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Formulating energy policies at national, European, and global levels is extremely challenging. The move away from fossil fuels is associated with a variety of technological, economic, and social implications, each of which is subject to dynamic changes and societal scrutiny and can hardly be predicted with certainty. Therefore, a fact-based assessment for the path to a sustainable green energy future is sought out in this paper, using the road-based mobility sector of the Federal Republic of Germany as an example. The analysis performed in this paper is built on publicly accessible, reputable sources like DESTATIS and EUROSTAT. In addition, some very simple calculations were made, e.g., on the potential for wind and photovoltaic energy within Germany. Such an analysis needs to start with the overall energy consumption of any one country. A basic assumption of the paper is that the energy system of the future will be based to a large extent on electricity and its storage in chemical energy. It is assumed that, in addition to hydrogen, liquid energy sources will play a significant role due to the simplicity of their logistics and the subsequent implications on cost. Examples of green, electricity-based fuels with great potential are methanol, methane, and ammonia. Additionally, biomass plays an important role, either for direct use as a fuel or as a source of non-fossil carbon. Today, biofuels, i.e., biodiesel and bioethanol, deliver the largest contribution to climate protection in the EU transport sector. The main goal—the reduction of greenhouse gas emissions—often collides with geopolitical circumstances or national political necessities. This includes, for example, the current world market situation and its national impacts caused by the Russian attack on Ukraine. The prospect for a green, sustainable, and defossilized energy supply are discussed in this context. The paper concludes that a defossilized world energy supply and trade based on renewable electricity and its derivatives, eHydrogen and refuels, and on biomass, is feasible. [ABSTRACT FROM AUTHOR]

Improving energy efficiency is the most important goal for buildings today. One of the ways to increase energy efficiency is to use the regenerative potential of elevators. Due to the special requirements of elevator drives, energy storage systems based on supercapacitors are the most suitable for storing regenerative energy. This paper proposes an energy storage system consisting of a supercapacitor bank and a bidirectional six-phase interleaved DC/DC converter. The energy savings achieved by the proposed system were investigated through simulation tests. The proposed system was modeled considering all physical constraints. A simulation model of the existing faculty elevator system was created in PLECS and verified with field measurements. Reliable results were ensured by using the verified simulation model and considering all physical constraints. The operation of the proposed energy storage system was tested under various conditions. In addition, the simulation model of the elevator system with the proposed energy storage system was tested using the elevator traffic data obtained from the measurements. The simulation results show the effectiveness of the proposed energy storage system and that significant energy savings can be achieved. [ABSTRACT FROM AUTHOR]

This paper proposes a super capacitor energy storage-based modular multilevel converter (SCES-MMC) for mine hoist application. Different from the conventional MMCs, the sub-modules employ distributed super capacitor banks, which are designed to absorb the regenerative energy of mine hoist and released in the traction condition, so as to improve energy utilization efficiency. The key control technologies are introduced in detail, followed by analysis of the configuration and operation principles. The feasibility of the proposed SCES-MMC topology and the control theory are also verified. Simulation results show that SCES-MMC can adapt to the variable frequency speed regulation of the motor drive, which shows good application prospects in the future for mediumand high-voltage mine hoist systems. [ABSTRACT FROM AUTHOR]

Due to the dramatic growth of the global population, building multi-story buildings has become a necessity, which strongly requires the installation of an elevator regardless of the type of building being built. This study focuses on households, which are the second-largest electricity consumers after the transportation sector. In residential buildings, elevators impose huge electricity costs because they are used by many consumers. The novelty of this paper is implementing a Hybrid Energy Storage System (HESS), including an ultracapacitor Energy Storage (UCES) and a Battery Energy Storage (BES) system, in order to reduce the amount of power and energy consumed by elevators in residential buildings. The control strategy of this study includes two main parts. In the first stage, an indirect field-oriented control strategy is implemented to provide new features and flexibility to the system and take benefit of the regenerative energy received from the elevator's motor. In the second stage, a novel control strategy is proposed to control the HESS efficiently. In this context, the HESS is only fed by regenerated power so the amount of energy stored in the UC can be used to reduce peak consumption. Meanwhile, the BES supplies common electrical loads in the building, e.g., washing machines, heating services (both boiler and heat pump), and lighting, which helps to achieve a nearly zero energy building. [ABSTRACT FROM AUTHOR]

Maximizing regenerative energy utilization is an important way to reduce substation energy consumption in subway systems. Timetable optimization and energy storage systems are two main ways to improve improve regenerative energy utilization, but they were studied separately in the past. To further improve energy conservation while maintaining a low cost, this paper presents a strategy to improve regenerative energy utilization by an integration of them, which determines the capacity of each Wayside Energy Storage System (WESS) and correspondingly optimizes the timetable at the same time. We first propose a dual-objective optimization problem to simultaneously minimize substation energy consumption and the total cost of WESS. Then, a mathematical model is formulated with the decision variables as the configuration of WESS and timetable. Afterwards, we design an ϵ -constraint method to transform the dual-objective optimization problem into several single-objective optimization problems, and accordingly design an improved artificial bee colony algorithm to solve them sequentially. Finally, numerical examples based on the actual data from a subway system in China are conducted to show the effectiveness of the proposed method. Experimental results indicate that substation energy consumption is effectively reduced by using WESS together with a correspondingly optimized timetable. Note that substation energy consumption becomes lower when the total size of WESS is larger, and timetable optimization further reduces it. A set of Pareto optimal solutions is obtained for the experimental subway line—based on which, decision makers can make a sensible trade-off between energy conservation and WESS investment accordingly to their preferences. [ABSTRACT FROM AUTHOR]

With the rapid development of urban rail transit, the energy consumption of trains is increasing dramatically. The shortage of electrical energy is becoming more and more serious. In this paper, a novel method is proposed to better use regenerative braking energy for energy saving. A 'time slot and energy grid' model is set up to analyze the utilization of regenerative energy among trains. Based on this model, an energy efficient strategy that integrates train dispatch with train control is designed. The running time of trains in sections, the dwell time of trains at stations and the headway can be adjusted to find the global optimal solution for energy saving. The operational data of Beijing Changping subway line and Beijing Yizhuang subway line are used in simulation to illustrate the effectiveness of the proposed method in different scenarios. Simulation results show that our approach can significantly improve the utilization of regenerative braking energy and minimize the energy consumption in different scenarios when compared with the existing method. [ABSTRACT FROM AUTHOR]