In the last decades terms like Global Warming and Sustainable development have arisen. The anthropogenic green house gases emissions have raised the concentration of CO2 in the atmosphere to levels that might lead to a high increase in the average temperature in Earth. One of the most effective ways to fight against this phenomenon is to promote clean renewable energies. Among them, solar energy has the biggest developing potential and has proved to be an efficient and cost-effective energy source for different applications; one of them being the production of Domestic Hot Water and Space Heating. The aim of this Thesis is to study the possibilities to provide a single family house with hot water and space heating in an environmental friendly way. To do so, a solar system with biomass support will be designed for a single family house in northern Spain. The building has total energy demand of 20.5 MWh a year, of which 18 MWh correspond to space heating and 2.5 MWh to domestic hot water. The chosen solution for the building includes 12 solar collectors with a total area of 23.4 m2, a biomass boiler with a nominal power of 30 kW and a 32 kW oil boiler. Additionally, a radiant floor system was used as it perfectly adapts to the low temperature of the solar system. The result is an installation working with an 85% of renewable energies. This high share of renewable energy entails savings of 2,000 liters of oil a year, avoiding the emission of 4.5 tones of CO2 to the atmosphere every year. The economic calculations show that the pay back of the investment is 10 years with a Internal Rate of Return of 13%. Therefore, it can be said that, for this particular building and due to the governmental subsidies granted, solar energy is a cost effective alternative to provide the basic energy needs of a house.

Biofuels like ethanol are gaining serious momentum because of concerns over climate change and the rising cost of fossil fuels. Saskatchewan is the first province in Canada to pass a law requiring ethanol blended into its gasoline. A blend rate of 7.5% is mandated as of January 2007. This legislation is not yet fully enforced as ethanol production cannot currently meet demand, but local production is increasing. The traditional method of production is via grain fermentation; however the food versus fuel debate indicates this is unethical when food shortages and prices are already on the rise. Gasification is a robust technology for processing raw, non-food grade biomass into syngas (H2 and CO) which can then be further converted to ethanol via gas-to-liquid conversion technology. Condensable materials called tars form during gasification and must be further converted to gaseous products to avoid problems downstream. This can be achieved via optimization of process conditions and catalysis. The research for this thesis was carried out in two phases. Phase 1 examined the effects of process conditions on the noncatalytic temperature-programmed gasification of wood (Jack Pine) biomass. Temperature was varied from 700 to 825oC, water flow rate was varied from 2 to 5 cm3/h, and N2 flow rate from 16 to 32 cm3/min. When varying biomass gasification conditions, overall % carbon conversion to gaseous products reached a maximum of 70% at 825oC, 5.0 cm3/h H2O, and 32 cm3/min N2. 670 cm3 product gas per g biomass was produced, with 35.8 mol% H2 and H2:CO of 1.56. In Phase 2, catalytic gasification of wood biomass was carried out using a double bed micro reactor in a two-stage process. Temperature programmed steam gasification of biomass was performed in the first bed at 200-850oC. Following in the second bed was isothermal catalytic decomposition gasification of volatile compounds (including tars). Dolomites from Canada, Australia and Japan were examined for their effects on tar abatement and the overall gaseous product. The gasification of pine sawdust resulted in 74% of carbon emitted as volatile matter during tar gasification (200-500oC biomass bed temperature). High temperature, high H2O flow rate and low carrier gas flow rate are recommended for improving biomass conversion to gaseous products. Dolomites improved tar decomposition by an average 21% at 750oC isothermal catalyst bed temperature. For Canadian dolomites, iron content was found to promote tar conversion and the water-gas shift reaction, but the effectiveness reached a plateau at 1.0 wt% Fe present in dolomite. The best dolomite was Canada # 1, from an area west of Flin Flon, Manitoba. This dolomite yielded 66% tar conversion (25% above noncatalytic results) at 750oC using 1.6 cm3 catalyst/g biomass. Carbon conversion increased to 97% using 3.2 cm3 catalyst/g biomass at the same temperature. The dolomite seemed stable after 15 hours of cyclic use at 800oC.

Mercury is a leading concern among the air toxic metals addressed in the 1990 Clean Air Act Amendments (CAAA) because of its volatility, persistence, and bioaccumulation as methylmercury in the environment and its neurological health impacts. The Environmental Protection Agency (EPA) reports for 2001 shows that total mercury emissions from all sources in USA is about 145 tons per annum, of which coal fired power plants contribute around 33% of it, about 48 tons per annum. Unlike other trace metals that are emitted in particulate form, mercury is released in vapor phase in elemental (Hg0) or oxidized (Hg2+, mainly HgCl2) form. To date, there is no post combustion treatment which can effectively capture elemental mercury vapor, but the oxidized form of mercury can be captured in traditional emission control devices such as wet flue gas defulrization (WFGD) units, since oxidized mercury (HgCl2) is soluble in water. The chlorine concentration present during coal combustion plays a major role in mercury oxidation, which is evident from the fact that plants burning coal having high chlorine content have less elemental mercury emissions. A novel method of co-firing blends of low chlorine content coal with high chlorine content cattle manure/biomass was used in order to study its effect on mercury oxidation. For Texas Lignite and Wyoming coal the concentrations of chlorine are 139 ppm and 309 ppm on dry ash free basis, while for Low Ash Partially Composted Dairy Biomass it is 2,691 ppm. Co-firing experiments were performed in a 100,000 BTU/hr (29.3 kWt) Boiler Burner facility located in the Coal and Biomass Energy laboratory (CBEL); coal and biomass blends in proportions of 80:20, 90:10, 95:5 and 100:0 were investigated as fuels. The percentage reduction of Hg with 95:5, 90:10 and 80:20 blends were measured to be 28- 50%, 42-62% and 71-75% respectively. Though cattle biomass serves as an additive to coal, to increase the chlorine concentration, it leads to higher ash loading. Low Ash and High Ash Partially Composted Dairy Biomass have 164% and 962% more ash than Wyoming coal respectively. As the fraction of cattle biomass in blend increases in proportion, ash loading problems increase simultaneously. An optimum blend ratio is arrived and suggested as 90:10 blend with good reduction in mercury emissions without any compromise on ash loading.

Dairy biomass (DB) is evaluated as a possible co-firing fuel with coal. Cofiring of DB offers a technique of utilizing dairy manure for power/steam generation, reducing greenhouse gas concerns, and increasing financial returns to dairy operators. The effects of cofiring coal and DB have been studied in a 30 kW (100,000 BTU/hr) burner boiler facility. Experiments were performed with Texas Lignite coal (TXL) as a base line fuel. The combustion efficiency from co-firing is also addressed in the present work. Two forms of partially composted DB fuels were investigated: low ash separated solids and high ash soil surface. Two types of coal were investigated: TXL and Wyoming Powder River Basin coal (WYO). Proximate and ultimate analyses were performed on coal and DB. DB fuels have much higher nitrogen (kg/GJ) and ash content (kg/GJ) than coal. The HHV of TXL and WYO coal as received were 14,000 and 18,000 kJ/kg, while the HHV of the LA-PC-DBSepS and the HA-PC-DB-SoilS were 13,000 and 4,000 kJ/kg. The HHV based on stoichiometric air were 3,000 kJ/kg for both coals and LA-PC-DB-SepS and 2,900 kJ/kg for HA-PC-DB-SoilS. The nitrogen and sulfur loading for TXL and WYO ranged from 0.15 to 0.48 kg/GJ and from 0.33 to 2.67 for the DB fuels. TXL began pyrolysis at 640 K and the WYO at 660 K. The HA-PC-DB-SoilSs began pyrolysis at 530 K and the LA-PC-DB-SepS at 510 K. The maximum rate of volatile release occurred at 700 K for both coals and HA-PC-DB-SoilS and 750K for LA-PC-DB-SepS. The NOx emissions for equivalence ratio (φ) varying from 0.9 to 1.2 ranged from 0.34 to 0.90 kg/GJ (0.79 to 0.16 lb/mmBTU) for pure TXL. They ranged from 0.35 to 0.7 kg/GJ (0.82 to 0.16 lb/mmBTU) for a 90:10 TXL:LA-PC-DB-SepS blend and from 0.32 to 0.5 kg/GJ (0.74 to 0.12 lb/mmBTU) for a 80:20 TXL:LA-PC-DB-SepS blend over the same range of φ. In a rich environment, DB:coal cofiring produced less NOx and CO than pure coal. This result is probably due to the fuel bound nitrogen in DB is mostly in the form of urea which reduces NOx to non-polluting gases such as nitrogen (N2).

Coal fired power plants will face many challenges in the near future as new regulations, such as the Clear Sky Act, are being implemented. These regulations impose much stricter limits on NOx emissions and plan to impose limits on mercury emissions from coal fired boilers. At this time no technologies are currently being implemented for control of Hg and this explains the strong interest in this area by the Department of Energy (DOE). Reburn technology is a very promising technology to reduce NOx emissions. Previous experimental research at TAMU reported that Feedlot Biomass (FB) can be a very effective reburn fuel, for reduction of NOx up to 90%-95%; however, little work has been done to model such a process with Feedlot Biomass as reburn fuel. The present work addresses the development of a reburn model to predict NOx and Hg emissions. The model accounts for finite rate of heating of solid fuel particles, mixing with NOx laden hot gases, size distribution, finite gas phase and heterogeneous chemistry, and oxidation and reduction reactions for NOx and Hg. To reduce the computational effort all the reactions, except those involved in mercury oxidation, are modeled using global reactions. Once the model was validated by comparison with experimental findings, extensive parametric studies were performed to evaluate the parameters controlling NOx reduction. From DOE research programs some experimental data regarding the capture of mercury from power plant is available, but currently no experimental data are available for Hg emission with reburn process. This model has shown a very large mercury reduction using biomass as a reburn fuel. The model recommends the following correlations for optimum reduction of NOx: Equivalence Ratio should be above 1.05; mixing time should be below 100ms (especially for biomass); pure air can be used as the carrier gas; the thermal power fraction of the reburner should be between 15% and 25%; residence time should be at least 0.5s and the Surface Mean Diameter (SMD) of the size distribution should be as small as possible, at least below 100 µm.

Biomass conversion technologies are receiving increasing attention due to global climate change and most recently plans from the President of the United States to reduce fossil fuel consumption. The MixAlco process converts a variety of feedstocks, such as agricultural residues, municipal solid waste, and sewage sludge, into mixed alcohols via microbial fermentation, which can then be used as fuel additives or independently as an alternative fuel. Optimizing the pretreatment step of this process is critical to improving product yields. The process uses lime pretreatment, which can be enhanced using new decrystallization pretreatment methods, namely hydrodynamic cavitation and shock tube pretreatment.Previous studies on biomass decrystallization showed an increase in biomass digestibility when hydrodynamic cavitation was utilized as a pretreatment step. This previous work was expanded by studying both acoustic and hydrodynamic cavitation. Computational fluid dynamics (CFD) was used to model the cavitator to improve its efficiency. The crystallinity before and after pretreatment was analyzed. A new laboratory-scale MixAlco lime-pretreatment system was developed to produce greater quantities of lime-pretreated biomass that could be subjected to decrystallization experiments. The length of pretreatment, water loading, and bagasse loadings were varied for the shock tube experiments. After each pretreatment, enzymatic hydrolysis was performed, and the equivalent glucose yield was measured by the DNS (dinitrosalicylic acid) assay. Additionally, mixed-acid fermentation was performed to show the benefits of reduced crystallinity on the MixAlco fermentation. The acoustic and hydrodynamic cavitation pretreatments had a modest effect on crystallinity. In contrast, the shock tube pretreatment shows greater promise as an effective decrystallization pretreatment, even for lime-treated bagasse. Repeated shocks had little effect on digestibility and the crystallinity; however, the water temperature used in shock tube pretreatment played an important role in bagasse digestibility and crystallinity.

Temporary changes in macroalgal abundance, percentage cover and areal biomass were surveyed on Nanwan (GPS: 21o56'00'N; 120o50'10'E) and Tiaoshi (GPS: 21o55'30'N; 120o 50'40'E) reefs (Kenting, Taiwan, Republic of China), during 1999-2000. Community structure and areal biomass showed significant changes in time and the maximal biomass was observed during March-April due to Sargassum spp. at Nanwan and Codium spp. at Tiaoshi. The maximal total areal biomass is not different between two years for Nanwan but significantly different for Tiaoshi mainly due to a marked biomass of Codium edule during 2000. Eutrophication on Nanwan and Tiaoshi reefs is the main cause for macroalgal blooming. Tissue composition analysis, nutrient enrichment and starvation treatments, bioassay and in situ extracellular alkaline phosphatase activity determination showed that growth of Sargassum duplicatum, Codium edule and Ulva latuca were limited by phosphorus during the early growth period while nitrogen during the fast growth period. Growth of Enteromorpha linza, Gracilaria coronopifolia and Laurencia papillosa were limited by phosphorus. Water temperature is the factor affecting the time for the start of development of young shoots and also for the peak of areal biomass and subsequent die-off of thallus. This investigation suggests that the reduction of water nutrient levels is an effective way in the retardation of over-growth of macroalgae on Nanwan and Tiaoshi reefs.

Growing rates of manure produced from large dairies have increased concern for the environmental quality of nearby streams and watersheds. Typically the manure from the freestalls on these dairies is flushed with water to a mechanical separator. Here, flushed dairy biomass (DB) is parted into separated solids and separated liquid. The separated liquid is discharged into lagoons for treatment and eventual land application. This thesis proposes thermodynamic models for firing DB in small scale boiler systems that would eliminate land application and lagoons, which are being claimed to be the source of nutrient leaching and overloading. Fuel analysis of flushed DB from a dairy in central Texas show that it contains 93%moisture (%M), 3%ash (%A), and 4%combustibles (%Cb), while separated DB solids contain 81%M, 2%A, and 17%Cb. The dry, ash-free higher heating value of DB is approximately 20,000 kJ/kg. Using dry, ash-free results, computations can be made over ranges of %M and %A. For example, DB containing 70%M requires 9.74%Cb to vaporize all moisture and produce gaseous products of combustion at 373 K, but requires 17.82%Cb to burn in a regenerative combustor with a flame temperature of 1200 K. Separated solids that are pressed in an auger to 70%M (3%A and 27%Cb) can burn at 1200 K with exhaust temperatures of up to 1130 K and a minimum required heat exchanger effectiveness of 15%. Pressed solids can thus be fired in a boiler, where the remaining separated liquid can be used as feed water. The pressed solids only can release about 30% of the heat required to vaporize the remaining unclean feed water. However, pressed DB solids can be blended with drier fuels to vaporize almost all the unclean water. The low quality steam produced from the unclean water can be used in thermal processes on the farm. A similar system can be developed for vacuumed DB without the need to vaporize unclean feed water. As for large dairies with anaerobic digester systems already installed, directly firing the produced biogas in a small scale boiler system may be another way to similarly vaporize the remaining effluent.

This thesis examines the economic implications of using agriculturally based feedstock for bio-energy production in East Texas. Specifically I examined the use of switchgrass, rice straw, and logging residue as a feedstock for electrical power generation in East Texas replacing coal. To examine the effects of such a substitution, an environmental bio-complexity approach is used to analyze the interactions of agricultural, technological, economic, and environmental factors. In particular, lifecycle analysis (LCA) and Cost-Benefit analysis is used. The results show that as we use more bio-energy for power generation, we will get less Greenhouse Gas (GHG) emission, which will be an environmental benefit in the long run. The main problem is that cost increases. Current biomass feedstock production costs are generally too high for biomass feedstock to replace coal in power generation. However I find that GHG offset prices can make biomass economically attractive. In particular GHG offset prices and forgiveness for the emissions from combustion based on photosynthetic absorption would raise the price people would be willing to pay for biomass feedstock making it competitive.

Thesis (M.S. in engineering)--Washington State University, December 2009. / Title from PDF title page (viewed on Jan. 21, 2010). "Department of Biological Systems Engineering." Includes bibliographical references.