GLBRC's Conversion Research Area


Research team achieves concentrated stream of sugars, cost savings

GLBRC Conversion research aims to increase the quantity, diversity, and efficiency of energy products derived from plant biomass. Researchers focus on improving biological and chemical methods to convert plant material into advanced biofuels or valuable chemicals that can replace petroleum. Basic research discoveries that enhance the efficiency and sustainability of biomass conversion can break down barriers to developing economically viable biofuels technologies.

Conversion Leadership

Scientific Director, Conversion Lead

Landick is an expert on structure, function and regulation of RNA polymerase, the central engine of gene expression. His work spans disciplines from single-molecule biochemistry to genome-scale mechanisms of gene regulation, and includes devising the first single-molecule observation of nucleic...

Conversion Lead

Hegg’s research team focuses on the variety of ways that nature uses metals to activate and/or produce small molecules such as O2, H2, NO, and H2O2.  In pursuit of this goal, his lab utilizes a combination of mechanistic enzymology, molecular...

Project Overview

Stacks of petri dishes in the Currie Lab

Within the Conversion group, researchers apply a combination of synthetic biology, directed evolution, systems biology, and computational modeling approaches to accelerate the rate and yield of microbial conversion of biomass to fuels. Microbial efforts focus on well-established models and biofuel-producing organisms to identify key genes and pathways that may illuminate opportunities for strain improvement. Chemical routes focus on direct catalytic conversion of biomass-derived sugars and lignin into liquid transportation fuels and/or high-value chemicals.

Specific Conversion projects fall in three categories:

  • Engineering microbe strains to enhance stress tolerance and improve conversion efficiency of sugars to biofuels
  • Developing flexible routes to biofuel production that can be adapted to diverse biomass feedstocks
  • Producing light-driven and lignin-derived advanced biofuels, and using catalytic conversion to convert biomass to biofuels and value-added chemicals


Conversion Publications

A co-solvent hydrolysis strategy for the production of biofuels: process synthesis and technoeconomic analysis

Wangyun Won; Ali H. Motagamwala; James A. Dumesic; Christos T. Maravelias

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We develop an integrated strategy for the production of ethanol from lignocellulosic biomass. Cellulose and hemicellulose fractions are first hydrolyzed into sugars using a mixture of γ-valerolactone (GVL), water, and toluene as a solvent containing dilute sulfuric acid as a catalyst, and the sugars are then co-fermented into ethanol over engineered yeast strains. Separation subsystems are designed to effectively recover GVL and toluene for reuse in biomass hydrolysis, and to recover lignin and humins for heat and power generation. We also develop an alternative process, in which we recover sugars and GVL from the residual biomass. To minimize utility requirements, we conduct heat integration, which allows us to meet all heating requirement using biomass residues. Finally, we perform a range of system-level analyses to identify the major cost and technological drivers. The proposed strategy is shown to be cost-competitive with other strategies.

Biochemical transformation of lignin for deriving valued commodities from lignocellulose

Daniel L. Gall; J. Ralph; Timothy J. Donohue; Daniel R. Noguera

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The biochemical properties of lignin present major obstacles to deriving societally beneficial entities from lignocellulosic biomass, an abundant and renewable feedstock. Similar to other biopolymers such as polysaccharides, polypeptides, and ribonucleic acids, lignin polymers are derived from multiple types of monomeric units. However, lignin’s renowned recalcitrance is largely attributable to its racemic nature and the variety of covalent inter-unit linkages through which its aromatic monomers are linked. Indeed, unlike other biopolymers whose monomers are consistently inter-linked by a single type of covalent bond, the monomeric units in lignin are linked via non-enzymatic, combinatorial radical coupling reactions that give rise to a variety of inter-unit covalent bonds in mildly branched racemic polymers. Yet, despite the chemical complexity and stability of lignin, significant strides have been made in recent years to identify routes through which valued commodities can be derived from it. This paper discusses emerging biological and biochemical means through which degradation of lignin to aromatic monomers can lead to the derivation of commercially valuable products.

Effect of ethanol blending on particulate formation from premixed combustion in spark-ignition engines

Stephen Sakai; David A. Rothamer

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Particulate formation due to combustion of a wide range of ethanol-gasoline blends were investigated in an internal combustion engine. The engine used for this study is a single-cylinder research engine, the architecture of which is representative of a modern spark ignited direct injected (SIDI) engine. Instead of direct injection, the engine was fueled using a premixed prevaporized (PMPV) mode, which supplied the fuel to the engine in a well-mixed, gas-phase air-fuel mixture in order to isolate physical effects of the fuel. This created a completely homogenous air-fuel mixture with no pockets of significantly differing equivalence ratio, liquid fuel droplets, or wetted surfaces, ensuring that particulate formation was due to homogenous, gas-phase combustion. The engine was operated at a fixed load and phasing so that the effects of varying equivalence ratio and ethanol content could be examined. The results in this work show that the addition of ethanol results in a consistent decrease in engine-out particulate proportional to ethanol content. Moreover, the critical equivalence ratio, the equivalence ratio at which significant sooting begins, increases in a linear fashion with ethanol addition. It was also shown that the shape of the particulate size distribution (PSD) is affected by ethanol content, with increased ethanol leading to more nucleation-mode dominated distributions.

Effect of increased fuel volatility on CDC operation in a light-duty CIDI engine

Michael A. Groendyk; David A. Rothamer

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Alternative diesel fuels derived from biomass can vary significantly in volatility compared to their petroleum-derived counterparts, and their appropriate utilization is contingent on their compatibility with existing engine infrastructure. To investigate this compatibility, experiments were carried out to study the effect of fuel volatility on conventional diesel combustion (CDC) performance under a wide range of in-cylinder thermodynamic conditions at start of injection (SOI). Fuels of matched reactivity (i.e., cetane number (CN)) and varying volatility were produced by blending binary mixtures of 2,6,10-trimethyldodecane (farnesane) and 2,2,4,4,6,8,8-heptamethylnonane, octane number primary reference fuels (PRF), and cetane number secondary reference fuels (SRF). Nine fuel blends were tested in total, consisting of 3 volatility characteristics at 3 reactivity levels. Five engine operating conditions were utilized, ranging from 14.7–29 kg/m3 and 980–1120 K in-cylinder density and temperature at SOI. Testing was performed in a single-cylinder GM 1.9 L diesel engine. Only small differences in ignition delay (ID), in-cylinder pressure, and heat release rate (HRR) were observed between fuels of matched CN, regardless of their volatility. An analysis of the spray breakup and mixture formation process indicated that there were only small variations in ambient air entrainment and jet temperature between fuel blends, in agreement with the observed combustion behavior.

Functionality and molecular weight distribution of red oak lignin before and after pyrolysis and hydrogenation

Daniel J. McClelland; Ali Hussain Motagamwala; Yanding Li; Marjorie R. Rover; Ashley M. Wittrig; Chunping Wu; Scott Buchanan; Robert C. Brown; John Ralph; James A. Dumesic; George W. Huber

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