The Invention 

Argonne’s Enhanced Renewable Methane Production System provides a low-cost process that accelerates biological methane production rates at least fivefold. The innovative system addresses one of the largest barriers to expanding the use of renewable methane — the naturally slow rate of production. To overcome this challenge, Argonne researchers examined the natural biology of methane production, the natural processes for carbon dioxide (CO2) sequestration, and the environmental quality of the water found in coal bed methane wells. Their research led to the novel, low-cost treatment that enhances the heating value of biogas, delivering a gas that is close to pipeline quality. This system offers an improved means of producing biological methane at wastewater treatment plants, farms, and landfills. 

Argonne’s system also simultaneously sequesters the CO2 produced during the process by reacting with magnesium and calcium silicate rocks. This innovation links the biological conversion (renewable carbon source being converted to methane and carbon dioxide) to a geochemical mechanism (producing solid carbonate-enriched minerals), thus eliminating CO2 emissions. 

Benefits 

• Produces near-pipeline-quality methane 
• Enables simultaneous carbon dioxide sequestration

Applications and Industries

• Wastewater treatment plants 
• Recovery of methane from manure and agricultural processing 
• Recovery of methane from food processing wastes 
• Methane from other carbonaceous feedstock. 

Developmental Stage 

Reduction to practice testing is complete. Researchers are now working on prototype-scale testing with field testing to follow. 

The Innovation

The biogas made from biosolids generated at wastewater treatment plants in the anaerobic digesters (ADs) contains high amounts of CO₂ and hydrogen sulfide (H₂S), and other gases as impurities that reduce its utility. H₂S is corrosive at very low levels. In order to make biogas usable as a transportation fuel, its methane content must be enriched to the level found in natural gas by depleting CO₂; and H₂S levels must also be reduced. Researchers have made various previous attempts to separate CO₂ in biogas production systems and thus enrich the methane content in biogas. However, among the disadvantages of this approach are that the H₂S must be removed separately. Most of these methods are not economical, because post-production processing of biogas is required.

Previously, researchers at Argonne National Laboratory had developed processes for in situ treatment of ADs to enrich the methane content in biogas to the levels found in natural gas. First, the Argonne researchers used pulverized rocks rich in CaCO₃ and MgCO₃ that sequesters the CO₂ (background patent 8,247,009). The pulverized rocks were placed in the AD in removable mesh buckets. However, such rocks must be mined, pulverized, and transported, each of which adds costs.

Argonne researchers next used a locally available agricultural by-product, biochar (charcoal), in the ADs and achieved reduction of both CO₂ and H₂S, with in situ sequestration of carbon, and methane enrichment of biogas to the pipeline-quality level of natural gas with >85% methane. Biochars from various sources perform similarly in methane enrichment in biogas. It is possible that some geographic regions may have biochar sources that may be functionally equivalent to the biochars used in Argonne studies and industrial-scale pilot testing.

The biochar used thus far by Argonne is rich in divalent and monovalent cations, calcium, potassium, and magnesium, which has increased these cations in the digestate that can be used as organic solid fertilizer—leading to a significant revenue stream. Chemical analysis reveals that organic solid fertilizer is rich in nitrogen, phosphorous, potassium, and sulphur.

Developmental Stage

Pilot-scale process evaluation performed at a third-party site.

Availability/Commercial Readiness

Ready for development under a research partnership

The Innovation

Production of fuels from renewable energy sources can address many important national and global issues. Rising energy costs and the uncertainty in supply of crude oil have the ability to affect national security. Rising CO2 levels resulting from the world’s thirst for liquid fuels pose substantial climate and ecosystem threats.

Photosynthetic bacteria can be a renewable source of fuel molecules. The photosynthetic machinery in these highly pigmented bacteria includes cofactors (chlorophyll, carotenoids, quinones, etc.) that are anchored in the proteins by long hydrocarbon tails. These anchors can be used directly as fuel substitutes once they are separated from the bacteria that produced them. They are more compatible with modern engines than are molecules that comprise current-day biodiesel formulations (sourced from plant fatty acids). In this alternative approach to efficient production of next-generation biofuels, Argonne researchers have engineered photosynthetic bacteria and developed specific Rhodobacter strains and processes that mass produce the fuel molecules (such as phytol, shorter isoprenols, and other atypical alcohols) and export them from the cell to be separated and used directly as fuel in compression-ignited (diesel) engines. The molecules require no further chemical upgrading for use.

The Rhodobacter species of photosynthetic bacteria are facultative and are frequently known to bloom in animal waste lagoons in the summer in the Midwest. This versatility, as such, can be exploited for adaptation of their growth to whatever feedstocks are prevalent in local areas. More than 115 engineered Rhodobacter strains are under evaluation at Argonne, and a variety of screening methodologies has allowed selection of strains that are relatively omnivorous with respect to the nutrient and energy requirements used for conversion processes (e.g., the use of light). Depending upon the type of separations process used downstream for recovery, fuel molecules can be secreted into the fermentation broth or internalized as storage reserves for later harvest and extraction from bacterial cell pellets.

Argonne is pursuing industrial partnerships to scale and commercialize this technology.

The Benefits

The Rhodobacter strains developed at Argonne have the following benefits over traditional approaches:

• Flexibility: the engineered bacteria produce biofuels using a variety of growth modes (including photosynthetic) and can thrive on carbon sources available in most areas. 
• Versatility: the bacteria can grow on waste materials (carbon and water) not currently used for food or as feedstocks for other processes. 
• Simplicity: Direct production is realized by single-celled organisms exporting product into the culture medium. 
• Compatibility: the biofuels produced can be consumed ​“as is” or mixed with other fuels without the need for refining (cracking) or distillation. 
• Transportability: Rhodobacter fuel bioreactors can be set up at any (including those seemingly most remote) location(s) for production of liquid fuel or for conversion in diesel generators to produce electricity on demand. 
• Sustainability: 30–70% of waste from the new process consists of lipids, which can be modified to produce conventional biodiesel. 

Application and Industries

• Transportation sector
• Waste-to-energy facilities
• Remote operations requiring liquid fuels or electricity

Developmental Stage

Experimental-scale production of biofuel achieved; ready for scale up.

Availability/Commercial Readiness

Available for licensing and scale up or further development to focus on production of specialized fuels or chemicals.

The Innovation

Cell membranes are the interface between an organism and its environment. These biological structures contain proteins that are extremely important for many cellular processes (e.g., nutrient uptake, metabolic waste excretion, energy metabolism, and response to external stimuli). Because of their mediating roles between external stimuli and internal cellular metabolism, membrane proteins account for more than 60% of drug targets.

Membrane proteins, however, present unique challenges because they are hydrophobic, which means they are highly unstable and insoluble in the aqueous environments typically used to produce and characterize hydrophilic proteins. It is therefore difficult to produce and purify them in quantities and at a level of quality sufficient for conducting structural or functional studies. That is also why the number of unique membrane protein structures determined to date lags far behind the number of those known for water-soluble proteins.

There are few available systems that enable heterologous expression of membrane proteins. Most were adapted from soluble protein expression systems and usually present challenges for research projects working on membrane proteins. For example, such systems using E. coli often produce insoluble aggregates or cause host toxicity as membrane space is limited. Alternatively, eukaryotic expression systems are costly and cumbersome to implement.

In contrast, a unique system for membrane protein expression invented by Philip Laible and Deborah Hanson in the Biosciences Division at Argonne National Laboratory makes it possible to obtain reasonable yields of functional membrane protein. This proprietary method uses photosynthetic bacteria (Rhodobacter) for the expression of heterologous membrane proteins.

Rhodobacter cells produce extremely large amounts of intracellular membrane when cultured under certain conditions.Synthesis of foreign (or native) membrane proteins and this intracellular membrane can be coordinated in these bacteria. Partial purification of the expressed membrane proteins is afforded because they are sequestered in these membrane vesicles, which are easily separated by size. Vesicles enriched in target membrane proteins can be used directly in many types of activity assays. Recently, work with the Rhodobacter expression system has become less cumbersome by additional engineering of strains that allow the direct uptake of foreign DNA (patent application pending). Previous methods used a two-step process: foreign DNA was first introduced into E. coli cells, which were then mated with Rhodobacter cells – mobilizing and transferring the foreign DNA by a process known as conjugation. Rhodobacter strains can now be manipulated using common laboratory methods (e.g., chemical or electroporetic transformation).

The Benefits

This method offers such advantages as lower production costs, ease of purification, scalability, and high yields of membrane proteins (0.5 mg/L to as high as 20 mg/L culture). The system permits the simultaneous production and sequestration of foreign membrane proteins, yielding a higher fraction of proteins in soluble form, as well as avoiding toxicity to the host. It has strong applications in both the pharmaceutical and biotechnology industries. As biologics become more mainstream, large quantities of active membrane proteins will be required for regulatory testing. Certain membrane proteins of therapeutic importance have been overexpressed with success, and research is under way to validate the method further for other classes of industrially relevant membrane proteins.

Application and Industries

• A research tool for expression of challenging proteins
• Scaled production for biologics testing and drug discovery efforts

Publication Information

P. D. Laible et al., J. Struct. Funct. Genomics 5: 167–172 (2004)

Developmental Stage

Ready for commercialization