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Subject: search.filters.subject.401102 Environmentally sustainable engineering

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    Carbon footprint of open-cut pipelines (NZ context) : Massey University, New Zealand
    (Massey University, 2023) Manalo, Kevin
    Society is currently facing a climate crisis; our human activities, notably the burning of fossil fuels, emit greenhouse gases into the atmosphere. The constant addition of GHG emissions is resulting in climate change. Nearly all countries agreed in the Paris Agreement 2015 to limit the global temperature increase to well below 2°C above pre-industrial levels. Science-based projections depict a concerning future. Should there be a failure to adequately mitigate our emissions, the impacts on humans and other species could be catastrophic. The Construction Industry is a vital sector that significantly contributes to a nation’s economic and social development. It builds and maintains infrastructure and serves as a significant source of employment. Buildings and construction account for 39% of global emissions, with 36% attributed to global energy use. While most research focuses on emissions from construction buildings, a literature review shows a lack of information regarding global infrastructure emissions. Recent research by Thacker et al. (2021) addresses this gap; when they combine infrastructure, building and construction, the total global emission amounts to a significantly higher value of 79%. Focusing on the stormwater, water, and wastewater sectors (three waters), the emissions amount to 5% of all emissions. Although water/wastewater emissions are only 5% of the costs, adaptation costs in the water sector are estimated to account for 54% of all costs. In Aotearoa, New Zealand, government and local authorities are making progress in capturing and reducing their carbon emissions. For instance, Auckland Council has set their goal to reduce greenhouse gas emissions by 50% by 2030, and Watercare aims to reduce its construction emissions by 40% by 2025; this is only two years away. Should local authorities impose the need to start reporting on carbon emissions on the construction industry, especially those in asset infrastructure delivery, research from the existing literature shows that the construction industry is not ready, not equipped, sees little need to do things differently, or does not know how to quantify carbon emission. The gaps in the research show that contractors should begin their carbon journey, and there are multiple carbon frameworks or standards without explicit critique on what works best. Understanding and knowing these standards takes time, and without a clear lead, information on critical inputs and variables required to represent the construction works accurately becomes muddy. As the standards were written to cater to different industries, the steps given are generic and do not go into detail about specific construction activities. Existing literature cautions that if the method and level of detail are unclear, final carbon footprint values can change. Further, emission sources need to be measured and quantified. However, units of measurement for these activities and productivity durations are typically not published as knowledge of these productivities is a trade secret and a competitive advantage to construction activity. To add to the complexity, the carbon science or emission factors that correspond to the emission activities are not readily available, and more research is needed to find local emission factor sources. In response to these challenges, the research aims to create and develop a simplified methodology and a template for contractors to create their carbon inventory on installing three waters open-cut pipeline excavation. A new Carbon Framework Methodology was developed based on the literature findings and data collection to fulfil the aim. A case study scenario was created where a 100ø PVC pipe is installed, and a 1.3m deep open-cut trench is excavated using standards based on Auckland Council stormwater and Watercare water and wastewater standards. An Excel-based carbon tool was created, and the steps in the carbon framework were followed. The final calculated carbon footprint values were verified using published Environmental Product Declarations (EPD). The carbon tool was presented to 18 participants from 1 tier one and multiple tier 2 contractors who have been installing water, wastewater and stormwater pipelines, with some contractors having over 20+ years in the industry. The research found that creating a carbon inventory is complex, multi-disciplined, requires construction methodology knowledge, and cannot avoid the need to learn carbon principles and carbon science (emission factors). The findings are significant as they discuss the implications of Carbon Accounting for Contractors, from knowing operation boundaries (Scope 1, 2 and 3) to the cost of upskilling, embedding, and implementing carbon management in construction projects. Minor findings were also discussed on the implications of Carbon Accounting for Designers and the heavy responsibility for Clients in ensuring that the capture of carbon emissions flows downstream to its value chain.
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    Assessing the use of hydrogels to harvest atmospheric water for agriculture in arid and semi-arid areas : a thesis presented in partial fulfilment of the requirements for the degree of Master of Environmental Management at Massey University, Manawatū campus, New Zealand
    (Massey University, 2021) Opoku, Daniel Gyamfi
    Agricultural production in arid and semi-arid regions globally faces a growing challenge of water scarcity and initiatives to increase water-availability for crops are needed. The hygroscopicity of hydrogels underpins the real opportunity to desorb water that can be used to support agricultural production in water scarce areas. Research to date has predominantly focussed on direct contact absorption of water in a liquid phase. The opportunity for hydrogels to absorb water from the atmosphere is less studied. Specifically, the impact of relative humidity and temperature on hydrogel hygroscopicity and potential for desorption of this water under environmental pressures that might be expected in a plant root zone are poorly described in literature. Such information will underpin assessment of the extent to which atmospheric water absorption might serve as an alternative water source for plants use in the arid and semi-arid regions. This study was therefore undertaken to ascertain hydrogels hygroscopicity and desorption potential with specific consideration of agriculture in arid and semi-arid regions. The research aimed to provide information on the hygroscopicity potential of different hydrogels, and how different relative humidity percentages and temperature influence hydrogels hygroscopicity and different applied pressures impact water desorption from hydrogels. The effect of relative humidity, time and temperature on hygroscopicity was investigated using replicates of five hydrogels of different composition placed in five different relative humidity chambers (63 %, 76 %, 84 %, 95 % and 100 %) and under three different temperature levels (10 ºC, 20 ºC and 30 ºC ). The results showed that hydrogel type, relative humidity and time influences hygroscopicity significantly, and that the chemical composition of hydrogels can explain hygroscopicity. There was no influence of temperature on absorption. Hydrogels with no N content showed increased absorption of atmospheric water with time, and this is explained through the absence of an N-driven crosslinking effect on water absorption. Absorption of atmospheric water by the best performing hydrogel (Yates Waterwise Water Storage Crystals; at 3.139 g/g at 100 % relative humidity and 30 ºC) in this study was explained by first order model behaviour at 20 ºC for all relative humidity levels except at 63 %. Further research was conducted on the hydrogels defined as the best and worst absorbing in the initial experiments. These hydrogels were placed in contact with liquid water to yield the freely swollen state, and then desorption potential for plant access was investigated using different pressure levels on suction plates. The results clearly showed that increasing pressure increases water desorption between 0.1 and 1 bar pressure. However, between 1 bar and 15 bar no further water is lost. The best absorbing hydrogels identified in this study desorbed more water than the worst. However, this work finds that for both tested hydrogels, pressure beyond 15 bar would be required to desorb hygroscopic water for plant access and use. The study therefore infers that the hygroscopicity potential of hydrogels is optimum for hydrogels with no N content exposed to high relative humidity (above 84 %) over periods of daily cooling from late night and early morning where the dew point might be reached. Such conditions do overlap with some arid and semi-arid regions. However, even where these environmental conditions for optimal absorption are reached, plants are unlikely to be able to desorb the hydrogel water. Therefore, an engineering approach would be needed to physically or mechanical desorb water. In this scenario it is unlikely that hydrogels would be mixed into the soil. Instead, a system could be deployed where hydrogels are exposed to atmospheric water in ‘banks’ which can be closed periodically for desorption. Released water could then be channelled for irrigation. Solar power may be a viable energy source to drive this scenario, although further work is required to fully explore the opportunity.
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    Enhancing statistical wind speed forecasting models : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering at Massey University, Manawatū Campus, New Zealand
    (Massey University, 2022) Yousuf, Muhammad Uzair
    In recent years, wind speed forecasting models have seen significant development and growth. In particular, hybrid models have been emerging since the last decade. Hybrid models combine two or more techniques from several categories, with each model utilizing its distinct strengths. Mainly, data-driven models that include statistical and Artificial Intelligence/Machine Learning (AI/ML) models are deployed in hybrid models for shorter forecasting time horizons (< 6hrs). Literature studies show that machine learning models have gained enormous potential owing to their accuracy and robustness. On the other hand, only a handful of studies are available on the performance enhancement of statistical models, despite the fact that hybrid models are incomplete without statistical models. To address the knowledge gap, this thesis identified the shortcomings of traditional statistical models while enhancing prediction accuracy. Three statistical models are considered for analyses: Grey Model [GM(1,1)], Markov Chain, and Holt’s Double Exponential Smoothing models. Initially, the problems that limit the forecasting models' applicability are highlighted. Such issues include negative wind speed predictions, failure of predetermined accuracy levels, non-optimal estimates, and additional computational cost with limited performance. To address these concerns, improved forecasting models are proposed considering wind speed data of Palmerston North, New Zealand. Several methodologies have been developed to improve the model performance and fulfill the necessary and sufficient conditions. These approaches include adjusting dynamic moving window, self-adaptive state categorization algorithm, a similar approach to the leave-one-out method, and mixed initialization method. Keeping in view the application of the hybrid methods, novel MODWT-ARIMA-Markov and AGO-HDES models are further proposed as secondary objectives. Also, a comprehensive analysis is presented by comparing sixteen models from three categories, each for four case studies, three rolling windows, and three forecasting horizons. Overall, the improved models showed higher accuracy than their counter traditional models. Finally, the future directions are highlighted that need subsequent research to improve forecasting performance further.
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    Development of a feasibility framework for lignite-based controlled-release fertilisers : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Engineering at Massey University, Manawatū campus, New Zealand
    (Massey University, 2020) Willemse, Sonja G.
    Excessive agricultural fertilisation of the essential nutrients nitrogen (N), phosphorus (P) and potassium (K) causes severe environmental damage and financial losses for farmers. The efficiency of conventional commercial fertilisers is low because nutrients are released at a faster rate than plants can uptake, resulting in surface runoff, leaching and volatilisation losses. The environmental concerns are pressing, and considerable resources are dedicated to the development of a new fertilisation strategy. The ultimate solution would be a controlled-release fertiliser that consists of a cheap and strong base material that requires simple pre-treatment, constitutes efficient controlled-release of nutrients independent of soil and environmental conditions, has soil remediating properties, and increases P bioavailability. Literature has shown that lignite, the lowest grade coal, has the potential to act as a matrix for adsorption, but no comprehensive research has been conducted on the feasibility of such a substrate in an agricultural context. The inhomogeneity of lignite poses so far unanswered challenges, in particular the requirement of a case-by-case assessment of individual lignite types and their potential to act as a fertiliser matrix. This research provides a solution to those challenges by offering a feasibility framework that experimentally assesses which pre-treatments are required to optimise the adsorption of nutrients onto any given lignite type, in order to produce prototypes for environmentally and economically feasible lignite-based controlled-release fertilisers. In order to maximise fertiliser efficiency, the focus is on maximising nutrient uptake by the lignite structure. In the framework, it is hypothesised that nutrient uptake can be maximised by manipulating certain properties of lignite. A case study with a local New Zealand type of lignite, Kai Point lignite, was used to develop methods that allow for the evaluation of a range of property manipulations. Parameters investigated were grinding time, solvent treatment, nutrient species, pH, temperature and initial concentration. The properties manipulated were particle size distribution, specific surface area, micro and meso pore volume and nutrient uptake capacity of lignite. Special emphasis is placed on solvent treatment of lignite. It is proposed that choosing an appropriate solvent can induce swelling of the lignite structure in such a manner that the availability of binding sites is increased, fostering nutrient uptake and retention capacity. The results of the case study showed that the combination of particle size distribution control and the use of acetone as the swelling solvent constituted solvent swelling of Kai Point lignite, attaining a maximum of 57 % swelling. When analysing nutrient uptake capacity, it was found that under specific conditions solvent swelling can increase nutrient adsorption by almost 94 %. In the scoping experiments, a minimum nutrient-N content of 6.5 % and a maximum of 37 % is attained for Kai Point lignite. During the case study it became apparent that the inhomogeneous nature of lignite demands a significant number of replicates to get statistically significant results in the feasibility framework. The large number of replicates is projected to make experimentation and analysis a time-consuming endeavour. In anticipation of this problem, a new rapid batch method was established for the automated gathering, processing and analysis of experimental lignite swelling data. This research shows the potential of specific manipulations to increase the cost-efficiency and environmental benefits of lignite-based controlled release fertilisers, and provides a practical feasibility framework with methods capable of tailoring those manipulations to any type of lignite.
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    Effects of operating a solar air heater on the indoor air quality in classrooms during the winter : a case study of Palmerston North primary schools : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) in Building Technology at Massey University, Auckland, New Zealand
    (Massey University, 2020) Wang, Yu
    Schools are densely populated places, where children spend a large amount of their time. The indoor air quality (IAQ) in classrooms impacts students’ health, academic outcomes and school absences (Borras-Santos et al., 2013; Mi et al., 2006; Shendell, Prill, et al., 2004; Smedje and Norbäck, 2000; Taskinen et al., 2007). Three New Zealand (NZ) studies have found low ventilation rates, low temperature levels, high relative humidity (RH) levels and high carbon dioxide (CO2) levels during the winter months in NZ primary schools (Bassett and Gibson, 1999; Cutler-Welsh, 2006; McIntosh, 2011). These results show a need to improve the indoor environment in NZ schools during the winter. NZ school hours, from 9 am to 3 pm, are well aligned with the optimum solar radiation and classrooms lend themselves to heat from solar energy. A project was undertaken to investigate if operating a roof-mounted solar air heater (SAH) could improve the classroom IAQ during the winter. This two-year crossover project was undertaken in four Palmerston North (PN), NZ primary schools in 2013 and six PN, NZ primary schools in 2014. These consisted of the four schools participated in 2013 plus two additional schools. In each school, two adjacent classrooms with similar construction characteristics and population characteristics participated in this project. The two adjacent classrooms were randomly assigned either to a treatment group (SAH installed and operated) or to a control group (SAH installed but not operated). The main objective of this project was to investigate the change in levels of the classroom temperature, RH, CO2, and ventilation rate from when a roof-mounted SAH was operating (treatment) and was not operating (control). Resulting from operating the roof-mounted SAH, the temperature in treatment classrooms was on average 0.5 °C higher than in the control classrooms, when both the control and treatment classrooms had the same heater use. When the control and treatment classrooms achieved the same temperature, the heater use in the treatment classrooms was 27% less than the heater use in the control classrooms. Across all schools, CO2 levels in the treatment classrooms were on average 96 ppm lower than in the control classrooms. In five out of 10 schools (50%), the levels of CO2 in the treatment classrooms were lower than in the control classrooms. Only in one treatment classroom did the ventilation rate meet the NZ Ministry of Education recommended level of 4 air changes per hour. Overall, operating a roof-mounted SAH played a positive role in increasing the temperature and ventilation rate in classrooms during the winter. However, there was not sufficient airflow to satisfy the ventilation requirements. Future research should investigate the impact of operating a SAH on the school ventilation and temperature considering increasing the SAH outlet air volumetric flow rate and keeping the outlet air temperature around 18 °C to bring more heated air into classrooms.