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This paper presents a multi-objective optimization model for a long-term generation mix in Indonesia. The objective of this work is to assess the economic, environment, and adequacy of local energy sources. The model includes two competing objective functions to seek the lowest cost of generation and the lowest CO2 emissions while considering technology diffusion. The scenarios include the use of fossil reserves with or without the constraints of the reserve to production ratio and exports. The results indicate that Indonesia should develop all renewable energy and requires imported coal and natural gas. If all fossil resources were upgraded to reserves, electricity demand in 2050 could be met by domestic energy sources. The maximum share of renewable energy that can be achieved in 2050 is 33% with and 80% without technology diffusion. The least cost optimization produces lower generation costs than the least CO2 emissions, as well as the combined scenario. Total CO2 emissions in 2050 are five to six times as large as current emissions. The least CO2 emissions scenario can reduce almost half of the CO2 emissions of the least cost scenario by 2050. The proposed multi-objective optimization model leads some optimal solutions for a more sustainable electricity system.

This paper presents experimental results of the impact of CO(2) co-feed on a gasification/pyrolysis process for various feedstocks (biomass, coal, and municipal solid waste (MSW)). Various feedstocks were thermo-gravimetrically characterized under various atmospheric conditions and heating rates. A substantial amount of char burn out was identified in the presence of CO(2) via a series of thermo-gravimetric analysis tests, which enabled high conversion of final mass (approximately 99%) to be achieved. The impact of CO(2) co-feed on the volatilization regime during the pyrolysis/gasification process was not apparent at a heating rate of 10-40 degrees C min(-1). However, the impact of CO(2) on the volatilization regime at a fast heating rate (950 degrees C min(-1)) was substantial. For example, significant enhancement in the generation of CO, by a factor of approximately 2, was observed in the presence of CO(2). The generation of major chemical species, such as CH(4) and C(2)H(4), were enhanced, but this was not as apparent as in the case with CO. In addition, introducing CO(2) to the pyrolysis/gasification process enabled the amount of condensable liquid hydrocarbons, such as tar (approximately 30-40%) to be significantly reduced in the presence of CO(2), in that injecting CO(2) into the pyrolysis/gasification process expedites cracking the volatilized chemical species. Experimental work confirmed that biomass and MSW could be feasible and desirable feedstocks for the pyrolysis/gasification process as these feedstocks can be easily treated compared to coal. To extend this understanding to a more practical level, various feedstocks were tested in a tubular reactor and drop tube reactor under various experimental conditions.

Abstract It is demonstrated that the fuel deposit has a significant influence on the NOx and particular matter (PM) emissions, especially with the consideration of the more and more strict emission regulations issued by the governments, which results in that the near-nozzle spray has been received the increased attention, recently. In this study, the near-nozzle spray characteristics at the initial and end stages were investigated by a high-resolution camera with a laser as the light source. At the initial stage, microscopic behaviors of the near-nozzle spray were observed at upstream, midstream and downstream, respectively. Moreover, the injection frequency was changed to check the effect on the near-nozzle spray morphology. Next, the micro spray length, width and angle were obtained from the processed images. While, at the end stage, the near-nozzle spray evolutions were observed and characterized at 0.5, 0.3, 0.2 and 0.1 ms before the end of injection (BEOI), the end of injection (EOI), 0.05, 0.1, 0.15 and 0.2 ms after the end of injection (AEOI), respectively. Furthermore, the droplet area, spray area without droplets, droplet number and averaged diameter were calculated. Results show that three structures of the near-nozzle spray at the initial stage can be classified as mushroom, steeple and cylinder shapes. And the injection frequency has an influence on their formations owing to the residual fuel and sucked air AEOI. Moreover, although more droplets can be identified at the end stage with time, it does not indicate the better atomization. On the contrary, these droplets AEOI are responsible for the injector deposit in the real engine.

Nuclear power generation is now one of the most important technologies in the energy supply in Japan. The operational experience of nuclear power plants for more than 20 years in Japan has shown that water chemistry is a key technology for safer and more economical operation of nuclear power plants. Extensive efforts have been made in the field of water chemistry to achieve the targets of radiation field control, to keep the integrities of piping and fuel elements and to reduce the radioactive waste generation. This paper briefly describes the present status of Japanese water chemistry technology with the main emphasis placed on BWRs.

With the spotlight on smart grid development around the world, it is critical to recognize the key factors contributing to changing power system characteristics. This is more apparent in distribution systems with the integration of renewable energy sources, energy storage, and microgrid development. Utilities are also focusing on the reliability and resiliency of the grid. These activities require distribution automation (DA) strategies that take advantage of available technologies while promoting newer solutions. It is necessary to create a roadmap for holistic DA strategies in a smarter grid. Sustainable and resilient grid development is a paradigm shift requiring a new line of thinking in the engineering, operation, and maintenance of the power system. International perspectives on DA are also addressed, with the understanding that one solution will not fit all. Integrating technical, business, and policy decisions into the challenges will generate the development of technologies, standards, and implementation of the overall solution. The challenges in the development of industry standards are also discussed. This paper explores the challenges and opportunities in the changing landscape of the distribution systems. Evolution of technologies and the business case for infrastructure investment in distribution systems are covered in another paper by the same authors.

Abstract A feasibility study has been conducted to determine whether thermal plasma with steam can be used for the treatment of carbonaceous wastes such as the carbide of the hazardous wastes. The gasification of carbonaceous wastes has been especially studied to reduce their weight and the volume and to produce the synthetic gas (H2+CO). The gasification applied to this study is often called “water gas reaction (C+H2O→CO+H2)”. In this study the thermal plasma generated by the hybrid plasma system was adopted as a heat source, where steam was injected to react with carbide. Charcoal was used as a test piece instead of carbonaceous wastes. Experiments of treating charcoal were conducted by three types of thermal plasma. The result showed that the treatment of thermal plasma with steam reduced the weight of charcoal and produced hydrogen from charcoal. The thermal plasma with steam will be an attractive heat source to dispose of carbonaceous wastes.

Abstract An estimation of passive cooling techniques was conducted for 14 cities in Brazil, using a fairly accurate algorithm that accounts for heat conduction, convection, radiation, and evaporation; this was done to determine the amount of heat gain/loss of room air, defined as a particular quantitative index for passive techniques. Heat gains and losses were calculated for four envelope conditions – namely, insulated, high-albedo, wet surface, and a combination of the previous two – and compared to a case assumed to be the standard condition. A conclusion drawn was that a passive design is efficient in decreasing the need for cooling in typical dwellings in Brazil; solutions should differ with regional climate characteristics. In semi-arid areas, evaporative cooling showed the best results. Reduced heat gain was found during the warm seasons for all cities, along with increased heat gain during the cool seasons for mid-latitude cities. In particular, a combination of high-albedo enveloping and evaporation can greatly decrease heat gain in building walls. High-albedo surfaces in the sub-tropical areas found in southern Brazil are more efficient. It is suggested that passive techniques should be conceived in such a way so as to work during the cooling season and be disabled during mild ones.

Abstract Utilization of solar thermal power for high temperature fuel production has the potential to significantly reduce the fossil fuel dependence of our current economy. Over the past two decades, remarkable progress has been made in the development of solar driven thermochemical reactors for the production of hydrogen and syngas as they are promising energy carriers for transportation, domestic and industrial applications. However, there are solar peculiarities in comparison to conventional thermochemical processes – high thermal flux density and frequent thermal transients because of the fluctuating insolation-, and conventional industrial thermochemical reactors are generally not suitable for solar driven reactors. Therefore, solar-specific modifications of reactor design are necessary to realize efficient solar driven thermochemical processes. In solar thermochemical reactors, the methods for solar-heating particulate solid feedstock to high temperatures can be broadly classified as solar “directly” and “indirectly” absorbing reactors. On solar thermochemical processes involving reacting solid particles at high temperatures, such as “solar two-step water splitting with metal oxides” and “solar gasification”, various types of solar directly and indirectly absorbing particle reactors have been developed. In this review, recent development of solar particle reactors for the above solar thermochemical processes is described.

Abstract Global energy consumption is increasing at a dramatic rate and will likely continue to do so. The major source of energy is still fossil fuel, which has resulted in the well-documented problem of global warming due to the emission of greenhouse gases from the burning of such fuel. Climate change and global warming are among the crucial and complex issues encountered by the world today, and they require an immediate solution. Technological innovation is the key to ensuring energy security without causing emissions and providing efficient cost-effective energy solutions. Power electronic technologies offer high reliability and renewable energy conversion efficiency, thus contributing to energy conservation, improving energy efficiency, and helping in the mitigation of harmful global emissions. This review focuses on various aspects of power electronic technologies and their importance in tackling carbon emission and global warming problems. The key topologies of power electronic converters are explained based on types, control difficulties, benefits, and drawbacks. Power electronic controllers utilized for energy conversion are comprehensively reviewed with regard to their structure, algorithm complexity, strengths and weaknesses, and mathematical modeling. The review focuses on power converters and controllers used in different applications and highlight their contributions to energy conservation, increasing the share of renewable energy sources, and mitigating emissions. Moreover, existing research gaps, issues, and challenges are identified. The insights provided by are expected to lead to the enhanced development of advanced power electronic converters and controllers for sustainable energy conversion. Such development can reduce carbon emissions and mitigate global warming.