1. Solving the Biomass recalcitrance challenge: Impacts go beyond 2010
Dr. Himmel from National Renewable Energy Laboratory(NREL) gave an overview on this biofuel subject and later focused on the biomass recalcitrance. He discussed that there were three pathways in research. Accelerated Evolutionary research is within 3 years and is industry driven. Distruptive takes 3-10 years and is techno driven. Revolutionary is 10 years or more and is basic science driven. Recalcitrance, by definition, means inherent tendency of cell wall structure and chemistry to hinder its breakdown into sugar. This is due to physical and chemical access inabilities, and intrinsic resistance to depolymerization. In one of their experiments, they found that cellulose penetration of cell wall increased with pretreatment, cell wall breaking down at 180°C. The plant is made to be recalcitrant by nature for defense mechanism purposes: vascular bundles, cell wall, enzymes, and molecular structure. To fight this recalcitrance problem, they found that making particles smaller through sieving made the particles more digestible and also found better tools (SRI) for tracking lignin removal.
2. What are the key substrate factors which limit the hydrolysis of biomass by cellulases?
Dr. Chandra from University of British Columbia discuss the factors that affect cellulase accessibility to pretreated substrates and how the characteristics of these substrates define the whole hydrolysis process. He then went into detail of how the different characteristics of hardwood , softwood and nonwood require different pretreatments and how their structure determined the extent of hydrolysis. For example, nonwoods required AFEX, IBUS, and steam pretreatments, while hardwood required steam and acid pretreatments. They found that treating softwood with steam resulted in smaller particles, which gave more surface area and ease for hydrolysis. Softwoods have longer tracheids, while hardwoods have smaller fibers and higher lignin content. Overall, all plants are heterogenous on structural, cellular, fibril,macrofibril and microfibril levels. He stressed how important it was for researchers to break this heterogeneity and how different methods were required.
3. Development of microalgal biomass feedstocks for the production of advanced, high-energy density biofuels
Dr. Darzins from NREL discusses how you could use microalgae, macroalgae, and microcrops for fuels. In their “Aquatic species program”, they have over 20 years of data on algae. Algae is a very good alternative for fuel because it has high lipid content (50%), 10-100 times more than land plants and has no competition with food. NREL currently has 18 projects on algae. One of their projects deals with water sampling from all over the US and characterizing algae in fresh, saline, and brackish waters. They use fluorescence activated tool to sort the organisms, in which the sensor senses organisms in water droplets and separates them into vials. They have made Cholera vulgaris their model organism. It is a freshwater algae (since lab is located in Colorado), grows on mixotropic growth, grows fast, and contains rigid glucosamine urine acid rich cell walls. They are doing lipid extraction, transesterification, FAME method, IR and NIR spectra to characterize the biomass. IR spectra are really good indicators because the triglycerides and phospholipids are unique in algae. Currently their lab is focusing on algal biology (transcriptomics and metabolimics), which is a small fraction of the whole picture (Algal biology ->Cultivation ->Harvesting->Extraction->Fuel production). Therefore, more research needs to be done on these areas as well.
4. The Global Sustainable bioenergy project: Gracefully reconciling large-scale biofuel production with other land use priorities
Dr. Lee Lynd (Dartmouth College, Mascoma Corp.) was a great and very knowledgeable presenter. Both his power point presentation and speech was very clear cut and to the point. There are two main impediments to biofuel production: recalcitrance of cellulosic material and land use concern. But a meta-analysis shows that all the current data and assessments are not clustered around a mean, which confuses policy makers and makes us wonder how people are reaching different conclusions with the same information. There must be some inconsistency. The two key questions Dr. Lynd says that has to be asked by everyone is: 1. Could we? Is it possible to produce large scale bioenergy while feeding the world, sustaining natural resources and preserving wildlife habitat? The answer is “maybe at best”. 2. Must we? Must we produce such large scale bioenergy? Probably not. Dr. Lynd says that electrification and hydrogen fuels are also other good alternative sources of renewable energy, even though they are not ideal for aviation and big engines. He also presented some interesting data by Yan et al. (2009), which found that crop residues burned in china had greater energy than current transportation energy demand if converted. The GSB Project, which started in june 2009, is an international committee on this issue. The 3 continental resolution was that Europe could produce 30% of its own energy from East Europe and Latin American could produce its own energy from corn ethanol in Brazil. Africa was an interesting issue because Africa has 12 times more land than India and yet 30% fewer people. In terms of land and agriculture, Africa is able to produce the same amount of food that India is producing, but Africa doesn’t feed its own people while India does.
5. Drop-in hydrocarbon chemicals, fuels and materials from plant biomass derived isobutanol: Progress towards commercialization
Dr. Glassner’s talk focused on drop-in hydrocarbons from plant biomass and the new five step pathway to make isobutanol from pyruvate. Isobutanol is made from fermentation of biomass and is the building block for jet and diesel fuels (pure distillates). The process goes like this: Crude oil (distillation)-> Heavy Oils -> (cracker)-> Reformer->Aromatics. There are two routes for hydrocarbon fuels. Once isobutanol is made, it is converted into gasoline after being dehydrated, oligemerized, and hydrogenated. Isobutanol is produced by yeast and naturally occurs in foods like grapes, bread, beer and wine. The microbial yield of isobutanol pathway involves manipulation of the NADH. Glucose produces 2 NADH’s, but if the pathway is changed so that the NADH is used again (cofactor butane), then isobutene is made.