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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.

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.

In the Mediterranean area most of the public authorities need to enhance their institutional capacity in the field of Energy Efficiency (EE) and use of Renewable Energy Sources (RES) in order to contribute to the Energy Performance of Buildings and the Energy Efficiency Directives, developing solutions suited to various regional contexts. The PrioritEE project, funded by the Interreg MED programme, aims at reinforcing the capacities of public administrations in selecting and implementing eco-friendly and cost-effective energy planning measures. This paper aims to describe the main efforts carried out by local public authorities and professional institutions from five MED countries (Italy, Portugal, Spain, Greece and Croatia) in order to reduce energy consumption and prioritize EE investments in Municipal Public Buildings (MPBs). In particular, it focuses on the methodological framework describing the main components of the proposed toolbox, the main objectives and expected outcomes but also the current achievements and the way forward.

Temperature record-breaking events, such as the observed more intense, longer-lasting, and more frequent heat waves, pose a new global challenge to health sectors worldwide. These threats are of particular interest in low-income regions with limited investments in public health and a growing urban population, such as Brazil. Here, we apply a comprehensive interdisciplinary climate-health approach, including meteorological data and a daily mortality record from the Brazilian Health System from 2000 to 2015, covering 21 cities over the Metropolitan Region of Rio de Janeiro. The percentage of absolute mortality increase due to summer extreme temperatures is estimated using a negative binomial regression modeling approach and maximum/minimum temperature-derived indexes as covariates. Moreover, this study assesses the vulnerability to thermal stress for different age groups and both genders and thoroughly analyzes four extremely intense heat waves during 2010 and 2012 regarding their impacts on the population. Results showed that the highest absolute mortality values during heat-related events were linked to circulatory illnesses. However, the highest excess of mortality was related to diabetes, particularly for women within the elderly age groups. Moreover, results indicate that accumulated heat stress conditions during consecutive days preferentially preceded by persistent periods of moderate-temperature, lead to higher excess mortality rather than sporadic single hot days. This work may provide directions in human health policies related to extreme climate events in large tropical metropolitan areas from developing countries, contributing to altering the historically based purely reactive response.

Abstract Recycled paper mill sludge (RPMS) was hydrothermally treated by subcritical water (SBW) in two modes of operation, namely semi-continuous and batch, at temperatures in the range 150–250 °C, and 100 bar. The performance of both systems was analyzed in terms of degree of hydrolysis, product yield and formation of degradation products. The highest degree of RMPS hydrolysis was achieved using the batch reactor configuration, while in the semi-continuous system higher yields of water soluble compounds (WSC) and monosaccharides were achieved. By using the semi-continuous system at 100 bar, 250 °C and a water flow rate of 5 mL/min, 40% of the organic carbon content of RPMS was recovered in the form of soluble compounds. Additionally 20% of total carbohydrates and 75% of total lignin of RPMS were recovered as soluble material. Detailed mass balances performed for both operational modes revealed that under batch mode, the naturally occurring compounds found in RPMS underwent significant transformation, generating derivatives referred to as degradation products. An analysis of the severity factor was performed for both operational modes. It was concluded that significant values of WSC were only obtained for severity factors higher than four.

The present work aims to perform a multistep upgrading of chars obtained in the co-pyrolysis of PE, PP and PS plastic wastes, pine biomass and used tires. The quality of the upgraded chars was evaluated by measuring some of their physico-chemical properties in order to assess their valorisation as adsorbents' precursors. The crude chars were submitted to a sequential solvent extraction with organic solvents of increasing polarity (hexane, mixture 1:1 v/v hexane:acetone and acetone) followed by an acidic demineralization procedure with 1M HCl solution. The results obtained showed that the upgrading treatment allow the recovery of 63-81% of the pyrolysis oils trapped in the crude chars and a reduction in the char's ash content in the range of 64-86%. The textural and adsorption properties of the upgraded chars were evaluated and the results indicate that the chars are mainly mesoporous and macroporous materials, with adsorption capacities in the range of 3.59-22.2 mg/g for the methylene blue dye. The upgrading treatment allowed to obtain carbonaceous materials with quality to be reused as adsorbents or as precursors for activated carbon.