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This research proposes an innovative solar thermal plant able to generate mechanical power through an optimized system of heliostats with Scheffler-type solar receivers coupled with screw-type steam expanders. Scheffler receivers appear to perform better than parabolic trough collectors due to the high compactness of the focal receiver, which minimizes convective and radiative heat losses even at high vaporization temperatures. At the same time, steam screw expanders are volumetric machines that can be used to produce mechanical power with satisfactory efficiency also by admitting two-phase mixtures and with further advantages compared to steam turbines: low working fluid velocities, low operating pressures, and avoidance of overheating. This study establishes a mathematical model to assess the energetic advantages of the planned solar thermal power system by evaluating the solar-to-electricity efficiency for different off-design working conditions. For this purpose, a numerical model on the Scheffler receiver is initially investigated, thus assessing all the energy losses which affect the heat transfer phase. A thermodynamic model is then developed to evaluate the energy losses and performance of the screw expander under real working conditions. Finally, parametric optimization of the solar energy conversion is performed in a wide range of operating conditions by establishing thermodynamic formulations related to the whole solar electricity generation system. Water condensation pressure and vaporization temperature are so optimized with respect to global energy conversion efficiency which, under the best operating conditions achieved in this research, rises from 10.9% to 14.4% with increasing solar irradiation intensity. Hence, the combined use of screw expanders and Scheffler receivers for solar thermal power system application can be a promising technology with advantages over parabolic dish concentrators. Novelty statement: This research proposes an innovative direct steam solar power plant based on an SRC, with water utilized as both heat transfer and working fluid, equipped with Scheffler solar receivers as a thermal source and screw expanders as work-producing devices. Technical studies and energy assessments of this kind of SEGS at part-load operation do not exist in scientific literature; after reviewing the literature, it was determined that volumetric expanders have been rarely combined with Scheffler receivers for solar thermal power system application. In effect, combined use of screw expanders and Scheffler-type solar concentrator in a direct steam solar power system represents a completely new plant configuration; however, as a promising DSG solar system, at present numerical model of this new sort of SEGS is lacked in literature and the optimum operating conditions have yet to be defined. For this reason, the chief objective of this paper is to define a first parametric optimization of all thermodynamic variables involved to maximize global efficiency of the proposed solar thermal power generation system for ordinary working conditions.

Abstract In this study, we investigate the driving forces behind the changes in residential energy consumption (REC) in China’s urban and rural areas over the 2001–2012 period. Based on the logarithmic mean Divisia index method, the REC changes are decomposed into seven driving forces, which are climate change, energy price, energy expenditure mix, energy cost share (in total expenditure), expenditure share (in income), per capita income and population effects. According to the results, climate effect due to increasing days with abnormal temperature, energy cost share effect characterized by more expenditure to be paid for energy use, income effect describing constant income growth in the residential sector definitely increase REC in both urban and rural areas. In contrast, energy prices and energy expenditure mix effects negatively contribute to the REC increase, respectively because of the increase in energy prices and the transition from the low-priced energy to high-priced energy. Expenditure share and population effects play opposite roles in urban and rural areas, and the reasons and implications are analysed in depth.

Introduction The European Union aims at raising the share of energy consumption produced from renewable resources to 20% in 2020 as compared to 1990. Moreover, the European Commission adopted a strategy called "Innovating for Sustainable Growth: a Bioeconomy for Europe" to shift the European economy towards greater and more sustainable use of renewable resources. The S2Biom project (www.s2biom.eu) - Delivery of sustainable supply of non-food biomass to support a "resource-efficient" Bioeconomy in Europe - supports the sustainable delivery of non-food biomass feedstock at local, regional and pan-European levels through developing strategies and roadmaps that will be render available to the user by a "computerized and easy to use" toolset (and respective databases) with updated harmonized datasets at local, regional, national and pan-European level for EU-28, Western Balkans, Moldova, Turkey and Ukraine. Methodology Taking in consideration the results and experiences of current and past EU projects, the S2Biom project activities are implemented in three individual but strongly interrelated Themes: 1) To focus on methodological approaches, data collection and estimation of sustainable biomass potentials resources, efficient pathways and optimal logistical supply routes as well as the development of a computerised toolset. 2) To make use of the findings of Theme 1 and develop a Vision, strategies and a R&D roadmap for sustainable delivery of non-food biomass feedstock at local, regional and pan- European levels. 3) To validate the results from themes 1 and 2 and ensure the project outreach; this will be performed through selected case studies which will efficiently capture the different scales of applications for biomass supply chains in a sufficient number of regions across Europe. Conclusion The first draft version of this toolset have been developed, allowing to analyse different levels of bioenergy production, its costs and feedstock biomass crops available across EU at a resolution level of Nuts3.

This empirical paper tests for trade-facilitated spillovers in the convergence of energy productivity across 16 European Union (EU) countries from 1995 to 2005. One might anticipate that by inducing specialization, trade limits the potential for convergence in energy productivity. Conversely, by inducing competition and knowledge diffusion, trade may spur sectors to greater energy productivity. Unlike most previous work on convergence, we explain productivity dynamics from cross-country interactions at a detailed sector level and apply a spatial panel data approach to explicitly account for trade-flow related spatial effects in the convergence analysis. Our study confirms the existence of convergence in manufacturing energy productivity, caused by efficiency improvements in lagging countries, while undermined by increasing international differences in sector structure. Further, we find that trade flows explain 30 to 40% of the unobserved variation in energy productivity. Trade continues to explain the unobserved variation in energy productivity even after accounting for geographic proximity. Last, we find that those countries and sectors with higher dependence on trade both have higher energy productivity growth and a higher rate of convergence, further implying that trade can enhance energy productivity. Thus, unlike concerns that trade may spur a 'race to the bottom', we find that promoting trade may help stimulate energy efficiency improvements across countries.

Artículos en revistas En este artículo examinamos el impacto de los cambios del precio del petróleo en los retornos bursátiles de cuatro corporaciones de petróleo y gas listadas en el NYSE durante el periodo de Enero 1974 a Diciembre 2015. Consideramos diferentes especificaciones lineares y no lineares del precio del petróleo y tomamos en cuenta el quiebre estructural del año 1986. La nueva evidencia sugiere un impacto significativo y positivo de los cambios del precio del petróleo en los retornos bursátiles a corto placo. También encontramos que la relación es más estadísticamente significativa durante el periodo post-1986. In this paper we examine the impact of oil price shocks on stock returns of four oil and gas corporations listed on NYSE over the period January 1974 to December 2015. We consider different linear and nonlinear oil price specifications and take into account the structural break date of the year 1986. The novelty evidence supports a significant positive impact of oil price shocks on stock returns in the short-run. We also find that the relationship has become statistically significant during the post-1986 period. info:eu-repo/semantics/publishedVersion

Over the last decade, significant attention has been devoted to Closed-Loop Supply Chain (CLSC) design problems. As such, this review aims at assessing whether the current modelling approaches for CLSC problems can support the transition towards a Circular Economy at a supply chain level. The paper comprehensively assesses the extent to which existing modelling approaches evaluate the performance of supply chains across the complete spectrum of sustainability dimensions. Also, the capability of the current approaches of incorporating strategic, tactical, and operational decisions is considered, along with adopted solution methodologies. As a result, a comprehensive analysis was performed on 254 selected articles. This paper emphasises how most of the current literature in the field is affected by a disconnection between supply chain design and the founding principles of Circular Economy. Specifically, the CLSC literature exhibits a reductionist interpretation of the Circular Economy. CLSC studies focusing on all three dimensions of sustainability are relatively rare, and performance measurement approaches appear to be very much focused on monetary issues. While methodological contributions appear adequate to focus on the non-deterministic nature of CLSC design problems, there is paucity of empirically-grounded research. Coherently, a research agenda is proposed, in order to address the mentioned gaps and increase the relevance of this research field to practice.

Recently, in the economics literature, several papers have put forward arguments for using a declining discount rate in social-cost benefit analysis. This paper examines the impact of employing a declining discount rate on the social cost of carbon-the marginal social damage from a ton of emitted carbon. Six declining discounting schemes are implemented in the FUND 2.8 integrated assessment model, including the recent amendments to the Green Book of HM Treasury (Treasury, H.M., 2003. The Greenbook: Appraisal and Evaluation in Central Government. TSO, London). We find that using a declining schedule of discount rates increases the social cost of carbon estimate by as little as 10% or by as much as a factor of 40, depending upon the scenario selected. Although the range of plausible estimates is large, using declining discounting schemes in FUND 2.8 in most cases does not yield values at the £70/tC level suggested by UK DEFRA [Clarkson, R., Deyes, K., 2002. Estimating the social cost of carbon emissions. Government Economic Service Working Paper. HM Treasury, London]. Indeed, only at the higher end of the values of social cost of carbon found here would many climate change related policies - such as the Kyoto Protocol - pass a cost-benefit analysis. This conclusion, however, does not necessarily undermine the ethical and political economic reasons for supporting international collective action on climate change. © 2006 Elsevier Ltd. All rights reserved.

AbstractThis study analyses the relationship between foreign direct investment, economic growth, urbanization, energy use, and carbon emissions in Brazil, Russia, India, China, and South Africa (BRICS countries) between 1990 and 2014. According to the empirical results, both environmental Kuznets curve (EKC) and pollution haven hypotheses (PHH) are confirmed. Urbanization contributes to reducing carbon emissions, while energy use is one of the main driving forces of ascending carbon emissions. The main advance of this paper lies in the moderating effect of foreign direct investment and energy usage on carbon emission in the case of the BRICS. The empirical results confirm a dampening impact of foreign direct investment on energy use, generating a correction in carbon emission. Thus, structural transformations are highlighted with a positive influence on energy efficiency and sustainable growth. It is expected that policymakers must promote renewable sources and boost clean foreign industries in selected host countries.