THE DESIGN OF A POWER SYSTEM FOR A WIRELESS SENSOR NETWORK FOR LONG-TERM OPERATION

Wireless sensor networks (WSNs) have shown wide applicability to many fields including monitoring of environmental, civil, and industrial settings. WSNs however are resource constrained by many competing factors that span their hardware, software, and networking. One of the central resource constrains is the charge consumption of WSN nodes. With finite energy supplies, low charge consumption is needed to ensure long lifetimes and success of WSNs. This thesis details the design of a power system to support long-term operation of WSNs. The power system’s development occurs in parallel with a custom WSN from the Queen’s MEMS Lab (QML-WSN), with the goal of supporting a 1+ year lifetime without sacrificing functionality. The final power system design utilizes a TPS62740 DC-DC converter with AA alkaline batteries to efficiently supply the nodes while providing battery monitoring functionality and an expansion slot for future development. Testing tools for measuring current draw and charge consumption were created along with analysis and processing software. Through their use charge consumption of the power system was drastically lowered and issues in QML-WSN were identified and resolved including the proper shutdown of accelerometers, and incorrect microcontroller unit (MCU) power pin connection. Controlled current profiling revealed unexpected behaviour of nodes and detailed current-voltage relationships. These relationships were utilized with a lifetime projection model to estimate a lifetime between 521-551 days, depending on the mode of operation. The power system and QML-WSN were tested over a long term trial lasting 272+ days in an industrial testbed to monitor an air compressor pump. Environmental factors were found to influence the behaviour of nodes leading to increased charge consumption, while a node in an office setting was still operating at the conclusion of the trail. This agrees with the lifetime projection and gives a strong indication that a 1+ year lifetime is achievable. Additionally, a light-weight charge consumption model was developed which allows charge consumption information of nodes in a distributed WSN to be monitored. This model was tested in a laboratory setting demonstrating +95% accuracy for high packet reception rate WSNs across varying data rates, battery supply capacities, and runtimes up to full battery depletion.

Anticipating climate-induced changes to forest cover in Ontario and the implications for future bioenergy development

Climate change is expected to have marked impacts on forest ecosystems. In Ontario forests, this includes changes in tree growth, stand composition and disturbance regimes, with expected impacts on many forest-dependent communities, the bioeconomy, and other environmental considerations. In response to climate change, renewable energy systems, such as forest bioenergy, are emerging as critical tools for carbon emissions reductions and climate change mitigation. However, these systems may also need to adapt to changing forest conditions. Therefore, the aim of this research was to estimate changes in forest growth and forest cover in response to anticipated climatic changes in the year 2100 in Ontario forests, to ultimately explore the sustainability of bioenergy in the future. Using the Haliburton Forest and Wildlife Reserve in Ontario as a case study, this research used a spatial climate analog approach to match modeled Haliburton temperature and precipitation (via Fourth Canadian Regional Climate Model) to regions currently exhibiting similar climate (climate analogs). From there, current forest cover and growth rates of core species in Haliburton were compared to forests plots in analog regions from the US Forest Service Forest Inventory and Analysis (FIA). This comparison used two different emission scenarios, corresponding to a high and a mid-range emission future. This research then explored how these changes in forests may influence bioenergy feasibility in the future. It examined possible volume availability and composition of bioenergy feedstock under future conditions. This research points to a potential decline of softwoods in the Haliburton region with a simultaneous expansion of pre-established hardwoods such as northern red oak and red maple, as well as a potential loss in sugar maple cover. From a bioenergy perspective, hardwood residues may be the most feasible feedstock in the future with minimal change in biomass availability for energy production; under these possible conditions, small scale combined heat and power (CHP) and residential pellet use may be the most viable and ecologically sustainable options. Ultimately, understanding the way in which forests may change is important in informing meaningful policy and management, allowing for improved forest bioenergy systems, now and in the future.

Three Essays on Economic Development in the Natural Resources Sector

This thesis examines two ongoing development projects that received financial support from international development organizations, and an alternative mining tax proposed by the academia. Chapter 2 explores the impact of commoditization of coffee on its export price in Ethiopia. The first part of the chapter traces how the Ethiopian’s current coffee trade system and commoditization come to be. Using regression analysis, the second part tests and confirms the hypothesis that commoditization has led to a reduction in coffee export price. Chapter 3 conducts a cost-benefit analysis on a controversial, liquefied natural gas export project in Peru that sought to export one-third of the country’s proven natural gas reserves. While the country can receive royalty and corporate income tax in the short and medium term, these benefits are dwarfed by the future costs of paying for alternative energy after gas depletion. The conclusion is robust for a variety of future energy-price and energy-demand scenarios. Chapter 4 quantifies through simulation the economic distortions of two common mining taxes, the royalty and ad-valorem tax, vis-à-vis the resource rent tax. The latter is put forward as a better mining tax instrument on account of its non-distortionary nature. The rent tax, however, necessitates additional administrative burdens and induces tax-avoidance behavior, both leading to a net loss of tax revenue. By quantifying the distortions of royalty and the ad-valorem tax, one can establish the maximum loss that can be incurred by the rent tax. Simulation results indicate that the distortion of the ad-valorem tax is quite modest. If implemented, the rent tax is likely to result in a greater loss. While the subject matters may appear diverse, they are united by one theme. These initiatives were endorsed and supported by authorities and development agencies in the aim of furthering economic development and efficiency, but they are unlikely to fulfill the goal. Lessons for international development can be learnt from successful stories as well as from unsuccessful ones.