Enabling the transition to renewable power sources requires further optimization of batteries in terms of energy/power density and cost-effectiveness. Increasing the practical thickness of Li ion battery electrodes not only can improve energy density on cell level but reduces manufacturing cost. However, thick electrodes exhibit sluggish charge-transport kinetics and are mechanically less stable, typically resulting in substandard battery performance compared to the current commercial standards (~50 μm). Here we disclose a novel method based on immersion precipitation by employing a non-solvent to solidify the battery binder, instead of solvent evaporation. This method allows for the fabrication of thick and suitable density electrodes (>100 μm with ultra-high mass loading) offering excellent electrochemical performance and mechanical stability. Using commercial electrode active materials at a remarkable mass-loading of 24 mg cm⁻², the electrodes processed via immersion method are shown to deliver 3.5 mAh cm⁻² at a rate of 2C and operate at rates up to 10C. As additional figure of merit, this method produces electrodes that are both stand-alone and highly flexible, which have been evaluated in flexible full-cells. Furthermore, via immersion precipitation the commonly used more toxic N-Methyl-2-pyrrolidone can be supplanted by environmentally benign dimethyl sulfoxide as solvent for processing electrode layers.

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The need for zero emission drive is a global necessity that can contribute to mitigate greenhouse gas emissions. In this context, fuel cell hybrid electric vehicles are increasingly attracting interest by governments, companies and academia. While parked they can operate as power generation units, given the proper connection to the electricity grid via vehicle-to-grid integration (V2G), or even power appliances directly (Vehicle-to-Load, V2L). In this study, we analysed the use of a hydrogen fuel cell electric scooter in combined driving, V2G and V2L mode. V2G resulted in the most efficient mode of the three, while V2L led to higher degradation rates. The measured average cell voltage degradation rate was 209 μV/h for driving mode, 356 μV/h for V2G and 648 μV/h for V2L. The insights provided in this study are useful to develop new, optimized and specifically targeted energy management systems for power generation of hydrogen hybrid electric drive vehicles.@en

Fuel Cell Electric Vehicles (FCEVs) in combination with green hydrogen (obtained from renewable sources), could make a significant contribution in decarbonizing the European transport sector, and thus help achieve the ambitious climate goals. However, most vehicles are parked for about 95% of their life time. This work proposes the more efficient use of these vehicles by providing vehicle-to-grid (V2G) services achieving the integration of the transport and energy systems. The aim of this work is to determine the technical and financial potential value that FCEVs could have by providing frequency reserves. Experiments were carried out with a Hyundai ix35 FCEV that was adapted with a power output socket so it can operate in V2G when parked, delivering maximum 10 kW direct current power. Results show that both power sources in the fuel cell electric vehicle, which are the fuel cell stack and the battery, can react in the order of milliseconds and thus are suitable to offer fast frequency reserves. The challenge lays in the communication between the car and the party that sends the signal for the activation of the frequency reserves. As one unit does not provide enough power to be able to participate in the electricity market, a car park acting as aggregator of FCEVs was designed taking into account current technology developments. A carpark with a direct current microgrid, a hydrogen local network and only occupied by FCEVs was designed. A financial model was developed to evaluate the economic potential of the car park to participate in the electricity market providing frequency reserves. Results show that by using the fuel cells in the FCEVs in V2G, monetary benefits could be obtained when providing automated frequency restoration reserves (aFRR) upwards. Key parameters are found to be the investment costs, amount of vehicles available, hydrogen price and price of aFRR. With a car park of approximately 400 cars all year long available, payback times of 11.8 and 3.5 years were obtained taking into account worst and best case scenarios for a 15 year period analysis, respectively.@en

This paper presents the results of a demonstration project, including building-integrated photovoltaic (BIPV) solar panels, a residential building and a hydrogen fuel cell electric vehicle (FCEV) for combined mobility and power generation, aiming to achieve a net zero-energy residential building target. The experiment was conducted as part of the Car as Power Plant project at The Green Village in the Netherlands. The main objective was to assess the end-user's potential of implementing FCEVs in vehicle-to-grid operation (FCEV2G) to act as a local energy source. FCEV2G field test performance with a Hyundai ix35 FCEV are presented. The car was adapted using a power output socket capable of delivering up to 10 kW direct current (DC) to the alternating current (AC) national grid when parked, via an off-board (grid-tie) inverter. A Tank-To-AC-Grid efficiency (analogous to Tank-To-Wheel efficiency when driving) of 44% (measured on a Higher Heating Value basis) was obtained when the car was operating in vehicle-to-grid (V2G) mode at the maximum power output. By collecting and analysing real data on the FCEV power production in V2G mode, and on BIPV production and household consumption, two different operating modes for the FCEV offering balanced services to a residential microgrid were identified, namely fixed power output and load following. Based on the data collected, one-year simulations of a microgrid consisting of 10 all-electric dwellings and 5 cars with the different FCEV2G modes of operation were performed. Simulation results were evaluated on the factors of autonomy, self-consumption of locally produced energy and net-energy consumption by implementing different energy indicators. The results show that utilizing an FCEV working in V2G mode can reduce the annual imported electricity from the grid by approximately 71% over one year, and aiding the buildings in the microgrid to achieve a net zero-energy building target. Furthermore, the simulation results show that utilizing the FCEV2G setup in both modes analysed, could be economically beneficial for the end-user if hydrogen prices at the pump fall below 8.24 €/kg.

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In this paper, a framework is presented for the evaluation of smart grid environment which is called the three-layer model. This three-layer model comprises three specific categories, or 'layers', namely, the stakeholder, market and technologies layers. Each layer is defined and explored herein, using an extensive literature study regarding their key elements, their descriptions and an overview of the findings from the literature. The assumption behind this study is that a solid understanding of each of the three layers and their interrelations will help in more effective assessment of residential smart grid pilots in order to better design products and services and deploy smart grid technologies in networks. Based on our review, we conclude that, in many studies, social factors associated with smart grid pilots, such as markets, social acceptance, and end-user and stakeholder demands, are most commonly defined as uncertainties and are therefore considered separately from the technical aspects of smart grids. As such, it is recommended that, in future assessments, the stakeholder and market layers should be combined with the technologies layer so as to enhance interaction between these three layers, and to be able to better evaluate residential smart energy systems in a multidisciplinary context.

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The world's future energy supply will include intermittent renewable sources, such as solar and wind power. To guarantee reliability of supply, fast-reacting, dispatchable and renewable back-up power plants are required. One promising alternative is parked and grid-connected hydrogen-powered fuel cell electric vehicles (FCEVs) in "Vehicle-to-Grid" systems. We modified a commercial FCEV and installed an external 9.5 kW three-phase alternating current (AC) grid connection. Our experimental verification of this set-up shows that FCEVs can be used for mobility as well as generating power when parked. Our experimental results demonstrate that present-day grid-connected FCEVs can respond to high load gradients in the range of -760 % s-1 to + 730 % s-1, due to the parallel connection of the high voltage battery and the fuel cell stack. Virtual power plants composed of multiple grid-connected FCEVs could perform higher power gradients than existing fast-reacting thermal power plants with typical power gradients of 1.67 % s-1. Hydrogen consumption in 9.5 kW AC grid-connected mode was 0.55 kg h-1, resulting in a Tank-To-Grid-AC efficiency of 43% on a higher heating value basis (51 % on a lower heating value basis). Direct current to alternating current efficiency was 95 %.@en

In this paper we present our project on interdisciplinary evaluations of existing smart grid environments regarding (1) the technical performance of smart energy products and services, (2) end users perceptions, (3) stakeholder processes and (4) market aspects. Our evaluations are based on data and information originating from real life pilots and demonstration projects in the field of smart grids in residential areas in the Netherlands and in Austria. The so-called CESEPS project is executed in the European ERA-Net Smart Grids Plus program. CESEPS stands for Co-Evolution of Smart Energy Product and Services. Its main objective is to support the development of smart energy products and services for local smart grids that better respond to the demands and concerns of all stakeholders in terms of performance, cost, reliability, safety and robustness, sustainability and energy-efficiency, and end users' comfort. Besides comparative data analyses and user surveys, this three year project comprises simulation activities to model existing and innovative smart grid energy products to evaluate their feasibility, given the aspects above mentioned. In this paper our approach will be explained and illustrated by several examples of ongoing subtopics of research and knowledge dissemination among stakeholders in the smart grid sector.@en