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PHPS is a mature energy storage technology, leading to more efficient energy management and further integration of Renewable Energy Sources (RES). This paper investigates the implementation of such a system at Kastraki, Greece, combined with a second upstream reservoir with a total capacity of 10 hm3 and evaluates its efficiency. The position and the geometric characteristics of the second reservoir are determined with ArcGIS. When excess of energy exists, water is pumped from Kastraki reservoir and stored in the upper one. Otherwise, the stored water is used for energy production. The simulation is performed for 40 years with a monthly time step. Furthermore, another simulation for a typical day in July is conducted, when water and energy needs are increased. The system is evaluated in terms of covering the water supply and energy needs, as well as in terms of efficient energy management. Several results can be obtained, as follows: i) the reliability of the PHPS system for the coverage of monthly water supply and irrigation needs is 82.84 %. ii) The coverage of water supply needs for a typical day in July is 99.99 %. iii) The average monthly coverage of energy needs amounts to 83.86 %. [ABSTRACT FROM AUTHOR]

The China Certified Emission Reduction scheme (CCER) and the Cap-and-Trade (CaT) mechanisms jointly constitute the Emission Trading Scheme (ETS), which is expected to have a profound impact on China's social and economic decarbonization. However, previous studies have primarily focused on the impact of the CaT mechanism, neglecting the fact that CCERs serve as a carbon offset trading mechanism. This paper focuses on the impact of the CCER mechanism on China's energy economy and environment by constructing a recursive dynamic computable general equilibrium model that couples CaT and CCER mechanisms. Introducing the CCER mechanism based on the CAT mechanism leads to increased output and reduced prices in renewable energy sectors, cascading positive effects across various energy-utilizing sectors to counter the decline in Gross Domestic Product (GDP) and residential welfare. The finding suggests that China's unique CCER mechanism is poised to play a more important role in promoting renewable energy to mitigate global warming, given its potential to transform the structure of energy production and consumption. Finally, targeted policy recommendations are proposed for implementing the CCER mechanism. [ABSTRACT FROM AUTHOR]

Offshore wind turbines (WTs) are crucial in offshore wind energy development. However, the dynamic responses of WTs are subject to significant uncertainties which are usually not properly considered. To the end, this paper proposes an efficient method for quantifying the uncertainties in WTs' dynamic responses based on cumulative distribution function (CDF)-manifold learning. First, a probabilistic model is developed to represent the environmental parameters and sampling for aerodynamic-hydraulic-servo-elastic simulations. Then, the CDF is obtained by statistically analyzing the simulated data. To tackle the higher dimensionality resulting from discretizing the CDF, a manifold learning-based approach is subsequently proposed to reduce its dimensionality and obtain a manifold space. Furthermore, a mapping relation is established between the environmental parameters and the low-dimensional data to efficiently obtain the response CDF under different environmental parameters, leading to the construction of a probability box (P-box) model. To demonstrate the effectiveness of the proposed method, the National Renewable Energy Laboratory (NREL) 5 MW offshore WT on an Offshore Code Comparison Collaboration (OC3) monopile is selected as a case study and analyzed accordingly. The results show P-box models of seven WT responses and validate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Ocean renewable energy (ORE) is one of the most important clean sources of energy and a major player towards the EU ambitions of being net zero emission by 2050. However, at present, there are few examples of commercially viable ORE technologies and no large-scale projects currently under implementation. Together with social and environmental analyses, the assessment of economic impacts is one of the key elements to help policy makers build a compelling case to gain local community acceptance and implement ORE projects. This paper presents a systematic methodology to assess local economic impacts of renewable energy projects, including jobs creation and impacts on gross value added and income. By combining the use of Location Quotients – which are indexes informing on local industrial specialisation – with the Input-Output multipliers the method can be used to map the supply-chain potential of a local economy and estimate local impacts compared to global ones. The method has been applied to a tidal project carried out in Orkney, Scotland. The research demonstrates the merit of early economic assessments for understanding the economic benefit of ORE projects, particularly for the local communities in which they are located, and it provides a methodological framework to be tested in other case studies. [Display omitted] [ABSTRACT FROM AUTHOR]

Green financing is essential because it guarantees that initiatives that seek to reduce the world's reliance on fossil fuels receive the necessary funding to be successful. Green financial metrics can be simultaneously made possible by specialized technological innovation and natural resource rent, thereby encouraging the adoption of sustainable energy. In this paper, we investigate the mediating mechanisms underlying the relationship between green financial indicators and renewable energy consumption RNEC and we contribute to the ongoing discussion surrounding this relationship. Our observational example is derived from data collected for 66 countries between 2004 and 2019 using a panel threshold regression model defined with the difference generalized method of moments (GMM). We find that green funding initiatives have accelerated the adoption of renewable energy sources by encouraging increases in the proportion of renewable energy in the fuel supply. Multiple analyses of reliability corroborate the existence of this link. Green funding has been shown to have an encouraging effect on the transition to renewable energy, and our findings indicate that technological advancement and natural resource leasing serve to mitigate this effect. To assist policymakers in reducing the world's reliance on polluting energy, our study demonstrates how green financial markets can be established through improved technological innovation and natural resource management. [ABSTRACT FROM AUTHOR]

The increasing generation of renewable energy and its concurrent technological innovation are driving the transformations of the energy sector, but little effort has been made at the regional level to specify the heterogeneous impacts of different types of renewable energy development on multi-dimensional energy security. Therefore, this paper establishes a four-dimensional energy security assessment system based on the current energy market situation and economic context of China. Renewable energy generation and technological innovation were simultaneously used as the core proxies for renewable energy development. Then, the panel quantile regression method was used to analyze the heterogeneity of the impact of solar, hydro, and wind energy on energy security, covering 30 provinces in China from 2006 to 2019. The empirical results show that renewable energy power generation generally promotes energy security, but it cannot be effectively applicable to all levels of energy security. Renewable energy technology innovation has surprisingly hindered energy security. These results can serve as a policy and practical guide, suggesting that provincial governments in China should implement energy security and renewable energy policies in line with local characteristics. • The redefined provincial energy security presents obvious spatial heterogeneity. • Panel quantile regression was applied to balanced provincial panel data. • Hydropower contributes only to medium and low levels of energy security. • Wind and solar power contribute differently to all levels of energy security. • Renewable energy technological innovation impedes energy security. [ABSTRACT FROM AUTHOR]

Open Cycle - Ocean Thermal Energy Conversion (OC-OTEC) is one of the most important renewable energy sources that generate electricity and fresh water from seawater utilizing the temperature gradient between the warm surface seawater and the cold deep seawater. This paper aims to develop non-linear data-driven model-based adaptive Feedback Control (FBC) schemes for the OC-OTEC process to track the output power and a dynamic Feed-Forward Control (FFC) scheme to reject the effects of temperature disturbance on power caused by climate variations in OC-OTEC. The experiments are conducted on a laboratory-scale OC-OTEC experimental setup at the National Institute of Ocean Technology, Chennai. Firstly, linear data-driven models are developed using system identification techniques. Based on the developed models, gain scheduling-based adaptive control schemes are developed: Proportional Integral (PI) control and Model Predictive Control (MPC). Secondly, the closed-loop performances of the developed FBC schemes are analysed under servo and regulatory operations. Furthermore, it is observed from the sensitivity analysis results that the temperature disturbance highly influences output over the manipulated variable. Hence, a dynamic FFC scheme is implemented to reject known disturbance of 1 °C variation in temperature gradient from 18 °C to 19 °C due to Sea Surface Temperature (SST) changes in temperature gradient. The results show that the proposed MPC-based FBC-FF scheme effectively enhances the tracking and disturbance rejection performance compared to the PI-based FBC-FF control scheme with a minimum Integral Square Error (ISE) of 3.055 and Control Effort (CE) of 7.505. This experimental data-based, data-driven modelling and adaptive control research provides a new direction for automating OC-OTEC. Further, these studies will help to develop a rugged and automated upscaling OC-OTEC plant control system with proposed feasible control schemes. [ABSTRACT FROM AUTHOR]

Electrical power production by renewable energy sources is unpredictable in nature and this may cause imbalance between power generation and demand. Therefore, an accurate prediction of solar radiation is crucial for the stability and efficient management of electric grid. This study focuses on very short-term forecasts of solar radiation with a horizon in the range of 5–15 min. In this paper, a Convolutional Neural Network is proposed that uses sequences of infrared images captured by an All-Sky Imager to forecast the Global Horizontal Irradiance on different time horizon. A real case study, exploiting six months of high-resolution data, is analyzed. Additionally, an innovative technique, the Enhanced Convolutional Neural Network (ECNN), is proposed in which exogenous data, as the solar radiation measurement, is encoded in terms of colored pixels in the upper corner of the images. Considering the naïve persistence method as a baseline, a clear improvement across the key metrics has been noted with the proposed methodology. A deeper analysis of the results reveals that the proposed models are more accurate than persistence when high fluctuations of solar radiation are experienced. In that case, the ECNN achieves a forecast skill exceeding 19% for all the tested forecast horizons. [Display omitted] • Enhanced Convolutional Neural Network (ECNN) is proposed by exploiting auxiliary information (exogeneous parameters) which are encoded on images of the All-Sky Imager. • The performance of ECNN, CNN, and other baseline models are used for very short-term GHI forecast (nowcasting). • The ECNN outperforms naïve persistence models in case of partially cloudy days and highly variable weather conditions. [ABSTRACT FROM AUTHOR]

The global energy sector is experiencing a transition towards renewable energy primarily driven by issues related to climate change and energy security. In this paper, we investigate the impact of uncertainties and potential drivers connected to energy security on the volatilities and returns of renewable energy stocks. Further, we examine how uncertainty and potential drivers connected to energy security affect the volatilities and returns of renewable energy stocks. By applying the MS-GARCH (1,1) and MS-GJR-GARCH (1,1) approach we calculate the Value at Risk (VaR) and Conditional Value-at Risk (CVaR). In addition, we estimate a fixed effects model to determine the impact of the uncertainty variables on the estimated conditional volatility and returns. Our findings indicate that economic policy uncertainty (EPU) positively impacts the returns of renewable stocks, attributing to an increased engagement towards a renewable transition. However, the prices of crucial green metals were found to have a negative impact on renewable stocks suggesting that the transition to renewable energy might impose implications regarding energy security if not managed correctly. The findings of this study have important implications for policymakers, market participants, and governmental agencies in devising a roadmap to promote the transition process to renewable energy sources. [ABSTRACT FROM AUTHOR]

—As a result of the increasing demand for different energies with technological development, and with the rapid development of energy hubs (EHs), issues such as computation speed, big data and information privacy, robustness, etc. are becoming increasingly vital. Also, the problem of communication packet loss leads to an incompatibility between the generated and consumed energy. In response to the above problems, this paper proposes an Internet of things-Fog-Cloud distributed consensus-based energy management algorithm to optimally solve the energy mismatch problem in an EH environment considering communication information loss and uncertainties of some EH elements. A MATLAB/Simulink-based model of a hypothetical EH system is modified to support real-time communication. Two case studies are applied to explain the performance and effectiveness of the proposed algorithm under different packet loss scenarios. The system's sensitivity was studied depending on the number of iterations and the uncertainties of the renewable energy sources, energy prices, and load demands. Also, a comparison was made between the results obtained by the proposed method and the optimization results using the genetic algorithm and particle swarm optimization techniques. The results prove the applicability and feasibility of the proposed method for the demand management system in EHs. The results show that the proposed algorithm decreases the daily system operating cost from 372.421 to 369.941 $ and the total CO 2 emissions cost from 4848.5 to 4103.1 $. In addition, the daily energy mismatch between the generated and consumed values decreases from 579.85 to 0 kWh in the electrical system and from 435.14 to 0.073 kWh th in the heating system. Based on the previous results, the proposed algorithm of EHs contributes significantly to the development of sustainable cities. [ABSTRACT FROM AUTHOR]

For realizing environment protection and carbon emission reduction strategy, the dominant position of renewable energy in the future power system has been clarified. Planning economic and efficient flexible resource system is the basis to balance multi fluctuations caused by large amount of renewable energy integration and ensure the safe operation of the whole power system. Considering that the flexibility adjustment demands of different links of the power system are not independent, but influence and restrict each other, this paper focuses on how to collaboratively allocate multi-flexible resources and achieve corresponding balancing interaction strategy. Firstly, a flexible resource system is composed through a fuzzy TODIM improved PROMETHEE-II model. Secondly, a multi-flexible resource collaborative allocation optimization model is proposed, which considers the Stackelberg game relationship of flexibility adjustment demand and ability in different links of the power system under varied fluctuation scenarios. The scientificity and effectiveness of the proposed model are verified by a practical case, and key incentive factors and specific development suggestions for improving flexible resources application efficiency are identified simultaneously. Since the collaborative planning of flexible resource system have not been deeply discussed by scholars yet, thus, this research contributes to the literature and expand the knowledge. • Design an effective flexible resources system through TODIM improved PROMETHEE-II model under multiple application scenarios. • Construct flexible resources optimal allocation scenarios according to the power generation and consumption characteristics of the new power system. • Construct a two-layer flexible resources equilibrium allocation model based on Stackelberg game theory. • Propose a multi-stage flexible resources equilibrium allocation model solution method. • Identify key factors influencing the allocation strategy of flexible resources in the new power system. [ABSTRACT FROM AUTHOR]

In order to accelerate the transition from carbon fuels to renewable energy sources, it is essential to extend our knowledge of the resources' availability to further improve or adjust the design of extraction devices. In the present paper, a first characterization of the tidal stream resource along the coast of The Netherlands is performed using a high-resolution unstructured grid implementation of the Thetis model. Extensive validation of the sea surface elevations was done by comparing with existing networks of tide gauges in the North Sea. The simulations from this study show that the highest tidal current intensities are generated mainly at Den Helder and Oost Vlieland, reaching values > 1.5 m s − 1 and power density estimates that are most frequently close to 300 W m − 2 and that can reach values ≥ 900 W m − 2 . Given the relatively reduced depths where these "hot spots" are found, most existing stream turbines will require further development to operate. Nevertheless, the existence of higher current intensities zones, along a commonly considered "low energy" coast, opens the door to include the tidal stream resource in near future plans to diversify the energy supply in The Netherlands. [Display omitted] • First tidal stream resource assessment for The Netherlands. • Identification of high energy sites for potential extraction. • Investigation on the persistence and magnitude of Dutch "hot-spots". [ABSTRACT FROM AUTHOR]

Identifying the research topics of China's energy transition policy and predicting future research trends are crucial for policymakers to make informed decisions and advance the energy transition. This study applied the Latent Dirichlet Allocation (LDA) to extract 26 major research topics from the 13,976 abstracts of Chinese policy research papers in web of science (WOS), conceptualized the five most popular topics and used the ARIMA model to predict trends over the next 36 months. The results show that except for Economic and Environmental Impact of Renewable Energy Consumption (Topic13), which will first experience unanticipated fluctuations and then show strong growth capacity, all other topics will continue to remain positive growth trend. Research and Development (Topic3) is driven by the urgency of China's energy transformation. Economic and Environmental Impact of Renewable Energy Consumption (Topic13) is driven by the potential for the development of renewable energy. Economic Impact of Climate Change (Topic26) is driven by the climate change debate. Economic Growth, Urbanization, and Energy Consumption (Topic7) is driven by a discussion of their relationship and the mechanisms influencing them. Regional Efficiency and Productivity Analysis (Topic19) is driven by regional differences in China's energy policies. [ABSTRACT FROM AUTHOR]

In this paper, a risk-based robust energy scheduling model for microgrids is proposed to address the uncertainty of renewable energy sources (RESs). The proposed model introduces a novel adjustable convex hull based uncertainty set (ACHUS), which is a subset of the maximum uncertainty set, to quantify the uncertainty of RESs. The operational risk of an ACHUS is evaluated by a historical data-based method. This method defines the operational risk as the expected penalty cost of all historical data when the operational safety of the microgrid is guaranteed in the ACHUS. Based on the evaluation of the operational risk, a day-ahead energy scheduling model with the ACHUS for microgrids is formulated as a mixed integer nonlinear programming. By introducing auxiliary variables and constraints, the mixed integer nonlinear programming is converted into a solvable mixed integer linear programming. The effectiveness of the proposed method is validated on the IEEE 6-bus and 118-bus systems. The simulation results show that the proposed method can effectively reduce the conservativeness of uncertainty quantification and the improve the economic efficiency of the microgrid. • An adjustable convex hull based uncertainty set is used to quantify the uncertainty. • A historical data-based method is proposed to evaluate the risk of microgrids. • An energy scheduling model considering the adjustable uncertainty set is formulated. [ABSTRACT FROM AUTHOR]

Tidal current energy is regarded as a promising renewable energy with strong predictability and high energy density advantages. Tidal current power generation farm (TCPGF) planning has obtained great concerns to improve the exploitation of tidal current energy. Substantial work has been conducted to derive a TCPGF planning scheme with high economy and engineering value. However, there is no overall review of existing TCPGF planning methods so far. To give a systematic overview for the methodologies, characteristics, and challenges on this topic, this paper presents a thorough review for TCPGF planning methods. First, the macro-sitting methods of TCPGFs, which are the premise and basis of TCPGF planning, are discussed in detail. Then, the progress in tidal current turbine (TCT) layout and electrical collector system (ECS) planning are thoroughly surveyed. Finally, the challenges in TCPGF planning and the potential applications of artificial intelligence in TCPGF planning are proposed to promote the development of tidal current energy. • A multi-indicator evaluation framework for macro-sitting is established. • The progress in TCT layout and ECS planning are surveyed. • The future research prospects and challenges are discussed. [ABSTRACT FROM AUTHOR]

This paper presents a model for optimizing the life cycle economic and environmental impacts of a hybrid renewable energy and battery storage system – as energy supply technologies (EST) for off-grid farms. Micro-hydropower and photovoltaics represent the primary renewable energy (RE) sources, with batteries and a diesel generator considered as possible back-up systems. A modified Non-dominated Sorting Genetic Algorithm II (NSGA-II) was developed and applied to a case study farm in Southern Spain and provided different EST solutions to optimize a design based on economic (life cycle costing or LCC) and environmental (life cycle assessment or LCA) constraints. The results highlighted that cases with a strong dependence on batteries could achieve minimum costs and lower impacts for climate change and energy resources (non-renewable fuels). In contrast, the optimal system for minimizing the consumption of material resources (metals/minerals) resulted in higher fuel use, which was up to 25% more expensive. The optimal EST solutions used up to 37% of the total energy generated; however, the results were sensitive to energy production-demand distributions. This methodology can help identify the most cost-effective solutions with the lower environmental impacts for decarbonizing the agricultural sector. [Display omitted] [ABSTRACT FROM AUTHOR]

Under the worldwide carbon neutralization targets, concentrating solar power (CSP) is arousing great attention. With the thermal energy storage (TES), CSP is friendly to the power system operation by supplying controllable renewable energy. The capacities of its solar field and TES are essential parameters for maximizing the profit of a CSP plant. This paper formulates an explicit expression of the CSP plant's profit instead of using a simulation-based method. Then, an unconstrained optimization model is proposed to calculate its optimal configuration directly. This model provides insights into the optimal configuration of CSP with different penetrations of wind power in the case study. The results show that to obtain a better profit for the CSP plant, large solar multiple (more than 3.0) and TES (more than 13 h) are preferred to collaborate with high penetration of wind and photovoltaic plants. The effectiveness of the proposed method is verified compared to the enumeration searching method. The economy and feasibility of installing an electric heater (EH) in CSP are also demonstrated. Generally, the optimal investment in EH is linearly correlated to the penetration of variable energy resources. [Display omitted] • A flexible operation model of CSP with EH is proposed. • An explicit model of CSP's profit based on the solar radiation curve and prices is constructed. • The configuration of the CSP plant is optimized through the first-order optimality conditions on the profit function. • The optimal configuration of CSP with high renewable energy is provided in the case study. [ABSTRACT FROM AUTHOR]

Citizen investment into wind energy is conducive to public acceptance and can contribute to closing the renewable energy investment gap, while promoting corporate social responsibility. This study addresses this topic and conducts a novel choice experiment to determine the investment preferences of a representative sample of 1,009 Irish households. First, the paper investigates the attributes determining willingness to invest into wind farms. Second, it considers to what extent public attitudes and proximity to wind farms affect investment. Third, it assesses the suitability of five specific investment mechanisms. Through these activities the findings enhance current understanding of the opportunities and challenges concerning the design of citizen investments within a centralised system which is predominantly reliant on incumbent wind energy developers. The findings show that the risk of loss and the expected annual return on investment are the main attributes determining investment decisions, but secondary criteria, such as the project location and ownership characteristics, also affect willingness to invest. Respondents living within 10 km of a wind farm or expressing support for wind energy are significantly more likely to consider investing. Recommendations include interventions to encourage joint ventures between community organisations and specialised developers as a mechanism to promote investment in wind farms. [ABSTRACT FROM AUTHOR]

In the recent years, decentralized power generation using locally available renewable energy resources has been recognized as a cost effective alternative of uneconomical grid extension. The present paper deals with the size optimization of Integrated Renewable Energy System (IRES) for a cluster of villages of Uttarakhand state in India. The proposed IRES consists of locally available renewable energy resources of Micro Hydro Power (MHP), biogas, biomass, wind and solar energy in order to meet the electrical and cooking demands of the study area. A system operation strategy has been developed in the paper for size optimization of IRES. Also, the loss of power supply probability (LPSP) has been used as the reliability criteria in order to ensure the continuous supply of power without any failure problems. Further, in order to utilize renewable energy resources in different contributions, four different resource scenarios are considered for the study area. Finally, the total net present cost (NPC) of the considered scenarios has been optimized using discrete harmony search (DHS) algorithm. Among different scenarios, MHP-biogas-biomass-wind-solar-battery based IRES offers the lowest net present cost of INR 49.0309 million at the estimated LCOE of INR 5.47/kWh. [ABSTRACT FROM AUTHOR]

This paper deals with a compact system developed to assure energy independence to buildings located in inner rural areas: the Off-Grid Box. This system features a combination of techniques that assure the use of several renewable energy sources, their storage and the rationalization of consumption. This research studies the base model of the Off-Grid Box, which entails the presence of photovoltaic panels as the energy capture system. The aim of this research is to evaluate the opportunity of realizing a system to ensure energy autonomy of rural residential buildings. To achieve energy independence, for an isolated dwelling, this paper assesses the optimal storage systems that may be combined with a photovoltaic system. To this end, an Off-Grid Box has been installed in a residential unit in central Italy. Starting from the real case, two alternative energy storage scenarios were constructed. The results can be applied to a variety of geographical settings and prove the feasibility and strategic importance of total off-grid systems for individual residential units, when they are designed in integrated terms in the area to implement small-scale-smart-grids. In rural areas, these grids should also cater for small farming businesses that feature a different consumption distribution compared to dwellings. [ABSTRACT FROM AUTHOR]

Bio-power and biofuels are promising alternative energy resources. This paper investigates their role in the long-term U.S. national energy and transportation portfolio planning, while considering the competition among other energy options. The paper presents a systematic modeling framework for integrating biomass pathways to the energy and transportation systems, and also captures the geographical variation in the feedstock availability and cost across the U.S. The paper then presents two different case studies-energy sector planning and integrated energy & transportation sectors planning. The studies reveal long-term cost and emission savings from bio-renewables, where the bulk of benefits are observed due to biofuels (with bio-power production limited by feedstock prices). Under a 40% CO 2 emissions reduction scenario over the next 40 years, penetration of bio-renewables promise up to 10-Trillion USD (2010$) savings in system costs (investments and operational). Simulations also show that the impediment with bio-renewable penetration is mostly influenced by the availability of low-cost feedstock, specifically for bio-power production. According to current estimation of long-term feedstock availability, U.S will be able to power upto 150 Billion Gallons Year (BGY) (or approx. 560*10 9 L per year) bio-refinery capacity around 2020s, and about 200 BGY (or approx. 750*10 9 L per year) by 2050. [ABSTRACT FROM AUTHOR]

Anaerobic bio-digestion/energy generation (ABD/EG) complexes that use animal waste have become increasingly important as renewable energy sources and logistics considerations are essential as animal biomass is of costly transportation due to its high weight per unit of energy generated. To ensure overall economic viability it is necessary to take into account the supply chain network when designing such a complex for at least two main reasons. First, these complexes provide power from energy sources which otherwise would go to waste and a well-designed supply chain network will significantly lower long-term operating costs. Second, because they provide an outlet for farm manure (their feedstock), these complexes allow farmers to expand production capacity whenever environmentally sound animal waste disposal is an active constraint to operations. This paper presents a methodology to design a supply chain which maximizes contribution and minimizes gas loss in the commonly found configuration in which feedstock providers are numerous small farms without on-site bio-digestion units, i.e., a configuration in which in-natura biomass is transported from those small farms to supply a nearby ABD/EG complex serving the region. The paper details three layers of analysis for designing optimal animal waste supply for anaerobic bio-digestion, including model formulation and mathematical solution for each stage. The broadest layer in the methodology is the identification of the optimal ABD/EG complex positioning given farm locations and consequent biomass transportation costs. The middle layer is the specification of the optimal logistics and transportation system, including the prioritization of supplying farms. The operational layer includes scheduling optimal biomass collection from each farm to minimize biogas loss. [ABSTRACT FROM AUTHOR]

Renewable energy has become the world's strategic choice to solve environmental pollution, address the energy crisis and achieve social sustainable development. The establishment of a regulatory system coincides with the development stage of renewable energy and electricity market operation is significant in standardizing the market competition and guaranteeing healthy development of renewable energy in China. This paper analyses the current situation of renewable energy development and the existing renewable energy regulation system in China, pointing out that the main problems restricting renewable energy development are institutional mechanisms and market factors. The existing regulatory mechanisms also have deficiencies, such as the inclination towards economic regulation and the lack of a market adjustment mechanism. This paper proposes that China should comprehensively consider the renewable energy development stage, electricity market trading mechanisms and other factors in electricity regulatory requirements when policy making, actively exploring a new renewable energy regulation model adapted to different development phases. In addition, this paper suggests China's regulatory policy path based on the forecasting of renewable energy developing models. [ABSTRACT FROM AUTHOR]

Finding ways to encourage investments in renewable electricity production is crucial to reach a transition to a sustainable energy system. While in the energy policy literature, investments are usually explained by economic or regulatory policies, recent studies have suggested that some investors are boundedly rational and may respond differently to policies. In this paper, a framework is proposed to make a more complete analysis of the institutional demands influencing emerging investors in renewable electricity production. Based on 35 cases, both formal and informal demands were identified and their impact on emerging investors' behavior was analyzed. Results show that besides formal institutional demands, emerging investors were influenced by their task environment and by various informal demands which originated in investors' collective and internal contexts. However, different investors were affected by different institutional demands. They also responded in different ways to the same demands; while some perceived a specific demand as imposing, others regarded it as inducing. These findings provide a better understanding of the institutional forces affecting emerging investors in renewable electricity. The paper suggests new policies to handle the heterogeneity of investors and opens up for a new panorama of informal policy channels, where network effects can be utilized to trigger emerging investors' decisions. [ABSTRACT FROM AUTHOR]

Spain must reduce its energy consumption by 23% and achieve 100% renewable energy in electricity generation by 2030. This paper presents the current energy scenario en Spain, and the outlooks for different renewable options, with special focus on photovoltaic (PV) solar energy. In 2012, Spain was the number two European country in terms of installed rewnewable energy power. Solar PV technology has the potential to meet Spain's future energy demand and its associated environmental challenges. This paper gives a review of solar energy economy at global scale for both PV and thermal power technologies. The Spanish energy scenario shows actual trends and progress made by solar power. Economic concepts of levelised cost of electricity and grid parity are presented. The financial analysis shows that PV electricity achieves grid parity at a plant profitability rate up to 7.26%. [ABSTRACT FROM AUTHOR]

The voltage rise of the low voltage (LV) power distribution grid to which multiple solar photovoltaic (PV) systems are integrated is a critical technical problem that should be addressed. With PV systems that are integrated to the LV power distribution grid (with an R to X ratio greater than unity) via voltage source converters, the opportunity exists to regulate the respective point of common coupling (PCC) voltages by dynamically controlling the active and reactive power response of PV systems. In this paper, two closed-loop controllers that are able to regulate the PCC voltage by dynamically controlling the active and reactive power response of the PV system are presented. The design methodology is presented with considerable detail. The plant model of each controller is derived and the design procedure of each controller is explained in detail. By combining the dynamic active and reactive power controllers proposed in this paper, two novel operating strategies for PV systems, fixed minimum power factor operation and fixed maximum apparent power operation, are introduced. The latter operating strategy has been identified as the most efficient way of regulating the PCC voltage of a PV system. The simulation results and experimental validation confirm the accuracy of the derived plant models, the robustness of the designed controllers and the feasibility of implementing the proposed novel operating strategies in PV systems. [ABSTRACT FROM AUTHOR]

This article is part of a two paper series presenting a development in the methodology for the calculation of response functions for geothermal fields with arbitrarly oriented boreholes. In the method utilized, boreholes are represented as sets of stacked line sources and the borehole temperatures are calculated by means of a superposition procedure. This particular paper is focused on the efficient computation of the building block of this approach, which is the non dimensional mean temperature response g ˜ ( t ) along a finite line due to a step heat injection along a second finite line, where the lines are arbitrarily oriented. The speed in computing this function is critical for the applicability of the method. The solution proposed to achieve the required performance is a hybrid approach involving analytical, numerical and implementation aspects: an analytical procedure to simplify the expression of g ˜ ( t ) was developed, the resulting problem was solved with a tailored numerical method, and the algorithm was implemented using a high-performing programming language. Each of these aspects showed to have a great impact from a performance perspective. The performance achieved in the calculation of g ˜ ( t ) enables the integration of this method within the scheme utilized for g-functions calculation. [ABSTRACT FROM AUTHOR]

Both developed and developing countries have committed to reduce their emissions through the increased use of renewable energy. This paper aims to compare renewable energy deployment in developed and developing countries represented by Australia and China. The paper firstly argues the validity of comparison of renewable energy deployment in Australia and China. Then, the governance structures in both countries are compared; the paper also compares management mechanisms in terms of funding and incentive support, renewable energy grid-connection and coordination between different levels of governments in both countries. Moreover, the current status of renewable energy development in two countries is summarized. From the study, it can be concluded both countries have set a Renewable Energy Target and promulgated legislation and regulations to enlarge the scale of renewable energy; China shows a stronger commitment to renewable energy than Australia. However, Renewable Energy Certificate mechanism is implemented more effectively in Australia than in China. The paper suggests: augmenting and rebuilding the electricity network and strengthening coordination between different levels of governments for both countries; enhancing manufacturing facilities and incentives for the solar and wind industry for Australia, while developing more-detailed implementation legislation and renewable power quota system for China. [ABSTRACT FROM AUTHOR]

While the member states of the Gulf Cooperation Council have economically and politically been dominated by the exploitation of fossil fuels, recent years have seen an increasing adoption of renewable energy technologies, the reasons of which are not yet sufficiently understood. This paper argues that the recent adoption of renewable energy technologies in the Gulf and its striking variation can be explained by theories of policy transfer. In addition, we find some support for the alternative hypothesis of endogenous policy development regarding political leadership. Yet there is no support for the alternative hypothesis of a strong direct influence of the international climate regime. Furthermore, the policy transfer hypothesis and political leadership stand as coexisting influences on renewable energy adoption, rather than competing ones. Based on an extensive study of primary and secondary sources, local reports and country analyses of international organizations, and personal interviews with key experts, this paper lays out in detail how transfers of renewable energy policies take place in the Gulf; their drivers; and their impacts. We also discuss the factors that lead countries to lag behind, which can be helpful for prospective research on a more extensive utilization of renewable energy in the region and beyond. [ABSTRACT FROM AUTHOR]

The recent growth of the Chinese district heating sector has been very high. No other country in the world can show the same growth rate during the last decades. The heated building area increased six times between 1995 and 2008. China has also enjoyed strong growth of scientific articles and papers about district heating in recent years. One third of all international scientific journal articles and conference papers about district heating came from Chinese scientists during 2010–2012, while Swedish scientists accounted for one quarter according to the Scopus scientific search engine. It is important to identify the Chinese district heating research to judge the potential for future collaborative research on district heating systems between Sweden/Europe and China. The 205 international publications on district heating by Chinese scientists published until 2013 have been mapped and summarised with respect to demand, supply, technology, market and environment. More diversified heat supply with renewable source was grasping the Chinese interest, since many new systems have been established, having more degrees of freedom when choosing various heat supply and technology options. The Chinese district heating systems were compared with sustainable district heating solutions in Sweden. Both countries would benefit from future research cooperation. [ABSTRACT FROM AUTHOR]

An increase in the number of Plug-in Hybrid Electric Vehicles (PHEVs) might negatively affect the performance of Microgrid (MG) such as, reducing power quality and efficiency, increasing power losses and voltage variations, and increasing customers' energy prices. An effective selection of the capacity and location of charging stations helps in reducing such negative impact. This paper proposes a method for finding the optimal location and capacity of PHEVs charging stations along with the optimal location of renewable energy sources (RESs). A multi-objective function including charging/discharging costs, losses, and voltage profile is adopted to formulate the paper problem. Differential Evolution algorithm is used to solve the proposed objective function. By applying the proposed method into a 69-bus network its performance is assessed. The simulation results support the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Thermal energy storage (TES) is recognised as a key technology for further deployment of renewable energy and to increase energy efficiency in our systems. Several technology roadmaps include this technology in their portfolio to achieve such objectives. In this paper, a first attempt to collect, organise and classify key performance indicators (KPI) used for TES is presented. Up to now, only KPI for TES in solar power plants (CSP) and in buildings can be found. The listed KPI are quantified in the literature and compared in this paper. This paper shows that TES can only be implemented by policy makers if more KPI are identified for more applications. Moreover, close monitoring of the achievements of the already identified KPI needs to be carried out to demonstrate the potential of TES. [ABSTRACT FROM AUTHOR]

This paper describes large scale tests conducted on a novel unglazed solar air collector system. The proposed system, referred to as a back-pass solar collector (BPSC), has on-site installation and aesthetic advantages over conventional unglazed transpired solar collectors (UTSC) as it is fully integrated within a standard insulated wall panel. This paper presents the results obtained from monitoring a BPSC wall panel over one year. Measurements of temperature, wind velocity and solar irradiance were taken at multiple air mass flow rates. It is shown that the length of the collector cavities has a direct impact on the efficiency of the system. It is also shown that beyond a height-to-flow ratio of 0.023 m/m³/hr/m 2 , no additional heat output is obtained by increasing the collector height for the experimental setup in this study, but these numbers would obviously be different if the experimental setup or test environment (e.g. location and climate) change. An equation for predicting the temperature rise of the BPSC is proposed. [ABSTRACT FROM AUTHOR]

The effects of humanity's carbon footprint deserve attention and remediation. The ocean can provide an abundant source of renewable energy instead of fossil fuels in the form of wave energy. However, wave energy collection needs to be comparable in terms of cost and efficiency to be considered a viable alternative. Point Absorber Wave Energy Converter (PA-WEC) is one method of capitalizing on the ocean's wave energy. Past research provides methods for optimizing control force parameters for single PA-WECs. This paper provides methods for optimizing control force parameters for arrays of PA-WECs; optimization considers factors such as radiation hydrodynamic interactions, diffraction hydrodynamic interactions, array arrangements, and wave incident angles. In section 2, we outline the steps to determining optimal control forces. In section 3, we present numerical simulations of PA-WECs and compared the results between single PA-WEC systems and arrayed PA-WEC systems. • Determining optimal control forces of PA-WEC in arrangement are derived theoretically. • Explores different PA-WEC array arrangements and incident wave angles to maximize power generation. • Explores different configurations and the resulting changes in expected efficiencies. • Discusses optimizing control parameters for maximum power out-put. [ABSTRACT FROM AUTHOR]

Extracting green hydrogen from renewable energy sources is a new concept in the energy industry. As an energy carrier, hydrogen is well capable of facilitating a strong coupling between various energy sectors, as well as integration of renewable energy sources. This paper investigates the system-wide technical factors that might limit the amount of producible hydrogen in a given power system. A non-linear programming formulation is proposed to quantify the impact of voltage security constraints, the location and size of power to hydrogen facilities, and finally the wind penetration levels on the harvest-able green hydrogen. The applicability of the proposed framework is demonstrated on the IEEE 39 bus system. • The clean green hydrogen is a game changing factor in energy industry. • The total producible green hydrogen should be calculated considering OPF. • Harness-able green hydrogen decreases in higher levels of voltage stability margins. • The power transmission system constraints influence the green hydrogen production. • Large Power-to-Hydrogen units can control the wind curtailment. [ABSTRACT FROM AUTHOR]

Pakistan is facing severe electricity crisis due to lack of investment in power sector, depleting gas resources and dependency on imported oil. Utilization of indigenous and renewable energy resources is the best way to compensate energy need and reduce fossil consumption. Being an agrarian country, huge amount of agricultural residue is generated each year, which can be used as a cheap input to generate electricity. Aim of this research is to assess the total potential of electricity that can be generated from Agricultural Residue (AR) in Pakistan. The paper focuses on district-wise resource assessment for electricity generation in the province of Punjab. Estimated 60 Mega Tonne (Mt) of AR is generated in Punjab every year from 5 major crops (wheat, sugarcane, rice, maize, and cotton). AR is used for various purposes but still large amount of residue is left unused and burnt openly in the fields. As a methodology, certain factors are used to calculate the Net Available Residue (NAR). This research shows that a lot of potential is available in Pakistan to generate electricity form biomass, in total around 1700 MW electricity can be generated from agricultural residues of 4 main crops (Maize, Cotton, Wheat and Rice). It is also found that maize stalk producing districts of central Punjab are the best location for installing BPP and also it is cheapest to produce electricity from maize stalk with LCOE of 6.8 cents/kWh. • The assessment of the power generation from Agricultural Residue (AR) in Punjab, Pakistan is performed. • District-wise resource assessment for electricity generation is done in the province of Punjab. • Estimated 60 Mega Tonne of AR is generated in Punjab every year from 5 major crops. • In total around 1700 MW electricity can be generated from agricultural residues of 4 main crops. • Maize stalk producing districts of central Punjab are the best location for installing BPP. [ABSTRACT FROM AUTHOR]

This paper investigates the relationship between biomass energy consumption and economic growth for 26 OECD countries for 1980 to 2013 period. This study used panel unit root analyses, panel cointegration analyses, dynamic OLS analyses, fully modified OLS analyses and panel VECM Granger causality to examine the relationship. The results reveal the presence of long-run equilibrium relationship between the variables supporting the feedback hypothesis. As policy implication, OECD countries have to improve the biomass energy infrastructure as an important source of renewable energy to promote economic growth. • Investigation of relationship between biomass consumption and economic growth. • Focus on 26 OECD countries for 1980 to 2013. • Feedback hypothesis is confirmed. • Policy suggestion: promotion of biomass will enhance economic growth. [ABSTRACT FROM AUTHOR]

In the last decades, an increase of energy consumption has been noted around the world. Hence, the excessive use of fossil fuels can lead to serious environmental concerns. Indeed, the use of renewable energy sources is needed to reduce the greenhouse gas effects and the CO 2 emissions in the atmosphere. Small-scale hydropower could be an interesting and renewable alternative solution. The cross-flow turbines present several advantages compared to the axial-flow turbines. Therefore, increasing efforts are taken to enhance the efficiency and extend the applicability of the cross-flow turbines. In this paper, experimental investigation was carried out to evaluate the performance of a delta blades turbine with leading edge sweep angle equal to γ = 30°. The experimental investigation was conducted in an irrigation channel characterized by a water current of constant velocity equal to V ∞ = 0.86 m s−1. In addition, numerical study was carried out to analyze the effect of the leading edge sweep angle on the performance of the delta blades turbine and the hydrodynamic characteristics of the flow around the turbine. Numerical findings confirm that the leading edge sweep angle has an impact on turbine efficiency and the hydrodynamic characteristics of the flow around the turbine. • A numerical-experimental study has been carried out on a hydrokinetic turbine with delta blades. • The maximum power coefficient value is given for a TSR of 0.7. • The effect of different leading edge sweep angle on the turbine performance is studied. • The leading edge sweep angle affects the hydrodynamic characteristics of the flow. • The optimal leading edge sweep angle is suggested finally. [ABSTRACT FROM AUTHOR]

The primary purpose of the study is to rank and evaluate renewable energy sources that are the only alternative of non-renewable energy sources, according to twenty-six regions in Turkey. Multi-criteria decision making methods are widely employed in the solution of energy selection problems because energy selection problems contain many criteria contradicting each other. In this study, the importance levels weights of the evaluation criteria were measured by the Fuzzy Entropy method. Later, with the Fuzzy COPRAS and Fuzzy MULTIMOORA methods, renewable energy sources alternative rankings were acquired for the regions. According to the fuzzy COPRAS results in Appendix 2, the hydroelectric energy source has been defined as the suitable renewable energy source alternative for seventeen regions. According to the fuzzy MULTIMOORA results in Appendix 2, the hydroelectric energy source has been determined as the suitable renewable energy source alternative in the first rank for eighteen regions. With this study, a resource is presented to regional investors to reach an investment decision for renewable energy sources. This study constitutes an indication for development agencies along with investors. • Ranking and evaluation of renewable energy sources. • Weights of the evaluation criteria were measured by the Fuzzy Entropy method. • The Fuzzy COPRAS and Fuzzy MULTIMOORA methods were applied for ranking. • Paper concentrates on choosing the most proper RES for twenty-six regions. • Hydropower have been classified as a suitable alternative RES for most regions. [ABSTRACT FROM AUTHOR]

Wind as a renewable energy source is characterized by rapid growth of installed power in many countries, including Poland, where its share in the electricity production has grown over 25 times in the last decade, now reaching about 10%. Since renewable energy has priority in access to the grid, it forces the dispatchable coal-fired power plants to adjust their load. This causes additional consumption of primary energy due to more frequent shut-downs/start-ups and due to efficiency penalty when operating below nominal parameters. In this paper, actual data on the operation of Polish power plants in several years are analysed. The analysis, together with simulations of performance of the power system without the presence of wind energy, focuses on the influence of wind power plants on the utility ones. The results of simulations are additionally processed using the concept of thermo-ecological cost to compare the "operational" impact of wind farms on the power system with their "investment" environmental burden. A conclusion is that current share of wind energy at the level of 10% is enough to have an adverse effect on the coal power plants, but depending on the structure of the power system it may actually increase its overall efficiency. • Introduction of wind power to the grid disrupts the operation of other power plants. • Average efficiency of individual utility power plants decreases. • The number of start-up/shut-down procedures greatly increases. • Depending on the structure of the system, overall efficiency may actually increase. • Thermo-ecological cost of compensation for wind energy is non-negligible. [ABSTRACT FROM AUTHOR]

Wind energy, with an exponential growth in the last years, is nowadays one of the most important renewable energy sources. Modern wind turbines are bigger and complex to produce more energy. This industry requires to reduce its operating and maintenance costs and to increase its reliability, safety, maintainability and availability. Condition monitoring systems are beginning to be employed for this purpose. They must be reliable and cost-effective to reduce the long periods of downtimes and high maintenance costs, and to avoid catastrophic scenarios caused by undetected failures. This paper presents a survey about the most important and updated condition monitoring techniques based on non-destructive testing and methods applied to wind turbine blades. In addition, it analyses the future trends and challenges of structural health monitoring systems in wind turbine blades. • A Survey Non-Destructive Testing in Wind Turbine Blades (WTB). • Most important and updated condition monitoring techniques and methods applied to WTB. • Analysis the future trends and challenges of structural health monitoring systems in WTB. • Condition monitoring systems to reliability, safety, maintainability and availability of WTB. [ABSTRACT FROM AUTHOR]

Renewable energy sources (RES) can play a significant role in economic growth. This article examines the development of the wind energy market in the EU. The applicable regulations, directives, and legal acts are reviewed, and the State's role in the development of the renewable energy market is discussed. The analyses were carried out based on the available literature and Eurostat data. The authors of the paper used basic statistics to summarize the changes in wind energy and make a prognosis. The data analysis uses the Autoregressive Integrated Moving Average Method (ARIMA). The survey found that the highest average wind cumulative installed capacities were in Germany (31026 MW), Spain (18602 MW), United Kingdom (7894 MW) and France (6108 MW). Our analysis indicates that the biggest average annual installed wind capacity was in Germany (2952.6 MW), Spain (1224.5 MW) and the United Kingdom (1363.8 MW). These same countries achieved the highest average wind gross electricity production in the years 2004–17: Germany (50.9 TWh), Spain (39.3 TWh) and United Kingdom (18.9 TWh). The study finds that wind cumulative installed capacity will increase in most countries of the EU. • The European Union onshore wind energy market seems to be stable. • Wind power plays an important role as a source of energy supply. • The most important wind gross electricity producers in the EU are: Germany and Spain. • The highest increase of wind cumulative installed capacity in 2022 will be in Croatia. [ABSTRACT FROM AUTHOR]

A major part of heat in Swiss residential buildings is supplied by fossil fuel boilers, leading to large CO 2 emissions. Heat supply can be decarbonised by replacing boilers with renewable energy sources (RES) such as solar thermal, but the mismatch between heat supply and heat demand needs to be overcome. Seasonal thermal energy storage (STES) can be used to store heat from solar collector (SC) thereby reducing the usage of boilers. A centralised heat pump (HP) is also an attractive alternative for heating. This paper assesses the techno-economic feasibility of different heating systems for decarbonising the Swiss residential heating sector. It uses the simulation method for assessing hourly energy flows in 500 and 1,000 multifamily households connected by a district heating (DH) system. Four different configurations of DH system are assessed by simulating hourly energy flows. The required capacity of equipment, cost of different systems, and the cost of decarbonisation of heat are calculated. Levelised cost of heat, CO 2 emissions and share of RES are compared. Peak electricity load due to use of HP and the impact of using different emission factors for electricity is examined. Results show that the heating system with a centralised HP has the least cost of decarbonisation but it adds a high peak load on the electricity grid infrastructure. A heating system with a SC, a STES, HP and a boiler emerges as a cost competitive option for decarbonising heating for 1,000 dwellings. • Simulates hourly energy flows in four types of centralised heating systems. • Examines techno-economic feasibility of seasonal thermal energy storage (STES). • Calculates levelised cost of heat, CO 2 emissions and share of renewable energy. • Evaluates impact of different CO 2 emission factors and cost of decarbonisation. • Heating systems with STES are cost competitive with centralised heat pumps. [ABSTRACT FROM AUTHOR]

This paper deals with the environmental assessment of two electricity scenarios in Sicily, for 2030, characterized by a high exploitation of renewable energy sources in order to quantify the potential contribution of the local strategies in the achievement of the European climate policies and the potential improvement in the future electricity mix, compared to the current one (2014). In order to match these goals, authors integrate the Life Cycle Assessment with a scenario analysis. The future electricity mix scenarios, characterized by a share of renewables (57% for 2030-BS scenario and 51% for 2030-DS scenario) show a reduction of the greenhouse gases emissions per kWh of electricity generated, compared to the current one in which renewables account for 24%. Greenhouse gases emissions decrease by 39.9% in 2030-BS and by 32.9% in 2030-DS. However, the analysis highlights that the state of development of technologies does not allow improvements in a whole set of impacts categories. Particularly, freshwater ecotoxicity increases by around 30% and resources depletion by more than 100%. Results of this study can be used by local authorities as knowledge base in the definition and "ex-ante" evaluation of site-specific low-carbon energy strategies in Sicily. • The scenario analysis integrated with the LCA methodology was presented. • Electricity generation scenarios in 2030 in the Italian context was build. • Marginal electricity generation technologies were identified based on site-specific data. • A high penetration of renewables in the electricity generation mix allows decreasing a wide range of environmental impacts; Improving renewable technologies is paramount for better resource efficiency A high penetration of renewables in the electricity generation mix allows decreasing a wide range of environmental impacts; Improving renewable technologies is paramount for better resource efficiency and toxicity control. [ABSTRACT FROM AUTHOR]

The penetration of renewable energy sources for electricity generation is critical to decarbonize electricity systems, a main goal in the context of the energy transition. Among renewable energies capacity additions, wind energy has played a dominant role in the European Union and elsewhere, fuelled by technology cost reductions and public promotion schemes. In turn, wind deployment has led to considerable socioeconomic and environmental benefits in terms of CO 2 emissions reductions, avoidance of fossil fuels and employment creation. The aim of this paper is to assess those socioeconomic and environmental benefits of wind energy deployment in the European Union and their evolution over time. Based on two novel methodologies, which allow a disaggregated analysis per country and stage of the supply chain (only for employment creation), an ex-post calculation of those benefits over the 2008–2016 period has been carried out. Our results show that, overall, those benefits are considerable and have increased over time. However, some benefits are more relevant than others. In fact, the monetary calculation of the fossil fuel savings is twice the benefits in terms of CO 2 emissions abatement. Their relevance also differs across countries and, for employment creation, across distinct stages of the value chain. • Ex-post calculation of the benefits of wind energy in the EU in the period 2008–2016. • Assessment of the emission reductions, avoidance of fossil fuels and employment creation. • The monetary quantification of the fossil fuel savings is twice the benefits of CO 2 emissions abatement. • More than 2.5 million jobs created in the period 2008–2016 in the EU28. • Policy costs are higher than benefits from CO 2 and fossil fuel reductions. [ABSTRACT FROM AUTHOR]

The present paper concerns the assessment of biomass by-products from the urban greenery maintenance with an energy perspective. Usually pruning is not organized by a consolidated planning practice, mainly because of lack of information. After estimating the quantity of wood pruning by-products by means of dendrometric equations and the availability of information on current greenery management, an innovative GIS-based method was implemented and tested on Milan, in northern Italy. The main outcome is the quantification of the energy potential in terms of available wood biomass, displayed on a geo-referred urban map. Moreover, the outcomes of the research could support the administrations in improving the management of these materials otherwise wasted and therefore in converting public expenses for maintenance into public profits available for further investments. On the energy supply side, the GIS database could support the local matching between available renewable sources and energy supply systems in operation (i.e. local district heating and cogenerative systems), providing a low-range and cost-effective renewable resource, also enhancing circular economy at the local scale. • A novel method for an effective urban greenery management is proposed and analysed. • Dendrometric equations and a GIS were combined for pruning by-products estimation. • The urban greenery of Milan was considered as case study. • A biomass PE potential between 26 and 76 GWh was assessed for the case study. • The use of pruning by-products in a biomass district heating plant is evaluated. [ABSTRACT FROM AUTHOR]

This paper conducts an energy and economic assessment of District Heating (DH) integrated Solar Thermal (ST) systems. An implementation with building-integrated ST collectors coupled to a Low Temperature District Heating (LTDH) system is studied, with special focus on unglazed collectors. ST heat is exploited in the building through direct use, while excess heat is delivered to the network. A novel control strategy for heat flows in the system is proposed. A meta-analysis of several DH configurations, interconnection schemes and installed ST capacity is performed in three different climates: Sevilla (Spain), Bordeaux (France) & Copenhagen (Denmark). Heat loads corresponding to buildings with various insulation levels and domestic hot water loads are assessed in hourly simulations. The proposed interconnection concept provides a variety of connection modes to the DH network, allowing up to a 50% increase in the provision of solar heat compared to an isolated ST system. Positive Return of Investment (ROI) for such a setup is achieved in 22% of the studied cases. The DH network is found to be a suitable heat sink in up to 25% of the buildings with ST systems installed. • A combined system, ST on facade with DH network, is simulated and analysed. • A meta-analysis with more than 23.00 different case studies is presented. • A data-driven model based on data from simulations is presented. • Above the 22% of the studied cases obtain positive economic metrics (dNPV > 0). • DH network is an ideal heat sink when <20% of the buildings include ST installation. [ABSTRACT FROM AUTHOR]

The operation of Renewable Energy Sources (RES) systems is highly affected by the continuously changing meteorological conditions and the design of a RES system has to be robust to the unknown weather conditions that it will encounter during its lifetime. In this paper, the use of Stochastic Weather Generators (SWGENs) is introduced for the optimal design and reliability evaluation of hybrid Photovoltaic/Wind-Generator systems providing energy to desalination plants. A SWGEN is proposed, which is based on parametric Markov-Switching Auto-Regressive (MSAR) models and is capable to simulate realistic hourly multivariate time series of solar irradiance, temperature and wind speed of the target installation site. Numerical results are presented, demonstrating that: (i) SWGENs enable to evaluate the reliability of RES-based desalination plants during their operation over a 20 years lifetime period and (ii) using an appropriate time series simulated with a SWGEN as input to the design optimization process results in a RES-based desalination plant configuration with higher reliability compared to the configurations derived when the other types of meteorological datasets are used as input to the design optimization process. • Renewable Energy Sources (RES) systems are highly sensitive to weather conditions. • Stochastic weather generators (SWGENs) generate realistic weather conditions and enrich available meteorological datasets. • SWGENs enable to estimate the reliability of RES systems and design RES systems which are robust to climate variability. [ABSTRACT FROM AUTHOR]

Tidal current energy is a promising renewable energy, and it has become a research hotspot all over the world. Tidal current turbines (TCTs) are the devices that capture tidal current energy and convert it into electricity. Power train is one of the key technologies, and a gearbox is traditionally used. Because of the disadvantages of the gearbox, several soft power transmission methods have been studied, such as hydraulic power train and direct-drive train. Aiming for maximum power point tracking (MPPT) and constant frequency simultaneously, this paper introduces the hydraulic-mechanical hybrid transmission for TCT. Different from the traditional mechanical transmission, the hydraulic-mechanical hybrid transmission uses a two-degree-of-freedom planetary gear (TDPG) as the power split device. In this transmission, the rotor speed can be regulated by hydraulic pump displacement control to realize the MPPT, and the power can be stabilized through the hydraulic system. In this paper, the hydraulic-mechanical hybrid transmission is introduced, and the characteristics of the TDPG are analyzed first. Then, the control strategy of TCT is proposed. Finally, the system is modeled and constructed, and the simulation results confirm the validity of the hydraulic-mechanical hybrid transmission of TCT. [ABSTRACT FROM AUTHOR]

Wind energy is a key portion of most clean and green energy strategy. However, wind energy is intermittent and uncertain. This uncertainty poses a techno-economic challenge of sourcing the least costing load balancing service (reserve). This paper looks to develop solutions for this challenge. Currently the system unbalance caused by the wind power is handled by the real time balancing market, which is operated by the system operators for maintaining reliable operation of power systems. This method cannot always work reliably when the amount of wind penetration increases in the future. A future electricity market, with no subsidies, is assumed in this paper where wind generators have to compete with other generators to sell energy. It is assumed that wind generators are competitively scheduled a day-ahead and would suffer penalties for under production while receiving a poor compensation for over production. To overcome the uncertainty in wind production, an options based network constrained intra-day secondary reserve market is proposed in this research with a mathematical formulation that considers purchasing energy from several reserve providers. Reserves may be purchased by procuring options ahead of transactions by paying premiums and paying strike prices while transacting. The market equilibrium amongst participants will be reached with proposed optimization and the lambda (LaGrange) multiplier associated with power balance equation at each bus determines optimal values of both premiums and strike prices. The amount of required reserve is calculated by using a Cauchy-Lorentz distribution model. The reserves are positive for under production and negative for over production. Transmission network MVA limits are considered to ensure feasibility of options contracts. A 5-bus test system and a real Ontario (Canada) wind farm data with IEEE 118-bus system illustrate the merits of this research. [ABSTRACT FROM AUTHOR]