Assessing wave conditions in a Norwegian fjord

Master's thesis in Offshore technology: Marine and subsea technologyThe focus of this thesis is to obtain an estimate of the significant wave height together with the corresponding peak period for the proposed bridge locations at Bjørnafjord. The task was conducted by modelling and calculations done in SWAN software. The methodology for transforming the NORA10 hindcast data into the design wave conditions for the 10-2 and 10-4 probability of exceedance was introduced for an offshore location. Furthermore a short description for the methods of transforming the metocean conditions to the fjord position were presented. The theory on the different wave generation and dissipation mechanisms present in the coastal waters was described. The description introduced the influence of those physical phenomena on the wave spectrum. The implementation of the dissipation mechanisms in SWAN was described with respect to the models produced for this thesis. As an introduction to modelling in the SWAN, the test case model analysis based on the master thesis by Engbretsen (2012) was performed. Furthermore a series of simplified idealized models was prepared. The models are reflecting the real bathymetry features found in the Bjørnafjord and are the basis for the analysis of the fjord. The cases were modelled to consider the influence of the bottom topography on the wave field. A number of sensitivity studies was executed to investigate the influence of the different coastal effects on the total sea characteristics. Finally the Bjørnafjord wave model was created. Real bathymetry data was modelled based on the maps acquired from Kystverket. The inputs in regard to the wind and incoming wave conditions were based on the reports by SINTEFF - Stefanakos (2015) and NORCONSULT - Lothe (2015). A number of cases with different environmental conditions was analysed. Sensitivity study in regard to the dominating dissipation mechanisms was conducted. The obtained results were compared with the analyses done in the source reports of Stefanakos and Lothe

Torrefaction of Sewage Sludge: Kinetics and Fuel Properties of Biochars

We propose a ‘Waste to Carbon’ thermal transformation of sewage sludge (SS) via torrefaction to a valuable product (fuel) with a high content of carbon. One important, technological aspect to develop this concept is the determination of activation energy needed for torrefaction. Thus, this research aimed to evaluate the kinetics of SS torrefaction and determine the effects of process temperature on fuel properties of torrefied products (biochars). Torrefaction was performed using high ash content SS at six (200~300 °C) temperatures and 60 min residence (process) time. Mass loss during torrefaction ranged from 10~20%. The resulting activation energy for SS torrefaction was ~12.007 kJ·mol−1. Initial (unprocessed) SS higher heating value (HHV) was 13.5 MJ·kg−1. However, the increase of torrefaction temperature decreased HHV from 13.4 to 3.8 MJ·kg−1. Elemental analysis showed a significant decrease of the H/C ratio that occurred during torrefaction, while the O/C ratio fluctuated with much smaller differences. Although the activation energy was significantly lower compared with lignocellulosic materials, low-temperature SS torrefaction technology could be explored for further SS stabilization and utilization (e.g., dewatering and hygienization)

Oxytree Pruned Biomass Torrefaction: Mathematical Models of the Influence of Temperature and Residence Time on Fuel Properties Improvement

Biowaste generated in the process of Oxytree cultivation and logging represents a potential source of energy. Torrefaction (a.k.a. low-temperature pyrolysis) is one of the methods proposed for the valorization of woody biomass. Still, energy is required for the torrefaction process during which the raw biomass becomes torrefied biomass with fuel properties similar to those of lignite coal. In this work, models describing the influence of torrefaction temperature and residence time on the resulting fuel properties (mass and energy yields, energy densification ratio, organic matter and ash content, combustible parts, lower and higher heating values, CHONS content, H:C and O:C ratios) were proposed according to the Akaike criterion. The degree of the models’ parameters matching the raw data expressed as the determination coefficient (R2) ranged from 0.52 to 0.92. Each model parameter was statistically significant (p \u3c 0.05). Estimations of the value and quantity of the produced torrefied biomass from 1 Mg of biomass residues were made based on two models and a set of simple assumptions. The value of torrefied biomass (€123.4·Mg−1) was estimated based on the price of commercially available coal fuel and its lower heating value (LHV) for biomass moisture content of 50%, torrefaction for 20 min at 200 °C. This research could be useful to inform techno-economic analyses and decision-making process pertaining to the valorization of pruned biomass residues

Waste to Carbon: Influence of Structural Modification on VOC Emission Kinetics from Stored Carbonized Refuse-Derived Fuel

The torrefaction of municipal solid waste is one of the solutions related to the Waste to Carbon concept, where high-quality fuel—carbonized refuse-derived fuel (CRDF)—is produced. An identified potential problem is the emission of volatile organic compounds (VOCs) during CRDF storage. Kinetic emission parameters have not yet been determined. It was also shown that CRDF can be pelletized for energy densification and reduced volume during storage and transportation. Thus, our working hypothesis was that structural modification (via pelletization) might mitigate VOC emissions and influence emission kinetics during CRDF storage. Two scenarios of CRDF structural modification on VOC emission kinetics were tested, (i) pelletization and (ii) pelletization with 10% binder addition and compared to ground (loose) CRDF (control). VOC emissions from simulated sealed CRDF storage were measured with headspace solid-phase microextraction and gas chromatography–mass spectrometry. It was found that total VOC emissions from stored CRDF follow the first-order kinetic model for both ground and pelletized material, while individual VOC emissions may deviate from this model. Pelletization significantly decreased (63%~86%) the maximum total VOC emission potential from stored CDRF. Research on improved sustainable CRDF storage is warranted. This could involve VOC emission mechanisms and environmental-risk management

Valorization of Sewage Sludge via Gasification and Transportation of Compressed Syngas

A significant challenge in the utilization of alternative gaseous fuels is to use their energy potential at the desired location, considering economic feasibility and sustainability. A potential solution is a compression, transportation in pressure tanks, and generation of electricity and heat directly at the recipient. In this research, the potential for generating syngas from abundant waste substrates was analyzed. The sewage sludge (SS) was used as an example of a bulky and abundant resource that could be valorized via gasification, compression, and transport to end-users in containers. A model was developed, and theoretical analyses were completed to examine the influence of the calorific value of the syngas produced from the SS gasification (under different temperatures and gasifying agents) on the efficiency of energy transportation of compressed syngas. First, the gasification simulation was carried out, assuming equilibrium in a downdraft gasifier (reactor) from 973–1473 K and five gasifying agents (O2, H2, CO2, water vapor, and air). Molar ratios of the gasifying agents to the (SS) C ranged from 0.1–1.0. The model predicted syngas composition, lower calorific values (LHV) for a given molar ratio of the gasification agent, and compressibility factor. It was shown that the highest LHV was obtained at 0.1 molar ratio for all gasifier agents. The highest LHV (~20 MJ∙(Nm3)−1) was obtained by gasification with H2 and the lowest (~13 MJ∙(Nm3)−1) in the case of air. Next, the available syngas volume in a compressed gas transportation unit and the stored energy was estimated. The largest syngas volume can be transported when O2 is used as a gasifying agent, but the highest amount of transported energy was estimated for gasification with H2. Finally, the techno-economic analyses showed that syngas from SS could be competitive when the energy of compressed syngas is compared with the demand of an average residential dwelling. The developed syngas energy transport system (SETS) concept proposes a new method to distribute compressed syngas in pressure tanks to end-users using all modes of transport carrying intermodal ISO containers. Future work should include the determination of energy demand for syngas compression, including pressure losses, heat losses, and analysis of the influence of syngas on storage and compression devices

Oxytree Pruned Biomass Torrefaction: Process Kinetics

Oxytree is a fast-growing energy crop with C4 photosynthesis. In this research, for the first time, the torrefaction kinetic parameters of pruned Oxytree biomass (Paulownia clon in Vitro 112) were determined. The influence of the Oxytree cultivation method and soil class on the kinetic parameters of the torrefaction was also investigated. Oxytree pruned biomass from a first-year plantation was subjected to torrefaction within temperature range from 200 to 300 °C and under anaerobic conditions in the laboratory-scale batch reactor. The mass loss was measured continuously during the process. The relative mass loss increased from 1.22% to 19.56% with the increase of the process temperature. The first-order constant rate reaction (k) values increased from 1.26 × 10−5 s−1 to 7.69 × 10−5 s−1 with the increase in temperature. The average activation energy for the pruned biomass of Oxytree torrefaction was 36.5 kJ∙mol−1. Statistical analysis showed no significant (p \u3c 0.05) effect of the Oxytree cultivation method and soil class on the k value. The results of this research could be useful for the valorization of energy crops such as Oxytree and optimization of waste-to-carbon and waste-to-energy processes

The Influence Of Urbanization Level Of Residence On The Health-Related Fitness Of University Students

The aim of the study was to assess the influence of place of residence on the health-related fitness (H-RF) of university students from Kielce, Poland. The research included 632 first-year students from the Jan Kochanowski University in Kielce between 2015-2017. The research analyzed two basic components of H-RF─ morphological and circulatory-respiratory. In terms of the morphological component, body height and weight, as well as BMI were measured. In terms of the circulatory-respiratory component, the V̇O2max was calculated utilizing the Astrand test, that allows the assessment of V̇O2max in l / min and V̇O2max in ml / kg / min and PWC170. Data regarding place of permanent residence of the students and physical activity in their free time were collected using a questionnaire. In this respect, the urban and rural environment were distinguished. Using the Vigorous Physical Activity index, two categories of physical activity in free time were distinguished, i.e. moderate and low. The obtained results indicate a differentiation of H-RF of the student, both in relation to the place of permanent residence and physical activity in their free time, that was slightly more pronounced in men than in women. This may denote that men are more eco-sensitive, meaning that they might be more susceptible to the influence of environmental factors