is passed to the gasification zone. At least a portion of the waste water stream can be passed to the gasification process where one use is to replace at least a portion of the process water. The waste water stream can be further processed to produce a clarified water stream and a biogas stream comprising methane either or both of which can be passed to the gasification process.

The process described herein converts biomass directly into a combination of hydrogen, methane and carbon dioxide. A portion of the gases are collected at pressures above the thermodynamic critical pressure for water, which is 3200 psi (pounds per square inch). Typical operating pressure at the point where the first portion of gas collected can range from 3200 psi to 6000 psi. Upon cooling, most of the CO.sub.2 condenses to a liquid. At this density and pressure, the CO.sub.2 can be injected into a deep well aquifer to sequester the carbon dioxide. The overall process is superior to carbon neutral processes, can be carbon negative, and possesses the potential to reverse atmospheric CO.sub.2 trends if implemented on a global scale.

A combined hydrothermal liquefaction (HTL) and catalytic hydrothermal gasification (CHG) system and process are described that convert various biomass-containing sources into separable bio-oils and aqueous effluents that contain residual organics. Bio-oils may be converted to useful bio-based fuels and other chemical feedstocks. Residual organics in HTL aqueous effluents may be gasified and converted into medium-BTU product gases and directly used for process heating or to provide energy.

The invention provides for the integration of a gas fermentation process with a gasification process whereby effluent downstream from the gas fermentation process is recycled to the gasification process. The invention is capable of recycling one or more effluents including biogas generated from a wastewater treatment process, tail-gas generated from the fermentation process, unused syngas generated by the gasification process, microbial biomass generated from the fermentation process, microbial biomass generated from a wastewater treatment process, crude ethanol from the product recovery process, fusel oil from the product recovery process, microbial biomass depleted water, wastewater generated from the fermentation process, and clarified water from a wastewater treatment process to a gasification process.

The disclosure provides for the separation and combustion of at least one hydrocarbon, oxygenate, sulfur compound, and or nitrogen compound, from industrial gas or gasification derived syngas to generate steam. A gasification process and a gas fermentation process may be integrated using tail gas from the fermentation process for the flame to combust tar and other compounds from the syngas generated by a gasification process. Integration may be achieved by removing tar and other compounds from industrial gas or gasification derived syngas using an adsorbent and regenerating the adsorbent using tail gas from the gas fermentation process. Tail gas enriched with the desorbed tar and other compounds may be used to generate steam in a steam boiler and the steam may be used for a variety of purposes including power generation to power, for example, a compressor of the gas fermentation process.