A carregar...
18 resultados
Resultados da pesquisa
A mostrar 1 - 10 de 18
- Methodology for the decision-making process in Social District Heating implementationPublication . Alonso, Rita; Azevedo, João; Martins, FlorindaDistrict heating is a centralized energetic system, capable of providing heat to different structures. This technology helps achieving energetic efficiency with a high fuel flexibility, enabling the use of various renewable sources, which will lead to a lower pollution potential. Beside the environmental perspective, these systems show a great ability concerning the social context. Benefits such as, tackling fuel poverty, increasing employment and population in areas suffering from desertification, along with forest fire prevention, lead to the social perspective as the primary motivation for the implementation of these systems, creating the concept of Social District Heating (SDH). Therefore, this paper developed a decision support tool to prioritize locations in the most need of an SHD, with the necessary features to include this technology in its area. A methodology intended to assess quantitative and qualitative variables is presented, step by step, evaluating each location relatively to community aspects, background context and council power criteria. The results presented enhance more than one location, however one appears as the most appropriate for the SDH implementation.
- Macro modeling of electricity price towards SDG7Publication . Martins, Florinda; Felgueiras, Carlos; Caetano, NídiaEnergy challenges are crucial issues to achieve Sustainable Development and its goals. Energy availability and affordability are pillars for ending poverty, giving access to commodities as well as water, etc. Modern lives rely on appliances and gadgets based on electric energy being its price a key issue making it worth to analyze and promote simple models able to predict electric energy prices to support in decision-making processes and in management. This work studied the correlation of electricity price with variables such as the electricity mix, GDP (gross domestic product), energy productivity, electricity consumption per capita, fossil fuel reserves, and diesel price, using Spearman correlation. To the significant correlations found it was then applied the Kruskal–Wallis test and the variables that presented statistically significant differences were then considered to model electricity price based on these macro variables. Our findings revealed that the best models were a logarithmic and a linear model of energy productivity to predict electricity price, which is fundamental to achieve Sustainable Development Goals (SDG), specifically SDG7. In the validation process, these models presented an average deviation of 10.3% and 11.7%, respectively, which is reasonable considering the simplicity of the models developed.
- Renewable Energy Support Mechanisms – Present StatusPublication . Martins, Florinda; Felgueiras, Carlos; Smitková, M.Renewable energy production is important to solve problems related to security of supply, economic competitiveness, reduction of the economic energy burden to citizens and environmental impacts such as CO2 emissions and pollution. Besides this the scenarios for the future foresee an increase in energy demand mainly due emerging economies and by this reason all the above mentioned issues will be crucial for EU Member States and many other countries around the world. Due to the inability of market to move to more sustainable energy systems, using a higher share of energy from renewable energy sources, it was necessary public action, creating RES support mechanisms in the majority of countries.
- Sustainability in buildings – a teaching approachPublication . Felgueiras, Carlos; Martins, Florinda; Caetano, NídiaEnergy consumption in buildings is responsible for an important share of global consumed energy. The current electric energy paradigm carries important consequences both at economic and environmental levels. The so called Zero Energy Buildings’ strategy provides some guidelines in order to achieve better results in buildings energy demand. This scenario is a highly multidisciplinary engineering issue, and poses several challenges at the higher education level, that is taught in separate areas. This paper presents some higher education teaching limitations to address new technological challenges in new buildings design.
- Life cycle assessment of butanol productionPublication . Brito, Marta; Martins, FlorindaThe goal of this work was to analyse and compare the environmental impacts of three production methods of butanol. The first one is based on the oxo synthesis and the others use ABE (acetone, butanol and ethanol) fermentation. A life cycle assessment for all alternatives under study was carried out. The ABE fermentation using corn as substrate presents the highest environmental impact and the ABE fermentation using wheat straw is the one that presents the lowest environmental impact, when the allocation method was based on mass. Considering an economic allocation method, the relative weight of butanol raised which increased considerably the environmental impact value in ABE processes due to the lower economic value of gases. A sensitivity analysis was performed for the production of butanol from the two ABE processes varying the data of lower quality to analyse how this would affect the environmental impacts. In the ABE process with wheat straw the variations performed within the scope of the sensibility analysis had no meaningful effect in the global impact (<4.0%) except when the production of gases was varied. In this case the reduction of 50% in the mass of gases produced could result in an increase of roughly 40% in the global impact. For the ABE process with the corn the variation of wastewater produced resulted in a decrease of global environmental impact lower than 1%.
- Life Cycle Assessment and Life Cycle Cost of an Innovative Carbon Paper Sensor for 17α-Ethinylestradiol and Comparison with the Classical Chromatographic MethodPublication . Martins, Florinda; Torrinha, Álvaro; Delerue-Matos, Cristina; Morais, SimoneNowadays there is a growing concern with the environment and sustainability, which means that better methods, including pollutants analysis, with less consumption of materials, organic solvents, and energy, need to be developed. Considering the almost inexistent information about the topic, the main goal of this work was to compare the environmental impacts of two analytical methods, a traditional one based on liquid chromatography with fluorescence detection and a newly developed carbon paper sensor. The selected analyte was 17α-ethinylestradiol, which is a contaminant of emergent concern in aquatic ecosystems due to its endocrine disruptor behavior. The life cycle assessment data showed that the sensor detection presents an almost negligible environmental impact when compared with the extraction step (the same for both methods) and the liquid chromatographic determination (roughly 80 times higher than with the sensor). The sensor values for all categories of damage are below 3% of the total method impacts, i.e., 1.6, 1.9, 2.4, and 2.9% for resources, climate change, human health, and ecosystem quality. The extraction represents 98.1% of the sensor environmental impacts (and 99.6% of its life cycle costing) and 38.8% of the chromatographic method. This study evidences the need of developing and applying greener analytical (detection and extraction) strategies
- LCA applied to nano scale zero valent iron synthesisPublication . Martins, Florinda; Machado, Susana; Albergaria, José Tomás; Delerue-Matos, CristinaPurpose Application of zero valent iron nanoparticles is an innovative technology for ground water treatment and soil remediation. There are several methods to synthesise nano scale zero valent iron (nZVI), namely through bottom-up methods which consists on chemical reactions using strong reducing agents. In this work, the environmental impacts and costs were determined for two methods, namely the traditional one that uses sodium borohydride and the green method that uses extracts obtained from natural products. Methods The consideration of environment and economic aspects in the earlier stages of the synthesis processes and in the development of new materials is of great importance since it can help to decide if alternative methods are promising and should be further developed aiming more sustainable processes. In this work, life cycle assessment (LCA) was used as an ecodesign strategy evaluating environmental performance of the two synthesis methods, identifying critical stages of the synthesis processes of nZVI. An economic evaluation and a sensitivity analysis considering a different scenario for electricity production were also performed. Results and discussion The results obtained in this study showed that the green synthesis method presents lower environmental impacts than the traditional one, roughly 50% lower in the first scenario. In the second scenario, environmental impact of green synthesis corresponds to 38% of the environmental impact of traditional synthesis. In the green method, the critical stage is the extraction process which is closely related to the electricity production. In the traditional method, the reactant use is the critical stage that is related to the production of sodium borohydride. The economic evaluation indicated that the traditional synthesis method is much more expensive than the green synthesis (roughly eight times higher). Conclusions From the results obtained, it is possible to conclude that the green synthesis method presents lower environmental impacts in both scenarios and lower costs than the traditional synthesis.
- Economic, environmental and mixed objective functions in non-linear process optimization using simulated annealing and tabu searchPublication . Martins, Florinda; Costa, Carlos A.V.Screening of topologies developed by hierarchical heuristic procedures can be carried out by comparing their optimal performance. In this work we will be exploiting mono-objective process optimization using two algorithms, simulated annealing and tabu search, and four different objective functions: two of the net present value type, one of them including environmental costs and two of the global potential impact type. The hydrodealkylation of toluene to produce benzene was used as case study, considering five topologies with different complexities mainly obtained by including or not liquid recycling and heat integration. The performance of the algorithms together with the objective functions was observed, analyzed and discussed from various perspectives: average deviation of results for each algorithm, capacity for producing high purity product, screening of topologies, objective functions robustness in screening of topologies, trade-offs between economic and environmental type objective functions and variability of optimum solutions.
- Assessment of Circular Economy within Portuguese OrganizationsPublication . Fonseca, Luís; Domingues, José; Pereira, Maria Teresa; Martins, Florinda; Zimon, DominikThe move towards a new Circular Economy (CE) economic model has been advocated and supported in Portugal, however, there is limited research on this topic. To address this gap, a quantitative research based on an online survey was carried out among 99 Portuguese organizations, encompassing a wide range of sectors and sizes. The results show that CE is regarded as a strategic and relevant issue for profitability and value creation. Furthermore, the perception that it requires the adoption of new business models in addition to the classical “reduce, reuse and recycle” approach is growing. Moreover, based on the hypotheses raised, results suggest that the level of CE adoption is positively impacted by the status of the EMS (Environmental Management System) certification and the willingness to improve the environmental performance and achieve a sustainable business model. However, CE activities are still relatively modest and a friendlier context (fiscal, legal, organizational, etc.) and the stronger support from supply chain agents and consumers are required. Future research should focus on how to design and shape the transition from a linear to a CE economy and to ascertain if the positive attitude towards CE is materialized in changing the way business is done.
- Raw material depletion and scenario assessment in European Union – A circular economy approachPublication . Martins, Florinda; Castro, HelioNowadays the production systems are linear and the consumption patterns are essentially based on products with a short life cycle, which contribute to increase the demand for raw materials and environmental impacts. The Circular Economy (CE) is playing a major role among scholars and practitioners. Many aspects are now defining this new trending paradigm such as the roles of product development, transformation and remanufacturing/recycling, and/or management of waste, ensuring the economic and environmental benefits. The increasing demand causes instability of the prices and markets, and there is also the risk of supply rupture. This is very unsustainable and puts at risk countries’ development. In this work we analyze and assess some EU critical raw material (CRM), considering existing global reserves and production. Correlation between several parameters was also analyzed. Under this assumption one scenario was considered to assess the depletion of two CRM. China is the main supplier in 15 out of 25 CRM considered in this analysis and its average percentage is 65%. Phosphate rock presents the highest value and antimony the lowest for depletion indicator. It was possible to conclude that no significant correlation was found between depletion, self-sufficiency and economic importance indicators.