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The possibility of electric vehicles to technically replace internal combustion engine vehicles and to deliver economic benefits mainly depends on the battery and the charging infrastructure as well as on annual mileage (utilizing the lower variable costs of electric vehicles). Current studies on electric vehicles’ total cost of ownership often neglect two important factors that influence the investment decision and operational costs: firstly, the trade-off between battery and charging capacity; secondly the uncertainty in energy consumption. This paper proposes a two-stage stochastic program that minimizes the total cost of ownership of a commercial electric vehicle under uncertain energy consumption and available charging times induced by mobility patterns and outside temperature. The optimization program is solved by sample average approximation based on mobility and temperature scenarios. A hidden Markov model is introduced to predict mobility demand scenarios. Three scenario reduction heuristics are applied to reduce computational effort while keeping a high-quality approximation. The proposed framework is tested in a case study of the home nursing service. The results show the large influence of the uncertain mobility patterns on the optimal solution. In the case study, the total cost of ownership can be reduced by up to 3.9% by including the trade-off between battery and charging capacity. The introduction of variable energy prices can lower energy costs by 31.6% but does not influence the investment decision in this case study. Overall, this study provides valuable insights for real applications to determine the techno-economic optimal electric vehicle and charging infrastructure configuration.

Detailed analysis of pathways to future sustainable energy systems is important in order to identify and overcome potential constraints and negative impacts and to increase the utility and speed of this transition. A key aspect of a shift to renewable energy technologies is their relatively higher metal intensities. In this study a bottom-up cost-minimizing energy model is used to calculate aggregate metal requirements in different energy technology including hydrogen and climate policy scenarios and under a range of assumptions reflecting uncertainty in future metal intensities, recycling rate and life time of energy technologies. Metal requirements are then compared to current production rates and resource estimates to identify potentially "critical" metals. Three technology pathways are investigated: 100 percent renewables, coal & nuclear and gas & renewables, each under the two different climate policies: net zero emissions satisfying the well-below 2 °C target and business as usual without carbon constraints, resulting together in six scenarios. The results suggest that the three different technology pathways lead to an almost identical degree of warming without any climate policy, while emissions peaks within a few decades with a 2 °C policy. The amount of metals required varies significantly in the different scenarios and under the various uncertainty assumptions. However, some can be deemed "critical" in all outcomes, including Vanadium. The originality of this study lies in the specific findings, and in the employment of an energy model for the energy-mineral nexus study, to provide better understanding for decision making and policy development. identifier:oai:t2r2.star.titech.ac.jp:50432542

Transitioning from fossil fuels to renewable energy (RE) is one of the core strategies in developing sustainable future energy systems. But in planning such a transition, it is common to consider primarily cost and greenhouse gas reduction, as typified by cost-mitigation curves that have become widespread. Such assessments tend to leave important considerations of energy justice on the periphery. This paper puts forward an alternative assessment technique, incorporating various indicators of social equity in order to assess the priority of power plant replacement that would lead to the greatest improvement in benefits, while placing the burden of system changes away from the most vulnerable. An example of the application of this approach is presented for prioritization of the retirement and replacement (with RE) of Australia s ageing fleet of coal-fired power plants. The assessment shows very different results from a standard cost-mitigation approach, with the retirement of the large brown coal power plants (including the recently retired Hazelwood power plant) and the replacement with wind power (where applicable) promoting the best overall outcomes on both cost and equity. Considering a selection of high priority indicators with many locally-specific data sets, the approach adds significant contextual relevance to prioritization, and is considered to offer useful findings for policy-makers.

A heat pump with low power consumption and a simple mechanical configuration is required to save energy and reduce carbon dioxide emissions. We show the design and demonstration of a novel heat pump using a Knudsen compressor, referring this device as a Knudsen heat pump. Water is employed as a refrigerant. The motionless nature of the Knudsen heat pump is accomplished by using a Knudsen compressor to transport the refrigerant vapor from the evaporator to the condenser, and thermal energy alone supplies the needed power. We employ a simple single-stage Knudsen compressor powered by light from a halogen lamp as an energy source. Experiments confirmed heat transport from the evaporator to the condenser with an output power of 3.09 W. The output power tended to increase linearly as the temperature difference between the evaporator and condenser decreased. The pressure-enthalpy diagram of the proposed Knudsen heat pump cycle was shown, and the thermal efficiency of this heat pump was analyzed. The application of a multi-stage Knudsen compressor to improve the heat pump performance was also discussed. This heat pump is free from noise, vibration, and maintenance, and it can utilize low-quality energy, such as a solar energy, and it does not require any electrical input. These properties make the Knudsen heat pump a particularly significant technology in harsh environments such as space and desert. ファイル公開：2021-09-15