Several approaches have been proposed to determine the optimal storage capacity and dispatch strategy in a power system with high renewable penetration. The deployment of alternatives such as sector coupling and reinforcing interconnections among neighbouring countries may reduce the storage capacity that results cost-effective. We use the model PyPSA-Eur-Sec-30, an open, hourly-resolved, one-node-per-country network of the sector-coupled European energy system to investigate the complex interactions among generation technologies, mainly wind and solar PV, storage technologies in the power system (pumped hydro storage [PHS], batteries, and hydrogen storage), and the additional storage brought to the system by coupling the transport (electric vehicle [EV] batteries) and heating sector (short-term and long-term thermal energy storage). The system configuration is optimised under decreasing CO 2 emissions targets. For the power system, significant storage capacities only emerge for CO 2 emissions reduction higher than 80% of 1990 level in that sector. For 95% CO 2 emissions reduction, battery and hydrogen storage energy capacities equivalent respectively to 1.4 and 19.4 times the average electricity demand result cost-effective. The former cycles daily counterbalancing solar generation while the dispatch pattern of the latter is determined by fluctuations in wind generation. Coupling heating and transport sectors enables deeper CO 2 emissions reductions before the required storage capacities diverge. The EV batteries provided by coupling the transport sector avoid the need for additional stationary electric batteries and large energy capacity of centralised thermal energy storage (CTES) is built to deal with the large seasonal variation in heating demand.

For a given carbon budget over several decades, different transformation rates for the energy system yield starkly different results. Here we consider a budget of 33 GtCO2 for the cumulative carbon dioxide emissions from the European electricity, heating, and transport sectors between 2020 and 2050, which represents Europe’s contribution to the Paris Agreement. We have found that following an early and steady path in which emissions are strongly reduced in the first decade is more cost-effective than following a late and rapid path in which low initial reduction targets quickly deplete the carbon budget and require a sharp reduction later. We show that solar photovoltaic, onshore and offshore wind can become the cornerstone of a fully decarbonised energy system and that installation rates similar to historical maxima are required to achieve timely decarbonisation. Key to those results is a proper representation of existing balancing strategies through an open, hourly-resolved, networked model of the sector-coupled European energy system.

Mobility management is one of the most challenging research issues for vehicular networks to support a variety of intelligent transportation system (ITS) applications. The traditional mobility management schemes for Internet and mobile ad hoc network (MANET) cannot meet the requirements of vehicular networks, and the performance degrades severely due to the unique characteristics of vehicular networks (e.g., high mobility). Therefore, mobility management solutions developed specifically for vehicular networks would be required. This paper presents a comprehensive survey on mobility management for vehicular networks. First, the requirements of mobility management for vehicular networks are identified. Then, classified based on two communication scenarios in vehicular networks, namely, vehicle-to-vehicle (V2V) and vehicle-toinfrastructure (V2I) communications, the existing mobility management schemes are reviewed. The differences between host-based and network-based mobility management are discussed. To this end, several open research issues in mobility management for vehicular networks are outlined.

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Ambitious targets for renewable energy and CO 2 taxation both represent political instruments for decarbonisation of the energy system. We model a high number of coupled electricity and heating systems, where the primary sources of CO 2 neutral energy are from variable renewable energy sources (VRES), i.e., wind and solar generators. The model includes hourly dispatch of all technologies for a full year for every country in Europe. In each model run, the amount of renewable energy and the level of CO 2 tax are fixed exogenously, while the cost-optimal composition of energy generation, conversion, transmission and storage technologies and the corresponding CO 2 emissions are calculated. We show that even for high penetrations of VRES, a significant CO 2 tax of more than 100 e/tCO 2 is required to limit the combined CO 2 emissions from the sectors to less than 5% of 1990 levels, because curtailment of VRES, combustion of fossil fuels and inefficient conversion technologies are economically favoured despite the presence of abundant VRES. A sufficiently high CO 2 tax results in the more efficient use of VRES by means of heat pumps and hot water storage, in particular. We conclude that a renewable energy target on its own is not sufficient; in addition, a CO 2 tax is required to decarbonise the electricity and heating sectors and incentivise the least cost combination of flexible and efficient energy conversion and storage.heating sectors in Europe. The annual end use demands in both sectors are similar: electricity consumption in Europe in 2015 accounted for 2,854 TWh el (in terms of electricity), while the heating demand in the residential and services sectors represented 3,562 TWh th (in terms of thermal energy), [5]. Regarding greenhouse gas emissions, electricity and low-temperature heating accounted for 1066 Mt and 556 Mt of CO 2 emissions respectively [6]. Previous energy models applied to different regions [2,3,[7][8][9] have shown that imposing a strong CO 2 constraint leads to high Variable Renewable Energy Sources (VRES) penetrations combined with a high-efficiency sector-coupled energy system, referred to as 'Smart Energy System' by Lund and coauthors [4,8]. For instance, under a 95% CO 2 reduction constraint relative to 1990 in Europe [10], energy modelling approaches based on scenario comparison [8] or cost optimisation [2]

Abstract For a given carbon budget over several decades, different transformation rates for the energy system yield starkly different results. We consider a budget of 33 GtCO2 for the cumulative carbon dioxide emissions from the European electricity, heating, and transport sectors between 2020 and 2050, which represents Europe's contribution to the Paris Agreement. We have found that following an early and steady path in which emissions are strongly reduced in the first decade is more cost-effective than following a late and rapid path in which low initial reduction targets quickly deplete the carbon budget and require a sharp reduction later. Costs of solar photovoltaic, onshore and offshore wind have plummeted during the last decade. We found that those technologies can become the cornerstone of a fully decarbonised energy system and that installation rates similar to historical maxima are required to achieve timely decarbonization. Key to those results is a proper representation of existing balancing strategies through an open, hourly-resolved, networked model of the sector-coupled European energy system.

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Due to its spatio-temporal variability, the mismatch between the weather and demand patterns challenges the design of highly renewable energy systems. A principal component analysis is applied to a simplified networked European electricity system with a high share of wind and solar power generation. It reveals a small number of important mismatch patterns, which explain most of the system's required backup and transmission infrastructure. Whereas the first principal component is already able to reproduce most of the temporal mismatch variability for a solar dominated system, a few more principal components are needed for a wind dominated system. Due to its monopole structure the first principal component causes most of the system's backup infrastructure. The next few principal components have a dipole structure and dominate the transmission infrastructure of the renewable electricity network.