Mark Laser

Central to the debate over the efficacy of biofuels is the question of whether plants could ever be grown, harvested, and converted to fuels in quantities sufficient to meet a substantial fraction of mobility demand while feeding the world, preserving wildlife habitat and environmental quality, and achieving large reductions in greenhouse gas emissions. Writing in 2007, Lynd et al. observed that estimates for the potential energy contribution of biomass exhibit a bimodal distribution such that either a very small or very large energy supply role is anticipated. Widely disparate assessments of the feasibility and desirability of large scale biofuel production have continued to appear since that time. Reaching reconciliation on this key point is needed to avoid over-supporting undeserving options, under-supporting deserving options, or - in light of the broad range of biomass energy feedstocks and technologies both. There is increasing recognition that achieving a sustainable and secu...

The ammonia fiber expansion (AFEX) process has been shown to be an effective pretreatment for lignocellulosic biomass. Technological advances in AFEX have been made since previous cost estimates were developed for this process. Recent research has enabled lower overall ammonia requirements, reduced ammonia concentrations, and reduced enzyme loadings while still maintaining high conversions of glucan and xylan to monomeric sugars. A new ammonia recovery approach has also been developed. Capital and operating costs for the AFEX process, as part of an overall biorefining system producing fuel ethanol from biomass have been developed based on these new research results. These new cost estimates are presented and compared to previous estimates. Two biological processing options within the overall biorefinery are also compared, namely consolidated bioprocessing (CBP) and enzymatic hydrolysis followed by fermentation. Using updated parameters and ammonia recovery configurations, the cost o...

In debates over whether the United States could transition to a transportation sector run on bio-fuels, it is often said that the country does not possess enough land to simultaneously feed and fuel the nation. This chapter explores the potential sufficiency of biomass resources ...

We have studied the spontaneous and nerve-evoked synaptic currents during the initial period of nerve-muscle contact in Xenopus cell cultures. The precise timing of the contact was achieved by physically manipulating embryonic muscle cells into contact with co-cultured spinal neurons. Previous studies have shown that physical contact of the muscle membrane induces pulsatile release of acetylcholine (ACh) from the growth cone of these neurons, resulting in spontaneous synaptic currents (SSCs) in the muscle cell within seconds following the contact. In the present work, we first showed that these SSCs at the manipulated nerve-muscle contacts are similar to those observed at naturally occurring synapses. We then examined the possible cellular mechanisms responsible for the marked variation in SSC amplitude and showed that it most likely results from differences in either the amount of ACh contained in each release event or the extent of close membrane apposition near the release sites....

Predominant forms of food and energy systems pose multiple challenges to the environment as current configurations tend to be structured around centralized one-way through-put of materials and energy. In addition, these configurations can introduce vulnerability to input material price and supply shocks as well as contribute to localized food insecurity and lost opportunities for less environmentally harmful forms of local economic development. One proposed form of system transformation involves locally integrating "unclosed" material and energy loops from food and energy systems. Such systems, which have been termed integrated food-energy systems (IFES), have existed in diverse niche forms but have not been systematically studied with respect to technological, governance, and environmental differences. As a first step in this process, we have constructed a taxonomy of IFES archetypes by using exploratory data analysis on a collection of IFES cases. We find that IFES may b...

... Joseph Lichwa, and Michael Jerry Antal, Jr. Hawaii Natural Energy Institute, University of Hawaii at Manoa, Honolulu, Hawaii 96822. Mark Laser and Lee Rybeck Lynd. Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755. Ind. Eng. Chem. Res. ...

Biologically mediated processes seem promising for energy conversion, in particular for the conversion of lignocellulosic biomass into fuels. Although processes featuring a step dedicated to the production of cellulase enzymes have been the focus of most research efforts to date, consolidated bioprocessing (CBP)--featuring cellulase production, cellulose hydrolysis and fermentation in one step--is an alternative approach with outstanding potential. Progress in developing CBP-enabling microorganisms is being made through two strategies: engineering naturally occurring cellulolytic microorganisms to improve product-related properties, such as yield and titer, and engineering non-cellulolytic organisms that exhibit high product yields and titers to express a heterologous cellulase system enabling cellulose utilization. Recent studies of the fundamental principles of microbial cellulose utilization support the feasibility of CBP.

... In comparison, US motor fuel use (both ethanol and gasoline) Potential for Enhanced Nutrient Cycling through Coupling of Agricultural and Bioenergy Systems Robert P. Anex,* Lee R. Lynd, Mark S. Laser, Andrew H. Heggenstaller, and Matt Liebman ...

Effectively releasing the locked polysaccharides from recalcitrant lignocellulose to fermentable sugars is among the greatest technical and economic barriers to the realization of lignocellulose biorefineries because leading lignocellulose pre-treatment technologies suffer from low sugar yields, and/or severe reaction conditions, and/or high cellulase use, narrow substrate applicability, and high capital investment, etc. A new lignocellulose pre-treatment featuring modest reaction conditions (50 degrees C and atmospheric pressure) was demonstrated to fractionate lignocellulose to amorphous cellulose, hemicellulose, lignin, and acetic acid by using a non-volatile cellulose solvent (concentrated phosphoric acid), a highly volatile organic solvent (acetone), and water. The highest sugar yields after enzymatic hydrolysis were attributed to no sugar degradation during the fractionation and the highest enzymatic cellulose digestibility ( approximately 97% in 24 h) during the hydrolysis step at the enzyme loading of 15 filter paper units of cellulase and 60 IU of beta-glucosidase per gram of glucan. Isolation of high-value lignocellulose components (lignin, acetic acid, and hemicellulose) would greatly increase potential revenues of a lignocellulose biorefinery.

... Shahab Sokhansanj, Oak Ridge National Laboratory, TN, USA Sudhagar Mani, University of Georgia, Athens, GA, USA Anthony Turhollow, Oak Ridge National Laboratory, TN, USA Amit Kumar, University of Alberta, Edmonton, Canada David Bransby, Auburn University, AL ...

... Biogas from the biocon-version process is separated into a methane-rich stream and ... Processing efficiencies for biorefinery scenarios (energy out as percent of feedstock lower heating value). ... Modeling and Analysis: Comparative analysis of mature biomass refining scenarios ...

... Perspective. The role of biomass in America's energy future: framing the analysis. Lee R. Lynd 1,* ,; Eric Larson 2 ,; Nathanael Greene 3 ,; Mark Laser 4 ,; John Sheehan 5 ,; Bruce E. Dale 6 ,;Samuel McLaughlin 7 ,; Michael Wang 8. Article first published online: 4 MAR 2009. ...

ABSTRACT Agriculture has changed greatly in the past in response to changing human needs. Now agriculture is being called on to provide raw materials for very large-scale fuel and chemical production. Agriculture will change again in response to this demand and all producers and users of agricultural feedstocks will be affected by this change. For example, livestock feeding practices have already changed in response to the availability of distillers' grains from corn ethanol production. A fuels industry based on herbaceous biomass energy crops will be many-fold larger than the existing corn ethanol industry and will produce its own set of impacts on livestock feeding. We explore here one of these impacts: the availability of large new sources of feed protein from biomass energy crops.In addition to structural carbohydrates, such as cellulose and hemicellulose, herbaceous biomass energy crops can easily be produced with approximately 10% protein, called ‘leaf protein’. This leaf protein, as exemplified by alfalfa leaf protein, is superior to soybean meal (SBM) protein in its biological value. Leaf protein recovery and processing fit well into many process flow diagrams for biomass fuels. When leaf protein is properly processed to concentrate it and remove antinutritional factors, as we have learned over the years to do with soybean meal protein, protein in leaf protein concentrate (LPC) will probably be at least as valuable in livestock diets as SBM protein.If LPC is used to meet 20% of total animal protein requirements (i.e., market penetration of 20%) then the potential utilization of leaf protein concentrate could reach as much as 24 million metric tons annually. This leaf protein will replace protein from SBM and other sources. This much leaf protein will reduce by approximately 16 million hectares the amount of land required to provide protein for livestock. Likewise the amount of land required to meet fuel needs will effectively be reduced by 8 million hectares because this land will effectively do ‘double duty’ by producing needed animal protein as well as feedstocks for fuel production. © 2009 Society of Chemical Industry and John Wiley & Sons, Ltd