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Abstract This paper presents a new methodology for impact assessment—SIAM (Spatial Impact Assessment Methodology)—which is based on the assumption that the importance of environmental impacts is dependent, among other things, on the spatial distribution of the effects and of the affected environment. The information generated by the use of Geographical Information Systems (GIS) in impact identification and prediction stages of Environmental Impact Assessment (EIA) is used in the assessment of impact significance by the computation of a set of impact indices. For each environmental component (e.g., air pollution, water resources, biological resources), impact indices are calculated based on the spatial distribution of impacts. A case study of impact evaluation of a proposed highway in Central Portugal illustrates the application of the methodology and shows its capabilities to be adapted to the particular characteristics of a given EIA problem.

Abstract The need to generate thermal and electrical energy, global warming caused by increased emissions of greenhouse gases, rising fossil fuel prices and demand for energy independence, have created a new industry focused on energy production through the use of renewable sources. Among the different options, biomass is the third most important source for obtaining electricity, and is the main source for the production of thermal energy. However, problems related to the low density of the different types of biomass, and the difficulty of transportation and storage, have led to the need to find solid fuels with higher density and greater hardness, known as pellets and briquettes. This paper seeks to develop an analysis of the current situation of the production of pellets, mainly with mixed biomass types, and the possible uses they have, with the main emphasis on the review of different combustion processes.

Abstract Molten salts are a very relevant member of industrial fluids for high temperature applications, such as catalytic medium for coal gasification, molten salt oxidation of wastes, heat transfer fluids or latent, sensible heat storage and solar (CSP) or nuclear power station operations. Available data on thermophysical properties, applications and a discussion of the state of the art for molten alkali carbonates and its mixtures like pure Li2CO3, Na2CO3 and K2CO3, mixtures of Li2CO3-Na2CO3, Li2CO3-K2CO3 (binary eutectics) and Li2CO3-Na2CO3-K2CO3 (ternary eutectic) and nanofluids based in these carbonate melts are presented. These melts are especially suitable for application at higher temperature regimes, like those involving high temperature energy storage, coolants or molten salts oxidations of wastes and therefore the accurate knowledge of their most important thermophysical properties is essential for efficient energy transfer and storage, because of their impact on energy efficiency, namely in energy savings and decrease of carbon footprint. From the analysis performed it can be concluded that the scatter of data found for molten alkali carbonates, added to present and future applications, still justifies further studies on these systems, to support their application as alternative engineering fluids. Additionally, some comments on how to improve present situation of methods and measurements are made, especially in the area of thermal conductivity.

Abstract The world has been experiencing a significant increase in daily average temperatures per decade and climate change scenarios are projecting high probability of more frequent heat waves. In vulnerable regions, like Southern Europe, where most of the residential buildings still rely on natural ventilation for cooling, impact on thermal comfort can be significant in terms of health, well-being and also energy consumption. The question is particularly important for the existing building stock, which was not designed considering the projected future climate conditions and is prone to be subjected to interventions with the purpose of improving thermal performance. The study presents a vulnerability framework and methodology for the assessment of thermal comfort in existing dwellings in the context of climate change. Results relating to a 1960s typical building case study in Lisbon, Portugal, suggest that specific dwelling characteristics, such as orientation, and occupancy profiles are relevant when assessing vulnerability, suggesting significant differences, of up to 91% in discomfort hours on an annual basis. Furthermore, increased insulation seems to be effective in decreasing discomfort, as the best results (48% in discomfort hours decrease) stem from a context of external insulation for a heatwave situation. The methodology can be useful for assessing vulnerability in existing dwellings and its specific conditions. It can also contribute to understanding the effect of energy retrofitting measures in future climate conditions, assisting energy efficiency policies and decision-making regarding retrofit interventions.

In the steel industry, the iron making system deals with large quantities of materials and energy and so it can play a critical role in reducing emissions and production costs. More specifically, excess by-product gases should be used for electricity generation; otherwise, they lead to pollution. A life cycle analysis is performed to compare the environmental impact of an iron making system with a combined cycle power plant (CCPP), to a system producing the same amount of electricity in a coal power plant. The results for a Chinese steel plant show a 33% reduction in the energy conservation and emission reduction potential for the CCPP system, which is thus more environmentally friendly. A mathematical programming formulation is then proposed for optimal scheduling. It incorporates key technological constraints and is sensitive to hourly changing electricity prices. The outcome is a 19% increase in revenue from electricity sales compared to a schedule that does not dynamically adjust to the price profile. The results also show that emissions from by-product gases can be avoided completely. The paper ends with a sensitivity analysis to evaluate the impact of changes in product demand, gas storage and CCPP capacity, and emission cost.

Abstract The study of sustainable energy systems is an interdisciplinary endeavour which entails the analysis of a large amount of diverse data and complex interactions that are better understood if developed from first principles. This paper reviews the approaches to this analysis and presents as a general case study, a fossil free imaginary island whose electricity, heat and mobility demand are fulfilled with sustainable and renewable energies only. The detailed hourly balance between supply and demand highlights the importance of energy storage, which is achieved by reversible hydropower and storage in electric vehicles.

Abstract Europe is a consolidated continent, characterized by a wide range of ancient buildings that urgently need refurbishments, especially in seismic zones such as Portugal, where structural reinforcement is imperative. However, demolishing and reconstructing also contributes to real estate renovation. In these cases it is simpler to build earthquake safe buildings that comply with current standards of comfort and quality. The question now is whether refurbishment (and what type) is environmentally and/or economically profitable or needed compared with new construction. To answer this question, this work used the life cycle approach in two complementary approaches: a literature review that theoretically compares different LCA works for refurbished and new buildings; and a real LCA and LCC case study for a classified ancient Portuguese building located in Lisbon, where real refurbishment is compared with hypothetical demolition, followed by complete reconstruction on the same site, respecting the same architecture, constraints and demands, and using reinforced concrete and clay brick walls. This issue is very urgent in Portugal, because of its extensive stock of ancient buildings needing refurbishment works. Moreover, there are few studies reporting whether the refurbishment can be economically and environmentally more efficient, according to the Portuguese economic environment. Thus, this study mostly contributes to this debate, first at a national level, and then as a new case study reporting this kind of benchmarking, and its significance is related to the actual results measured at the construction site for the traditional refurbishment works made in Portugal. This comparison showed that structural refurbishment seems to be environmentally more positive. Nevertheless, in the case-study gains were not as high as commonly suggested, mainly because of the massive use of structural steel and shotcrete required for the seismic and structural strengthening of the ancient building. Finally, as far as the economic approach is concerned, this paper concludes that in those conditions rebuilding would make more economic sense than refurbishing. These conclusions indicate that an integrated decision-making process is needed and also stress the development of new financial facilities for refurbishment and, especially, the development of less costly solutions that could save scarce resources and incentives.

Abstract The future residential energy demand is expected to be significantly affected by increasing electrification rates and climate change. This study uses a Monte Carlo-based approach and an ensemble of climate models to address potential changes in electricity demand in this sector. The whole Portuguese residential building stock in 2050 is used as a case study. It is performed a sensitivity analysis for the retrofitting and new construction, floor area of new buildings, electrification of domestic hot water and cooking and, finally, adoption of heat pumps for space heating and cooling. Results show a potential increase of 5 to 60% of the total electricity consumption in the sector. Space heating is expected to decrease by 33% while space cooling shows a possible 20-fold increase. The electrification of domestic hot water and the development of housing stock characteristics are the factors with the largest impact on the overall electricity consumption changes.

Abstract Energy consumption has long been emphasized as an important policy issue in today's economies. In particular, the energy efficiency of residential buildings is considered a top priority of a country's energy policy. The paper proposes a genetic programming-based framework for estimating the energy performance of residential buildings. The objective is to build a model able to predict the heating load and the cooling load of residential buildings. An accurate prediction of these parameters facilitates a better control of energy consumption and, moreover, it helps choosing the energy supplier that better fits the energy needs, which is considered an important issue in the deregulated energy market. The proposed framework blends a recently developed version of genetic programming with a local search method and linear scaling. The resulting system enables us to build a model that produces an accurate estimation of both considered parameters. Extensive simulations on 768 diverse residential buildings confirm the suitability of the proposed method in predicting heating load and cooling load. In particular, the proposed method is more accurate than the existing state-of-the-art techniques.