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Accelerating the transition to a cleaner global energy system is essential for tackling the climate crisis, and green hydrogen energy systems hold significant promise for integrating renewable energy sources. This paper offers a thorough evaluation of green hydrogen's potential as a groundbreaking alternative to achieve near-zero greenhouse gas (GHG) emissions within a renewable energy framework. The paper explores current technological options and assesses the industry's present status alongside future challenges. It also includes an economic analysis to gauge the feasibility of integrating green hydrogen, providing a critical review of the current and future expectations for the levelized cost of hydrogen (LCOH). Depending on the geographic location and the technology employed, the LCOH for green hydrogen can range from as low as EUR 1.12/kg to as high as EUR 16.06/kg. Nonetheless, the findings suggest that green hydrogen could play a crucial role in reducing GHG emissions, particularly in hard-to-decarbonize sectors. A target LCOH of approximately EUR 1/kg by 2050 seems attainable, in some geographies. However, there are still significant hurdles to overcome before green hydrogen can become a cost-competitive alternative. Key challenges include the need for further technological advancements and the establishment of hydrogen policies to achieve cost reductions in electrolyzers, which are vital for green hydrogen production. [ABSTRACT FROM AUTHOR]

To achieve an energy sector independent from fossil fuels, a significant increase in the penetration of variable renewable energy sources, such as solar and wind power, is imperative. However, these sources lack the inertia provided by conventional thermo-electric power stations, which is essential for maintaining grid frequency stability. In this study, a grid resembling Madeira Island's power generation mix was modeled using the Matlab/Simulink platform. The model included solar, wind, hydro, and thermo-electric generation to accurately represent the energy landscape of Madeira Island. Three scenarios were examined: one reflecting the current power generation on Madeira Island, a future scenario with a substantial rise in the percentage of photovoltaic (PV) generation, and the same future scenario but incorporating a battery energy storage system (BESS). Various analyses were conducted to assess the impact on frequency stability during a ground fault and rapid load/generation changes. In the future scenario without a BESS, the thermoelectric power plant generator desynchronized, leading to system collapse in several simulations. However, with the addition of a BESS, a significant improvement in frequency stability was observed. The thermoelectric power plant generator could return to a steady state after each disturbance. Furthermore, both the maximum frequency deviation and the absolute value of the Rate of Change of Frequency (ROCOF) were reduced, indicating enhanced system performance and stability. [ABSTRACT FROM AUTHOR]

Despite the widespread usage of high-voltage alternating current (HVAC) for the connection of offshore wind farms (OWF), its use to power-from-shore (PFS) offshore oil and gas (O&G) production sites is often not feasible. Its limitations for long-distance subsea transmission are usually found at 50–70 km from shore and might be even shorter when compared commercially to a direct-current (DC) alternative or conventional generation. Therefore, this research paper aims to address the standardization of offshore transmission with a particular focus on the high-voltage direct current (HVDC) alternative. While the distance is typically not a limiting factor when using DC, and the voltages used are rather standard, the concept of power envelopes can be quite useful in addressing the high variability of offshore site power requirements and setting a design baseline that would lead to improved lead time. In this article, a full back and front-end genetic optioneering model purposely built from the ground up in Python language is used to #1 define up to three DC power envelopes that would cater to most of the candidate's requirements and #2 provide the lowest cost variance. The results will demonstrate that this can be achieved at a minor overall cost expense. [ABSTRACT FROM AUTHOR]

The world is facing many challenges to keep up with growing energy demand and greenhouse gas and pollutant emissions. A possible solution is to integrate renewable energy sources (RESs) into residences and create energy management systems (EMSs) that reduce consumption and relieve the main grid in critical hours. This paper is focused on analyzing different EMSs using solar photovoltaic (PV) modules and three energy storage systems (ESSs) to increase savings without affecting the user's needs, with thirty-three power consumption profiles and three energy tariffs over a 25-year investment to compare which solution presents the best economic result in each of the 297 analyzed scenarios. The results show that the higher the overall daily consumption values, the greater the profits for all EMSs. The lowest demand profiles lead to the best self-consumption and self-sufficiency results. PV-only systems with a tri-hourly tariff have the best overall results. In the case of battery operation, each case should be carefully analyzed in order to choose the correct technologies and tariff. The results also allowed us to verify that even though having more PV modules generates more energy, it can make a project less economically desirable. [ABSTRACT FROM AUTHOR]

In recent years, there has been a significant increase in investment in renewable energy sources, leading to the decarbonization of the electricity sector. Accordingly, a key concern is the influence of this process on future electricity market prices, which are expected to decrease with the increasing generation of renewable power. This is important for both current and future investors, as it can affect profitability. To address these concerns, a long-term analysis is proposed here to examine the influence of the future electricity mix on Iberian electricity prices in 2030. In this study, we employed artificial intelligence forecasting models that incorporated the main electricity price-driven components of MIBEL, providing accurate predictions for the real operation of the market. These can be extrapolated into the future to predict electricity prices in a scenario with high renewable power penetration. The results, obtained considering a framework featuring an increase in the penetration of renewables into MIBEL of up to 80% in 2030, showed that electricity prices are expected to decrease by around 50% in 2030 when compared to 2019, and there will be a new pattern of electricity prices throughout the year due to the uneven distribution of renewable electricity. The study's findings are relevant for ongoing research on the unique challenges of energy markets with high levels of renewable generation. [ABSTRACT FROM AUTHOR]

The need for decarbonization has become an urgent objective being pursued across borders and sectors. The energy sector is one example to follow, with the penetrations of renewable energy sources increasing year after year and already having an impact on carbon emissions. Despite their benefits, as these penetration levels grow, grid frequency is likely to be affected, namely in small, isolated power systems. Part of this instability is caused by the different types of connections to the grid used by most renewable energy sources. These converter-connected technologies do not contribute to the grid's inertia the same way synchronous generators do, therefore the difficulties in keeping the frequency under control. Focusing on the behaviour of the system's frequency, following some disturbances, a grid model of the Portuguese Terceira Island is created to assess the potential benefits of using hydrogen technologies (electrolysers and fuel cells) to provide grid services. In this paper, two scenarios are analyzed, the system's frequency response to large imbalances and steady-state imbalances stemming from load and wind power forecasting errors. The results reflect how the frequency behaviour is affected by the amount of the system's inertia, synchronous generators characteristics, and the presence of electrolysers and fuel cells. Hydrogen systems impact positively on the frequency containment after large disturbances, the impact related to the response to steady-state imbalances being lesser and prone to affect the stacks lifespan. • A grid model of a Portuguese island is created to assess the benefits of hydrogen to provide frequency control. • Models are developed for electrolysers, fuel cells and synchronous generators. • Two scenarios are analyzed: the response to large imbalances and steady-state imbalances (load and wind forecasting errors). • Hydrogen systems positively impact the frequency containment after large disturbances. • The impact related to the response to steady-state imbalances is lesser and prone to affect the stacks lifespan. [ABSTRACT FROM AUTHOR]

Virtual power plants (VPPs) have emerged as a way to coordinate and control the growing number of distributed energy resources (DERs) within power systems. Typically, VPP models have focused on financial or commercial outcomes and have not considered the technical constraints of the distribution system. The objective of this article is the development of a technical VPP (TVPP) operational model to optimize the scheduling of a diverse set of DERs operating in a day-ahead energy market, considering grid management constraints. The effects on network congestion, voltage profiles, and power losses are presented and analyzed. In addition, the thermal comfort of the consumers is considered and the tradeoffs between comfort, cost, and technical constraints are presented. The model quantifies and allocates the benefits of the DER operation to the owners in a fair and efficient manner using the Vickrey–Clarke–Grove mechanism. This article develops a stochastic mixed-integer linear programming model and various case studies are thoroughly examined on the IEEE 119 bus test system. Results indicate that electric vehicles provide the largest marginal contribution to the TVPP, closely followed by solar photovoltaic (PV) units. Also, the results show that the operations of the TVPP improve financial metrics and increase consumer engagement while improving numerous technical operational metrics. The proposed TVPP model is shown to improve the ability of the system to incorporate DERs, including those from commercial buildings. [ABSTRACT FROM AUTHOR]

Growing renewable energy deployment worldwide has sparked a shift in the energy landscape with far-reaching geopolitical ramifications. Hydrogen's role as an energy carrier is central to this change, facilitating global trade and the decarbonisation of hard-to-abate sectors. This analysis offers a new method for optimally sizing solar/wind-to-hydrogen systems in specifically suitable locations. These locations are limited to the onshore and offshore regions of selected countries, as determined by a bespoke geospatial analysis developed to be location-agnostic. Furthermore, the research focuses on determining the best configurations for such systems that minimise the cost of producing hydrogen, with the optimisation algorithm expanding from the detailed computation of the classic levelised cost of hydrogen. One of the study's main conclusions is that the best hybrid configurations obtained provide up to 70% cost savings in some areas. Such findings represent unprecedented achievements for Italy and Portugal and can be a valuable asset for economic studies of this kind carried out by local and national governments across the globe. These results validate the optimisation model's initial premise, significantly improving the credibility of this work by constructively challenging the standard way of assessing large-scale green hydrogen projects. [Display omitted] • Identification of current locations suitable for RES-to-Hydrogen systems in Italy and Portugal. • Computation of a novel factor that enables calculation of country-wide LCOH 2 • Optimisation model for single and hybrid, onshore and offshore configurations. [ABSTRACT FROM AUTHOR]

Emerging technologies are helping to accelerate the ongoing energy transition. At the forefront of these new technologies is blockchain, which has the potential to disrupt energy trading markets. This article explores this potential by presenting an innovative multilevel transactive energy (TE) optimization model for the scheduling of distributed energy resources (DERs) within connected virtual power plants (VPPs). The model allows for energy transactions within a given VPP as well as between connected VPPs. A blockchain-based smart contract layer is applied on top of the TE optimization model to automate and record energy transactions. The model is formulated to adhere to the new regulations for the self-generation and self-consumption of energy in Portugal. This new set of regulations can ease barriers to entry for consumers and increase their active participation in energy markets. Results show a decrease in energy costs for consumers and increased generation of locally produced electricity. This model shows that blockchain-based smart contracts can be successfully integrated into a hierarchical energy trading model, which respects the novel energy regulation. This combination of technologies can be used to increase consumer participation, lower energy bills, and increase the penetration of locally generated electricity from renewable energy sources. [ABSTRACT FROM AUTHOR]

The integration of intermittent renewable energy sources (RES) represents a great challenge for any energy system. In particular, islanded microgrids with a high penetration of renewables experience a strong need for technologies that allow to match demand and production at any moment. This work aims at proposing an optimised design for the energy system of Faial, an island in the Azores archipelago, featuring the highest possible renewable energy penetration that can be obtained respecting the technological and financial feasibility constraints. To this purpose, a model has been developed, using weather and electric demand measured data to combine and size optimally the components of a hybrid energy system. The model can be varied in its constraints to fit at best the multi-objective nature of the problem, where the conflicting objectives are the Net Present Value, its Renewable Energy Fraction and the Energy Index of Reliability. Once a set of possible optimal design has been determined, a system design featuring 5504 kW of geothermal installed power and 6208 kWh of BESS (Battery Energy Storage System) capacity, together with the already present thermal generators and 4250 kW of wind turbines, has been analysed more in detail. Monte Carlo simulations with synthetic time series have been performed to investigate the impact on the project of the variability in wind speed and in energy demand, highlighting the robustness of the selected design. • We propose an optimised design for the energy system of Faial, an island in the Azores archipelago. • The model features the highest possible renewable energy penetration respecting the technological and financial constraints. • Monte Carlo simulations were performed to investigate the impact of the variability in wind speed and energy demand. [ABSTRACT FROM AUTHOR]

Isolated power systems present high levels of Renewable Energy Sources (RES) curtailment as intermittency and isolation impose challenging difficulties regarding the integration of this energy into the electrical grid. The recent developments in electrical vehicles have decreased the kWh cost of lithium-ion batteries below a threshold value that was previously prohibitive for grid-scale applications. Therefore, the integration of RES considering the installation of a Battery Energy Storage System (BESS) into an isolated power grid is an up-to-date research topic and is assessed in this paper. The BESS is inserted into the Unit Commitment and Economic Dispatch (UC + ED) platform and regarded as another dispatchable generator. To keeps the costs down, the BESS is mainly used to provide a portion of the spinning reserve needs and secondly to alleviate the load of the thermal generators, using the free modules. The BESS configurations that maximises the economic viability and minimises the RES curtailment are presented. The results suggest that the investment in this technology may be profitable and considerably decreases the levels of RES curtailment. [ABSTRACT FROM AUTHOR]

The lack of predictability in the output of solar, wind, and small hydroelectric power plants aggravates the problem of consistently matching supply with demand on electric grids. In this paper, a database of renewable power injection, at 15-minute intervals during 2010–2014, into the Portuguese electric transmission system is analysed to characterize the variability and other patterns of renewable energy injection into the system. The system, operated by REN (Redes Energéticas Nacionais), received 20–28% of its electricity from the three renewable energy sources (RES) mentioned, with wind contributing about 90% of that amount. A strong complementarity (smoothing effect) between wind and PV was found, with correlation factors of − 0.92 and − 0.83 for typical summer and winter days, respectively. The correlation factors for different time scales decrease from annual totals (− 0.88) to hourly totals (− 0.24), as expected. The results suggest that lower wind power years correspond to sunnier ones. Moreover, the reserve regulation costs appear to decrease when the installed capacity of the three considered RES increase. [ABSTRACT FROM AUTHOR]

Despite the fact that the current level of energy supply security in Europe is quite satisfactory, new challenges present a potential risk of jeopardising the current state of affairs. Among others, key challenges are related to the strengthening of the market framework (in the context of deregulation and unbundling as imposed by EU directives) and the increasing penetration of renewable energy sources in the generation mix (with inherently greater variability). Under these circumstances, assessing the value of lost load (VoLL) is useful to support energy decision-making, including benefit-cost analysis and the design of suitable regulatory frameworks. This paper develops VoLL estimation using a macroeconomic technique, namely the production-function approach. The VoLL determines the foregone value added due to electricity outage. The production-function method is applied to the Portuguese case and an average VoLL of 5.12 €/kWh is found. The paper also presents the VoLL results obtained for various economic sectors as well as households. Moreover, the temporal variation of the VoLL along typical weekdays and weekend, in winter and in summer, and for the most relevant sectors (manufacturing, retail services, and households) is demonstrated and discussed. [ABSTRACT FROM AUTHOR]

Photovoltaic microgeneration (μG) located near the domestic consumers is expected to increase more in the future. Known issues regarding high μG penetration are voltage rise and reverse power flow. The concept of selfconsumption and storage is emerging as a way to improve network power supply quality and to facilitate the integration of small renewable energy sources in low voltage networks. This paper intends to give a further contribution by assessing the improvements provided by allowing domestic clients to consume and store the energy they produce. The tool at hand to study the situation is the unbalanced three-phase load flow algorithm, based on the power summation technique, improved with the capability of explicitly compute the neutral voltages. The behaviour of a test radial distribution grid is assessed in different operating conditions, namely winter/summer, μG penetration level and μG operating mode. Voltage profile, active power flow in the service transformer and losses are monitored. The results suggest that self-consumption with storage operating mode is a promising solution. Voltage excursions above normal grid voltage operating limits were not observed, the situation of reverse active power flow does not occur and the power losses are reduced. [ABSTRACT FROM AUTHOR]

The incorporation of clean energy sources in the power system is a topic of discussion almost everywhere. After the "wind (farms) of change", small, dispersed, urban photovoltaic (PV) generators are being installed in the roofs of the buildings, connected to the local Low Voltage (LV) grid. A boost in this type of renewable micro generation is expected in the near future. Due to the domestic loads, LV grids are inherently unbalanced, its analysis requiring the use of three-phase load flow methods. This same methodology is used in this paper to assess the problem of the concurrent unbalanced generation and load and to cope with the presence of both single and three-phase equipment in the same grid. A review of existent models for three-phase equipment is performed. The issue of modelling three-phase loads (isolated star and delta connected) and singlephase PV generators and associated power electronics is given special attention. Finally, a case-study is presented, enabling to draw some conclusions regarding the impacts on the Medium Voltage (MV) grid and the behaviour of the system facing different climacteric conditions. [ABSTRACT FROM AUTHOR]

Energy-efficient building retrofits must be approached from three perspectives: law regulation approach, financial incentives approach, and practice approach. The concepts of zero energy building and life cycle energy building are presented as the basis for energy retrofits. Multi-criteria boards to assess the decision-making process are reviewed, analysed, and categorised under an architectonic perspective. Some examples are presented, with different packages of measures, from deep to non-invasive energy retrofits. Passive and active energy generation systems, together with control and management strategies, are the physical elements identified with the potential to improve buildings' energy efficiency. From a practice approach, this literature review identifies the concept of performance-based architectural design to optimise the planning and design of buildings' energy retrofits. In addition, tools such as Building Information Modelling are described as part of optimisation processes, as they enable designers to rapidly analyse and simulate a building's performance at the design stage. [ABSTRACT FROM AUTHOR]

Abstract: In the European Union, promotion of renewable energies, in particular wind energy, has become a fundamental vector of the strategy to tackle the challenges associated with the growing awareness of environmental matters. All over Europe, aggressive incentive schemes, e.g. feed-in tariffs, came into force to promote renewable technologies. In Portugal, those tariffs are applicable for a definite period of the project’s lifecycle, typically 15–20years, after which the legislation establishes a remuneration method based on market prices. This work’s purpose is to examine, from a technical and economical perspective, the operation of a wind producer when, in the future, he will be forced to compete into the electricity market. Accordingly, a simulator of a day-ahead market is implemented using a market splitting model and the economic outcome of a wind farm is assessed, considering various strategies. The results gathered show its great dependency on market prices volatility, production forecast accuracy, balancing prices and liquidity and frequency of intraday markets. A few actions are identified to mitigate some drawbacks associated with the wind farm operation in a market environment. [Copyright &y& Elsevier]

This study aims to analyse whether the Australian commitment to the Paris Agreement in 2016 and national energy policies will have a visible effect in decreasing the historical dependence of the NEM (National Electricity Market) on fossil fuels by 2030 and consequently decreasing the carbon emissions generated. In this paper, we model the 2030 electricity mix in the NEM in Australia. EnergyPlan , which is the modelling tool adopted for this study, is described and a reference model is conceived and calibrated based on the 2018 electricity situation on the NEM. The simulations are implemented considering three different supply scenarios and three potential electricity demands, to evaluate how different variables can influence the NEM electricity mix by 2030. This study concludes that by 2030 wind and solar power (including rooftop-PV systems) will be the major renewable energy contributors in the NEM, as opposed to 2018 where hydropower represented the main renewable energy source. Nonetheless, the electricity system in 2030 will continue to rely on fossil fuels, which will account for more than 50% of the final energy mix in every scenario, depicting that new efforts will still be needed beyond 2030. • We foresee the electricity mix in Australia by 2030. • We study three generation and three demand scenarios. • Fossil fuels will still account for more than 50% of the final electricity mix. • We expect a visible CO2 emissions reduction, due to the bet in RES in recent years. [ABSTRACT FROM AUTHOR]

As the demand for renewable energy sources energy grows worldwide, small-scale urban wind energy (UWE) has drawn attention as having the potential to significantly contribute to urban electricity demand with environmental and socio-economic benefits. However, there is currently a lack of academic research surrounding realizable UWE potential, especially in the South African context. This study used high-resolution annual wind speed measurements from six locations spanning Cape Town to quantify and analyze the city's UWE potential. Two-parameter Weibull distributions were constructed for each location, and the annual energy production (AEP) was calculated considering the power curves of four commonly used small-scale wind turbines (SWTs). The two Horizontal Axis Wind Turbines (HAWTs) showed higher AEP and capacity factors than Vertical Axis Wind Turbine (VAWT) ones. A diurnal analysis showed that, during summer, an SWT generates the majority of its electricity during the day, which resembles the typical South African electricity demand profile. However, during winter, the electricity is mainly generated in the early hours of the morning, which does not coincide with the typical load demand profile. Finally, the calculation of Levelized Cost of Electricity (LCOE) showed that SWT generation is more expensive, given current electricity market conditions and SWT technology. The study provides a detailed, large-scale and complete assessment of UWE resources of Cape Town, South Africa, the first of its kind at the time of this work. [ABSTRACT FROM AUTHOR]