This study investigated hydrogen produced from feeding three types of biomass wastes (rice straw, banyan leaves, and dry algae) into the microwave plasma system. When operating the microwave plasma system atmospherically (including 12SLM of central and vortex air flow at a power of 800W, 900W, or 1000W), different feeding methods were adopted, and the researchers measured the concentration of hydrogen and other gas products, calculated the conversion rate, and evaluated the feasibility of the technique. For feeding rice straws into the microwave plasma system at 800W, 900W, and 1000W using the upstream method, the concentrations of the produced hydrogen were 47.92%, 52.66%, and 56.08%, respectively. For feeding rice straws using the downstream method, the concentrations of the produced hydrogen were 33.65%, 40.15%, and 45.39%, respectively. For feeding banyan leaves using the upstream method, the concentrations of the produced hydrogen were 40.61%, 48.63%, and 52.82%, respectively. For feeding banyan leaves using the downstream method, the concentrations of the produced hydrogen were 34.08%, 37.97%, and 40.52%, respectively. For feeding dry algae using the upstream method, the concentrations of the produced hydrogen were 36.75%, 41.34%, and 45.13%, respectively. For feeding dry algae using the downstream method, the concentrations of the produced hydrogen were 30.80%, 33.20%, and 37.58%, respectively. This data indicates that the upstream feeding method is better than the downstream one for hydrogen production, and an increase of power can enhance the production of hydrogen. The most optimum hydrogen production was achieved when rice straws were fed into the system using the upstream method at a power of 1000W; each gram of rice straws produced about 40.47mg of hydrogen (conversion rate = 67.45%). For banyan leaves and dry algae, 40.40mg (conversion rate = 67.33%) and 31.46mg (conversion rate = 52.43%) of hydrogen were produced respectively. For other gas products, no CH4 was produced in this study because most of the produced CH4 from microwave plasma conversion had reacted with CO2 and produced CO and H2. The study also revealed that the concentration of CO2 decreased as the power decreased, and this drop of concentration was more apparent in the upstream feeding method than in the downstream method. Nevertheless, the result from t-test suggested that the different CO2 concentration at different power was not statistically significant. SWOT analysis was performed to examine the feasibility of using microwave plasma atmospherically for converting biomass wastes to hydrogen, and the result revealed that internally, the emphasis should be placed on the quality and quantity of products, as well as the techniques and performance, while externally, economy, policies, and energy sources should be the focuses.

Assessment of vegetation productivity on rangelands is needed to assist in timely decision making with regard to management of the livestock enterprise as well as to protect the natural resource. Characterization of the vegetation resource over large landscapes can be time consuming, expensive and almost impossible to do on a near real-time basis. The overarching goal of this study was to examine available technologies for implementing near real-time systems to monitor forage biomass available to livestock on a given landscape. The primary objectives were to examine the ability of the Climate Prediction Center Morphing Product (CMORPH) and Next Generation Weather Radar (NEXRAD) rainfall products to detect and estimate rainfall at semi-arid sites in West Texas, to verify the ability of a simulation model (PHYGROW) to predict herbaceous biomass at selected sites (patches) in a semi-arid landscape using NEXRAD rainfall, and to examine the feasibility of using cokriging for integrating simulation model output and satellite greenness imagery (NDVI) for producing landscape maps of forage biomass in Mongolia’s Gobi region. The comparison of the NEXRAD and CMORPH rainfall products to gage collected rainfall revealed that NEXRAD outperformed the CMORPH rainfall with lower estimation bias, lower variability, and higher estimation efficiency. When NEXRAD was used as a driving variable in PHYGROW simulations that were calibrated using gage measured rainfall, model performance for estimating forage biomass was generally poor when compared to biomass measurements at the sites. However, when model simulations were calibrated using NEXRAD rainfall, performance in estimating biomass was substantially better. A suggested reason for the improved performance was that calibration with NEXRAD adjusted the model for the general over or underestimation of rainfall by the NEXRAD product. In the Gobi region of Mongolia, the PHYGROW model performed well in predicting forage biomass except for overestimations in the Forest Steppe zone. Cross-validation revealed that cokriging of PHYGROW output with NDVI as a covariate performed well during the majority of the growing season. Cokriging of simulation model output and NDVI appears to hold promise for producing landscape maps of forage biomass as part of near real-time forage monitoring systems.

Cattle biomass (CB) has been proposed as a renewable, supplementary fuel for co-firing and reburning. Reburning coal with CB has the potential to reduce NOx and Hg emissions from coal fired systems. The present research focuses on three areas of combustion: 1) Biomass reburning experiments are conducted to determine the optimum operating conditions for the NOx reduction using blends of coal and CB as reburn fuels. 2) Since CB contains higher ash contents compared to coals, the fouling behavior is also investigated under the transient and short-time operation. 3) Finally CB contains higher Cl compared to coals, which oxidizes Hg to HgCl2. To understand the Hg oxidation behavior, a fundamental study of Hg oxidation in coal combustion is conducted using a plug flow reactor (PFR). The main parameters investigated are types of the reburn fuel, reburn equivalence ratios (ERRBZ), O2 concentrations in the reburn gas, injection angles of the reburn fuel, cross-sectional geometries of the reburn nozzles, symmetric and asymmetric reburn injections, reburn heat inputs, baseline NOx concentrations, and presence and absence of the heat exchangers (HEX). The results of reburning show that CB is a very effective fuel in NOx reduction, and the extent of NOx reduction is strongly dependent to the ERRBZ. The optimum conditions of the boiler operation for biomass reburning are as follows: ERRBZ = 1.1, 45° upward circular reburn nozzles, 12.5% O2 in the reburn gas, symmetric injection, and presence of HEXs. To make an effective reburn process, the baseline NOx concentrations must be higher than 230 g/GJ (0.5 lb/mmBTU) and the reburn heat input higher than 20%. The results of ash fouling show the presence of ash in the hotter region of the furnace seems to promote heat radiation thus augmenting the heat transfer to the HEX. The growth of the layer of ash depositions over longer periods typically lowers overall heat transfer coefficients. The addition of HCl to Hg containing gases in the PFR significantly increases Hg oxidations. The addition of NO inhibited the overall reaction and shifted the reaction temperature higher while the addition of O2 promoted Hg oxidations and lowered the reaction temperature. For heterogeneous cases, the use of the VWT catalyst promotes the reduction of Hg0 and shifted the reaction temperatures lower than those for homogeneous cases.

In this study, I examined the influence of hydrological seasonality on spatiotemporal variation of algal biomass and shrimp abundance on sandbanks of the Cinaruco River in southwestern Venezuela. Seasonal variations of abiotic and biotic variables in the Cinaruco were driven by the hydrological regime. During the highwater periods, river sites in the main channel and lagoon sites were similar in water physicochemical variables and algal biomass. In contrast, physicochemical variables and algal biomass differed between river and lagoon sites during the low-water period. The absence of flow in lagoons and consistently low algal biomass on river sandbanks were the most important features of the spatial variability between main-channel and lagoon sandbanks during low-water phases. Benthic algal biomass was highly uniform at small spatial scales and significantly heterogeneous at large spatial scales. In the second major part of this dissertation, I found a relatively species-rich shrimp assemblage with seven species inhabiting the sandbanks of the Cinaruco. I also observed clear patterns of temporal and spatial variation in shrimp abundance on the Cinaruco sandbanks. Abundance of shrimp on the sandbanks presented remarkable diel variation, showing almost exclusive use of this habitat at nights. Seasonally, shrimp were more abundant during rising- and falling-water periods, when rapid changes of environmental conditions occur. Shrimp abundance was high on those sandbanks with absence of troughs and presence of submerged vegetation. These environmental features presumably promote colonization/establishment and survival/persistence of shrimp in the sandbanks. In a patch-dynamic view of communities, a mobility control model seems to apply to shrimp of the sandbanks in the Cinaruco during the period of rapid changes in hydrology and habitat structure. During low-water periods, when habitat structure of sandbanks is relatively constant, low shrimp abundance appears to be heavily controlled by high fish predation. The annual flood regime of the Cinaruco, which drives the concentrations of dissolved materials, affects material interchanges between aquatic and terrestrial systems, and modifies aquatic habitat structural complexity, is responsible for creating strong patterns of seasonal and spatial variation in benthic algal crops and shrimp abundance on the sandbanks of this large floodplain river.

With the inevitable depletion of the petroleum supply and increasing energy demands in the world, interest has been growing in bioconversion of lignocellulosic biomass (e.g., sugarcane bagasse). Lignocellulosic biomass is an abundant, inexpensive, and renewable resource. Most of current conversion technologies require expensive enzymes and sterility. In contrast, the patented MixAlco process requires no enzymes or sterility, making it attractive to convert lignocellulosic biomass to transportation fuels and valuable chemicals. This study focuses on pretreatment and thermophilic fermentation in the MixAlco process. Ammonium bicarbonate (NH4HCO3) was discovered to be a better pH buffer than previously widely used calcium carbonate (CaCO3) in anaerobic fermentations under thermophilic conditions (55°C). The desired pH should be controlled within 6.5 to 7.5. Over 85% acetate content in the product was found in paper fermentations and bagasse fermentations. Hot-lime-water-treated bagasse countercurrent fermentations buffered by ammonium bicarbonate achieved 50–60% higher total product concentrations than those using calcium carbonate. It was nearly double in paper batch fermentations if the pH was controlled around 7.0. Ammonium bicarbonate is a “weak” methane inhibitor, so a strong methane inhibitor (e.g., iodoform) is still required in ammonium bicarbonate buffered fermentations. Residual calcium salts did not show significant effects on ammonium bicarbonate buffered fermentations. Lake inocula from the Great Salt Lake, Utah, proved to be feasible in ammonium bicarbonate buffered fermentations. Under mesophilic conditions (40°C), the inoculum from the Great Salt Lake increased the total product concentration about 30%, compared to the marine inoculum. No significant fermentation performance difference, however, was found under thermophilic conditions. The Continuum Particle Distribution Model (CPDM) is a powerful tool to predict product concentrations and conversions for long-term countercurrent fermentations, based on batch fermentation data. The experimental acid concentrations and conversions agree well with the CPDM predictions (average absolute error < 15%). Aqueous ammonia treatment proved feasible for bagasse. Air-lime-treated bagasse had the highest acid concentration among the three treated bagasse. Air-lime treatment coupled with ammonium bicarbonate buffered fermentations is preferred for a “crop-tofuel” process. Aqueous ammonia treatment combined with ammonium bicarbonate buffered fermentations is a viable modification of the MixAlco process, if “ammonia recycle” is deployed.

Concentrated animal feeding operations such as cattle feedlots and dairies produce a large amount of manure, cattle biomass (CB), which may lead to land, water, and air pollution if waste handling systems and storage and treatment structures are not properly managed. However, the concentrated production of low quality CB at these feeding operations serves as a good feedstock for in situ gasification for syngas (CO and H2) production and subsequent use in power generation. A small scale (10 kW) countercurrent fixed bed gasifier was rebuilt to perform gasification studies under quasisteady state conditions using dairy biomass (DB) as feedstock and various air-steam mixtures as oxidizing sources. A DB-ash (from DB) blend and a DB-Wyoming coal blend were also studied for comparison purposes. In addition, chlorinated char was also produced via pure pyrolysis of DB using N2 and N2-steam gas mixtures. The chlorinated char is useful for enhanced capture of Hg in ESP of coal fired boilers. Two main parameters were investigated in the gasification studies with air-steam mixtures. One was the equivalence ratio ER (the ratio of stochiometric air to actual air) and the second was the steam to fuel ratio (S:F). Prior to the experimental studies, atom conservation with i) limited product species and ii) equilibrium modeling studies with a large number of product species were performed on the gasification of DB to determine suitable range of operating conditions (ER and S:F ratio). Results on bed temperature profile, gas composition (CO, CO2, H2, CH4, C2H6, and N2), gross heating value (HHV), and energy conversion efficiency (ECE) are presented. Both modeling and experimental results show that gasification under increased ER and S:F ratios tend to produce rich mixtures in H2 and CO2 but poor in CO. Increased ER produces gases with higher HHV but decreases the ECE due to higher tar and char production. Gasification of DB under the operating conditions 1.59<ER less than6.36 and 0.35<s:f>less than0.8 yielded gas mixtures with compositions as given below: CO (4.77 - 11.73 %), H2 (13.48 - 25.45%), CO2 (11-25.2%), CH4 (0.43-1.73 %), and C2H6 (0.2- 0.69%). In general, the bed temperature profiles had peaks that ranged between 519 and 1032 degrees C for DB gasification.

Sweet sorghum (Sorghum bicolor) has potential as a bioenergy feedstock due to its high yield potential and the production of simple sugars for fermentation. Sweet sorghum cultivars are typically tall, high biomass types with juicy stalks and high sugar concentration. These sorghums can be harvested, milled, and fermented to ethanol using technology similar to that used to process sugarcane. Sweet sorghum has advantages in that it can be planted by seed with traditional planters, is an annual plant that quickly produces a crop and fits well in crop rotations, and it is a very water-use efficient crop. Processing sweet sorghum is capital intensive, but it could fit into areas where sugarcane is already produced. Sweet sorghum could be timed to harvest and supply the sugar mill during the off season when sugarcane is not being processed, be fit into crop rotations, or used in water limiting environments. In these ways, sweet sorghum could be used to produce ethanol in the Southern U.S and other tropical and subtropical environments. Traditionally, sweet sorghum has been grown as a pureline cultivar. However, these cultivars produce low quantities of seed and are often too tall for efficient mechanical harvest. Sweet sorghum hybrids that use grain-type seed parents with high sugar concentrations are one way to overcome limitation to seed supply and to capture the benefits of heterosis. There are four objectives of this research. First to evaluate the importance of genotype, environment, and genotype-by-environment interaction effects on the sweet sorghum yield and composition. The second objective is to determine the presence and magnitude of heterosis effects for traits related to sugar production in sweet sorghum. Next: to study the ability of sweet sorghum hybrids and cultivars to produce a ratoon crop and determine the contribution of ratoon crops to total sugar yield. The final objective is to evaluate variation in composition of sweet sorghum juice and biomass. Sweet sorghum hybrids, grain-type sweet seed parents, and traditional cultivars that served as male parents were evaluated in multi-environment trials in Weslaco, College Station, and Halfway, Texas in 2007 and 2008. Both genotype and environment influenced performance, but environment had a greater effect than genotype on the composition of sweet sorghum juice and biomass yield. In comparing performance, elite hybrids produced fresh biomass and sugar yields similar to the traditional cultivars while overcoming the seed production limitations. High parent heterosis was expressed among the experimental hybrids for biomass yield, sugar yield and sugar concentration. Additional selection for combining ability would further enhance yields and heterosis in the same hybrid. Little variation was observed among hybrids for juice and biomass composition suggesting that breeding efforts should focus on yield before altering plant composition.

Biomass is one of the renewable and non-conventional energy sources and it includes municipal solid wastes and animal wastes in addition to agricultural residue. Concentrated animal feeding operations produce large quantities of cattle biomass which might result in land and water pollution if left untreated. Different methods are employed to extract the available energy from the cattle biomass (CB) which includes co-firing and gasification. There are two types of CB: Feedlot biomass (FB), animal waste from feedlots and dairy biomass (DB), animal waste from dairy farms. Experiments were performed in the part on gasification of both FB and DB. Earlier studies on gasification of DB with different steam-fuel ratios resulted in increased production of hydrogen. In the present study, dairy biomass was gasified in a medium with enriched oxygen percentage varying from 24% to 28%. The effect of enriched air mixture, equivalence ratio and steam-fuel ratio on the performance of gasifier was studied. Limited studies were done using a mixture of carbon dioxide and oxygen as the gasification medium and also a methodology was developed to determine the gasification efficiency based on mass and heat contents of gas. The results show that the peak temperature within the bed increases with increase in oxygen concentration in the gasification medium. Also carbon dioxide concentration in the mixture increases with corresponding decrease in carbon monoxide with increase in oxygen concentration of the incoming gasification medium. The peak temperature increased from 988°C to 1192°C as the oxygen concentration increased from 21% to 28% at ER=2.1. The upper limit on oxygen concentration is limited to 28% due to high peak temperature and resulting ash agglomeration. Higher heating value (HHV) of the gases decreases with increase in equivalence ratio. The gases produced using carbon dioxide and oxygen mixture had a higher HHV when compared to that of air and enriched air gasification. Typically the HHV of the gases increased from 2219 kJ/m³ to 3479 kJ/m³ when carbon dioxide and oxygen mixture is used for gasification instead of air at ER=4.2 in the absence of steam.

If renewable energy and biofuels are to attain success in the market place, each step of their production and the system as a whole must be optimized to increase material and energy efficiency, reduce production cost and create a competitive alternative to fossil fuels. Systems optimization techniques may be applied to product selection, process design and integration, feedstock procurement and supply chain management to improve performance. This work addresses two problems facing a biorefinery: technology selection and feedstock scheduling in the face of varying feedstock supply and cost. Also addressed is the optimization of a biorefinery supply chain with respect to distributed processing of biomass to bio-products via preprocessing hubs versus centralized processing and facility location selection. Two formulations are proposed that present a systematic approach to address each problem. Case studies are included to demonstrate model capabilities for both formulations. The scheduling model results display model sensitivity to feedstock price and transport distance penalized through carbon dioxide emissions. The distributed model shows that hubs may be used to extend the operating radius of a biorefinery and thereby increase profits.

Sweet sorghum is a highly versatile C4 grass noted for its improved drought tolerance and water use efficiency relative to sugarcane. Sweet sorghum is well suited for ethanol production due to a rapid growth rate, high biomass production, and a wide range of adaptation. Unlike the 12-18 month growth cycle of sugarcane, sweet sorghum produces a harvestable crop in three to five months. Sweet sorghum and sugarcane crops are complementary and in combination can extend the sugar mill seasons in many regions of the world to an estimated 8 months. Seasonal growth and weather patterns both optimize and restrict production of each crop to specific times of the year, however these are different for the two crops. In addition to temporally spacing the date of harvest between crops, the genetic variability of maturity within the crops may also be used to extend the mill seasons; specific hybrids can be used and selected to maximize yield throughout the harvest season. Under favorable growing environments, sweet sorghum hybrids of all maturity groups produced sugar yields ranging from 2.8 to 4.9 MT/ha. Early/medium, late, and very late maturity hybrids planted during April, May, and June planting dates are necessary to maximize the mill season. In this study, early/medium maturity hybrids planted during April and May matured for harvest between late July and mid-August. June planting dates were unfavorable for early/medium maturity hybrids. In addition, late and very late maturity hybrids planted during April matured for harvest in late August; the additional growing season thus resulted in higher sugar yields. Timely planting of late and very late maturity hybrids in April, May, and June produce the maximum yields for harvests after mid August. Intermittent use of late and very late maturity hybrids can therefore extend sugar milling seasons into mid November if so desired.