• Energy Research
• Closed Access close
• Restricted close
• Open Source close
• CA close
• US close
• CN close
• English close

Clima 2000: 01 November 1993, London, England, UK Available on CD-ROM

There is a growing awareness of the valuable nutrients (nitrogen and phosphorus) being lost in conventional wastewater treatment systems. Although the removal of these nutrients has been well addressed, efforts for nutrient recovery have seen little development. As the emphasis on sustainability in the wastewater treatment industry increases, conventional wastewater treatment processes are being re-evaluated and new treatment systems developed. A possible nutrient recovery mechanism is the precipitation of magnesium ammonium phosphate hexahydrate (MgNH4PO4·6H2O), commonly known as struvite. Human urine has been identified as a rich source of nutrients in wastewater; hence the separate collection of urine is considered a viable method of enabling struvite recovery. Since dilution of urine to a certain degree is inevitable, reconcentration of urine beyond the solubility limit of struvite is critical. Currently available methods for reconcentration (e.g., evaporation, freeze-thaw, reverse osmosis and electrodialysis) are relatively expensive with high energy demand. Thus, the research here aims to demonstrate nutrient reconcentration from diluted urine and simultaneous organic removal by using the principles of microbial desalination cells (MDCs), where energy released from organic oxidation is partially used for the separation of nutrient ions. With reduced energy demand, a sustainable method for the utilization of source-separated urine is examined. The performance of bioelectrochemical systems relies on the activity of exoelectrogenic bacteria to transfer electrons to the anode. An examination of exoelectrogen sensitivity at various wastewater treatment conditions (i.e. ammonia and oxygen) is an important component of this research. Methanogenesis is considered the greatest challenge in achieving practical applications in anaerobic bioelectrochemical systems. An electrolytic oxygen production method is suggested for effective control of methanogenesis in a feasible and cost-effective manner. Master of Applied Science (MASc) Thesis

Latent thermal energy storages (LTESs) in combination with heat pumps and smart control strategies can maximize the utilization of renewable energy sources for heating and cooling. However, smart energy management with model predictive control (MPC) requires monitoring the total energy stored in the LTES, which is determined by the liquid fraction of the phase change material (PCM). Measuring the liquid fraction is challenging and the diverse liquid-fraction sensing approaches pose a trade-off between accuracy and ease of implementation. The present study aims to quantify the effect of the liquid fraction sensing accuracy on the performance of MPC strategies for heating systems with LTES. For this purpose, a residential heating application with an energy management system is analyzed. The heating system consists of a heat pump, an LTES and a photovoltaic array. The heat pump can be driven by the photovoltaic array and the electric grid. The energy management system uses MPC based on Mixed-Integer Linear Programming. Representative seasonal profiles for the heating load and weather conditions are used as forecasts for the MPC. The performance of the energy management system is assessed in terms of total heating cost for different error values in the estimation of the liquid fraction of the PCM in the LTES. The heating cost is found to proportionally increase with the absolute error in liquid fraction due to reduced utilization of the LTES capacity.

A novel design of hybrid thermal energy storage (HTES) using Phase Change Material (PCM) was evaluated using a mathematical model. Both single and multi-tank (cascaded) storage were explored to span small to large-scale applications (200-1600 litres). The storage element was based on the concept of a fully-mixed modular tank which is charged and discharged indirectly using two immersed coil heat exchangers situated at the bottom and top of the tank. A three-node model was developed to simulate different thermal behaviors during the operation of the storage element. Experiments were conducted on full-scale 200-l single-tank sensible heat storage (SHS) and hybrid thermal energy storage (HTES) to provide validation for the mathematical model. The HTES incorporated rectangular PCM modules submerged in the water tank. Satisfactory agreement was found between the numerical results and the experimental results obtained by Mather (2000) on single and multi-tank SHS. In addition, good agreement was noticed with the experiments performed by the author on single-tank SHS and HTES at McMaster University. The developed model was found to provide high levels of accuracy in simulating different operation conditions of the proposed design of storage element as well as computational efficiency. A parametric study was undertaken to investigate the potential benefits of the HTES over the SHS, operating under idealistic conditions. The HTES can perform at least two times better than the SHS with the same volume. The PCM volume fraction, melting temperature and properties were found to have critical impact on the storage gains of the HTES. All the parameters must be adjusted such that: (1) the thermal resistance of the storage element is minimized, and (2) most of the energy exchange with the storage element takes place in the latent heat form. The performance of the single-tank HTES was evaluated numerically while operating in a solar thermal domestic hot water (DHW) system for a single-family residence. The PCM parameters were selected to maximize the solar fraction during the operation on a typical spring day in Toronto. The use of the HTES can reduce the tank volume by 50% compared to the matched size of the SHS tank. However, the HTES was found to underperform the SHS when the system was operated in different days with different solar irradiation intensities. The effect of different draw patterns was also investigated. The results indicated that thermal storage is needed only when the energy demand is out-of-phase with the energy supply. For the same daily hot water demand, different consumption profiles; ex. dominant morning, dominant evening, dominant night and dispersed consumptions, showed slight impact on the performance of the system. The concept of multi-tank (cascaded) HTES storage was explored for medium/large scale solar heating applications such as for restaurants, motels, and multi-family residences. The design was based on the series connection of modular tanks through the bottom and top heat exchangers. Each individual tank had a PCM with different melting temperature. The results showed that the cascaded storage system outperformed the single-tank system with the same total volume as a result of the high levels of sequential or tank-to-tank stratification. The use of the cascaded HTES resulted in slight improvement in the solar fraction of the system. Doctor of Philosophy (PhD) Thesis

Recent concerted efforts to conserve energy have resulted in increasing use of loose-fill cellulose insulation which is particularly attractive because it has excellent thermal properties for its intended use, is relatively inexpensive, easily manufactured, simple to install, lends itself to retrofit applications and uses recycled material. It is combustible, however, and can undergo both flaming combustion and smouldering combustion when involved in fire. In spite of efforts by industry to reduce fire risk by incorporation of fire retardant chemicals, the flammable nature of the material is giving concern to consumers and the fire safety community. The need for a standard test for smouldering resistance is discussed. Copie papier conservée au CNRC. Version numérique disponible sur demande. Contactez NRC.NSL-BSN.CNRC@nrc-cnrc.gc.ca Print copy held at NRC. Digital version available upon request. Contact NRC.NSL-BSN.CNRC@nrc-cnrc.gc.ca

In this dissertation, we study several quantitative approaches centered on supply chain management, sustainability development, performance measurement frameworks, and environmental regulation mechanisms. The topic of sustainability has been of great interest for the past few years in academia. Many governments also have taken actions to incentivize firms to reduce their negative environmental and social impacts. It is unclear, however, how successful policy makers have been in reducing the sustainability threats. This raises the question of ``how can policy makers play an effective role in helping businesses become more sustainable, while complying with entrepreneurs and investors' expectations?'' This dissertation is organized on the basis of six chapters. Having reviewed the literature and research directions of sustainable supply chain management in Chapter 1, we present a review of sustainability performance measurement frameworks in Chapter 2. In addition to proposing a framework to assess sustainability efficiency in supply chains, we discuss research questions with a focus on the social aspect of sustainability development. In Chapter 3, we develop a two-stage data envelopment analysis model with an application to the energy sector. This approach measures relative efficiencies of a number of comparable decision makers and does not require predetermined weights of indicators. We relax some restricting assumptions used in previous studies and obtain a nonlinear problem, for which we develop a solution method. Chapter 4 investigates a more general multi-stage assessment framework that monitors suppliers, manufacturers, distributers, and retailers' sustainable practices. The major finding is developing a multi-stage data envelopment analysis to measure supply chains' sustainability efficiency. In Chapter 5, we investigate market-based schemes with a focus on curbing pollution emitted by business entities and develop a game-theoretic formulation. Finally, we summarize the major contributions of this dissertation and future research directions in Chapter 6. Doctor of Philosophy (PhD) Thesis

Statistical QCD predicts that with increasing density, strongly interacting matter will undergo a transition to a plasma of deconfined quarks and gluons. High energy heavy ion collisions are expected to permit experimental studies of this transition and of the predicted new state of matter. 22 refs., 6 figs.

Detailed cradle-to-grave life cycle analyses are performed for bulk-scale solid oxide fuel cell power plants fueled by gasified coal. These results are compared to cradle-to-grave life cycle analyses of the supercritical pulverized coal and integrated gasification combined cycle power generation plants, which are also performed as a part of this study. Life cycle inventories for each plant including the inputs (resources and fuels) and outputs (emissions and waste) of the gate-to-gate plants and their associated up- and down-stream sub-processes are computed. The impact of carbon capture and sequestration on each plant is quantified and assessed using the ReCiPe 2008 life cycle inventory method for three socioeconomic perspectives. The results of each coal plant are compared to one another and to plants generating power from natural gas at the end-point level. Results indicate that not only do coal-fed SOFCs generate power with a significantly lower life cycle impact than the current state-of-the-art coal plants, but when carbon capture is enabled they can do so with a lower impact than the most modern plants utilizing natural gas, as well. NSERC Vanier Scholarship, Ontario Research Fund - Research Excellence

The Bay of Fundy is home to some of the world's largest tides and has long been identified as one of the world's premier locations for the installation of tidal power generating systems. This paper deals with the assessment of hydrodynamic impacts throughout the Bay of Fundy and Gulf of Maine due to power generation by tidal lagoons located in Minas Basin. The lagoon concept involves temporarily storing seawater behind an impoundment dike and generating power by gradually releasing the seawater through conventional low-head hydroelectric turbines. Tidal lagoons represent a relatively novel approach to tidal power generation, and are intended to achieve high efficiency while avoiding some of the environmental problems associated with tidal barrages. A detailed two-dimensional (depth-averaged) finite-element numerical model, based on the TELEMAC system, has been developed, calibrated against observed water levels and velocities, and applied to simulate tidal hydrodynamics throughout the Bay of Fundy and Gulf of Maine, both for existing conditions without a lagoon and for two scenarios with tidal lagoons operating in Minas Basin. A 12 km 2 offshore lagoon with 14 turbines generating ∼124 MW on average and a 24 km 2 coastal lagoon with 24 turbines generating ∼220 MW on average have been investigated. This paper provides a summary of the work that has been performed to date and presents results describing the local and far-field changes in water levels and tidal currents due to tidal lagoons operating in the upper Bay of Fundy. Annual Conference of the Canadian Society for Civil Engineering 2011, CSCE 2011, 14 June 2011 through 17 June 2011, Ottawa, ON

To date, the majority of world's primary energy is derived from fossil fuels. However, the fossil fuel recourses are in an inevitable decline as energy demand continues to grow exponentially with population growth, urbanization, and improved standards of living. Crude oil prices have recently risen several times and their current annual volatility exceeds 30%. The potential scarcity of fossil fuels has prompted a global search for alternative energy resources. Biodiesel fulfills the major requirements for production of alternative fuels such as feedstock availability, technical feasibility, and economic competitiveness. Together with other renewable biofuels, the use of biodiesel as a substitute of fossil-based fuels is expected to reduce the dependence on imported petroleum and associated political and economic vulnerability, decrease greenhouse gas emissions, and revitalize the economy. The objective of this article was to provide an update of the most recent technological advancements toward clean and sustainable biodiesel production through a thorough overview of biodiesel feedstocks, most promising transesterification processes, and opportunities for glycerol utilization for value-added products. A critical analysis of the techno-economical barriers and environmental challenges that need to be addressed in future R&D efforts toward commercialization and establishment of a sustainable and cost-efficient biodiesel production is provided. Keywords: biodiesel; waste oil; microbial oil; transesterification; microwave irradiation; lipase; glycerol; triacetin; greenhouse gas emissions; trends in biodiesel R&D