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Optimization of a Grid-Connected Microgrid Using Tidal and Wind Energy in Cook Strait
The Cook Strait in New Zealand is an ideal location for wind and tidal renewable sources of energy due to its strong winds and tidal currents. The integration of both technologies can help to avoid the detrimental effects of fossil fuels and to reduce the cost of electricity. Although tidal renewable sources have not been used for electricity generation in New Zealand, a recent investigation, using the MetOcean model, has identified Terawhiti in Cook Strait as a superior location for generating tidal power. This paper investigates three different configurations of wind, tidal, and wind plus tidal sources to evaluate tidal potential. Several simulations have been conducted to design a DC-linked microgrid for electricity generation in Cook Strait using HOMER Pro, RETScreen, and WRPLOT software. The results show that Terawhiti, in Cook Strait, is suitable for an offshore wind farm to supply electricity to the grid, considering the higher renewable fraction and the lower net present cost in comparison with those using only tidal turbines or using both wind and tidal turbines.
<p>How can humanity possibly become sustainable in the future if we cannot think or plan sustainably in the present? This project aims to challenge people’s current thinking, raising awareness that the issue of sustainability will not be resolved without a significant cultural shift in our relationship with our world’s environmental systems. The thesis addresses this through an architectural narrative conceived to enhance the viewer’s awareness of how our interdependent relationship with machines and industry has led to this dire situation. Prior to the Industrial Revolution the environment could regenerate and recover faster than humanity could destroy it. With the advent of the Industrial Revolution this changed and environmental degradation has rapidly increased out of control. The result is that today we need to evolve and change our thinking rather than be limited by our tools if we are to be sustainable. It is this at present unsustainable relationship between mechanical industry and human behaviour that this thesis exposes through speculative architecture. The investigation explores how architectural allegory can be an effective way of conveying a message with multiple layers of interpretation and meaning - a message capable of addressing important environmental, political, economic and social issues. The title of the thesis is taken from Albert Camus’s novel l’Étranger (The Stranger) as well as Georg Simmel’s essay “The Stranger”, which was written as an excursus to a chapter dealing with sociology of space in his book Soziologie. In this thesis, as an architectural allegory, the Stranger’s architectural habitat is composed of a myriad of integrated machines that symbolise our time and place identity: a Theodolite that surveys the land; a Clock that keeps the time; a Loom that reflects the folklore of fate; a Compass that represents direction, and a Camera Obscura through which the Stranger views his/her surroundings. The Stranger lives in the Camera Obscura, a compartment with a periscopic lens focused across the Cook Strait to South Island. When (s)he activates the Loom, it pulls the living compartment along tracks toward the core, where (s)he descends into the central volume of the Theodolite. A Compass on the top of the structure points towards landmarks across the Cook Strait while the mechanical workings are inspired by the internals of a mechanical Clock. The overall programme for the thesis investigation is an Aquaponics Lab, a self-contained environment that grows marine life in an aquaculture system, using their waste to fertilise plant life in a hydroponic system, and using their nutrients in turn to feed the marine life. The flora and fauna continually sustain one another in an eternal cycle - the machines replicating a perfect natural system. The thesis takes the form of a day in the life of the Stranger. The reader witnesses the sequential daily rituals of the Stranger as (s)he moves through the machines from sunrise to sunset.</p>
<p>How can humanity possibly become sustainable in the future if we cannot think or plan sustainably in the present? This project aims to challenge people’s current thinking, raising awareness that the issue of sustainability will not be resolved without a significant cultural shift in our relationship with our world’s environmental systems. The thesis addresses this through an architectural narrative conceived to enhance the viewer’s awareness of how our interdependent relationship with machines and industry has led to this dire situation. Prior to the Industrial Revolution the environment could regenerate and recover faster than humanity could destroy it. With the advent of the Industrial Revolution this changed and environmental degradation has rapidly increased out of control. The result is that today we need to evolve and change our thinking rather than be limited by our tools if we are to be sustainable. It is this at present unsustainable relationship between mechanical industry and human behaviour that this thesis exposes through speculative architecture. The investigation explores how architectural allegory can be an effective way of conveying a message with multiple layers of interpretation and meaning - a message capable of addressing important environmental, political, economic and social issues. The title of the thesis is taken from Albert Camus’s novel l’Étranger (The Stranger) as well as Georg Simmel’s essay “The Stranger”, which was written as an excursus to a chapter dealing with sociology of space in his book Soziologie. In this thesis, as an architectural allegory, the Stranger’s architectural habitat is composed of a myriad of integrated machines that symbolise our time and place identity: a Theodolite that surveys the land; a Clock that keeps the time; a Loom that reflects the folklore of fate; a Compass that represents direction, and a Camera Obscura through which the Stranger views his/her surroundings. The Stranger lives in the Camera Obscura, a compartment with a periscopic lens focused across the Cook Strait to South Island. When (s)he activates the Loom, it pulls the living compartment along tracks toward the core, where (s)he descends into the central volume of the Theodolite. A Compass on the top of the structure points towards landmarks across the Cook Strait while the mechanical workings are inspired by the internals of a mechanical Clock. The overall programme for the thesis investigation is an Aquaponics Lab, a self-contained environment that grows marine life in an aquaculture system, using their waste to fertilise plant life in a hydroponic system, and using their nutrients in turn to feed the marine life. The flora and fauna continually sustain one another in an eternal cycle - the machines replicating a perfect natural system. The thesis takes the form of a day in the life of the Stranger. The reader witnesses the sequential daily rituals of the Stranger as (s)he moves through the machines from sunrise to sunset.</p>
<p>Cominella maculosa and C. virgata are common rocky shore whelk species from New Zealand. This study used DNA sequences from the mitochondrial gene cytochrome c oxidase subunit 1 (CO1) to expand an earlier unpublished dataset and examine the phylogeographic structure of both species in the Cook Strait region, of C. maculosa in the Chatham Islands, and of C. virgata in the northern North Island. Both species are found to have a considerable degree of phylogeographic structure, concordant with that reported by an earlier study and for other species with direct development. South Island sites sampled for C. maculosa had several private haplotypes and a high frequency haplotype that is shared with populations from the southern North Island. Together, these formed a ‘southern haplogroup’. Low diversity in ‘southern’ populations may reflect founder effects that would have occurred as part of a southward range expansion during the onset of the present interglacial period. The Chatham Islands samples had two haplotypes that formed a separate sub-group to the ‘southern haplogroup’, suggesting Chatham Islands populations are moderately isolated from those on mainland New Zealand but may have been founded from ‘southern’ populations relatively recently. The high frequency haplotype present in South Island samples of C. virgata is absent in Wellington samples but widespread in those from the north-eastern North Island. South Island populations may have been founded from the Hauraki Gulf through human-mediated translocation events. Phylogenetic analyses with a focus on C. virgata were conducted using the mitochondrial genes CO1 and 16SrRNA, and the nuclear gene 18S rRNA, to expand an earlier published dataset. The purported northern subspecies C. virgata brookesi does not form a monophyletic lineage and voucher specimens fluidly intergrade with the nominal subspecies, with which it is synonymised. A lectotype is designated for Buccinum lineolatum Quoy & Gaimard, 1833, for which Cominella virgata is a replacement name. Potential causes of the disjunct distribution patterns of C. virgata and other mollusc taxa are discussed with particular reference to the formation and timing of marine straits through the Auckland Isthmus and Cook Strait.</p>
<p>Cominella maculosa and C. virgata are common rocky shore whelk species from New Zealand. This study used DNA sequences from the mitochondrial gene cytochrome c oxidase subunit 1 (CO1) to expand an earlier unpublished dataset and examine the phylogeographic structure of both species in the Cook Strait region, of C. maculosa in the Chatham Islands, and of C. virgata in the northern North Island. Both species are found to have a considerable degree of phylogeographic structure, concordant with that reported by an earlier study and for other species with direct development. South Island sites sampled for C. maculosa had several private haplotypes and a high frequency haplotype that is shared with populations from the southern North Island. Together, these formed a ‘southern haplogroup’. Low diversity in ‘southern’ populations may reflect founder effects that would have occurred as part of a southward range expansion during the onset of the present interglacial period. The Chatham Islands samples had two haplotypes that formed a separate sub-group to the ‘southern haplogroup’, suggesting Chatham Islands populations are moderately isolated from those on mainland New Zealand but may have been founded from ‘southern’ populations relatively recently. The high frequency haplotype present in South Island samples of C. virgata is absent in Wellington samples but widespread in those from the north-eastern North Island. South Island populations may have been founded from the Hauraki Gulf through human-mediated translocation events. Phylogenetic analyses with a focus on C. virgata were conducted using the mitochondrial genes CO1 and 16SrRNA, and the nuclear gene 18S rRNA, to expand an earlier published dataset. The purported northern subspecies C. virgata brookesi does not form a monophyletic lineage and voucher specimens fluidly intergrade with the nominal subspecies, with which it is synonymised. A lectotype is designated for Buccinum lineolatum Quoy & Gaimard, 1833, for which Cominella virgata is a replacement name. Potential causes of the disjunct distribution patterns of C. virgata and other mollusc taxa are discussed with particular reference to the formation and timing of marine straits through the Auckland Isthmus and Cook Strait.</p>
<p>Temperate rocky shores around the world are characterised by so-called ‘universal’ zonation. An interesting exception to this rule can be seen along the shores of Wellington’s South Coast where there is a virtual absence of mussels and poorly developed rocky shore intertidal community. Yet just kilometres away in Wellington Harbour there is a fully developed intertidal community, including extensive multi-species mussel beds. This thesis aims to determine if the quality of seston is limiting the presence of mussels on Wellington’s South Coast. We now have the technology to see what types of particles the mussels are selecting in low and high quality seston conditions using a FlowCAM that allows identification of particle types and their physical properties. This study compared environmental data for Wellington Harbour (seston-rich) and the South Coast (seston-poor). These data included chlorophyll a, turbidity and suspended sediment concentrations and were collected by CTD and satellite remote sensing. Mussel feeding experiments took place under a high and low quality diet during summer, autumn and winter using Perna canaliculus and Mytilus galloprovincialis. The physiological responses recorded were clearance rate, absorption efficiency and net energy balance for individual mussels. Environmental variables recorded were total particulate matter, particulate organic matter and percent organic matter. Water samples were collected during the feeding experiments and processed using the FlowCAM. By comparing the control chambers to chambers that had mussels feeding in them it was possible to see what particles the mussels were selecting. The environmental variables revealed that Wellington Harbour had a much higher quality seston whereas in Cook Strait the seston quality was too low for mussels to be able to inhabit, as the chlorophyll a concentrations did not reach the required levels for mussel growth. Perna canaliculus and Mytilus galloprovincialis both showed physiological responses that would allow them to grow in Cook Strait waters, both species had positive absorption efficiencies and net energy balances. These responses were greater in the high quality diet in the enriched pond water in Nelson during summer and winter. The FlowCAM analysis revealed an inter-specific difference in preferential particle selection, which varied as a function of site and season. With more particles being preferentially selected in the high quality diet compared to when the mussels were feeding on Cook Strait seawater. This new information of particle selection helps to determine why mussels are absent from Wellington’s South Coast and contributes to the extensive information on mussel feeding.</p>
<p>Intertidal boulder fields are heterogeneous mosaics of different micro-habitat patches providing high structural complexity and spatial variability of environmental conditions that shape the heterogeneity of abundance of species. The influence of the spatial scale at which ecological patterns are measured has gained much attention over the last two decades. The adaptations to environmental conditions as well as the ability to disperse vary among species and, consequently, result in species-specific responses to heterogeneous environments. Understanding the causes and consequences of spatial patterns of abundance of organisms is a central problem in ecology and insight in underlying mechanisms may have important implications for fisheries management and conservation biology. The competing demands organisms are subject to require compromises to optimise fitness and facilitate the persistence of a population. Reproductive trade-offs, for example, may be largely the result of adaptive processes, constrained by phylogenetic effects. Generally, trade-offs are regarded as a key to understand the evolution of life history characteristics. The present study investigates the spatial dynamics and life history adaptations of an aggregating species, the New Zealand half crab, Petrolisthes elongatus. This species has a biphasic lifecycle and occurs in geographically isolated benthic metapopulations that are associated with cobble beaches, where it reaches extremely high densities. Even though sampling was conducted exclusively in the Wellington region, sites at Cook Strait as well as within Wellington Harbour exhibited considerable differences in habitat structure and temperatures as well as wave exposure and food supply. Cobble size was an excellent predictor of both population density and mean carapace width on almost every scale of observation and, therefore, appeared to be an important indicator of habitat quality for P. elongates because cobble size is closely related to availability and size of interstitial space between boulders the crabs utilize as shelters against predation and desiccation pressure. Crab densities were significantly (6-fold) higher within the harbour compared to south coast sites, presumably due to 1) the different availability of shelter space, 2) lower settlement and recruitment rates at Cook Strait, and 3) higher food supply within the harbour. Population structure was mainly influenced by settlement and recruitment, but also by rock size (i.e. shelter size), size selective predation and a higher mobility of larger crabs. Under laboratory conditions, predation rates among small crabs strongly depended on rock size, whereas large crabs were generally rarely to never preyed upon. Migrated distances did not exceed 100cm over 25h in most cases but were different at different sites. While structural complexity could affect mobility (i.e. easier movement among larger rocks), local density and resulting levels of intraspecific competition were possibly the main drivers of limited mobility of adult crabs. P. elongatus exhibits a high phenotypic plasticity of reproductive traits in response to the variable environmental conditions across sites. Female crabs at Island Bay (Cook Strait) showed the highest fecundity, higher percentage of ovigerous females, higher proportion of clutch to body weight (i.e. reproductive output) and higher egg numbers among large individuals compared to similarsized individuals at other sites at the harbour entrance (Breaker Bay) as well as within the harbour (Hutt River mouth). Larvae of P. elongatus strongly responded to waterborne settlement cues released by conspecific adults both in the laboratory and in the field. The average numbers of settlers was 4-fold higher in basket traps deployed in the field if conspecific adults were present. Therefore, settlement patters are strongly influenced by conspecific density, even on a small spatial scale (tens of centimetres). Recently metamorphosed individuals may still respond to conspecific cues, presumably providing guidance to conspecific adults that protect juveniles from predation and desiccation pressure in addition to shelters between boulders. Under laboratory conditions, individual growth rates as well as mortality depended on density but not on food level. Differences in density dependent growth rates and mortality varied with body size and were both more pronounced among smaller crabs. Limb loss significantly influenced the increase in body weight over time, especially among small individuals; however, no differences could be detected regarding changes in body size due to few moults over the course of the experiment. Crabs with removed chelipeds gained more weight over 7 weeks relative to uninjured individuals, presumably due to the limb regeneration process. Reproductive output, however, appeared not to be affected by limb loss and the associated costs of regenerating chelipeds; however, sample sizes were low to reliably detect such differences. The results of my thesis underline the importance of the consideration of spatial scale in ecological studies in order to meaningfully compare results with other studies. Additionally, the present study contributes to elucidate the influence of environmental conditions on density dependence and reproductive traits of mobile intertidal invertebrates.</p>
<p>Intertidal boulder fields are heterogeneous mosaics of different micro-habitat patches providing high structural complexity and spatial variability of environmental conditions that shape the heterogeneity of abundance of species. The influence of the spatial scale at which ecological patterns are measured has gained much attention over the last two decades. The adaptations to environmental conditions as well as the ability to disperse vary among species and, consequently, result in species-specific responses to heterogeneous environments. Understanding the causes and consequences of spatial patterns of abundance of organisms is a central problem in ecology and insight in underlying mechanisms may have important implications for fisheries management and conservation biology. The competing demands organisms are subject to require compromises to optimise fitness and facilitate the persistence of a population. Reproductive trade-offs, for example, may be largely the result of adaptive processes, constrained by phylogenetic effects. Generally, trade-offs are regarded as a key to understand the evolution of life history characteristics. The present study investigates the spatial dynamics and life history adaptations of an aggregating species, the New Zealand half crab, Petrolisthes elongatus. This species has a biphasic lifecycle and occurs in geographically isolated benthic metapopulations that are associated with cobble beaches, where it reaches extremely high densities. Even though sampling was conducted exclusively in the Wellington region, sites at Cook Strait as well as within Wellington Harbour exhibited considerable differences in habitat structure and temperatures as well as wave exposure and food supply. Cobble size was an excellent predictor of both population density and mean carapace width on almost every scale of observation and, therefore, appeared to be an important indicator of habitat quality for P. elongates because cobble size is closely related to availability and size of interstitial space between boulders the crabs utilize as shelters against predation and desiccation pressure. Crab densities were significantly (6-fold) higher within the harbour compared to south coast sites, presumably due to 1) the different availability of shelter space, 2) lower settlement and recruitment rates at Cook Strait, and 3) higher food supply within the harbour. Population structure was mainly influenced by settlement and recruitment, but also by rock size (i.e. shelter size), size selective predation and a higher mobility of larger crabs. Under laboratory conditions, predation rates among small crabs strongly depended on rock size, whereas large crabs were generally rarely to never preyed upon. Migrated distances did not exceed 100cm over 25h in most cases but were different at different sites. While structural complexity could affect mobility (i.e. easier movement among larger rocks), local density and resulting levels of intraspecific competition were possibly the main drivers of limited mobility of adult crabs. P. elongatus exhibits a high phenotypic plasticity of reproductive traits in response to the variable environmental conditions across sites. Female crabs at Island Bay (Cook Strait) showed the highest fecundity, higher percentage of ovigerous females, higher proportion of clutch to body weight (i.e. reproductive output) and higher egg numbers among large individuals compared to similarsized individuals at other sites at the harbour entrance (Breaker Bay) as well as within the harbour (Hutt River mouth). Larvae of P. elongatus strongly responded to waterborne settlement cues released by conspecific adults both in the laboratory and in the field. The average numbers of settlers was 4-fold higher in basket traps deployed in the field if conspecific adults were present. Therefore, settlement patters are strongly influenced by conspecific density, even on a small spatial scale (tens of centimetres). Recently metamorphosed individuals may still respond to conspecific cues, presumably providing guidance to conspecific adults that protect juveniles from predation and desiccation pressure in addition to shelters between boulders. Under laboratory conditions, individual growth rates as well as mortality depended on density but not on food level. Differences in density dependent growth rates and mortality varied with body size and were both more pronounced among smaller crabs. Limb loss significantly influenced the increase in body weight over time, especially among small individuals; however, no differences could be detected regarding changes in body size due to few moults over the course of the experiment. Crabs with removed chelipeds gained more weight over 7 weeks relative to uninjured individuals, presumably due to the limb regeneration process. Reproductive output, however, appeared not to be affected by limb loss and the associated costs of regenerating chelipeds; however, sample sizes were low to reliably detect such differences. The results of my thesis underline the importance of the consideration of spatial scale in ecological studies in order to meaningfully compare results with other studies. Additionally, the present study contributes to elucidate the influence of environmental conditions on density dependence and reproductive traits of mobile intertidal invertebrates.</p>
<p>Temperate rocky shores around the world are characterised by so-called ‘universal’ zonation. An interesting exception to this rule can be seen along the shores of Wellington’s South Coast where there is a virtual absence of mussels and poorly developed rocky shore intertidal community. Yet just kilometres away in Wellington Harbour there is a fully developed intertidal community, including extensive multi-species mussel beds. This thesis aims to determine if the quality of seston is limiting the presence of mussels on Wellington’s South Coast. We now have the technology to see what types of particles the mussels are selecting in low and high quality seston conditions using a FlowCAM that allows identification of particle types and their physical properties. This study compared environmental data for Wellington Harbour (seston-rich) and the South Coast (seston-poor). These data included chlorophyll a, turbidity and suspended sediment concentrations and were collected by CTD and satellite remote sensing. Mussel feeding experiments took place under a high and low quality diet during summer, autumn and winter using Perna canaliculus and Mytilus galloprovincialis. The physiological responses recorded were clearance rate, absorption efficiency and net energy balance for individual mussels. Environmental variables recorded were total particulate matter, particulate organic matter and percent organic matter. Water samples were collected during the feeding experiments and processed using the FlowCAM. By comparing the control chambers to chambers that had mussels feeding in them it was possible to see what particles the mussels were selecting. The environmental variables revealed that Wellington Harbour had a much higher quality seston whereas in Cook Strait the seston quality was too low for mussels to be able to inhabit, as the chlorophyll a concentrations did not reach the required levels for mussel growth. Perna canaliculus and Mytilus galloprovincialis both showed physiological responses that would allow them to grow in Cook Strait waters, both species had positive absorption efficiencies and net energy balances. These responses were greater in the high quality diet in the enriched pond water in Nelson during summer and winter. The FlowCAM analysis revealed an inter-specific difference in preferential particle selection, which varied as a function of site and season. With more particles being preferentially selected in the high quality diet compared to when the mussels were feeding on Cook Strait seawater. This new information of particle selection helps to determine why mussels are absent from Wellington’s South Coast and contributes to the extensive information on mussel feeding.</p>
<p>Wellington Harbour which lies near the southern tip of the North Island, New Zealand, exhibits a typical rocky intertidal shoreline with groups of species similar to those found on many temperate rocky coasts around the world. A short distance away, the Cook Strait displays a very different shoreline in community composition compared with Wellington Harbour, most notably a distinct lack of filter feeders. This thesis aims to examine how exactly the community composition is different between the two coasts at a species level and if there are any environmental factors that can explain the differing distributions. Here, a series of field and laboratory experiments aim to examine why certain filter feeders (mussels) are absent from the Cook Strait shore, yet so abundant in Wellington Harbour ... This work indicates that the Cook Strait coastline has lower filter feeder abundances and an overall different community composition than Wellington Harbour. The cause of these differences appears to be bottom up regulation through the lack of food availability (phytoplankton) during winter months in the Cook Strait. The high commercial value of coastal environments in both fisheries and tourism heightens the need to understand these habitats. Unravelling the complex relationships between the seasonal changes in the water column and onshore biota is important for conserving and protecting these essential ecosystems in New Zealand and temperate shores worldwide.</p>
