Search

This paper presents the Positive Energy District Database (PED DB), a pivotal web tool developed collaboratively by the COST Action 'PED-EU-NET', in alignment with international initiatives such as JPI Urban Europe and IEA EBC Annex 83. The PED DB represents a crucial step towards sharing knowledge, promoting collaboration, reinforcing decision-making, and advancing the understanding of Positive Energy Districts (PEDs) in the pursuit of sustainable urban environments. The PED DB aims to comprehensively map and disseminate information on PEDs across Europe, serving as a dynamic resource for sustainable urban development according to the objective of making the EU climate-neutral by 2050. Indeed, PEDs imply an integrated approach for designing urban areas—the districts—where a cluster of interconnected buildings and energy communities produce net zero greenhouse gas emissions, managing an annual local/regional overflow production of renewable energy. The paper describes the collaborative step-by-step process leading to the PED DB implementation, the current results and potentials of the online platform, and introduces its future developments towards a more user-friendly and stakeholders-tailored tool. The interactive web map offers a customizable visualizations and filters on multiple information related to PED case studies, PED-relevant cases, and PED Labs. Users can access detailed information through a table view, facilitating comparisons across different PED projects and their implementation phase. The paper offers insights and detailed analysis from the initial dataset that includes 23 PED cases and 7 PED-related projects from 13 European countries, highlighting the key characteristics of surveyed PEDs. [ABSTRACT FROM AUTHOR]

This paper describes a new underwater pumped storage hydropower concept (U.PSH) that can store electric energy by using the high water pressure on the seabed or in deep lakes to accomplish the energy transition from fossil to renewable sources. Conventional PSH basically consists of two storage reservoirs (upper and lower lake) at different topographical heights. It needs special topographic conditions, which are only limitedly available in mountain regions. Furthermore, due to the lack of acceptance and the environmental impact, new conventional PSH projects are very unlikely to be built in larger numbers in Europe in the near future. The presented solution solves these issues by placing the storage system on the seabed, thus having other geographical requirements. It operates as follows: in contrast to well-known conventional PSH plants, which use two separated water reservoirs of different heights, the U.PSH concept uses the static pressure of the water column in deep waters by installing a hollow concrete sphere in deep water. Storage of electricity is achieved by using a reversible pump in the hollow sphere. Upon opening a valve, water flows into the sphere, driving a turbine/generator, thereby discharging the storage device. In order to re-charge, the water is pumped out of the sphere against the pressure of the surrounding water. The power and energy, respectively, are proportional to the surrounding water pressure at the seabed. The amount of energy stored depends on the water depth and the volume of the spheres. The spheres need a cable connection to the shore or to a close-by floating transformer station (e.g., an offshore wind plant). No other connections such as pipes are needed. The functional principle of this energy storage technology, its state of the art, its storage capacity and the shape and size of the required spheres are discussed in this paper. [ABSTRACT FROM AUTHOR]

An underappreciated source of renewable energy is wastewater, both municipal and industrial, with global production exceeding 900 km3 a year. Wastewater is currently perceived as a waste that needs to be treated via energy-consuming processes. However, in the current environmental nexus, traditional wastewater treatment uses 1700–5100 TWh of energy on a global scale. The application of modern and innovative treatment techniques, such as microbial fuel cells (MFC), would allow the conversion of wastewater's chemical energy into electricity without external energy input. It has been demonstrated that the chemically bound energy in globally produced wastewater exceeds 2.5 × 104 TWh, which is sufficient to meet Europe's annual energy demand. The aim of this paper is to answer the following questions. How much energy is bound in municipal and industrial wastewaters? How much of that energy can be extracted? What benefits will result from alternative techniques of waste treatment? The main finding of this report is that currently achieved energy recovery efficiencies with the use of microbial fuel cells technology can save about 20% of the chemical energy bound in wastewater, which is 5000 TWh on a global scale. The recovery of energy from wastewater via MFC technology can reach as much as 15% of global energy demands. [ABSTRACT FROM AUTHOR]

As a solution to mitigate the effects of climate change, scientists have been looking for more environmentally friendly energy production alternatives, so, since the 2000s, renewable energy production has increased across Europe. Climate change has a negative impact on our planet, with increased emissions of greenhouse gases contributing to global warming. In this context, biogas has become a promising solution for reducing greenhouse gas emissions and improving environmental quality. The purpose of the study is to review the evolution of research and development in this field, identify trends and gaps in existing knowledge, and assess the impact and significance of published research. In this sense, a bibliometric analysis was carried out, based on the topics "renewable energy" and "biogas", in which VosViewer software was used to create maps. The research results show that existing policies worldwide encourage transfer and synergy between researchers from different countries, achieving important results. Practically, researches and examples of good practise show that biogas can be a viable solution to mitigate the effects of climate change, and in the coming decades, under the conditions of the population growth estimates materialization, we will most likely witness an intensification of agriculture to ensure the population's food needs. [ABSTRACT FROM AUTHOR]

In the last decade, there have been several initiatives for the deployment of cross-Mediterranean HVDC (High Voltage Direct Current) links to enable the transmission of electrical power from renewable energy sources between North Africa and Europe. These initiatives were mainly driven by the potential economic, environmental and technical benefits of these HVDC interconnections. In previous studies on these projects, some technical aspects of critical importance have not been addressed or studied in sufficient detail. One of these key aspects relates to the impact and possible benefit of these HVDC links on the dynamic performance of the European system which is the major focus of this paper. Several issues relating to the dynamic performance of the system are addressed here. Based on the experience gained from existing AC/DC projects around the world, this paper shows that the HVDC links between North Africa and Europe can greatly improve the dynamic performance of the European system especially in the southern regions. In addition, some challenges on the operation and control of these HVDC links are highlighted and solutions to overcome these challenges are proposed. This review paper, therefore, serves as a preliminary study for further detailed investigation of specific impacts or benefits of these interconnections on the overall performance of the European system. [ABSTRACT FROM AUTHOR]

Offshore wind energy is recognized as an important source of renewable energy and has experienced rapid growth in recent years especially in north-western European countries. In this paper, the efficiency of 71 offshore wind farms across five north-western European countries is assessed using the Data Envelopment Analysis (DEA) Method. The number of turbines, cost, distance to shore, and area of the wind farms are selected as the inputs and the connectivity to population centres, the produced electricity and the water depth are considered as the outputs. The results show that the average CCR efficiency score of all offshore wind farms considered in this study is 87%, and the relative median efficiency of offshore wind farms in different countries is not statistically different. This study offers a practical and holistic performance assessment to the offshore wind stakeholders and policy makers via including economic, environmental, technical and social inputs and outputs in the analysis. • A benchmark study of the current status of European offshore wind farms. • The average efficiency score of 71 offshore wind farms across Europe is 87%. • Median efficiency scores across countries is not statistically different. [ABSTRACT FROM AUTHOR]

This paper presents a set of policy recommendations for the market design of a future European electricity system characterized by a dominant share of renewable energy supply (RES), in line with the stated targets of European governments. We discuss the market failures that need to be addressed to accommodate RES in liberalized electricity markets, review the evolution of the EU's RES policy mechanisms, and summarize the key market impacts of variable RES to date. We then set out economic principles for wholesale market design and use these to develop our policy recommendations. Our analysis covers the value of interconnection and market integration, electricity storage, the design of RES support mechanisms, distributed generation and network tariffs, the pricing of electricity and flexibility as well as long-term contracting and risk management. [ABSTRACT FROM AUTHOR]

By 2020 Europe has to increase its energy efficiency and share of renewables in 20%. However, even accomplishing these challenging objectives Europe will be effectively wasting energy as we demonstrate in this paper. In our way towards a fully renewable scenario, we need at least to stop wasting energy in order to guarantee the energy supply needed for growth and comfort. We waste energy when we employ more primary energy than the final energy we ultimately use and this excess cannot be reutilized. In this paper we propose the WE (wasted energy) as a novel metric to measure the performance of energy systems and set up appropriate targets. The WE incorporates information about energy efficiency and renewable sources. Unlike European legislation, the WE considers them in an integrated way. This approach will help Member States to exploit their intrinsic capabilities and design their optimum strategy to reach their objectives. Using the information in Eurostat, we calculate the WE of Member States in EU-28 and their evolution. We also analyze illustrative examples to highlight strategies to reduce the WE, study the connection between economic development and WE, and provide a tool to diagnose the potential of improvement of an energy system. [ABSTRACT FROM AUTHOR]

The increasing share of intermittent Renewable Energy Sources (iRES) in the energy mix leads to a growing need for their accurate representation in energy system models. In this paper, we analyze how the results of generation planning models are impacted by the spatial representation used to model intermittent renewable technologies. It is shown that the spatial resolution, and to a lesser extent the spatial aggregation method used in a planning model, have a significant influence on the obtained system cost. The effect is quantified in a case study of European geographical scale, by varying the spatial resolution from highly resolved (hundreds of sites) to highly aggregated (1 site). A resolution-dependency of the system cost is observed under multiple renewable generation targets, and different renewable capacity restrictions. In doing so, we highlight the importance of implementing an appropriate capacity limit, especially when a high spatial resolution is used. Additionally, basic spatial aggregation methods -to process high resolution input data- are compared. • Isolation of renewable representation effects in a stylized GEP model. • iRES resolution has a strong impact on GEP model results for Europe. • Capacity limits play an important role in this effect, especially in high resolution. • Spatial aggregation method only impacts models with low resolutions. [ABSTRACT FROM AUTHOR]

Given the abundant availability of resources, the market potential, and their cost competitiveness, onshore wind farms and photovoltaic units are expected to drive the overall growth of renewable energy sources in the next decade. However, Europe is a small and densely populated continent, which results in many countries experiencing a severe shortage of suitable land sites for installing new wind and photovoltaic facilities. This, combined with the fact that many existing wind turbines and photovoltaic units reach the end of their operational lifetime, has laid the groundwork for 'repowering'. Repowering includes upgrading or retrofitting renewable energy sources' components and exploits existing land sites, in which renewables are operating for years. This paper intends to emphasise the multiple dimensions of repowering, also delving in its surrounding socio-economic context in various European countries, to identify its barriers and allies as well as gather best practices and lessons learnt from its implementation. Considering data availability, extent of spatial use and bulk equipment, and consequent attention in literature and practice, the analysis mainly orbits around repowering of wind projects, rather than solar photovoltaics. Finally, the paper presents key directions toward wider future exploitation of repowering. • Land scarcity problem with high renewable energy potential addressed by repowering. • In-depth socio-economic extensions of repowering are discussed. • Semi-quantified evaluation highlighting main implementation pillars of repowering. • Best practices and lessons learnt from the implementation of repowering. • Legislative barriers against the wider implementation of repowering. [ABSTRACT FROM AUTHOR]

Renewable energy in Middle East and North Africa (MENA) region, particular solar energy, can be connected to Europe to provide the Northern neighbouring countries with electricity. To achieve this long term objective, it is necessary to understand the local domestic consumption of electricity in the MENA region as the main consumer of energy. The understanding of current and future trends could help to provide a complete picture of the energy situation in MENA region and the feasibility of exporting energy to Europe. For this reason, this paper investigates the domestic energy use and occupants’ energy behaviour in Libya. The aim of this study is to evaluate the effect of domestic energy consumption and householders’ awareness, attitudes and behaviour on the overall energy consumption in Libya and how this could affect the peak demand, capacity, future trends and government energy budget. The paper also investigates the sustainability aspect of consumer products and the awareness and attitude of consumers towards consumption and demand. A comprehensive survey has been conducted to evaluate several aspects of domestic energy demand and characteristics in Libya. The findings have indicated that there is a significant increase in energy demands in the household sector in Libya and it is significant to have a clear strategy to reduce carbon emission and energy use by improving occupants’ behaviour as well as utilising other sustainable measures. Minor adjustment in householders’ energy consumption behaviour and the technology used to generate energy could provide significant financial savings and contribute significantly to the reduction in carbon emission and energy consumption. This will allow significant benefit to the local economy and the energy sector in Libya but at the same time could provide sustainable energy resources for Europe on the long term. [ABSTRACT FROM AUTHOR]

This paper examines the optimal capacity choices of conventional power generators after the introduction of renewable production. We start with a basic and generally accepted model of the liberalized wholesale electricity market in which firms have insufficient incentives to invest and we illustrate how the entry of renewable generation tends to aggravate that problem. We show that the incentives to invest in firm capacity (e.g. conventional thermal plants) may be restored by means of a capacity auction mechanism. That mechanism is vulnerable and, hence, may prove ineffective unless governments can credibly commit not to sponsor the entry of new capacity outside the auction mechanism. We explain that such commitment may be particularly difficult in the current political context where energy policy is conditioned by environmental and industrial-policy goals. We finally propose a way to enhance the credibility of capacity auctions by committing to optimally retire idle (conventional) power plants in response to entry outside the auction. [ABSTRACT FROM AUTHOR]

Renewable energy has a crucial role in facing climate change. One promising strategy is the creation of energy communities that require active involvement from a bottom-up perspective. Their implementation is difficult, as they currently rely on local policies, community readiness, and technological availability. The objective of this paper is to provide a qualitative overview of energy community concepts and strategies at the European level. The aim is to identify common approaches that are framing the development of energy communities, and to understand the most successful steps leading to their creation and growth. To achieve this objective, a threefold methodology is provided: (1) an updated review on policies dealing with energy communities at the European and Italian level; (2) a qualitative overview of European-funded projects under the Horizon 2020 work program; and (3) a qualitative overview of some of the most successful existing energy communities in Europe. The results outline a series of considerations and lessons learned that are useful for implementing this transition pathway in a real case, which is also presented in the paper. The conclusions will identify some future directions of this research, particularly in relation to the results coming from the implementation of actions in the real case. [ABSTRACT FROM AUTHOR]

Incentivizing development and deployment of renewable energy sources (RES), but also other low carbon technologies (LCT), has been a successful way of promoting new technologies by creating a feasible investment case and making them competitive with traditional energy sources. Although different incentive mechanisms exist, feed-in tariffs have shown to be the best model for accelerating LCT development guaranteeing producers preferential prices for the produced electricity over a period of time and enabling them access to the power network to sell/inject produced electricity. Due to these benefits, feed-in tariff models are the most common model for stimulating RES integration in southeast Europe. The paper reviews the current state of preferential tariffs for RES in countries of southeast Europe. While some countries already have significant installed RES capacity, others are still in the planning stage. The review shows that the amount of installed capacity of a specific technology has a strong impact on the support for the future projects for same technology. This comprehensive review of legislative development supporting RES, as well as technologies preferred in different countries of the region, is supported with feasibility assessment of investing in RES using the example of two different technology projects, wind and photovoltaic, analysing the impact of the current tariffs on the return on investment for each country of the region. [ABSTRACT FROM AUTHOR]

Renewable energy sources are vital to achieving Europe's 2030 energy transition goals. Technological innovation, driven by public expenditures on research and development, is a major driver for this change. Thus, an extensive dataset on these expenditures of the European Member States and the European Commission, dating back to the early 1970s, was created. This paper creates predictive scenarios of public investment in renewable energy research and development in Europe based on this historical dataset and current trends. Funding from both, European Member States and the European Commission, between today and 2030 are used in the analysis. The impact on the cumulative knowledge stock is also estimated. Two projection scenarios are presented: (1) business as usual; and (2) an advanced scenario, based on the assumption that the Mission Innovation initiative causes public expenditures to increase in the coming years. Both scenarios are compared to the European 2030 climate and energy framework target sets. Results indicate that Member States in Europe currently tend to fund renewables more than the European Commission, but funding from both sources is expected to increase in the future. Furthermore, the European Commission distributes its funding more equally across the various renewable energy sources than Member States. [ABSTRACT FROM AUTHOR]

Increasing the share of renewable energy is deemed essential to reduce the carbon intensity of the current electricity mix. The promotion of renewable energy technologies should thus be as effective and efficient as possible. Therefore, support schemes should explicitly consider the balance between demand-pull (e.g. production subsidies) and supply-push efforts (public RD&D investments). In this paper we estimate the deployment costs for renewable generation technologies between 2005 and 2030 in the EU-27. Then, we relate our findings to public RD&D expenditures (2005–2010) on these technologies. Based on several “lags” between RD&D spending and market impact, we obtained cumulative pull/push ratios between 100 and 190 for wind technologies and between 80 and 210 for PV. For solid biomass, pull/push ratios are lower, in a range of 60–120. The imbalance for biogas is much larger; the cumulative pull/push ratio for biogas is about 700 in the ‘5 year lag’ case and about 1200 in the other cases (10 yr. lag or more). Although the debate on optimal RD&D efforts is not conclusive and very sector-specific, it is relevant to compare our findings to average pull/push ratios of about 20 in the engineering sector. Overall, we can safely conclude that European governments should critically evaluate current renewables subsidy schemes, and increase public RD&D investments to support next waves of renewable energy technologies. [ABSTRACT FROM AUTHOR]

Environmental change created worldwide interest in investing in renewable energy. Less reliance on fossil fuels would have a substantial influence on investors for alternative energy, especially renewable energy. The literature has concentrated on empirical studies of herding behaviour in finance, but not in renewable energy. This paper fills the gap by investigating herding in renewable energy, using daily closing prices in renewable and fossil fuel energy stock returns in the USA, Europe, and Asia, for March 24, 2000–May 29, 2020, which covers the Global Financial Crisis (GFC) (2007–2009), the coronavirus crises of SARS (2003). And the ongoing COVID-19 (2019–2020) pandemic. The paper shows that: (1) for low extreme oil returns, investors are more likely to display herding in the stock market; (2) for SARS and COVID-19, herding is more likely during extremely high oil returns after the GFC; and (3) herding is more likely during periods of extremely low oil returns during the coronavirus crises. These results suggest that after the GFC, investors are more sensitive to asset losses, so they will be more likely to display herding in the stock market. However, during SARS and COVID-19, investors panic so they may unwisely sell their assets. There are strong cross-sector herding spillover effects from US fossil fuel energy to renewable energy, especially before the GFC, while the US fossil fuel energy market has a significant influence on the Europe and Asia renewable energy returns during COVID-19. During SARS, which was not a pandemic, US fossil fuels only had an impact on US renewable energy returns. • Environmental change has led to investing in renewable energy as an alternative to fossil fuels. • The literature has concentrated on herding behaviour in finance, but not in renewable energy, so this paper investigates herding in renewable energy for the USA, Europe, and Asia, for the period March 24, 2000–May 29, 2020 that covers the GFC, SARS, and COVID-19. • For (1) low extreme oil returns, herding is more likely in the stock market; (2) SARS and COVID-19, herding is more likely during extremely high oil returns after the GFC; and (3) extremely low oil returns during SARS and COVID-19, herding is more likely. • After the GFC, investors are more likely to display herding in the stock market but, during SARS and COVID-19, investors may unwisely sell their assets. • There are strong cross-sector herding spillover effects from US fossil fuel energy to renewable energy, especially before the GFC. [ABSTRACT FROM AUTHOR]

• Analysis conducted with data on 14 European countries for the period 1990–2014. • Prevailing cross-sectional dependence and heterogeneity issues are addressed with our method. • The inverted U-shaped nexus (EKC hypothesis) is not valid in Europe when we employ CO 2 emissions. • The EKC hypothesis depends on the environmental indicators used. • Fossil fuels extert more distortion on environmental sustainability. The nexus between environment-economic development has been investigated for a long time. Many empirical studies have measured environmental degradation by CO 2 emissions and ignored the possibility that the use of such metric as environmental degradation indicator may be invalid in some cases when it comes to resource stocks. This paper focuses on two indicators of environmental degradation including ecological footprint (EF) and CO 2 emissions as target variables to provide new insights into the ongoing discussions of whether the environmental Kuznets Curve (EKC) hypothesis is related to the indicators of environmental pressure used. Estimating a heterogeneous panel model with data on 14 European countries over the period 1990–2014, we provide evidence for the sensitivity of the EKC hypothesis to the type of environmental degradation proxy used. Furthermore, we provide new insights regarding the relevance of EF as an appropriate environmental tool that fits the EKC prediction in contrast to CO 2 emissions. Regarding the explanatory variables, the results show that renewable energy is an environmentally friendly source while fossil fuels contribute to environmental degradation. The inclusion of renewable energy and fossil fuel does not alter the behavior of economic growth in all environmental degradation indicators. The empirical results demonstrate the need to implement environmental management policies that encourage the production/supply of renewable energy and to reduce reliance on fossil fuel consumption. This paper is expected to provide policy makers with a set of policy proposals to achieve sustainable environmental and economic development. [ABSTRACT FROM AUTHOR]

[Display omitted] • Detailed assessment of Organic Rankine Cycles is presented. • Mixture working fluids achieves higher thermodynamic efficiency. • Biomass and solar energy are still rarely adopted as ORC's heat resources. • USA and Europe have major share in ORC systems. • Studies for reducing the levelized cost of electricity is needed to be carried out. This paper presents state-of-the-art review on organic Rankine cycle (ORC) by assessing the working fluids, thermal resources, cooling utilities, and commercial status with future aspects. It is found that the mixture working fluids achieve higher thermodynamic efficiency. However, the difficulty in obtaining the optimum composition and components limits their applications. The thermal resources with different temperature ranges and cooling utilities are then assessed to investigate their effects on the thermodynamic performance of ORC. The low-temperature ORC utilizing waste heat and geothermal heat is dominant, while biomass and solar energy are still rarely adopted as ORC's heat resources. From the commercial perspective, the USA and Europe are the leaders in conversion of low-grade waste heat into useful power using ORC. Furthermore, the main challenges of ORC are: (a) selection of appropriate working fluid with suitable expander, and (b) reducing the specific cost of the small-scale ORC system to compete with the renewable energy. Finally, several future research directions are identified such as: (1) overall performance of the ORC system including its thermodynamic efficiency, stability and safety needs to be investigated with experimental studies; (2) a general methodology should be developed for the selection of working fluids; (3) studies for reducing the net present cost and levelized cost of electricity with techno-economic optimization are needed to be carried out. This study benchmarks the recent progress on ORC technology and presents an insight into the scientific problems that need to be explored to nexus low-grade heat to power in the future. [ABSTRACT FROM AUTHOR]

Earth-to-air heat exchangers (EAHEs) can be used in the ventilation systems of various types of buildings. Multipipe structures can be found in large-volume buildings, yet scientific analysis of such systems is rare. Annual energy gains and electricity consumption for equivalent single-pipe and multipipe systems are typically not available. This paper bridges this gap, presenting the results of experimental studies on pressure losses in three-, five- and seven-pipe EAHEs and analysis for the annual energy gains and electric energy consumption as compared to a single-pipe exchanger. The results showed that the multipipe EAHE can be successfully replaced by a single-pipe structure with the same thermal performance and similar pressure losses if a tube with the appropriate diameter is used. However, multipipe heat exchangers can also use pipes of larger diameter (manifolds and/or branches), which improves their energy efficiency and may then make them more advantageous than single-pipe structures. From this reason, ultimately, the final selection of exchanger geometry should take into account economic and environmental issues and also user preferences and their importance in the hierarchy. [ABSTRACT FROM AUTHOR]

Providing more affordable and cleaner energy for all raises complex and significant financial, political, technical, and institutional issues, which must all be addressed to ensure sustainable development. Energy technology innovation has a critical role to play as one of the best pathways to achieve the transition to a global clean energy system. This paper is an endeavor to study the impact of government energy technology research, development, and demonstration (RD&D) budget, which is the primary input of energy technology innovations on cleaner energy supply and carbon footprints (CFP). In this study, a cleaner energy supply is measured as the contribution of renewable energy to total primary energy supply (RE). We assumed that the effect of energy innovation is not uniform but varies according to the descending and ascending movements in a government's energy technology RD&D budget. To this end, we distinguished the impact of the descending and ascending movements in government energy technology RD&D budgets on cleaner energy supply, and CFP in Europe over the period 1985 to 2016. Additionally, we carried out a comparative examination of the effects of energy technology RD&D expenditures on RE and CFP under both linear and nonlinear panel techniques. To increase room for policy implications, we also controlled for the role of economic growth and trade openness and performed several robustness check analyses. We found that the reduction of carbon footprints associated with an increase in public support to energy technology RD&D is more pronounced than the contribution of energy technology innovation to the deployment of renewable energy in Europe. This study provided little evidence in favor of the effectiveness of a government energy technology RD&D budget to substantially boost renewable energy in Europe. Following these results, we suggest that the knowledge of the asymmetric linkage between public energy technology innovation, RE, and CFP is a starting point to achieve win-win solutions that favor clean energy and environmental sustainability. • Optimizing the nonlinear effects of energy technology RD&D budgets over different time horizons. • Asymmetries in the responses of RE and CFP to shocks in energy technology innovation budgets. • The influences of energy technology innovation vary over different time horizons. • The public budget devoted to energy innovation is fundamental for curbing CFP rather than boosting RE. [ABSTRACT FROM AUTHOR]

The growing rate of electricity generation from renewables is leading to new operational and management issues on the power grid because the electricity generated exceeds local requirements and the transportation or storage capacities are inadequate. An interesting option that is under investigation by several years is the opportunity to use the renewable electricity surplus to power electrolyzers that split water into its component parts, with the hydrogen being directly injected into natural gas pipelines for both storage and transportation. This innovative approach merges together the concepts of (i) renewable power-to-hydrogen (P2H) and of (ii) hydrogen blending into natural gas networks. The combination of renewable P2H and hydrogen blending into natural gas networks has a huge potential in terms of environmental and social benefits, but it is still facing several barriers that are technological, economic, legislative. In the framework of the new hydrogen strategy for a climate-neutral Europe, Member States should design a roadmap moving towards a hydrogen ecosystem by 2050. The blending of "green hydrogen", that is hydrogen produced by renewable sources, in the natural gas network at a limited percentage is a key element to enable hydrogen production in a preliminary and transitional phase. Therefore, it is urgent to evaluate at the same time (i) the potential of green hydrogen blending at low percentage (up to 10%) and (ii) the maximum P2H capacity compatible with low percentage blending. The paper aims to preliminary assess the green hydrogen blending potential into the Italian natural gas network as a tool for policy makers, grid and networks managers and energy planners. [ABSTRACT FROM AUTHOR]

As the share of variable renewable energies in the power system increases, so does the need for flexibility options. These include, inter alia, energy storage, network optimization and expansion, and demand side management. In this paper, a broad sensitivity analysis is carried out to assess the potential role of innovative electrical energy storage technologies in comparison to well-established ones. The innovative technologies considered include compressed heat energy storage, adiabatic compressed air energy storage, power-to-heat-to-power storage, and reversible solid oxide fuel cells storage. To this aim, the cost-optimizing energy system model REMix has been applied to analyze the impact of main techno-economic parameters of electrical energy storages on their role in the future European power supply system. Two main studies have been calculated. The first one deals with a cost sensitivity analysis on a generic storage technology. Among the main findings is that – beside cost – the ratio between photovoltaics and wind power potentials in a particular region have a relevant impact on the capacity as well as on the energy to power ratio of the installed storages. In addition, a strong competition has been observed between energy storages and gas turbines. The second scenario evaluates the competition between well-established and innovative energy storage technologies. The results show that while some of the regions – namely southern Europe, alpine regions and Scandinavia – mainly rely on pumped hydro storage, in most of Central European regions and United Kingdom the cost optimal solution consists of a mix of pumped hydro storage (totaling 64.2 TWh/y of discharged energy in Europe), hydrogen underground storage (45.1 TWh/y) and batteries (27.1 TWh/y), with an additional small share of power-to-heat-to-power storages (0.1 TWh/y). In line with earlier studies, hydrogen storage is found mostly in regions with high wind power supply, while the distribution of batteries is more spread overall in Europe. The model results underline the high sensitivity of the economic efficiency of storage facilities to the investment costs and their components. [ABSTRACT FROM AUTHOR]

• AHP applied to sustainable supply chain development in the renewable energy sector. • The AHP model takes into account both logical and quantitative information. • The proposed approach provides decision makers with main factors and sub-criteria. • Main European countries producers of PV energy are compared. • Results agree with the PV development in the period 2000-2017 in these countries. The aim of this paper is to provide a multi-criteria decision making framework based on the Triple Bottom Line principles and Analytic Hierarchy Process methodology for sustainable supply chain development in the renewable energy sector. The proposed framework encompasses the whole energy production supply chain, from raw materials' suppliers to disposal. In particular, the photovoltaic energy sector has been used as case study and represents the focus of this work. The framework is based on the three Triple Bottom Line dimensions such as social, economic and environmental. Furthermore, literature review and expert opinions are used to identify and assess the sub-criteria for each dimension, followed by pair-wise comparison. Finally, the proposed framework is used to evaluate the seven European countries that conjointly represent the 86.8% of the total photovoltaic installed capacity in Europe, using both logical and quantitative information. Results are in agreement with the photovoltaic development in the period 2000-2017 in these countries. The proposed framework provides the decision makers with a powerful tool for making sustainable investment decisions in the photovoltaic energy sector. [ABSTRACT FROM AUTHOR]

This paper represents an expert view from Europe of future emerging technologies within the wind energy sector considering their potential, challenges, applications and technology readiness and how they might evolve in the coming years. These technologies were identified as originating primarily from the academic sector, some start-up companies and a few larger industrial entities. The following areas were considered: airborne wind energy, offshore floating concepts, smart rotors, wind-induced energy harvesting devices, blade tip-mounted rotors, unconventional power transmission systems, multi-rotor turbines, alternative support structures, modular high voltage direct current generators, innovative blade manufacturing techniques, diffuser-augmented turbines and small turbine technologies. The future role of advanced multiscale modelling and data availability is also considered. This expert review has highlighted that more research will be required to realise many of these emerging technologies. However, there is a need to identify synergies between fundamental and industrial research by correctly targeting public and private funding in these emerging technology areas as industrial development may outpace more fundamental research faster than anticipated. • A set of emerging technologies in the wind power sector was identified and studied. • For each technology, an analysis of the main advantages and challenges was made. • Potential for scaling each technology was identified. • Technology Readiness Levels and their development trends were assessed. [ABSTRACT FROM AUTHOR]