1,093 research outputs found
Hydropower Potential for Energy Recovery in Wastewater Systems. Assessment Methodology and Practical Application
Tesis por compendio[ES] Los Objetivos de Desarrollo Sostenible (ODS) plantean un llamamiento global para conseguir la sostenibilidad en aspectos esenciales de la vida humana. El actual consumo de energía para el tratamiento de aguas residuales es muy elevado, y las previsiones apuntan a un incremento de la demanda en la próxima década. En este contexto, resulta necesario aplicar la perspectiva de sostenibilidad, para conseguir de forma simultánea todos los ODS. Un desempeño energético más sostenible de las Estaciones Depuradoras de Aguas Residuales (EDAR) implica acciones en dos líneas, reducir el consumo, y generar energías renovables in situ. Para implantar medidas a corto plazo, es necesario explorar las posibilidades que pueden ofrecer las tecnologías ya maduras, y evaluar su potencial contribución a la descarbonización del sector. La generación de electricidad mediante maquinaria hidráulica aprovechando la energía potencial de los efluentes podría ser una de ellas.
El principal objetivo de esta tesis doctoral consiste en desarrollar una metodología, dirigida a los agentes de gobernanza, para evaluar el potencial de generación de energía hidráulica en EDAR, considerando las tres dimensiones de sostenibilidad. De este modo, poder ilustrar las posibilidades de aplicación de esta tecnología, actualmente poco conocida para el sector, que podría contribuir a una gestión más sostenible de las aguas residuales. Las fases desarrolladas incluyeron:
1) Contextualización: Se revisó el estado del arte sobre las necesidades energéticas y las tecnologías para la generación de energía renovable en EDAR. Paralelamente sobre el estado de la tecnología para la recuperación de energía en redes de agua existentes mediante maquinaria hidráulica. Para completar este marco, la revisión se amplió con una búsqueda exhaustiva de casos de estudio reales de aplicación en EDAR. En esta fase se identificaron 49 casos de estudio y se analizó su desempeño energético. Los resultados de esta fase en general demostraron que existe una experiencia real en la aplicación práctica de esta tecnología que no se está utilizando para el desarrollo de todo su potencial en este sector.
2) Desarrollo de la metodología: Se analizaron las metodologías existentes para evaluación del potencial de esta tecnología, y el resultado se comparó con la información obtenida en la contextualización. Como resultado, durante esta tesis se ha desarrollado una metodología con una nueva perspectiva. En primer lugar, se introduce la necesidad de considerar el nivel al que se produce la toma de decisiones, para adaptar el alcance del estudio (un grupo de EDAR). A continuación, la metodología se desarrolla en dos etapas. En la etapa 1 (evaluación técnica) el potencial de generación de energía hidráulica se estima de forma individual para cada EDAR. En la etapa 2 (evaluación global) se propone un método de decisión multicriterio (MCDA) introduciendo criterios de sostenibilidad. La alineación de la metodología con su contexto de aplicación se considera una cuestión clave, de modo que el método propuesto se basa en las directrices del instrumento de gobernanza para aguas residuales en España (Plan DSEAR).
3) Aplicación práctica: Esta fase completa el estudio con la aplicación a un grupo de 186 EDAR de la Comunidad Valenciana (España), con la misma modalidad de financiación. Se estimó una generación de electricidad de 340,472 kWh/año, aunque como hallazgo se observó la posibilidad de que dicho potencial sea mayor. En la etapa 2 se mostró que, cuando los resultados de la etapa 1 se ponen en el contexto de sostenibilidad, se obtiene una nueva perspectiva. Esta investigación demuestra que, en el marco de los ODS, la recuperación de energía hidráulica del agua residual podría ser una opción más en la descarbonización de este sector. Tomando como base esta propuesta, agentes de gobernanza para la gestión de aguas residuales en otro contexto podrían desarrollar metodologías similares adaptadas a su propio entorno.[CA] Els Objectius de Desenvolupament Sostenible (ODS) plantegen una crida global per a aconseguir la sostenibilitat en aspectes essencials de la vida humana. L'actual consum d'energia per al tractament d'aigües residuals és molt elevat, i les previsions apunten a un increment de la demanda en la dècada vinent. En este context, resulta necessari aplicar la perspectiva de sostenibilitat, per a aconseguir de manera simultània tots els ODS. Un acompliment energètic més sostenible de les Estacions Depuradores d'Aigües Residuals (EDAR) implica accions en dues línies, reduir el consum, i generar energies renovables in situ. Per a implantar mesures a curt termini, és necessari explorar les possibilitats que poden oferir les tecnologies ja madures, i avaluar la seua potencial contribució a la descarbonització del sector. La generació d'electricitat mitjançant maquinària hidràulica aprofitant l'energia potencial dels efluents podria ser una d'elles.
El principal objectiu d'esta tesi doctoral consisteix a desenvolupar una metodologia, dirigida als agents de governança, per a avaluar el potencial de generació d'energia hidràulica en EDAR, considerant les tres dimensions de sostenibilitat. D'aquesta manera, poder il·lustrar les possibilitats d'aplicació d'esta tecnologia, actualment poc coneguda per al sector, que podria contribuir a una gestió més sostenible de les aigües residuals. Les fases desenvolupades van incloure:
1) Contextualització: Es va revisar l'estat de l'art sobre les necessitats energètiques i les tecnologies per a la generació d'energia renovable en EDAR. Paral·lelament sobre l'estat de la tecnologia per a la recuperació d'energia en xarxes d'aigua existents mitjançant maquinària hidràulica. Per a completar este marc, la revisió es va ampliar amb una cerca exhaustiva de casos d'estudi reals d'aplicació en EDAR. En esta fase es van identificar 49 casos d'estudi i es va analitzar el seu acompliment energètic. Els resultats d'esta fase en general van demostrar que existeix una experiència real en l'aplicació pràctica d'esta tecnologia que no s'està utilitzant per al desenvolupament de tot el seu potencial en este sector.
2) Desenvolupament de la metodologia: Es van analitzar les metodologies existents per a avaluació del potencial d'esta tecnologia, i el resultat es va comparar amb la informació obtinguda en la contextualització. Com a resultat, durant esta tesi s'ha desenvolupat una metodologia amb una nova perspectiva. En primer lloc, s'introdueix la necessitat de considerar el nivell al qual es produeix la presa de decisions, per a adaptar l'abast de l'estudi (un grup de EDAR). A continuació, la metodologia es desenvolupa en dues etapes. En l'etapa 1 (avaluació tècnica) el potencial de generació d'energia hidràulica s'estima de manera individual per a cada EDAR. En l'etapa 2 (avaluació global) es proposa un mètode de decisió multicriteri (MCDA) introduint criteris de sostenibilitat. L'alineació de la metodologia amb el seu context d'aplicació es considera una qüestió clau, de manera que el mètode proposat es basa en les directrius de l'instrument de governança per a aigües residuals a Espanya (Pla DSEAR).
3) Aplicació pràctica: Esta fase completa l'estudi amb l'aplicació a un grup de 186 EDAR de la Comunitat Valenciana, amb la mateixa modalitat de finançament. Es va estimar una generació d'electricitat de 340,472 kWh/any, encara que com a troballa es va observar la possibilitat que aquest potencial siga major. En l'etapa 2 es va mostrar que, quan els resultats de l'etapa 1 es posen en el context de sostenibilitat, s'obté una nova perspectiva. Esta investigació demostra que, en el marc dels ODS, la recuperació d'energia hidràulica de l'aigua residual podria ser una opció més en la descarbonització d'este sector. Prenent com a base esta proposta, agents de governança per a la gestió d'aigües residuals en un altre context podrien desenvolupar metodologies similars adaptades al seu propi entorn.[EN] The Sustainable Development Goals establish a universal agenda to call for action and achieve sustainability in essential aspects of human life. Nowadays the energy demand for wastewater treatment is very high and it is expected to increase in the next decade. Therefore, the performance of this industry will have an effect on SDG 6, but also on SDG 7 and 13. In this context, it is necessary to apply the sustainability approach to wastewater systems to simultaneously achieve all these goals. More sustainable energy performance of wastewater treatment plants (WWTPs) implies two parallel steps: a reduction of energy consumption and the implementation of renewable energy technologies. To take action in the short term, existing mature technologies should be explored to evaluate their potential contribution to the decarbonization roadmaps in the wastewater industry. Hydropower might be one of these technologies.
The main objective of this thesis is to develop a methodology, addressed to wastewater governance stakeholders, to assess the potential of hydropower application to WWTPs, regarding all three dimensions of sustainability. According to this, the final aim of this study is to illustrate the practical possibilities, usually unknown, that hydropower could offer to the wastewater sector in the pathway towards more sustainable systems.
To achieve that aim, the steps in this research included:
1) Contextualization: The review of the state of the art was conducted in two lines. Firstly, about the energy needs for wastewater treatment and technologies for renewable energy generation. Secondly, about hydropower for energy recovery from existing networks. To complete the framework, this stage was extended with an exhaustive search and analysis of real case studies of hydropower applications to WWTPs. In this stage, 49 case studies were identified, and their energy data were extracted to obtain energy self-sufficiency indicators and analyze their renewable energy profiles. Furthermore, the technical data of their hydropower systems were examined. The overall results of this stage showed that there is an existing experience that is not being used to explore hydropower as an option for energy recovery in the wastewater sector.
2) Methodology development: In a preliminary step, existing methodologies for hydropower potential assessment were analyzed and compared with the framework obtained from the contextualization. As a result, a methodology with a broader approach was developed. First, it introduces the consideration of the decision-making level to select the scope of the study (a group of WWTPs). Then, the proposed methodology consists of two steps. In step 1 (technical assessment of hydropower potential) individual power output is estimated for each site. This step was validated with the data obtained during the contextualization. In step 2 (global assessment), after analyzing existing guidelines, a multi-criteria decision analysis (MCDA) method with sustainability criteria is defined. As the alignment with the context is a key issue introduced in this proposal, this method is based on the guidelines in the wastewater governance instrument in Spain (PDSEAR).
3) Practical application: This stage completes the research with the application of the proposed methodology to a case study, a group of 186 WWTPs in the region of Valencia (Spain), selected according to their management model. The generation was estimated at 340,472 kWh/year, but it was found that the potential could be higher. The results also showed that the perspective may be different, if the outcomes from step 1, are put into context in step 2, with the application of the MCDA method. This research demonstrates that, in a sustainability framework, hydropower might be an interesting option to consider for the decarbonization of wastewater systems. Based on this study, decision-making stakeholders could design their own methodologies, adapted to the specific context.The authors would like to acknowledge grant PID2020–114781RA-I00 funded
by MCIN/AEI/ 10.13039/501100011033.Llácer Iglesias, RM. (2023). Hydropower Potential for Energy Recovery in Wastewater Systems. Assessment Methodology and Practical Application [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/201558Compendi
Climate Change and Critical Agrarian Studies
Climate change is perhaps the greatest threat to humanity today and plays out as a cruel engine of myriad forms of injustice, violence and destruction. The effects of climate change from human-made emissions of greenhouse gases are devastating and accelerating; yet are uncertain and uneven both in terms of geography and socio-economic impacts. Emerging from the dynamics of capitalism since the industrial revolution — as well as industrialisation under state-led socialism — the consequences of climate change are especially profound for the countryside and its inhabitants. The book interrogates the narratives and strategies that frame climate change and examines the institutionalised responses in agrarian settings, highlighting what exclusions and inclusions result. It explores how different people — in relation to class and other co-constituted axes of social difference such as gender, race, ethnicity, age and occupation — are affected by climate change, as well as the climate adaptation and mitigation responses being implemented in rural areas. The book in turn explores how climate change – and the responses to it - affect processes of social differentiation, trajectories of accumulation and in turn agrarian politics. Finally, the book examines what strategies are required to confront climate change, and the underlying political-economic dynamics that cause it, reflecting on what this means for agrarian struggles across the world. The 26 chapters in this volume explore how the relationship between capitalism and climate change plays out in the rural world and, in particular, the way agrarian struggles connect with the huge challenge of climate change. Through a huge variety of case studies alongside more conceptual chapters, the book makes the often-missing connection between climate change and critical agrarian studies. The book argues that making the connection between climate and agrarian justice is crucial
Evaluating the sustainability and resiliency of local food systems
With an ever-rising global population and looming environmental challenges such as climate change and soil degradation, it is imperative to increase the sustainability of food production. The drastic rise in food insecurity during the COVID-19 pandemic has further shown a pressing need to increase the resiliency of food systems. One strategy to reduce the dependence on complex, vulnerable global supply chains is to strengthen local food systems, such as by producing more food in cities. This thesis uses an interdisciplinary, food systems approach to explore aspects of sustainability and resiliency within local food systems.
Lifecycle assessment (LCA) was used to evaluate how farm scale, distance to consumer, and management practices influence environmental impacts for different local agriculture models in two case study locations: Georgia, USA and England, UK. Farms were grouped based on urbanisation level and management practices, including: urban organic, peri-urban organic, rural organic, and rural conventional. A total of 25 farms and 40 crop lifecycles were evaluated, focusing on two crops (kale and tomatoes) and including impacts from seedling production through final distribution to the point of sale. Results were extremely sensitive to the allocation of composting burdens (decomposition emissions), with impact variation between organic farms driven mainly by levels of compost use. When composting burdens were attributed to compost inputs, the rural conventional category in the U.S. and the rural organic category in the UK had the lowest average impacts per kg sellable crop produced, including the lowest global warming potential (GWP). However, when subtracting avoided burdens from the municipal waste stream from compost inputs, trends reversed entirely, with urban or peri-urban farm categories having the lowest impacts (often negative) for GWP and marine eutrophication. Overall, farm management practices were the most important factor driving environmental impacts from local food supply chains.
A soil health assessment was then performed on a subset of the UK farms to provide insight to ecosystem services that are not captured within LCA frameworks. Better soil health was observed in organically-farmed and uncultivated soils compared to conventionally farmed soils, suggesting higher ecosystem service provisioning as related to improved soil structure, flood mitigation, erosion control, and carbon storage. However, relatively high heavy metal concentrations were seen on urban and peri-urban farms, as well as those located in areas with previous mining activity. This implies that there are important services and disservices on farms that are not captured by LCAs.
Zooming out from a focus on food production, a qualitative methodology was used to explore experiences of food insecurity and related health and social challenges during the COVID-19 pandemic. Fourteen individuals receiving emergency food parcels from a community food project in Sheffield, UK were interviewed. Results showed that maintaining food security in times of crisis requires a diverse set of individual, household, social, and place-based resources, which were largely diminished or strained during the pandemic. Drawing upon social capital and community support was essential to cope with a multiplicity of hardship, highlighting a need to develop community food infrastructure that supports ideals of mutual aid and builds connections throughout the food supply chain. Overall, this thesis shows that a range of context-specific solutions are required to build sustainable and resilient food systems. This can be supported by increasing local control of food systems and designing strategies to meet specific community needs, whilst still acknowledging a shared global responsibility to protect ecosystem, human, and planetary health
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Software Architecture in Practice: Challenges and Opportunities
Software architecture has been an active research field for nearly four
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