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Abstract Bioenergy systems are expected to expand over the coming decades due to their potential to address energy security and environmental pollution challenges. Nevertheless, any renewable energy project can only survive if approved environmentally superior to its conventional counterparts. Life cycle assessment (LCA) is an internationally standardized and validated methodology to evaluate and quantify the environmental impacts of bioenergy systems. However, due to its methodological scope, the LCA method measures only the environmental consequences of the target products of energy systems. The LCA approach can neither allocate the environmental impacts at the component level nor measure the environmental impacts of intermediate products. These challenges can be substantially resolved by systematically integrating the LCA approach with the thermodynamically-rooted exergy, offering a powerful environmental sustainability assessment tool known as “exergoenvironmental analysis“. Due to the unique methodological and conceptual characteristics of exergoenvironmental analysis in revealing the possibilities and trends for improvement, it has recently received increasing attention to mitigate the environmental impacts of bioenergy systems. Therefore, this review is aimed to thoroughly summarize and critically discuss the evaluation of sustainability aspects of bioenergy systems based on exergoenvironmental analysis. The pros and cons of using exergoenvironmental analysis in bioenergy research are also outlined to identify possible future directions for the field. Overall, exergoenvironmental analysis can offer more detailed information on the environmental consequences of each flow and component of bioenergy production plants, thereby diagnosing the breakthrough points for additional environmental improvements.

Anaerobic digestion of Iberian pig slaughterhouse and tomato industry wastes, as well as codigestion operations from such residues, are reported to achieve 54-80% reduction in Chemical Oxygen Demand and 6-19 N m(3)/m(3) substrate methane production. Furthermore, 0.79-0.88 m(3)water/m(3) substrate is seen to be recovered after the above mentioned operations, which might be used as irrigation water, and 0.12-0.21 m(3)agricultural amendment/m(3) substrate with 91-98% moisture content. The present paper also reports on the economic feasibility of both an anaerobic codigestion plant operating with 60% slaughterhouse wastes/40% tomato industry wastes (optimal ratio obtained in previous laboratory-scaled experiments), and an anaerobic digestion plant for Iberian pig slaughterhouse waste. Payback times are reported as 14.86 and 3.73 years, respectively.

In order to improve the startup flexibility of steam turbines, it becomes relevant to analyze their dynamic thermal behavior. In this work, the relative expansion between rotor and casing was studied during cold-start conditions. This is an important property to monitor during startup given that clearances between rotating and stationary components must be controlled in order to avoid rubbing. The investigation was performed using a turbine thermal simplified model from previous work by the authors. The first step during the investigation was to extend and refine the modeling tool in order to include thermomechanical properties. Then, the range of applicability of the model was validated by a twofold comparison with a higher order finite element (FE) numerical model and measured data of a cold start from an installed turbine. Finally, sensitivity studies were conducted with the aim of identifying the modeling assumptions that have the largest influence in capturing the correct thermal behavior of the turbine. It was found that the assumptions for the bearing oil and intercasing cavity temperatures have a large influence ranging between ±25% from the measured values. In addition, the sensitivity studies also involved increasing the initial temperature of the casing in order to reduce the peak of differential expansion. Improvements of up to 30% were accounted to this measure. The studies performed serve as a base toward further understanding the differential expansion during start and establishing future clearance control strategies during turbine transient operation.

The fabrication of a 11.4% efficient thin film solar cell based on CuInS2 with an Inx(OH,S)y buffer layer is described. The device parameters and performance are compared to heterojunctions with a standard Us buffer layer. A junction breakdown at negative bias under illumination is related to the buffer layer. A simple model implying photoconductive shunting paths is presented.

Abstract A new reactor configuration is proposed under the requirements of providing a high value of breeding ratio and very high safety standards in all conditions, particularly in severe accidents. This double objective conveys the need of very fast neutron spectrum and the use of fuels with a relatively high content of transuranium nuclei, particularly plutonium isotopes. These facts define a narrow design window where a solution must be found to the safety problems created by the lack of Doppler effect and by a strong reduction in the percentage of delayed neutrons. The operational range in safe conditions almost vanishes, because of the lack of negative feedback mechanism and the very small reactivity margin before arriving to prompt-criticality. In order to improve operation conditions, the reactor is kept subcritical, and power level is kept constant with the help of an external source of neutrons, generated by spallations induced by accelerated protons. Main innovations are found in the fuel configuration, because the fuel is embodied into small disks with suitable cladding and different diameters, and the disks are fixed to a geometrical structure forming a virtual spherical surface or cage. The reactor core is therefore a pebble bed, but the pebbles are not actual pebbles, as already said, although they can be evacuated from the core by letting them fall down into a core catcher where subcriticality and decay heat cooling are guaranteed.

ePLANET project is a Coordination and Support Action cofounded by the European Commission through Horizon 2020 program. ePLANET aims to deploy a new clustering governance for energy transition based on a digital framework to share harmonised information, facilitating the adoption of coordinated energy transition actions by the European public sector. The development of ePLANET is justified to deploy Energy Transition (ET) in the public sector, for which the following challenges are targeted: Improving coordination between local authorities and regional governments, Enhancing the decision-making process in the deployment of ET projects, Providing coherence and consistency to the energy transition measures (ETM) to be implemented, Encouraging the digitalisation of measures and plans, Enabling an interoperable ecosystem of data and tools, Building capacity of local authorities. All these targeted objectives will give the needed support for the energy transition decision-making process and its practical implementation. The present report is part of WP4, User empowerment. WP4 aims to empower policymakers, public officers, new ePLANET governance figures and key stakeholders with the necessary tools to implement Energy Transition Measures (ETM) with enough information and the proper tools.In Task 4.1, we investigated the main barriers and capacity building needs that ePLANET local authorities face when developing energy transition planning and implementation. In Task 4.2, we co-designed the capacity-building strategy and program for each ePLANET pilot territory. The present deliverable offers a comprehensive report on the capacity-building activities implemented in each pilot territory, outlining the engagement strategy and providing a detailed description of each activity. Finally, the last section summarises the key takeaways from the capacity-building program and outlines the next steps.

A lightwell is a daylighting design that brings daylight (including sunlight and skylight) to the lower floors in a multi-storey building. A lightwell has a similar function to a lightpipe or an atrium, but its size is medium. This paper presents construction, measurement and RADIANCE simulation of a model lightwell. The model lightwell has a scale factor of 1:20 to simulate a real lightwell design for a multi-storey hotel. The model lightwell has the dimension of 100mm (width) x 150 mm (length) x 800 mm (height) contained in a six-storey model building section with a dimension of 400 mm x 500 mm x 800 mm. Comparison of the measured daylighting performance is made for two different inner surfaces (matt white paint and mirror-finish) of the model lightwell under overcast and sunny sky conditions, respectively. Computational analysis on the daylight factor (DF) or illuminance ratio provides essential information to determine key design parameters and applicability of a lightwell.

Abstract Thermal storage heaters, charged using overnight off-peak electricity, have been used for domestic space heating in the UK and other countries since the 1980s. However, they have always been difficult for consumers to manage efficiently and, with the advent of a high proportion of renewables in the electricity generation mix, the time of day when they are charged needs to be more flexible. There is also a need to reduce peaks in the demand profile to allow distribution networks to support new sources of demand such as electric vehicles. We describe a trial of a smart control system that was retrofitted to a group of six dwellings with this form of heating, with the objectives of providing more convenient and efficient control for the users while varying the times at which charging is performed, to flatten the profile of demand and make use of locally-generated renewable electricity. The trial also employs a commercially-realistic combination of a static time-of-day tariff with a real time tariff dependent on local generation, to provide consumers with the opportunity and incentive to reduce their costs by varying times of use of appliances. Results from operation over the 2015–16 heating season indicate that the objectives are largely achieved. It is estimated that on an annualised and weather-adjusted basis most of the users have consumed less electricity than before intervention and their costs are less on the trial tariffs. Critical factors for success of this form of system are identified, particularly the need to facilitate hands-on control of heating by thrifty users and the importance of an effective and sustained user engagement programme when introducing the technology, to ensure users gain confidence through a readily-accessible source of support and advice.

Abstract Background Parabolic Trough Solar Collector (PTSC) is one of the most popular and an effective device that converts solar radiation into a heat or useful energy. However, it suffers from high temperature gradient and low thermal efficiency. The solution for this problem is to use new advanced coolants (hybrid nanofluids) in order to enhance PTSC's thermal efficiency. Methods A numerical analysis on the thermo-hydraulic performance of a PTSC receiver's tube equipped with conical turbulators is presented. The Navier-Stokes equations are solved using Finite Volume Method (FVM) coupled with Monte Carlo Ray Tracing (MCRT) method. The flow and thermal characteristics as well as entropy generation of the PTSC's receiver tube are investigated for three hybrid nanofluids (Ag-SWCNT, Ag-MWCNT, and Ag-MgO) having a mixing ratio of (50:50) dispersed in Syltherm oil 800, Reynolds number (5000 to 100,000) and fluid inlet temperatures (400 to 650 K). Significant findings The conical turbulators effectively augmented the thermal performance by 233.4% utilising Ag-SWCNT/Syltherm oil instead of pure Syltherm oil. The performance evaluation criterion is found to be in the range of 0.9–1.82. The thermal and exergetic efficiencies increased by 11.5% and 18.2%, respectively. The maximum decrement in the entropy generation rate and entropy generation ratio are 42.7% and 33.7%.