Thermodynamics of Energy Production from Biomass

With high quality petroleum running out in the next 50 years, the world governments and petrochemical industry alike are looking at biomass as a substitute refinery feedstock for liquid fuels and other bulk chemicals. New large plantations are being established in many countries, mostly in the tropics, but also in China, North America, Northern Europe, and in Russia. These industrial plantations will impact the global carbon, nitrogen, phosphorus, and water cycles in complex ways. The purpose of this paper is to use thermodynamics to quantify a few of the many global problems created by industrial forestry and agriculture. It is assumed that a typical tree biomass-for-energy plantation is combined with an efficient local pelleting facility to produce wood pellets for overseas export. The highest biomass-to-energy conversion efficiency is afforded by an efficient electrical power plant, followed by a combination of the FISCHER-TROPSCH diesel fuel burned in a 35%-efficient car, plus electricity. Wood pellet conversion to ethanol fuel is always the worst option. It is then shown that neither a prolific acacia stand in Indonesia nor an adjacent eucalypt stand is “sustainable.” The acacia stand can be made “sustainable” in a limited sense if the cumulative free energy consumption in wood drying and chipping is cut by a factor of two by increased reliance on sun-drying of raw wood. The average industrial sugarcane-for-ethanol plantation in Brazil could be “sustainable” if the cane ethanol powered a 60%-efficient fuel cell that, we show, does not exist. With some differences (ethanol distillation vs. pellet production), this sugarcane plantation performs very similarly to the acacia plantation, and is unsustainable in conjunction with efficient internal combustion engines.     

Digestion of Algal Biomass for Electricity Generation in Microbial Fuel Cells

We developed a semi-automated genome analysis system called GAMBLER in order to support the current whole-genome sequencing project focusing on alkaliphilic Bacillus halodurans C-125. GAMBLER was designed to reduce the human intervention required and to reduce the complications in annotating thousands of ORFs in the microbial genome. GAMBLER automates three major routines: analyzing assembly results provided by genome assembler software, assigning ORFs, and homology searching. GAMBLER is equipped with an interface for convenience of annotation. All processes and options are manipulatable through a WWW browser that enables scientists to share their genome analysis results without choosing computer platforms.     

Phosphorus Removal from Natural Waters Using Controlled Algal Production

A series of experiments designed to demonstrate the potential of using managed, attached algal production to permanently remove excess phosphorus from agricultural run-off is described. The experiments were carried out on a secondary canal in the New Hope South region of the Florida Everglades Agricultural Area from October, 1991, to May, 1992. Natural algal populations of periphyton, including species of the genera Cladophora, Spirogyra, Enteromorpha, Stigeoclonium, and a variety of filamentous diatoms such as Eunotia and Melosira, were grown on plastic screens in raceways, under a wave surge regime. Considerable biomass production of algae occurred, and the resulting algal canopy also trapped plankton and organic particulates from the water column. A seven- to eight-day harvest interval was determined to be optimal, and both hand harvesting and vacuum harvesting were employed. The vacuum device is applicable to large scale-up. In source water having total phosphorus concentrations of 0.012–0.148 ppm, mean macro-recovery dry biomass production levels of 15–27 g/m²/day were achieved. The lower rates occurred in the winter, the higher rates in the late spring. Two techniques were employed to reduce losses of fine material at harvest during the March to May period. Gravity sieving increased mean dry production levels to 33–39 g/m²/day. The mean phosphorus content of harvested biomass ranged from 0.34% to 0.43%. Total phosphorus removal rates during the spring period of average solar intensity and low nutrient supply, by methods demonstrated in this study, ranged from 104 to 139 mgTP/m²/day (380–507 kgP/ha/year). Over the incoming nutrient range studied, phosphorus removal was independent of concentration and was 16.3% of total phosphorus for 15 m of raceway. Up-stream-downstream studies of overflowing water chemistry (total P, total dissolved -P, orthophosphate -P) showed highly -significant reductions of all phosphorus species. Total phosphorus reduction closely correlated with phosphorus yield from biomass removal. Yearly, minimum phosphorus removal rates are predicted that are 100–250 times that achieved both experimentally and in long-term, large-area wetland systems. Engineering scale-up to systems of hundreds of acres is being studied.     

Sustainable Cultivation Concepts for Domestic Energy Production from Biomass

Referee: Dr. J. Grant McLeod, Semiarid Prairie Agricultural Research Centre, Research Branch, Agriculture and Agri-Food Canada, P.O. Box 1030 Swift Current, Saskatchewan S9H 3X2, Canada According to the European Union, biomass will play a major role in the substitution of fossil fuels with renewable resources. Biomass will contribute 83% to the increased use of renewable resources by the year 2010. In contrast to other solar energy sources, plant biomass is always available and can be converted into energy continuously. An important objective in the production of energy crops on arable farm land should be to realize a high net energy yield and fulfill obligations in the field of environmental protection. The “double cropping system” was developed to meet these obligations. Silaging as a conservation method for wet biomass makes this sustainable cultivation system possible. It includes a diverse array of crops and provides the opportunity to integrate rural organic wastes into this energy concept. The model presented, “the energy self supplying farm”, shows that it is possible to meet the energy consumption requirements of a livestock farming operation with energy crop production on 10 to 18% of the arable farm land. According to a new rape energy concept, a land resource requirement of roughly 10% is feasible if biomass residues from rape oil production for liquid fuels are also utilized for energy production. For a farm with livestock, anaerobic digestion technology is an appropriate technique to deliver heat and electricity for the farmstead. Digestion residues, used as fertilizer in energy crop production, results in an almost complete nutrient recycling. Energy output can be increased above the demand of the farm via the biogas reactor, using the total biomass produced with double cropping. Surplus electricity is supplied to the grid at a guaranteed price. Biomass is a domestic energy resource, and farmers have the chance to extend their function from a supplier of raw material to managers of domestic energy resources. Under the currently established framework, monetary return per hectare could be more than double with biomass energy production via biogas. This will allow the agricultural economy to recover and promote a sustainable regional development. In addition to being a convenient method of waste management, sustainable energy crop production can make a significant contribution to environmental protection and the improvement of the social and economic cohesion within a community.     

Theoretical Maximum Algal Oil Production

Interest in algae as a feedstock for biofuel production has risen in recent years, due to projections that algae can produce lipids (oil) at a rate significantly higher than agriculture-based feedstocks. Current research and development of enclosed photobioreactors for commercial-scale algal oil production is directed towards pushing the upper limit of productivity beyond that of open ponds. So far, most of this development is in a prototype stage, so working production metrics for a commercial-scale algal biofuel system are still unknown, and projections are largely based on small-scale experimental data. Given this research climate, a methodical analysis of a maximum algal oil production rate from a theoretical perspective will be useful to the emerging industry for understanding the upper limits that will bound the production capabilities of new designs. This paper presents a theoretical approach to calculating an absolute upper limit to algal production based on physical laws and assumptions of perfect efficiencies. In addition, it presents a best case approach that represents an optimistic target for production based on realistic efficiencies and is calculated for six global sites. The theoretical maximum was found to be 354,000 L·ha^?1·year^?1 (38,000 gal·ac^?1·year^?1) of unrefined oil, while the best cases examined in this report range from 40,700–53,200 L·ha^?1·year^?1 (4,350–5,700 gal·ac^?1·year^?1) of unrefined oil.     

利用废弃物原料生产燃料乙醇的研究进展

乙醇是一种十分重要的工业用途的化工原料。目前国内外学者纷纷采用不同的方法和手段对乙醇发酵进行研究,目前,利用废弃物为原料生产乙醇是热点。本文阐述了利用各种废弃原料生产乙醇的必要性,并分别论述了利用纤维质废弃物、淀粉质废弃物、糖质废弃物等生产乙醇的研究进展,着重论述了利用纤维质废弃物的生产情况,提出了需进一步研究和解决的问题。     

Farm-Scale Production Cost of Switchgrass for Biomass

The economic potential of cellulosic biomass from switchgrass has heretofore been evaluated using estimates of farm costs based on extrapolation from experimental data and budget estimates. The objective of the project reported here was to estimate the cost of production that would be experienced by farmers on commercial production situations. Switchgrass was produced as a biomass crop on commercial-scale fields by ten contracting farmers located from northern North Dakota to southern Nebraska. Results showed a wide range of yields and costs across the five production years and ten sites, with an overall average cost of $65.86 Mg^?1 of biomass dry matter, and annualized yield of 5.0 Mg ha^?1. The low-cost half of the producers were able to produce at an average cost of $51.95 Mg^?1over the 5-year period. When projected to a full 10-year rotation, their cost fell further to $46.26 Mg^?1. We conclude that substantial quantities of biomass feedstock could have been produced in this region at a cost of about $50 Mg^?1 at the farm gate, which translates to about $0.13/l of ethanol. These results provide a more reliable benchmark for current commercial production costs as compared to other estimates, which range from $25 to $100 Mg^?1.     

Influence of Algal Biomass on Extracellular Enzyme Activity in River Biofilms

Abstract Relationships between biofilm structural components (algal and bacterial biomass) and the activities of some extracellular enzymes that contribute to the ability to degrade organic matter) were explored for six Atlantic and three Mediterranean streams and rivers. The biofilms in these fluvial systems accounted for a wide range of bacterial and algal biomass and colonized the most common benthic habitats. Ratio of bacteria/algae biomass was lower in Atlantic than in Mediterranean streams, but enzymatic activities (β-glucosidase, β-xylosidase, phosphatase) were in general greater in the Mediterranean stream biofilms. Climatic characteristics (especially temperature) may explain the differences in enzymatic activities between biofilms of similar structure but different flow regime. The ratio β-xylosidase: β-glucosidase was similar (around 0.5) for all streams and substrata considered, showing that there is a general higher utilization of cellobiosic than xylobiosic molecules in fluvial systems. In general, highly heterotrophic biofilms showed lower extracellular enzymatic activities than more autotrophic biofilms. Maximum enzymatic activity is achieved when the algal biomass is two- to threefold higher than the bacterial biomass. The relevance of algal biomass on the heterotrophic ability of biofilms may be related to the physical proximity between the two, but also to the high proportion of polymeric carbohydrates included in algal exudates and lysis products, whose use is enzyme-mediated. Received: January 2000; Accepted: April 2000; Online Publication: 18 July 2000     

Fractionation of the Biopolyols from Lignocellulosic Biomass for the Production of Rigid Foams

The objective of this investigation was to find a simple method for the production of phenolic-rich products and sugar derivatives via separation of liquefied lignocellulosic materials. After liquefaction, the liquefied products were separated by addition of a sufficient amount of water. It was found that those hydrophobic phenolics could be largely separated from aqueous solutions. Preparation of polyurethane foams using biopolyol and isocyanate was studied. Water was used as an environmentally friendly blowing agent. The factors influencing the cell structure of foams such as catalyst, dosage of blowing agent, and mass ratio of biopolyol to PEG were studied. The microstructure of synthesized foams was characterized by SEM.     

Alteration of Nutrient Cycles and Algal Production Resulting from Fish Introductions intoMountain Lakes

The introduction of salmonid fishes into naturally fishless lakes represents one of the most prevalent environmental modifications of aquatic ecosystems in western North America. Introduced fish may alter lake nutrient cycles and primary production, but the magnitude and variation of these effects have not been fully explored. We used bioenergetics modeling to estimate the contributions of stocked trout to phosphorus (P) cycles across a wide range of fish densities in lakes of the Sierra Nevada, California. We also assessed the larger effects of fish-induced changes in phosphorus cycling on primary production using paleolimnological analyses from lakes in the southern Canadian Rockies. Our analyses showed that total P recycling by fish was independent of fish density but positively related to fish biomass in the Sierra Nevada. In lakes with fish populations maintained by continued stocking, fish recycled P at over twice the rate of those in lakes where introduced fish populations are maintained by natural reproduction and stocking has been discontinued. We estimate that P regeneration by introduced fishes is approximately equivalent to atmospheric P deposition to these lakes. Paleolimnological analyses indicated that algal production increased substantially following trout introductions to Rocky Mountain lakes and was maintained for the duration of fish presence. The results of our modeling and paleolimnological analyses indicate that introduced trout fundamentally alter nutrient cycles and stimulate primary production by accessing benthic P sources that are not normally available to pelagic communities in oligotrophic mountain lakes. These effects pose a difficult challenge for managers charged with balancing the demand for recreational fisheries with the need to maintain natural ecosystem processes. Received 28 March 2000; accepted 4 January 2001.     

Production and Analysis of Fast Pyrolysis Oils from Proteinaceous Biomass

Fast pyrolysis of lignocellulosic biomass is a facile method for producing high yields of liquid fuel intermediates. However, because most fast pyrolysis oils are highly oxygenated, acidic, and unstable, identification of feedstocks that produce higher quality pyrolysis liquids is desirable. Therefore, the effect of feedstock protein content was studied by performing fast pyrolysis experiments on biomass with varying protein content. The feedstocks ranged from low-protein content, ??5% up to feedstocks with >40 wt.% protein content. Protein content was not a major factor in the yield of pyrolysis oil or the distribution of biomass carbon into the pyrolysis products. However, elevated levels of protein did cause a deoxygenation effect in the pyrolysis process with more of the oxygen rejected from the biomass as water. The deoxygenation caused the pyrolysis oil from the higher protein containing biomass to have higher energy content. Furthermore, the concentration of basic nitrogen groups caused the pyrolysis oil from the higher protein biomass to shift to a more neutral pH and lower total acid number than has been measured typically for lignocelluloic biomass pyrolysis oils. Some of the pyrolysis oils, particularly those from the mustard seed family presscakes exhibited better thermal stability than low-protein pyrolysis oils.     

Bioethanol from Macroalgal Biomass: Utilization of Marine Yeast for Production of the Same

The present study deals with the first systematic study on the isolation, characterization, and utilization of marine yeast for bioethanol production using seaweed biomass. The ability and efficiency of isolated marine yeast to grow and ferment sugar to ethanol in the presence of 2.5 % to 15 % salt concentration was validated by fermenting galactose in the presence of different salts at varied concentrations. Successively, this yeast was employed for fermentation of seaweed hydrolysate, containing high salt concentration, to ethanol. The hydrolysate having varying sugar as well as salt contents, from 2.7 % to 5.5 % and from 6.25 to 11.25 %, respectively, yielded 1.23–1.76 % ethanol. Through biochemical, fatty acid methyl ester analysis, and BioLog, the yeast was identified as Candida sp. The ability of this yeast to function at high salinity can be commercialized for its use to convert seaweed polysaccharide based hydrolysate, rich in salt, to ethanol without desalting process, ultimately making the process more efficient and economically viable. This is the first organized study for the utilization of marine yeast for converting Kappaphycus alvarezii, a red algal biomass, into ethanol as a byproduct, under highly saline condition.     

Feasibility of Spectroscopic Characterization of Algal Lipids: Chemometric Correlation of NIR and FTIR Spectra with Exogenous Lipids in Algal Biomass

A large number of algal biofuels projects rely on a lipid screening technique for selecting a particular algal strain with which to work. We have developed a multivariate calibration model for predicting the levels of spiked neutral and polar lipids in microalgae, based on infrared (both near-infrared (NIR) and Fourier transform infrared (FTIR)) spectroscopy. The advantage of an infrared spectroscopic technique over traditional chemical methods is the direct, fast, and non-destructive nature of the screening method. This calibration model provides a fast and high-throughput method for determining lipid content, providing an alternative to laborious traditional wet chemical methods. We present data of a study based on nine levels of exogenous lipid spikes (between 1% and 3% (w/w)) of trilaurin as a triglyceride and phosphatidylcholine as a phospholipid model compound in lyophilized algal biomass. We used a chemometric approach to corrrelate the main spectral changes upon increasing phospholipid and triglyceride content in algal biomass collected from single species. A multivariate partial least squares (PLS) calibration model was built and improved upon with the addition of multiple species to the dataset. Our results show that NIR and FTIR spectra of biomass from four species can be used to accurately predict the levels of exogenously added lipids. It appears that the cross-species verification of the predictions is more accurate with the NIR models (R ²?=?0.969 and 0.951 and RMECV?=?0.182 and 0.227% for trilaurin and phosphatidylcholine spike respectively), compared with FTIR (R ²?=?0.907 and 0.464 and RMECV?=?0.302 and 0.767% for trilaurin and phosphatidylcholine spike, respectively). A fast high-throughput spectroscopic lipid fingerprinting method can be applied in a multitude of screening efforts that are ongoing in the microalgal research community.     

Algal Photosynthesis as the Primary Driver for a Sustainable Development in Energy, Feed, and Food Production

High oil prices and global warming that accompany the use of fossil fuels are an incentive to find alternative forms of energy supply. Photosynthetic biofuel production represents one of these since for this, one uses renewable resources. Sunlight is used for the conversion of water and CO₂ into biomass. Two strategies are used in parallel: plant-based production via sugar fermentation into ethanol and biodiesel production through transesterification. Both, however, exacerbate other problems, including regional nutrient balancing and the world's food supply, and suffer from the modest efficiency of photosynthesis. Maximizing the efficiency of natural and engineered photosynthesis is therefore of utmost importance. Algal photosynthesis is the system of choice for this particularly for energy applications. Complete conversion of CO₂ into biomass is not necessary for this. Innovative methods of synthetic biology allow one to combine photosynthetic and fermentative metabolism via the so-called Photanol approach to form biofuel directly from Calvin cycle intermediates through use of the naturally transformable cyanobacterium Synechocystis sp. PCC 6803. Beyond providing transport energy and chemical feedstocks, photosynthesis will continue to be used for food and feed applications. Also for this application, arguments of efficiency will become more and more important as the size of the world population continues to increase. Photosynthetic cells can be used for food applications in various innovative forms, e.g., as a substitute for the fish proteins in the diet supplied to carnivorous fish or perhaps—after acid hydrolysis—as a complex, animal-free serum for growth of mammalian cells in vitro.     

Cumulative Energy and Global Warming Impact from the Production of Biomass for Biobased Products

The cumulative energy and global warming impacts associated with producing corn, soybeans, alfalfa, and switchgrass and transporting these crops to a central crop processing facility (called a "biorefinery") are estimated. The agricultural inputs for each crop are collected from seven states in the United States: Illinois, Indiana, Iowa, Michigan, Minnesota, Ohio, and Wisconsin. The cumulative energy requirement for producing and transporting these crops is 1.99 to 2.66 megajoules/kilo-gram (MJ/kg) for corn, 1.98 to 2.04 MJ/kg for soybeans, 1.24 MJ/kg for alfalfa, and 0.97 to 1.34 MJ/kg for switchgrass. The global warming impact associated with producing biomass is 246 to 286 grams (g) CO₂ equivalent/kg for corn, 159 to 163gCO₂ equivalent/kg for soybeans, 89 g CO₂ equivalent/ kg for alfalfa, and 124 to 147 g CO₂ equivalent/kg for switch-grass. The detailed agricultural data are used to assess previous controversies over the energy balance of bioethanol and, in light of the ongoing debates on this topic, provide a needed foundation for future life-cycle assessments.     

Singlet Oxygen Production from the Reactions of Superoxide Ion in Aprotic Solvents: Implications for Hydrophobic Biochemistry

A number of reactions of superoxide ion in aprotic solvents have been reported to produce singlet oxygen. There is strong evidence for singlet oxygen generation from the reactions of superoxide ion with chlorine-containing halocarbons, bromine-containing halocarbons, hexafluorobenzene, diacylperoxides, lead tetraacetate. iodobenzene diacetate, cerium (IV) cation and tetranitromethane. Earlier studies reporting singlet oxygen generation from the reactions of superoxide ion with iodine. ferricenium ion, thianthrene cation radical, tris (N,N'-dioxobipyridyl) manganese (III) cation and di-μ-oxo-bis(phenanthrolinato manganese (IV)] cation need to be repeated because of the methods used to detect singlet oxygen had low specificity.

The results of studies of superoxide ion chemistry in aprotic solvents should not be uncritically extrapolated to hydrophobic biological microenvironments. such as the cell membrane.     

Spatial Synchrony in Intertidal Benthic Algal Biomass in Temperate Coastal and Estuarine Ecosystems

Microphytobenthos plays a vital role in estuarine and coastal carbon cycling and food webs. Yet, the role of exogenous factors, and thus the effects of climate change, in regulating microphytobenthic biomass is poorly understood. We aimed to unravel the mechanisms structuring microphytobenthic biomass both within and across ecosystems. The spatiotemporal distribution of the biomass of intertidal benthic algae (dominated by diatoms) was estimated with an unprecedented spatial extent from time-series of Normalized Differential Vegetation Index (NDVI) derived from a 6-year period of daily Aqua MODIS 250-m images of seven temperate, mostly turbid, estuarine and coastal ecosystems. These NDVI time-series were related to meteorological and environmental conditions. Intertidal benthic algal biomass varied seasonally in all ecosystems, in parallel with meteorology and water quality. Seasonal variation was more pronounced in mud than in sand. Interannual variation in biomass was small, but synchronized year-to-year biomass fluctuations occurred in a number of disjointed ecosystems. Air temperature explained interannual fluctuations in biomass in a number of sites, but the synchrony was mainly driven by the wind/wave climate: high wind velocities reduced microphytobenthic biomass, either through increased resuspension or reduced emersion duration. Spatial variation in biomass was largely explained by emersion duration and mud content, both within and across ecosystems. The results imply that effects on microphytobenthic standing stock can be anticipated when the position in the tidal frame is altered, for example due to sea level rise. Increased storminess will also result in a large-scale decrease of biomass.     

Effects of pH,Salinity, Biomass Concentration,and Algal Organic Matter on Flocculant Efficiency of Synthetic Versus Natural Polymers for Harvesting Microalgae Biomass

This study investigated the effects of pH, salinity, biomass concentration, and algal organic matter (AOM) on the efficiency of four commercial cationic flocculants. The tannin-based biopolymers Tanfloc SG and SL and the polyacrylamide polymers Flopam FO 4800 SH and FO 4990 SH were tested for flocculation of two microalgae models, the freshwater Chlorella vulgaris and the marine Nannochloropsis oculata. Both biomass concentration and AOM presence affected all polymers evaluated, whereas salinity and pH affected only Flopam and Tanfloc, respectively. A restabilization effect due to overdosing was only observed for Flopam polymers and increasing Tanfloc dose resulted in improved efficiency. Flopam polymers showed a significant decrease in the maximum quantum yield of photosystem II as function of polymer dose for Chlorella, which supported the need for toxicological studies to assess the potential toxicity of Flopam. In overall, Tanfloc was not affected by salinity nor presented potential toxicity therefore being recommended for the flocculation of both freshwater and marine species.