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The energy transformation requires a shift in the energy sector from fossil fuels and their related technologies to carbon free technologies which are mainly renewable energy technologies. In addition to them, three key elements foster the realization of smooth and stringent transformation paths: coal phase out, energy efficiency, and electricity exchange. By applying the techno-economic energy system model REMod-D, the German case is analyzed in this paper with a focus on effects created by emphasizing these three elements in an energy transformation strategy. The analysis covers their impact on the power sector, heating sector, and transport sector which are influenced by the actual shaping of these elements. Overall, the model results show a shift in the German energy system towards a system using more electricity. This electricity is generated up to 85% from photovoltaics, wind power, and other renewable energy sources. Each of the three elements, if employed, leads by itself to a reduction of efforts on the level of developments such as the deployment of renewable energy and renovations, as well as the electrification of vehicles. In the case of combining the three elements, complementary effects can even be summed up. In the Active scenario with a joint use and implementation of the three key elements, this combination is analyzed as part of a cross-sectoral energy strategy for the transformation. Each element can reduce the total system cost by around 16 billion EUR per year. This paper concludes to prioritize these three key elements in the energy strategy in addition to the strong expansion of renewables and the change of heating systems and vehicle concepts. [ABSTRACT FROM AUTHOR]

Green growth has become an increasingly important paradigm for sustainable economic growth, resource development, and environmental protection. As the main focus in energy led green growth is a move away from fossil energy to clean energy, sustainable green growth resource development needs to measure both energy and environmental efficiencies. As the largest global energy consumer and carbon emitter, China has had to deal with serious energy and environmental issues in recent years, with its regional green growth performances being poorly assessed. Therefore, green growth clean energy-environmental efficiency assessments were examined in this paper, for which an integrated principal component analysis-data envelopment analysis based analysis approach was developed. It was found that while China's green growth has had a significant increasing trend in recent years, overall it was still at a low level, with the imbalances in China's regional economic development being reflected in its green growth. However, the excellent development and utilization of clean energy in most regions have significantly promoted a continuous improvement in China's green growth and the move toward sustainable resource development and utilization is contributing to long-term green growth. Green growth has also placed new demands on sustainable resource development in China. Therefore, underdeveloped regions that have sustainable resource endowments need to develop industrial systems that have clean energy as the main axis, and developed regions need to develop high-end industries that have low energy consumption and encourage mutual support systems between regions to ensure optimal sustainable resource, green growth development patterns. [ABSTRACT FROM AUTHOR]

This paper presents detailed energy and exergy analysis and comparison of low-grade solar heat source powered superheated and saturated organic Rankine cycle (ORC) using zeotropic mixture butane/R1234ze. The required expression to evaluate the power output, first law efficiency exergetic efficiency, exergy destruction, and required heat exchangers area are coded in Matlab 2015a interfaced with REFPROP 9.0. Moreover, saturated and superheated ORCs are further optimized by genetic algorithm by selecting exergetic efficiency and product of overall heat transfer coefficient and heat exchanger area. It is observed that superheated ORC exhibits better net power output, first law and exergetic efficiency, lower exergy destruction and poorer economy than saturated ORC. Further, the performance of saturated ORC is increased by 34.02% and that of superheated ORC by 17.06% by the multiobjective genetic algorithm. [ABSTRACT FROM AUTHOR]

Tibet is located in the southwest of China, with unique geographical conditions and natural resources, new energy reserves like solar energy and wind resources are in the forefront of other provinces in China, and it is also one of the solar energy resource richest regions in the world. Since central Tibet is the economic center of the Tibet autonomous region and Lhasa is the outside sending end of Qinghai-Tibet DC, developing new energy resources in central Tibet would play an important role in inter-provincial delivery of renewable energy power generation, reducing fossil energy consumption to achieve a clean alternative and stimulating the economic growth of Tibet. In this paper, the renewable energy consumptive situation in central Tibet was studied. Through the analysis of renewable energy reserves, distribution and utilization, the current situation of the renewable energy development and the electricity load in Tibet, the solutions and suggestions for new energy generation consumption were put forward in the end. [ABSTRACT FROM AUTHOR]

Biomass (straw) gasification with oxygen-enriched air was studied in a lab-scale entrained-flow gasifier. Effects of oxygen concentration (OC), equivalence ratio (ER), and reactor temperature on the produced gas composition, gasification index and tar yield were investigated. Compared with air, oxygen-enriched air as gasifying agent was beneficial to increase the H2 content, H2/CO ratio, and lower heating value (LHV) of the gas, and decrease the yield of tar contained in the flue gas. The H2/CO reached 1 when OC was 50%, which was an optimal value for dimethyl ether, methanol, and higher alcohol production in the process of alcohols synthesis. A reference value of OC was given approximately to 40% according to economic consideration. A reference value of ER was given around 0.25 when OC was 40%, achieved a relatively high LHV of 8.2 MJ/Nm3 and low tar yield of 2.6 mg/g. In addition, high reaction temperature could improve both gas quality and gasification indexes significantly. The better gasification performance achieved in the paper verified that the oxygen-enriched gasification was a good option for the improvement of direct air gasification. [ABSTRACT FROM AUTHOR]

Faster consumption of hydrocarbon fuel in the transport sector is posing global threat of depletion of fossil fuel reserves. Studies are being extensively done to search for an alternative energy source and/or to find out appropriate energy conversion system. Among various alternatives, the use of compressed atmospheric air in air turbine is an attractive option provided the atmospheric air is compressed by natural sources such as sun energy, wind energy, etc. It has the capability to produce shaft work with almost zero pollution in the environment. This paper details the mathematical modeling of a small capacity compressed air driven multivane air turbine. The effect of having different vane angles and inlet pressure on shaft work output has been studied and analyzed here. The study shows that the flow work has significant contribution in total work output and varies from 1.5% to 16.3% at different pressures, 2–6 bars, and injection angles, 30°–60°. The total shaft work is found to be maximum at vane angle θ=36° (ten vanes) when injection angle is kept at 60°, and it reduces at vane angle θ=45° (eight vanes) when injection angle is kept at 45° and further goes down at vane angle θ=60° (six vanes) when injection angle is 30°, if injection pressure is maintained at 6 bars and speed of rotation at 2500 rpm. [ABSTRACT FROM AUTHOR]

This paper compares the use of sugar cane and corn for the production of ethanol, with a focus on global warming and the current international debate about land use competition for food and biofuel production. The indicators used to compare the products are CO2 emissions, energy consumption, sugar cane coproducts, and deforestation. The life cycle emission inventory as a methodological tool is taken into account. The sustainability of socioeconomic development and the developing countries’ need to overcome barriers form the background against which the Brazilian government energy plans are analyzed. [ABSTRACT FROM AUTHOR]

This paper examines the relationship between renewable energy consumption and economic efficiency. For this reason, conditional Data Envelopment Analysis estimators alongside with nonparametric regressions are applied in a sample of 25 European countries for the year 2010 with emphasis given to Eastern and Western European countries. Our results reveal that renewable energy consumption has a positive effect on countries' economic efficiency for lower consumption levels while for higher levels, the analysis reveals mixed effects, which are also subject to regional disparities. Finally, it appears that the effect of renewable energy consumption on countries' economic efficiency depends also on countries' specific regional characteristics as well as on the environmental policies adopted. [ABSTRACT FROM AUTHOR]