• Energy Research
• engineering and technology close
• 7. Clean energy close
• 1. No poverty close
• TH close
• AT close

Abstract Socio-technical transformations towards low-carbon energy systems are on the way in developed countries. Conversely, developing countries tend to be locked in fossil fuels and foster coal-based energy structures, emphasizing reliable and cost-effective energy provision and sidelining environmental concerns. In this study, we identified and analysed the predominant factors related to coal-based power generation in Bangladesh. We applied a mixed-method approach, initially conducting a systematic literature review and, subsequently, semi-structured expert interviews to identify and validate relevant factors. We then assessed their relative importance using an Analytical Hierarchy Process based on expert judgments. The results of this assessment reveal that socio-economic aspects and environmental issues scored highest, while technological aspects and sector regulations were considered to be less relevant for large-scale coal power implementation. We conclude that future energy policies created in Bangladesh will need to use appropriate legal instruments and address issues such as human displacement and resettlement, low levels of public acceptance, health hazards and environmental pollution. Participative policy frameworks should be deployed in coal plant projects, and active monitoring systems are necessary to reduce the negative consequences associated with increased electrification and energy consumption. To address foreseeable structural challenges, it furthermore will be crucial to explore sustainable alternatives.

In this study, the thermal performance of a compact heat sink thermoelectric cooling module with water, nanofluid, and ferrofluid as the coolants is investigated experimentally. The TiO2 nanofluid and Fe3O4 ferrofluid were tested at concentrations of 0.005% and 0.015%, respectively. The dummy battery pack was filled with water under a constant temperature and represented as a heat load. The results reveal that the Fe3O4 ferrofluid showed a maximum heat transfer rate 11.17% and 12.57% higher, respectively, than that of the TiO2 nanofluid and water. The TiO2 nanofluid and Fe3O4 ferrofluid with a 0.015% concentration enhanced the Peltier effect by lowering the contribution of the Fourier effect of the thermoelectric cooler (TEC), decreasing the temperature difference of the TEC cooling module by 4.6% and 9.6%, respectively, which decreases the thermal resistance of the heat sink by 7% and 14%, respectively. More importantly, the use of nanofluids and ferrofluids with a 0.015% concentration as coolants increased the pressure drop significantly, by 0.5 kPa and 2.7 kPa, respectively, compared with water.

The objectives of this study are to experimentally investigate the effect of meandering turn numbers on thermal performance and to predict the optimum meandering turn number of vertical and horizontal closed-loop pulsating heat pipes (CLPHP). The CLPHPs were made from a copper capillary tube with internal diameter of 2.0 mm. The CLPHPs were bent into undulating tubes with various meandering turn numbers, such as 5, 7, 10, 16, and 30. Each set of the CLPHPs had different evaporator section lengths of 50 mm and 150 mm. Heat input was supplied to the CLPHP by allowing the flow of distilled water as the heating medium through the evaporator section. The adiabatic section temperature was constantly controlled at 50°C. It could be concluded that the optimum meandering turn number of vertical CLPHPs with an evaporator section length of 50 mm is 10 for both R123 and water, and the optimum meandering turn numbers of vertical CLPHPs with an evaporator section length of 150 mm are 5 and 10, respectively, for R123 and water. However, the optimum meandering turn number of the horizontal CLPHP could not be found since the heat flux directly varies with the turn number. In addition, the correlation to predict the optimum meandering turn number of the vertical CLPHP was successfully established.

Purpose This paper aims to investigate the current energy status in the West Balkan countries and the related perspectives for renewable energy sources (RES) cooperation mechanisms, within the framework of RES Directive 2009/28/European Commission (EC), through the elaboration of a SWOT (strengths, weaknesses, opportunities, threats) analysis. Particular emphasis is laid on the case of Bosnia-Herzegovina, Croatia and Serbia. The SWOT analysis provides a clearer view of expanding RES in the West Balkans, as well as the level of utilization and potential of cooperation mechanisms and renewable energy in each country. Design/methodology/approach The adopted approach is mainly based on the context of a project co-financed by the Intelligent Energy Europe Programme, titled “Bringing Europe and Third countries closer together through renewable Energies (BETTER)” (project number: IEE/11/845/SI2.616378). The adopted approach incorporates the steps of desktop analysis, stakeholders’ mapping and engagement, key factors’ identification and analysis of results. Findings The barriers to expand RES in the region are significant. Currently, the region is electricity importer and by far not in the position to efficiently exploit the large RES potentials. It remains to be seen whether and to what extent cooperation mechanisms may be used in the Western Balkans and the EU by 2020. The unification of the fragmented electricity system and market-oriented reforms aim to join regional power markets and then to integrate with the European Union power market. There is a multitude of market barriers for RES, resulting in a high risk perception n by investors. Cooperation mechanisms could strengthen the regions’ policy frameworks and be a starting point to integrate the region’s energy systems and to overcome the fragmentation of the past two decades. Originality/value The potential of West Balkan countries to make use of the cooperation mechanisms provides opportunities for RES exporting between West Balkan and other European countries. An analysis of these opportunities for cooperation will allow drawing clearer conclusions on cooperation potentials and business cases for the region.

Due to the progresses in exhaust emission after-treatment systems and in the development of new combustion processes, the S.I. engine has been booming in the past few years. But the efficiency will have to be improved in the future. Because of its thermodynamic benefits, the S.I. direct injection engine of the second generation — so called air guided system — shows the highest potential for gasoline engines to reduce fuel consumption. However, there are restrictions when using conventional spark ignition system. They concern the optimum position of ignition initialization and spark-plug wear, the latter being caused by inhomogeneous mixture distribution. The laser-induced ignition enables a flexible choice of the ignition location and a wear resistant initialization of the combustion process. The most crucial component here is the optics (the combustion-chamber window), through which the laser beam passes into the combustion chamber. In this paper, laser-induced ignition is discussed and its potential compared to a conventional ignition system is presented. In addition, several optic configurations are presented as well as tests regarding the minimum required laser energy and the optic contamination and self-cleaning effect of the optics. At the Institute of Internal Combustion Engines at the Vienna University of Technology the optic contamination and self-cleaning effect, which is crucial for a long-term operation, was tested on a two-cylinder research engine.

Energy efficiency is an objective of public interventions at least since the Public Utility Regulatory Policy Act of 1978 (PURPA). Recently, conservation has received considerable attention in the United States and in particular in the European Union but this time in order to mitigate global warming. Policy measures include regulations at the technical level and the introduction of white certificates in order to force utilities and firms to invest into conservation in a way similar to the already existing renewable energy quota. This paper derives the optimal mechanism if utilities must deal with white certificates facing consumers holding private information. The optimal mechanism has some theoretically interesting features like restricted participation and a discontinuity.

The accumulation of dust on any given photovoltaic (PV) module surface depends on the type of dust, environment, surroundings, weather, module properties, and its installation design. In this research, equations were developed for the preliminary evaluation and comparison of the reduction in power from PV modules because of dust soiling. Use of these equations shows that dust accumulation decreases solar irradiance and thus the power output of modules, and that there is a linear relationship between the power output degradation and density or amount of accumulated dust. The equations can be used to conduct analysis of average photon energy and the PV module power output reduction from accumulated dust. The study also showed that type of PV module can also affect the degree of power output reduction. The amorphous silicon PV modules are more affected compared to poly crystalline silicon PV modules as the latter has a spectrum response which still has the range that can produce full energy and therefore, dust soiling has lesser impact on them. PV power plants should regularly clean the modules, if not, production of electricity decreases, and so too the revenue from selling electricity, making the payback of the power plant longer.

AbstractChemical looping combustion is a highly efficient CO2 separation technology without direct contact between combustion air and fuel. A metal oxide is used as an oxygen carrier in dual fluidized beds to generate clean CO2. The use of biomass is the focus of current research because of the possibility of negative CO2 emissions and the utilization of biogenic carbon. The most commonly proposed OC are natural ores and residues, but complete combustion has not yet been achieved. In this work, the direct utilization of CLC exhaust gas for methane synthesis as an alternative route was investigated, where the gas components CO, CH4 and H2 are not disadvantageous but benefit the reactions in a methanation step. The whole process chain, the coupling of an 80 kWth pilot plant with gas cleaning and a 10 kW fluidized bed methanation unit were for this purpose established. As OC, ilmenite enhanced with limestone was used, combusting bark pellets in autothermal operation at over 1000 °C reaching high combustion efficiencies of up to 91.7%. The fuel reactor exhaust gas was mixed with hydrogen in the methanation reactor at 360 °C and converted with a methane yield of up to 97.3%. The study showed especially high carbon utilization efficiencies of 97% compared to competitor technologies. Based on the experimental results, a scale-up concept study showed the high potential of the combination of the technologies concerning the total efficiency and the adaptability to grid injection. Graphical Abstract