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Reduced storage and balancing needs in a fully renewable European power system with excess wind and solar power generation
Abstract
The storage and balancing needs of a simplified European power system, which is based on wind and solar power generation only, are derived from an extensive weather-driven modeling of hourly power mismatches between generation and load. The storage energy capacity, the annual balancing energy and the balancing power are found to depend significantly on the mixing ratio between wind and solar power generation. They decrease strongly with the overall excess generation. At 50% excess generation the required long-term storage energy capacity and annual balancing energy amount to 1% of the annual consumption. The required balancing power turns out to be 25% of the average hourly load. These numbers are in agreement with current hydro storage lakes in Scandinavia and the Alps, as well as with potential hydrogen storage in mostly North-German salt caverns.
... Reports show that demand response could improve load following capability of the power systems [2][3][4]. Energy storage also has the potential to improve grid flexibility and increase grid penetration of variable renewable energy resources while curtailment was reported to lead to high penetration at reduced storage and conventional balancing resources [1,[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. In a recent study, the link between curtailment, penetration and storage need was reported to play a significant role in system design during energy transition [24]. ...
... Particularly, the study by [6] reported that resource complementarity carries multi-dimensional benefits to the system. Even though there is a clear consensus that complementarity of resources, such as wind and solar technologies, leads to a smoothing effect that may reduce ramping requirements and transmission congestion while also significantly improving grid matching of these resources [4,5,20,[22][23][24][25][26][27][28][29], the magnitude of this benefit against other measures and how this could be implemented during system design is not yet clear. ...
... Impacts of complementarity on energy storage were examined in studies by [5,7] for the European power system and [6] for the Californian power system. Due to significant differences in underlying assumptions and methods as well as reporting, a detailed comparison was difficult. ...
Resource complementarity carries significant benefit to the power grid due to its smoothing effect on variable renewable resource output. In this paper, we analyse literature data to understand the role of wind-solar complementarity in future energy systems by evaluating its impact on variable renewable energy penetration, corresponding curtailment, energy storage requirement and system reliability. Results show that wind-solar complementarity significantly increases grid
penetration compared to stand-alone wind/solar systems without the need of energy storage. However, as capacity increases, the capability of complementarity to increase grid penetration approaches its limit due to the reduced matching of output to the load profile and pursuant increase in excess generation. Thus, achieving very high penetration requires appropriately designed energy storage and curtailment. Yet, even at higher grid penetration, complementarity carries significant
multidimensional benefits to the power system. The most important observation was the achievement of very high grid penetration at reduced energy storage and balancing requirements compared to
stand-alone systems. Researchers reported that using the same energy storage capacity, wind-solar complementarity led to significantly higher penetration of up to 20% of annual demand compared to stand-alone systems. In addition, by coupling to curtailment as an enabler, and related dispatch flexibility that comes with storage application, lower balancing capacity need was reported at higher penetration. Wind-solar complementarity was also found to reduce ramping need while contributing to improved system adequacy. Complementarity from other dispatchable renewable resources further reduces storage need and curtailment and improve system reliability, whereas power grid integration and relative cost changes allow for further optimisation while transitioning to 100% renewable energy.
... To supplied by renewable powered BESS, sizing and optimisation of storage, considering the whole grid supply and demand scenario, needs to be assessed. Some studies have examined the sizing of energy storage for grid-level peak demand management, but they are restricted to investigation into the potential replacement of an existing fossil-fuel based grid with 100% RES [46] or storage sizing and demand management for a fully renewable grid [47,48]. Especially, the analysis in Ref. [46] argued that two thirds of coal generation from Alberta electricity grid could be replaced by renewables but that would require a large size of battery (350MW/350 MWh) and gas power plants as backup sources to meet peak demands. ...
... The charge and discharge of the BESS can be modelled as Eq. (3) [47]: ...
... The maximum size of the infinitely large storage calculated in Eq. (5) works well where the average excess energy available to store in batteries with losses is equal to or less than the average excess demand at the grid. If the opposite is true then the batteries' storage filling level will drift in time by storing more energy than is required to discharge to meet the demand at the grid [47]. In such a situation the selection of maximum storage size using Eq. ...
With more and more renewable energy sources (RES) going into power grids, the balancing of supply and demand during peak times will be a growing challenge due to the inherent intermittency and unpredictable nature of RES. Grid level batteries can store energy when there is excess generation from wind and solar and discharge it to meet variable peak demand that is traditionally supplied by combined cycle gas turbine (CCGT) plants. This paper assesses the potential of battery storage to replace CCGT in responding to variable peak demand for current and future energy scenarios (FES) in the UK from technical and environmental perspectives. Results from technical analysis show that batteries, assuming size is optimised for different supply and demand scenarios proposed by the National Grid, are able to supply 6.04%, 13.5% and 29.1% of the total variable peak demand in 2016, 2020 and 2035, respectively while CCGT plants supply the rest of the demand. Particularly, to phase out CCGT variable generation from the UK grid in 2035, electricity supply from wind and solar needs to increase by 1.33 times their predicted supply in National Grid's FES. The environmental implications of replacing CCGT by batteries are studied and compared through a simplified life cycle assessment (LCA). Results from LCA studies show that if batteries are used in place of CCGT, it can reduce up to 87% of greenhouse gas emissions and that is an estimated 1.98 MtCO2 eq. for an optimal supply, 29.1%, of variable peak demand in 2035.
... Some studies have assessed the benefits from the negatively correlated seasonal cycles of wind and solar resources over Europe [353,223]; or the synergies of wind power in northern Europe and solar power in the MENA region [309,524,480]. Impact of complementarity on energy storage is examined for the European [252,251] and Californian [490] power systems reporting a decrease in storage needs and balancing capacity requirements which increase the grid RE penetration. Instead of evaluating the benefits from complementarity, the majority of studies focus on assessing the spatial and temporal variability of solar resources [231,91], PV output [146,409], their implications on smart grid [487] and on the value of solar power in electricity markets [115]. ...
... In fact, so far, existing research works-focusing on optimal renewable-based mix-address questions related either to the minimization of variability only or to the minimization of cost of production only. For instance, Alhamwi et al. apply, for Morocco, the standard deviation of mismatch between demand and RE production and the so-called storage model approach adapted from previous contributions [251,252] to quantify the optimal mix of a 100% solar-wind scenario [50], and of solar-wind-hydropower combination [51,49]. Weitemeyer et al. [541] use the same approach for the European power supply. ...
... Different criteria are thus important when selecting a suitable optimization approach: (i) ability to characterize the variability (i.e., risk of not covering the load), providing a better adequacy risk assessment of alternative technologies; and (ii) ability to evaluate the cost impact on the penetration of given technology. Therefore, instead of minimizing the economic costs alone [299,113] or carbon costs [377] or balancing needs alone [51,541,252] or/and transmission needs [454,84,85] or applying a range of uncertainty to future cost of production generation and storage technologies [479] or minimizing the difference between the benefits and costs [284,156,451], approaches based on the Mean-Variance Portfolio (MVP) optimization rely on some measures of the variance of the RE production in addition to its expectation. The MVP do not reflect least-cost electricity systems in terms of investment and operational costs, but an optimized operational behavior taking into account all these elements, i.e., total costs, resource variability making use of regional and technological synergies, in order to leverage weaker correlations between production sites and sources, to minimize the variability of the production or production-demand mismatch once aggregated over regions, and to avoid the construction of RE power over-capacities and consequently to lower economic costs. ...
It appears that at the moment, many countries tend to favor Concentrated Solar Power (CSP) combined with its low-cost Thermal Energy Storage (TES) system over Photovoltaic (PV) as it can enhance the resilience of their energy system. However, their interplay in optimal mixes has not yet been addressed deeply enough by any study and particularly to confirm this perception in future warming climate. For instance, if the judging criteria is only money, does PV stand at a leading position? but, it is not fairly to justify those two technologies merely by cost but also by the correlation of production with peak consumption. Here comes another question: PV or its counterpart CSP? as they have distinct sensitivity to temperature and clouds. Moreover, if PV is coupled with expensive Battery Energy Storage (BES), does this mean CSP-TES will be replaced by PV-BES? This thesis discusses a set of scenarios of large-scale solar integration with wind in optimal Moroccan prospective mix under different penetration levels, storage configurations and combinations of renewable (RE) technologies. We take as objective not only to maximize the RE production, but also to reduce its variability. This Mean-Variance approach is implemented in the E4CLIM model, which we have adapted to the four Moroccan electricity zones to fit the demand model and correct biases in the Capacity Factors (CFs) calculated using climate data; ignoring the grid constraints and exchanges of electricity with neighboring countries. We add a maximum-total cost constraint to the optimization problem; and propose a method to define the rental cost of each production technology taking their dependence on the hours of production into account, which is designed in the developed storage model implemented to BES and to the added CSP-TES modules. We present, for each penetration regime, some ratios that contribute to determine what region a given capacity will be assigned to; and propose some production-demand adequacy diagnostics to evaluate which technology displaces more expensive fossil fuel generators during peak, mid and base load hours; and which one increase or reduce the curtailment. The first study addresses the questions associated with wind/PV/CSP/CSP-TES integration while the second study determines the conditions under which CSP-TES can provide an advantage against PV-BES so as to be part of the mix until a more advantageous condition prevents its integration; by examining how the integration of CSP and storage would influence the benefits from time-space complementarity in the actual climate. We conclude that contrary to the integration of CSP/CSP-TES with PV, the addition of BES to PV reveals a higher sensitivity of the mixes to solar technologies not only at low penetrations due to the reduced variability but also at high penetrations due to the differences in the storage capacity and cost. Finally, the third study assesses the impact of climate change on the resources and their implications on CFs and demand by the end-21st century relative to the historical observed forcing. We find that there are some indications of a potential impact in mixes with high penetrations but which are trivial with the eventual cost reduction effect on capacity pathways projected by climate models.However, climate change is unlikely to have a discernible effect on optimal mixes with low proportions of REs, but the key message is that the future impact on each technology is considered to be highly uncertain. We discuss the sources of uncertainty and the main options for climate-resilient RE mixes.
... Some studies have assessed the benefits from the negatively correlated seasonal cycles of wind and solar resources over Europe [353,223]; or the synergies of wind power in northern Europe and solar power in the MENA region [309,524,480]. Impact of complementarity on energy storage is examined for the European [252,251] and Californian [490] power systems reporting a decrease in storage needs and balancing capacity requirements which increase the grid RE penetration. Instead of evaluating the benefits from complementarity, the majority of studies focus on assessing the spatial and temporal variability of solar resources [231,91], PV output [146,409], their implications on smart grid [487] and on the value of solar power in electricity markets [115]. ...
... In fact, so far, existing research works-focusing on optimal renewable-based mix-address questions related either to the minimization of variability only or to the minimization of cost of production only. For instance, Alhamwi et al. apply, for Morocco, the standard deviation of mismatch between demand and RE production and the so-called storage model approach adapted from previous contributions [251,252] to quantify the optimal mix of a 100% solar-wind scenario [50], and of solar-wind-hydropower combination [51,49]. Weitemeyer et al. [541] use the same approach for the European power supply. ...
... Different criteria are thus important when selecting a suitable optimization approach: (i) ability to characterize the variability (i.e., risk of not covering the load), providing a better adequacy risk assessment of alternative technologies; and (ii) ability to evaluate the cost impact on the penetration of given technology. Therefore, instead of minimizing the economic costs alone [299,113] or carbon costs [377] or balancing needs alone [51,541,252] or/and transmission needs [454,84,85] or applying a range of uncertainty to future cost of production generation and storage technologies [479] or minimizing the difference between the benefits and costs [284,156,451], approaches based on the Mean-Variance Portfolio (MVP) optimization rely on some measures of the variance of the RE production in addition to its expectation. The MVP do not reflect least-cost electricity systems in terms of investment and operational costs, but an optimized operational behavior taking into account all these elements, i.e., total costs, resource variability making use of regional and technological synergies, in order to leverage weaker correlations between production sites and sources, to minimize the variability of the production or production-demand mismatch once aggregated over regions, and to avoid the construction of RE power over-capacities and consequently to lower economic costs. ...
... Using an optimization they also quantify the necessary backup storage capacity. In a further paper of these authors, this concept is extended to hourly balancing power and annual balancing energy required depending on the share of wind and PV built in Europe [18]. While these studies model potentials of RE with high spatial resolution and for a large territory (e.g., the whole of Europe) and although some of the papers calculate RE output with a higher temporal resolution (e.g., hourly), most studies in this research field are more interested in the spatial component of RE generation and thus use mostly annual values. ...
... • High temporal and regional resolution • Focus exclusively on supply [16][17][18]23,35,36] Demand or DR simulation models • Simulation of individual demand drivers such as single consumers • Future load peaks • Input for supply-side energy system models • Partly high temporal and spatial resolution • Focus exclusively on demand [3,24,25] Urban expansion planning models ...
Decentralized systems seeking to balance electricity supply and demand regionally are increasingly being discussed. Regional flexibility concepts, however, require spatially and temporally highly resolved knowledge. To provide this, we investigate the 2030 demand, supply, and demand-side flexibility for the German NUTS-3 regions. We (1) model the hourly regional electricity demand and supply, (2) cluster regions with regard to the regional demand and supply fit and (3) evaluate demand response for the identified clusters. While in windy or industrialized regions, the impact of demand response is low, in urban regions on the other hand, the effectiveness of flexible end uses is higher and residual load is flattened. Regions with medium-sized cities or those with smaller energy-intensive industries show a good regional fit. Here, demand response can be used very effectively to increase the regionally consumed share of electricity.
... This is not a universal strategy and can give satisfactory results only under some assumptions about local weather conditions. This was also a conclusion drawn in further works by the same authors cited above [27,28] which suggest the application of some means for long-term energy storage or keeping some balancing reserves based for example on thermal power plants [29]. ...
... Such an approach requires advanced analysis and is sensitive to the future network changes or reconfigurations. The other solution consists in, as mentioned above, the application of large-scale energy storage to hold energy during overproduction periods and to release it during the highest demand periods [27,28]. Solutions based on energy storage in batteries, flywheels or superconducting magnets have become more and more popular but pumped storage hydroelectricity is the most common solution. ...
Network working conditions are influenced noticeably by the connection of renewable energy sources to distribution networks. This becomes more and more important due to the increase in renewable energy source penetration over the last few years. This in turn can lead to a mass effect. As a result, the classical open network model with simple unidirectional direction of energy flow has been replaced with an active model that includes many local energy sources. This paper deals with the analysis of long- and short-term changes in power and energy generated by three types of renewable energy sources with similar rated power and which operate in the same region (i.e., located no more than tens of kilometers away). The obtained results can be a starting point for a broader evaluation of the influence of renewable energy sources on power quality in power systems, which can be both positive (supply reliability) and negative (voltage fluctuations and higher harmonics in current and voltage waveforms). It is important not only to correctly place but also to assure the diversity of such sources as it has been confirmed by the source variability coefficient. The long-term analysis allows us also to estimate the annual repeatability of energy production and, furthermore, the profitability of investment in renewable sources in a given region.
... Heide et al. [17] analysed the different seasonal supply patterns of wind and solar energy in applying 100% RE in the European electricity system. In subsequent studies, energy storage's role in mismatched power generation from wind and solar power is reviewed [18]. Schlachtberger et al. [19] examined the optimum electricity system for achieving emission reduction targets in Europe using a techno-economic model. ...
This study assesses Indonesia power system's transition pathway to reach 100% renewable energy in 2050. The pathway is determined based on least-cost optimisation in the TIMES model comparing 27 power plants and 3 energy storage technologies and using hourly demand and supply operational profile using 24-hour time slices. From this study, it can be concluded that nuclear and solar PV utility-scale will play an essential role up to 16% and 70% of total electricity production, corresponding to 1,396 TWh in 2050. The investment cost in 2050 is three times higher, and the emission is one-sixth lower than in Business as Usual, equal to 95 billion USD and 215 million tons of CO2-eq. The RE mix based on current policy generates a higher CO2 abatement cost, 120 USD/ton CO2-eq in 2050. The optimistic demand projection will increase the coal by 82% in Business as Usual also nuclear and solar PV utility-scale of about 126% and 62% in 100% RE, respectively. The exclusion nuclear in power system increase the installed capacity of solar PV utility-scale and battery, increase land requirement by 78% to 83%, increase the variability of supply from other power plants and batteries, and increase 9.7% of electricity production cost.
... Due to the rapid consumption and environmental pollution of fossil fuel, the renewable energy sources (RESs) should be integrated into the power system in order to meet the future requirements. RESs (solar energy, wind energy, ocean energy, bioenergy, geothermal energy, etc.) have been installed in many places around the world especially in the rural places [1][2][3][4][5]. Wind energy and solar energy are the most prevalent renewable energy sources. ...
In this paper, a new application of Equilibrium Optimizer (EO) is proposed for design hybrid microgrid to feed the electricity to Dakhla, Morocco, as an isolated area. EO is selected to design the microgrid system due to its high effectiveness in determining the optimal solution in very short time. EO is presented for selecting the optimal system design which can minimize the cost, improve the system stability, and cover the load at different climate conditions. Microgrid system consists of photovoltaic (PV), wind turbine (WT), battery, and diesel generator. The objective function treated in this paper is to minimize the net present cost (NPC), respecting several constraints such as the reliability, availability, and renewable fraction. The sensitivity analysis is conducted in two stages: Firstly, the impact of wind speed, solar radiation, interest rate, and diesel fuel on the NPC, and levelized cost of energy (LCOE) is analyzed. Secondly, the influence of size variation on loss of power supply probability (LPSP) is investigated. The results obtained by EO are compared with those obtained by recent metaheuristics optimization algorithms, namely, Harris Hawks Optimizer (HHO), Artificial Electric Field Algorithm (AEFA), Grey Wolf Optimizer (GWO), and Sooty Tern Optimization Algorithm (STOA). The results show that the optimal system design is achieved by the proposed EO, where renewable energy sources (PV and WT) represent 97% of the annual contribution and fast convergence characteristics are obtained by EO. The best NPC, LCOE, and LPSP are obtained via EO achieving 74327 $, 0.0917 $/kWh, and 0.0489, respectively.
... Clearly the prevalence of electric heating means that there are demand peaks during the polar night (when solar power generation is negligible) [3]. [4]. For such reasons, the Arctic seems an unlikely place, at first glance, to develop solar energy. ...
In this manuscript we evaluate the potential of photovoltaic systems to meet some dedicated energy demand in specific geographic locations. Our approach is based on location-specific constraints rather than on pre-established, location-independent methodologies or assumptions. First, we propose that a thorough analysis of the socio-economic and technical possibilities of a location must act as the guide to optimize the deployment of renewables. This requires detailed knowledge of the area. Second, we propose that optimizing the exploitation of renewables by focusing on a particular location can also lead to successful outcomes with global impact. With this in mind we focus our attention on the Arctic region, known for its highly seasonal solar availability, and the challenge posed by increasing cruise ship tourism and corresponding air pollution. Our study targets Tromsø city, Norway, and we show that solar energy generation could be a strong contribution for charging cruise ships in the summer with no need for generation and transmission investments. Our study opens the door to shifting to a location specific paradigm to seek sustainable energy solutions with the possibility to have a global impact.
... These models consider the production and the demand of electrical energy based on historical data and can assess the impacts of different scenarios, e.g., for the transmission through power grids or local storage of electrical energy. Heide et al. [15,16] examined a simplified European power system which relies mostly on renewable energies, in terms of storage requirements and balancing needs. They concluded that the minimum need of required energy storage occurs at an optimal mix of about 60% wind and 40% solar power generation for a 100% renewable energy scenario. ...
Solar and wind energy play an important role in current and future energy supply in Germany and Europe. The production of renewable energy highly depends on weather conditions resulting in an increasing impact of meteorological fluctuations on energy production. Here, climatological data of solar radiation and wind speed are used to simulate hourly capacity factors for solar and wind energy for Germany from 1995 to 2015. Using renewable energy production data for 2015 these data are converted into time series of generated electrical power. Events with very low energy production, i.e., shortfall events, have been identified and related to large-scale weather regimes over Europe.
In Germany, on average about twice as much electrical energy is generated from wind compared to solar radiation; in addition there is a distinct annual cycle with an equal share of generated energy during summer and a 70/30% wind/solar share in winter. There is an unambiguous dependency of wind and solar energy production on weather regimes. Shortfall events in Germany only occur in winter, often associated with a high pressure system over Central Europe. During this weather regime, the renewable energy potential in Northern and Southeastern Europe is above average, possibly allowing to balance shortfall events in Germany.
... On a similar note to the generation cases, Kitzing [34] maximized the Sharpe ratio (the mean-risk ratio of a resource) with respect to the different support levels (price levels that the renewable generation does not fall below). Another interesting approach taken in Heide et al. [35] aims at minimizing the storage energy capacity, the balancing energy, and the balancing power in their different combinations (this case is a double minimization instead of a parallel maximization and minimization, but the concept remains the same, as the two minimized quantities work in opposite ways). ...
We analyzed the role of predictable and unpredictable variability in the identification of optimal renewable energy mixes in an electricity system. Renewable energy sources are the fastest growing energy generation technology, but the variable nature of production linked to climate variability raises structural, technological and economical issues. This work proposes the differentiation of the treatment applied to predictable and unpredictable variability in the context of Markowitz portfolio theory for optimal renewable deployment. The e4clim model was used as a tool to analyze the impact of predictable sources of generation variability on the optimal renewable energy mixes. Significant differences appeared, depending on the consideration of risk, all of them showing room for improvement with respect to the current situation. The application of the methods developed in this study is encouraged in mean-variance analyses, since its contribution favors scenarios where unpredictable variability in the climate-powered renewable energy sources are considered for their risk introduction.
... Fortunately, wind generation typically shows the opposite seasonal trend. 97 Furthermore, most of the world's population lives in the Sun Belt close to the equator where the solar resource is abundant and seasonal variation is low (see Figure 4). Tropical locations, despite repeating weather patterns such as monsoon, show low seasonal variation in solar resources. ...
Thanks to fast learning and sustained growth, solar photovoltaics (PV) is today a highly cost-competitive technology, ready to contribute substantially to CO 2 emissions mitigation. However, many scenarios assessing global decarbonization pathways, either based on integrated assessment models or partial-equilibrium models, fail to identify the key role that this technology could play, including far lower future PV capacity than that projected by the PV community. In this perspective, we review the factors that lie behind the historical cost reductions of solar PV and identify innovations in the pipeline that could contribute to maintaining a high learning rate. We also aim at opening a constructive discussion among PV experts, modelers, and policymakers regarding how to improve the representation of this technology in the models and how to ensure that manufacturing and installation of solar PV can ramp up on time, which will be crucial to remain in a decarbonization path compatible with the Paris Agreement.
... Their results showed that an integrated CSP-WE system not only improved the electrical load compared to standalone wind technology but also a higher generating capacity was obtained. Other studies [8,195,196] revealed that combining CSP plants with wind farms can improve the electrical load matching conducted. Vick and Moss [195] compared the electrical generation from renewable energy systems (i.e. ...
Integration concept of energy resources can complement between the competing energy technologies. This manuscript presents a comprehensive review on the state-of-the-art of concentrated solar power (CSP) integration technology with various energy sources. Compared to CSP alone, integration of CSP and fossil fuel provides promising solution to solar energy intermittence, emissions and installation cost reduction, with 25% increase in electric power generation. On the other hand, integration of CSP with other sources such as geothermal and biomass can supply dispatchable power with almost zero emissions. The electricity produced via integrated CSP and photovoltaic (PV) has better power quality and less cost compared to that produced by PV alone or CSP alone, respectively. Integration of CSP and wind energy can meet peak demand, reduce power fluctuation and provide electrical power at a high capacity factor. However, the lack of reliable biomass, geothermal and wind data with the solar availability at specific locations is the main obstacle for the acceptance and further deployment of hybridization systems. The advantages and limitations of the hybrid technologies presented in this paper according to the literature are reviewed. Moreover, future directions of CSP such as production of hydrogen, solid particles receivers and the integration of supercritical carbon dioxide cycle are also discussed.
... In Europe, Heide et al [5] optimized the photovoltaic (PV) and wind turbine capacities in each country to reduce the need for storage given the load curve. The effect of excess generation was then investigated in [6]. Rasmussen et al [7] adopted a similar approach but aggregated at the European level. ...
With large parts of the world moving toward renewable energies, there is an urgent need to organize this large-scale transition effectively. This paper presents a new methodology to guide the planning and siting of renewable electricity generation for countries or larger geographical regions. Its flexible approach accounts for the specific boundary conditions, constraints and available resources of the region of interest and enables solutions that optimize the interplay between the various types of generation. Evolution strategy permits a simultaneous optimization of the placement and the share of renewable electricity generation technologies that are to be added to a system, while most efficiently combining the new with the existing electricity generation and respecting the constraints of the electrical grid. Using Switzerland as case study, we demonstrate the method's ability to devise national installation scenarios that are efficient, realistic with respect to land use and grid infrastructure and reduce significantly the need for seasonal storage. We show how the spatio-temporal variability of weather-driven electricity generation can be exploited to benefit the electrical system as a whole.
... Previous research has found that the grid dispatch flexibility might increase using curtailment with [71] and without [72] storage. The authors of [73,74] also found that the use of curtailment would reduce the required storage system's capacity. The curtailment-storage-penetration nexus concept has been recently addressed by the authors of [75] which provided empirical-based evidence that power systems which are designed with curtailment are likely to cost less than the ones which are designed without curtailment. ...
Ensuring the supply of affordable energy, improving energy efficiency and reducing greenhouse gas emissions are some of the priorities of the governments of several countries. The pursuit of these energy goals has triggered interest in the exploration and usage of Renewable Energy Sources (RES), which can be particularly appropriate for island systems as is the case of Cape Verde. This work proposes a generation expansion planning model for Cape Verde considering a 20 years’ period. Different scenarios were analysed, each one representing a possible RES contribution for electricity production, reaching a 100% RES share. The results demonstrate that the increase of the RES in the system will lead to an increase of the total cost of energy. However, both CO2 emissions and external energy dependency of the country significantly decrease. The seasonality of the RES resources, and in particular of wind power is shown to be one of the most important challenges for the effective uptake of such a renewable power system. While the proposed model allowed already to present some useful scenarios, it becomes also evident the need to expand the analysis, and the paper concludes with directions for future research.
... Some studies show that it is possible to integrate high levels of renewable electricity via a combination of wind and solar with flexible and dispatchable renewable technologies (e.g. hydro-electricity with dams, geothermal, biomass) and demand side response measures (Lund and Mathiesen, 2009;Heide et al., 2011;Rasmussen et al., 2012;Schlachtberger et al., 2016;Diesendorf and Elliston, 2018). Other studies question the degree to which reliability can be maintained when factors such as temporal and spatial variability are also considered (Heard et al., 2017). ...
This paper explores the trends, step changes and innovations that could impact the integration of renewable energy into electricity systems, explores interventions that may be required, and identifies key areas for policy makers to consider. A Delphi approach is used to collect, synthesise, and seek consensus across expert viewpoints. Over sixty experts across a range of geographies including the US, Europe, New-Zealand, Australia, Africa, India and China participated. They identified 26 trends, 20 step changes, and 26 innovations that could lead to major shifts in the design, operation, or management of electricity systems. Findings suggest that key challenges are not technological. Instead they are with delivering an aligned vision, supported by institutional structures, to incentivise, facilitate, and de-risk the delivery of a completely different type of energy system. There is a clear role for government and policy to provide a future energy vision and steer on strategic issues to deliver it; to create space for new actors and business models aligned with this vision; and to create an environment where research, development, demonstration and deployment can promote technologies, system integration and business model innovation at a rate commensurate with delivering net-zero electricity systems.
... (4) The energy from the purge stream is ignored since it is difficult to recover the heat from process flare. (5) The compressors modelled in this work are assumed to be isentropic with an efficiency of 75%. (6) All mechanical work and process heating (except the integrated heating) are powered by electricity only. ...
Chemical process electrification and renewable energy integration facilitate one another along the pathway towards a greener industry. However, integrating intermittent and variable renewable power into large-scale chemical processes, which conventionally are preferred to operate at a steady-state with a constant load, could lead to prohibitive costs if intermittency is addressed solely by energy storage. Here, we consider the concept of a flexible chemical process which can operate with a variable load throughout the year while meeting a specified annual production target. Using methanol production via carbon dioxide hydrogenation as a case study and by means of process conceptual design and optimisation, we investigate how the over-sizing of flexible process units and the introduction of intermediate storage in the chemical process offer the possibility to improve the overall performance of systems. The impact of the characteristics of renewable power is also explored by performing the analysis using meteorological data from two locations dominated respectively by wind and solar energy. This study shows clear potential benefits of process flexibility when the renewable energy supply is highly variable and is to achieve a high level of penetration. For a 100% renewable production, the introduction of flexibility reduces the levelised cost of methanol by approximately 21 and 34% for the two case study locations, respectively. The cost attribution reveals further insights into the origin of the economic advantages through examining the comparative costs of chemical production, energy generation, intermediate product storage and renewable energy storage. The learning from this work suggests that incorporating process flexibility through a holistically optimised design of energy storage and chemical production has the potential to offer an economically viable route to large-scale green chemical production through renewables-enabled electrification.
... Austria, Switzerland, Norway, and Sweden have the largest available energy storage capacities in PSPs [25]. The countries with the highest pumped storage installed capacity are Italy (7685 MW), Germany (6364 MW), Spain (6117 MW), France (5837 MW), and Austria (5596 MW) [22]. ...
This paper presents a technical review of the existing pumped storage plants in Norway. The power system is changing towards integrating more and more renewable energy, especially from variable renewable energy sources, leading to new challenges for the security of supply, power, frequency, and voltage regulation. Thus, energy storage options are a highly researched topic in the current situation. Even though there are many energy storage technologies, most are optimal for short term grid balancing, and few are capable of providing long term (weekly or seasonal) storage. One exception is pumped storage, a mature technology capable of delivering both short term and long term energy storage. In this paper, the ten existing pumped storage plants in Norway are presented, several of which are capable of seasonal energy storage. The Norwegian knowledge and experience with pumped storage plants technology is provided as a basis for future research within the field. The review provides information about energy production and storage capabilities, construction costs, specific costs per kW and stored kWh, electromechanical installation, technical specifications, and operational experience with focus on the design of the tunnel system layout. The data presented in this review are unique and previously unpublished. A discussion and conclusions regarding the current situation, trends, and future outlook for pumped storage plants in Norway within the European power market are provided.
... Therefore, in recent years, investigations have been conducted into the possibility of introducing energy-storage systems to support wind-power and PV generation, whereby different storage options can be considered, that are applicable to both larger and smaller systems. The work by (Heide et al. 2011) examines Europe's storage and balancing needs for a fully renewable electric power system (i.e., 100% renewable electrical energy on an annual basis) which often has excess instantaneous wind and solar power generation. A method gaining more and more importance for dealing with the RES fluctuations and ensuring a supply/demand balance is to promote active demand response and cross-sector integration (Ponnaganti et al. 2018). ...
This volume constitutes a collection of research that brings to the fore one of the most important global challenges facing the world today: the energy transition. Addressing this challenge and achieving the sustainable development goals calls for international collaboration, and as the chapters in this report illustrate, bringing together scholars from different disciplines, backgrounds and geographies offers a holistic perspective for a sustainable transition. Moreover, the report simultaneously addresses the development, context, implementation and dissemination of energy transition solutions.
... transformation in substations) and the simulated feed-in of different power plants, which is the electric energy generated by, for instance, a wind turbine or a heating power station. A multiyear simulation of the power grid allows establishing strategies for energy storage and grid expansion (Heide et al., 2011;Zerrahn and Schill, 2017). ...
To accurately calculate the impact of renewables on power production in complex electric power grids, high-resolution and ideally seamless data within the planetary boundary layer are required. Therefore, the quality of different regional reanalyses and hindcasts is evaluated with respect to the representation of the planetery boundary layer and related sub-daily processes. On the one hand, high resolution regional reanalysis from the UERRA (UE-SMHI, UE-UKMO) and a similar project (COSMO-REA6) are considered. On the other hand, two hindcasts based on the COSMO-REA6 configuration are included in this study, i.e. a simulation with perfect boundaries and a simulation additionally utilizing spectral nudging. The focus of the evaluation is on measurements at four flux towers that are not part of any assimilation procedure. In this paper, we will show that the model’s quality depends on both the complete model system – assimilation method, resolution and physical parameterization – as well as on the performance measure. The daily cycle is best depicted by the hindcasts and even COSMO-REA6 hardly introduces spurious variability. UE-SMHI (3D-Var) suffers from spin-up in particular visible at the elevated levels, whereas the spin-up is damped in UE-UKMO (4D-Var). Investigation of atmospheric stability reveals that diurnal variation of stratification is for the most part well reproduced, but strong deficits were found for all COSMO simulations in reproducing strong stratification and corresponding wind speed gradients. Moreover, an overestimation of superadiabatic lapse rates and corresponding overly weak turbulent mixing is found for UE-UKMO. Furthermore, a combination of ramp statistics and contingency tables is utilized to detect a clear advantage of sophisticated assimilation systems over hindcasts. The evaluation framework presented underpins the importance of ramp statistics and vertical measurement profiles, especially with respect to assessing long-term simulations.
... Third, we use perfect foresight assumption for operating the electrical storage capacity. These assumptions have been broadly used on the complementarity literature (e.g., [13][14][15]19,38,48,53,62,63] and many others . . . ) and none is expected to significantly influence the assessment of the sensitivity of the complementarity between CHP and solar PV/RoR hydropower described in this study. ...
Combined heat and power systems (CHP) produce heat and electricity simultaneously. Their resulting high efficiency makes them more attractive from the energy managers’ perspective than other conventional thermal systems. Although heat is a by-product of the electricity generation process, system operators usually operate CHP systems to satisfy heat demand. Electricity generation from CHP is thus driven by the heat demand, which follows the variability of seasonal temperature, and thus is not always correlated with the fluctuation of electricity demand. Consequently, from the perspective of the electricity grid operator, CHP systems can be seen as a non-controllable energy source similar to other renewable energy sources such as solar, wind or hydro. In this study, we investigate how ‘non-controllable’ electricity generation from CHP systems combines with ‘non-controllable’ electricity generation from solar photovoltaic panels (PV) and run-of-the river (RoR) hydropower at a district level. Only these three energy sources are considered within a 100% renewable mix scenario. Energy mixes with different shares of CHP, solar and RoR are evaluated regarding their contribution to total energy supply and their capacity to reduce generation variability. This analysis is carried out over an ensemble of seventeen catchments in North Eastern Italy located along a climate transect ranging from high elevation and snow dominated head-water catchments to rain-fed and wet basins at lower elevations. Results show that at a district scale, integration of CHP systems with solar photovoltaic and RoR hydropower leads to higher demand satisfaction and lower variability of the electricity balance. Results also show that including CHP in the energy mix modifies the optimal relative share between solar and RoR power generation. Results are consistent across the climate transect. For some districts, using the electricity from CHP might also be a better solution than building energy storage for solar PV.
... For example,Heide et al. (2011) andRasmussen et al. (2012) employ a more elaborated time series analysis, which accounts for storage losses but not for charging limitations. ...
In the context of 100% renewable electricity systems, prolonged periods with persistently scarce supply from wind and solar resources have received increasing academic and political attention. This article explores how such scarcity periods relate to energy storage requirements. To this end, we contrast results from a time series analysis with those from a system cost optimization model, based on a German 100% renewable case study using 35 years of hourly time series data. While our time series analysis supports previous findings that periods with persistently scarce supply last no longer than two weeks, we find that the maximum energy deficit occurs over a much longer period of nine weeks. This is because multiple scarce periods can closely follow each other. When considering storage losses and charging limitations, the period defining storage requirements extends over as much as 12 weeks. For this longer period, the cost-optimal storage capacity is about three times larger compared to the energy deficit of the scarcest two weeks. Adding other sources of flexibility for the example of bioenergy, the duration of period that defines storage requirements lengthens to more than one year. When optimizing system costs based on single years rather than a multi-year time series, we find substantial inter-annual variation in storage requirements with the most extreme year needing more than twice as much storage as the average year. We conclude that focusing on short-duration extreme events or single years can lead to an underestimation of storage requirements and costs of a 100 % renewable system.
... The societal and political decision-making process is accompanied by energy system research, which proposed manifold approaches to support the integration of renewable resources. 2,3 These approaches include the large-scale integration of storage technologies, 4,5 the extension of the transmission grid, 6,7 the over-installation of renewable capacities, 8 the use of meteorological information to find the optimal spatial deployment, 9 or optimizing the mix of different renewable generation sources. [10][11][12] The question whether resources such as nuclear or fossil power plants with carbon capture and storage can help achieve the decarbonization of the power system has recently been addressed by Sepulveda et al. 13 and Brown and Botterund 14 (among others). ...
Optimization models are a widely used tool in academia. In order to build these models, various parameters need to be specified, and often, simplifications are necessary to ensure the tractability of the models; both of which introduce uncertainty about the model results. However, a widely accepted way to quantify how these uncertainties propagate does not exist. Using the example of power system expansion modeling, we show that uncertainty propagation in optimization models can systematically be described by quantifying the sensitivity to different model parameters and model designs. We quantify the sensitivity based on a misallocation measure with clearly defined mathematical properties for two prominent examples: the cost of capital and different model resolutions. When used to disclose sensitivity information in power system studies our approach can contribute to openness and transparency in power system research. It is found that power system models are particularly sensitive to the temporal resolution of the underlying time series.
... Thanks to ICT technologies which drive the sector to new heights. The Virtual Power Plant is one such technology-driven entity aimed at solving the technical-economic problems in renewable energy sources (Dotzauer et al., 2015;Houwing et al., 2009;Koraki and Strunz, 2017;Garcia et al., 2013;Heide et al., 2011;Hochloff and Braun, 2013;Petersen et al., 2013;Mashhour and Moghaddas-Tafreshi, 2010;Zamani et al., 2016;Candra et al., 2018). As named, a virtual power plant does not reflect reality like concrete and-turbine. ...
The growth of renewable energy technologies as an alternative source of power is a great boon to the rural masses where energy is predominantly a challenge. This paper focuses on studying the microeconomic benefits of the virtual power plant as a solution to the rural masses who either have no access to energy or has limited access. The model here uses HOMER as a tool for modelling the design. The simulation results discuss the profitability of the virtual power plant as a solution not only to the virtual power plant operator but also to the rural households while ensuring a sustainable income source with the use of solar power PV as a generator.Keywords: Virtual Power Plant; Levilised cost; Annualised Cost;JEL Classifications: D0, E0, Q4DOI: https://doi.org/10.32479/ijeep.9602
... For example,Heide et al (2011) andRasmussen et al (2012) employ a more elaborated time series analysis, which accounts for storage losses but not for charging limitations. ...
In the context of 100% renewable electricity systems, prolonged periods with persistently scarce supply from wind and solar resources have received increasing academic and political attention. This article explores how such scarcity periods relate to energy storage requirements. To this end, we contrast results from a time series analysis with those from a system cost optimization model, based on a German 100% renewable case study using 35 years of hourly time series data. While our time series analysis supports previous findings that periods with persistently scarce supply last no longer than two weeks, we find that the maximum energy deficit occurs over a much longer period of nine weeks. This is because multiple scarce periods can closely follow each other. When considering storage losses and charging limitations, the period defining storage requirements extends over as much as 12 weeks. For this longer period, the cost-optimal storage needs to be large enough to supply 36 TWh of electricity, which is about three times larger than the energy deficit of the scarcest two weeks. Most of this storage is provided via hydrogen storage in salt caverns, of which the capacity is even larger due to electricity reconversion losses (55 TWh). Adding other sources of flexibility, for example with bioenergy, the duration of the period that defines storage requirements lengthens to more than one year. When optimizing system costs based on a single year rather than a multi-year time series, we find substantial inter-annual variation in the overall storage requirements, with the average year needing less than half as much storage as calculated for all 35 years together. We conclude that focusing on short-duration extreme events or single years can lead to an underestimation of storage requirements and costs of a 100 % renewable system.
... This is a challenging task, solutions proposed by literature are manifold [1,2]. They include the large-scale integration of storage technologies [3,4], the extension of the transmission grid [5,6], the overinstallation of renewable capacities [7] or optimising the mix of different renewable generation sources, e.g. solar and hydro power [8], wind power and solar PV [9] or wind power and concentrated solar power [10]. ...
Power system expansion models are a widely used tool for planning powersystems, especially considering the integration of large shares of renewableresources. The backbone of these models is an optimization problem, whichdepends on a number of economic and technical parameters. Although theseparameters contain significant uncertainties, the sensitivity of power systemmodels to these uncertainties is barely investigated. In this work, we introduce a novel method to quantify the sensitivity ofpower system models to different model parameters based on measuring theadditional cost arising from misallocating generation capacities. The value ofthis method is proven by three prominent test cases: the definition of capitalcost, different weather periods and different spatial and temporal resolutions.We find that the model is most sensitive to the temporal resolution. Fur-thermore, we explain why the spatial resolution is of minor importance andwhy the underlying weather data should be chosen carefully.
... Using an optimization they also quantify the necessary backup storage capacity. In a further paper of these authors, this concept is extended to hourly balancing power and annual balancing energy required depending on the share of wind and PV built in Europe [170]. ...
Im Zuge der Transformation des Stromsystems werden regelbare, konventionelle Kraftwerke durch erneuerbare Energien ersetzt. Da ein Großteil der Stromerzeugung aus erneuerbaren Energien volatil ist, werden alternative Flexibilitätsoptionen benötigt, um zu jeder Zeit einen Ausgleich von Stromangebot und –nachfrage zu schaffen. Aus diesem Grund befasst sich die vorliegende Dissertation mit der Flexibilisierung der Stromnachfrageseite und geht dabei der Frage nach, inwieweit ein dezentral koordinierter Flexibilitätseinsatz aus lokaler sowie aus systemischer Perspektive vorteilhaft sein kann.
Aus der Volatilität und Dezentralität der Stromversorgung aus Photovoltaik- und Onshorewindenergie-Anlagen resultieren zwei Herausforderungen: Der große Bedarf an Flexibilität, die die volatile Stromerzeugung integriert sowie die zunehmende Komplexität des Stromsystems durch die hohe Anzahl Erneuerbarer-Energien-Anlagen und daraus resultierende bidirektionale Stromflüsse im Mittel- und Niederspannungsnetz. Angesichts dessen spielen dezentrale Energiesysteme eine wachsende Rolle in der Diskussion zur Weiterentwicklung des Elektrizitätssystems. Die vorliegende Dissertation adressiert die skizzierten Herausforderungen; sie besteht aus vier wissenschaftlichen Papieren und damit vier Bausteinen.
Der erste Baustein legt die Motivation dezentraler Energiesysteme dar. Diese sehen vor, Herausforderungen, die aus der zunehmend dezentralen Stromerzeugung resultieren, gleichsam auf dieser Ebene zu adressieren. Dazu wird die lokale Stromerzeugung stärker auf die lokale Nachfrage ausgerichtet, während gleichzeitig Teile der Nachfrage stärker als bislang flexibilisiert werden. Ein wesentlicher Treiber für die Umsetzung dezentraler Energiesysteme ist jedoch auch das Streben nach Energieautonomie. Im Rahmen des ersten Papiers wird daher am Beispiel der Stadt- und Landkreise Süddeutschlands für das Jahr 2030 betrachtet, welche Effekte auftreten, wenn die Energieautonomie auf Stadt- und Landkreisebene durch die verstärkt regionale Nutzung von erneuerbarem Strom erhöht wird. Hierzu wird auch der regionale Einsatz von Flexibilität in Form von Batteriespeichern simuliert. Es zeigt sich, dass eine deutliche Erhöhung der Kapazität Erneuerbarer-Energien-Anlagen in allen untersuchten Regionen wirtschaftlich vorteilhaft ist. Das Erreichen höherer Autarkiegrade verursacht jedoch zusätzliche Kosten und führt zu Überkapazitäten, obgleich die Abhängigkeit vom übergeordneten Stromsystem bestehen bleibt.
Der zweite Baustein der Dissertation nimmt Elektrofahrzeuge als eine vielversprechende Flexibilitätsoption in den Blick. Um das zukünftige techno-ökonomische Potenzial des gesteuerten Ladens für Deutschland zu quantifizieren, wird innerhalb dieses Bausteins von einem zentralen System ausgegangen. Im Rahmen der Untersuchung werden ein Lademanagement von Elektrofahrzeugen sowie Rückkopplungen des Strommarktes modelliert. Hierbei wird einerseits untersucht, welchen Implikationen das gesteuerte Laden auf die Systemlast und den Strompreis hat. Andererseits wird analysiert, wie sogenannte Lawineneffekte, die auftreten, wenn eine kritische Masse flexibler Fahrzeuge unkoordiniert auf ein Signal reagiert, vermieden werden können. Aus den Ergebnissen kann geschlussfolgert werden, dass das gesteuerte Laden von Elektrofahrzeugen ein großes Flexibilitätspotenzial mit positiver Systemwirkung bietet, vorausgesetzt, dass Rückkopplungen der Laststeuerung berücksichtigt werden. Der koordinierte Einsatz kann sich jedoch negativ auf die finanzielle Attraktivität des Lademanagements auswirken.
Aus den Ergebnissen der ersten beiden Bausteine lässt sich schlussfolgern, dass nachfrageseitige Flexibilitäten wie Elektrofahrzeuge prinzipiell ein hohes Potenzial für den Ausgleich von Stromerzeugung und -nachfrage bieten. Gleichzeitig skizzieren die Bausteine die Herausforderungen, die bei einer zentralen, aber auch in einer dezentralen Koordination dieser Flexibilitäten bestehen. Die Konzeptionierung und Umsetzung dezentraler Stromversorgungskonzepte setzt voraus, dass Informationen zu Stromerzeugung, Stromnachfrage und den daraus resultierenden Flexibilitätspotentialen in hoher Auflösung zur Verfügung stehen. Im Rahmen des dritten Dissertationsbausteins wird deshalb eine Methode entwickelt, mit der ein räumlich und zeitlich hochaufgelöster Datensatz erstellt werden kann. Diese wird angewandt, um die Nachfrage und das Angebot für die deutschen Landkreise im Jahr 2030 zu modellieren. Darüber hinaus wird unter Nutzung der regionalen, stündlichen Energiebilanz regionales Lastmanagement simuliert. Außerdem werden die Landkreise abhängig von der Stromnachfrage- und Angebotsstruktur in Cluster eingeteilt. Die Clusteranalyse unterstreicht die hohe Heterogenität zwischen den Regionen im Hinblick auf die Ausgeglichenheit von Angebot und Nachfrage und die Wirksamkeit von Lastmanagement zur Reduktion von Stromimporten und -exporten: Speziell in urbanen Regionen ist die Effektivität von flexiblen Endverbrauchern zur Integration von erneuerbaren Energien über den Tagesverlauf hoch. Regionen mit mittelgroßen Städten oder solche mit kleineren energieintensiven Industrien haben bereits ohne den Einsatz von Lastmanagement vergleichsweise ausgeglichene Energiebilanzen. Hier kann Lastmanagement dennoch effektiv eingesetzt werden, um durch Lastverschiebungen über den Tagesverlauf den Anteil des regional verbrauchten Stroms nochmals zu erhöhen.
Die Modellierung der dezentralen Nachfrageflexibilität im Rahmen des dritten Bausteins der Dissertation basiert hauptsächlich auf technischen Kenngrößen. Funktionierende dezentrale Stromversorgungskonzepte bedürfen darüber hinaus Anreizen, die eine Teilnahme dezentraler Akteure fördern. Dieser Überlegung trägt der vierte Dissertationsbaustein Rechnung: Hierbei wird ein lokaler Strommarkt für Prosumer simuliert. Diese haben die Möglichkeit den flexiblen Anteil ihrer Nachfrage sowohl auf die Stromerzeugung ihrer Erneuerbaren-Energien-Anlagen als auch auf den lokalen Marktpreis anzupassen und minimieren auf diese Weise ihre Strombezugskosten. Der lokale Strommarkt aggregiert den Strombezug und die Stromeinspeisung aller teilnehmenden Prosumer und reflektiert somit die lokale Angebots- und Nachfragesituation. Zur Bewertung wird dieser einerseits mit der Eigenverbrauchsoptimierung der Prosumer und zum anderen mit der Integration der Prosumer in einen zentralen Spotmarkt verglichen. Dabei zeigt sich, dass die direkte Teilnahme an einem zentralen Spotmarkt unter den unterstellten Rahmenbedingungen finanziell für die untersuchten Prosumern attraktiver wäre als die Teilnahme an einem regionalen Handel oder die Eigenversorgung und auch die systemdienlichste Option zur Flexibilitätsnutzung im Hinblick auf die Integration erneuerbarer Energien darstellt. Die Ergebnisse lassen jedoch auch den Schluss zu, dass die Systemdienlichkeit eines lokalen Prosumermarkt höher einzuschätzen ist als die reine Eigenversorgung.
In allen vier Bausteinen dieser Dissertation wird die Nutzung von nachfrageseitiger Flexibilität untersucht. Insbesondere wird die Wirkung eines Ausgleichs von Stromerzeugung und -nachfrage in dezentralen Energiesystemen analysiert. Anreize hierfür können nicht-monetär sein, wie das Streben nach Autarkie, oder monetär wie die Minimierung der Strombezugskosten. Die Ergebnisse zeigen, dass das technische Flexibilitätspotenzial vorhanden ist, um die Volatilität der Stromerzeugung aus erneuerbaren Energien zumindest in Teilen auszugleichen und somit dazu beizutragen, den durch die Energiewende entstehenden Herausforderungen zu begegnen. Die ökonomische Attraktivität eines lokal begrenzten Ausgleichs von Angebot und Nachfrage ist im Vergleich zu einem überregionalen Handel gering. Verglichen mit der heutzutage üblichen Eigenversorgung von Prosumern zeigt sich jedoch auch die Vorteilhaftigkeit dezentraler Anreize im Hinblick auf die Systemintegration erneuerbarer Energien. Insofern kann die Etablierung dezentraler Energiesysteme eine Möglichkeit darstellen, ein flexibles Verhalten nachfrageseitiger Akteure anzureizen.
... Some previous contributions developed simplified models to investigate the optimal mix of renewable power generation at national level (40) and continental scales like in (41). The model was also utilized to assess continental scale storage needs with excess generation (42) and to consider the optimal mix of generation with regard to seasonal effects (43). The methodology used for this case study will be described in the following sections. ...
In this paper, an open source tool is introduced to represent urban energy infrastructure in the City of Philadelphia, and different renewable energy scenarios are compared with respect to minimization of the standard deviation of the residual load. Renewable energy sources play a critical role in the world’s ongoing energy transition in response to climate change. Urban Energy Systems may be particularly sensitive to this transition due to the high energy demand density associated with urban environments. Open energy analysis and modeling tools can provide important information that can be used by urban energy planners, policy makers, and other stakeholders during this transition. In the present study, we apply FlexiGIS, an open energy modeling tool developed in a European context, to a case study in the City of Philadelphia. Due to the importance of open access to energy data, we pay particular attention to open energy data sources. Notably, OpenStreetMap was incomplete in its spatial coverage, but alternate open data resources were identified. This work conducts an optimization of the renewable energy mix to minimize the amount of balancing energy required for the residual load. We observe that Philadelphia has an optimal mix of renewables that favors a roughly even share of wind and solar, but that, compared to a previous case study in Oldenburg, Germany, requires more balancing energy at comparable levels of renewable penetration.
... The best way to overcome the uncertainty caused by the inherent variability of PV technology is to modernize the electricity grid itself and make it more flexible to maintain the balance of the electricity system. This increased flexibility can be attained by including storage capacities in the system, whose back-up potential can level the highs and lows of PV generation [25][26][27]. ...
As photovoltaic (PV) electricity generation is becoming ubiquitous, the ability to forecast solar power becomes crucial for such aspects as economical dispatch, optimal unit commitment and the stability of the grid. Our research investigated the discrepancies between day-ahead and intraday country-specific PV power generation forecasts and the real generation data in the member states of the European Network of Transmission System Operators for Electricity for the year 2021. The goal of the research was, firstly, to offer an insight into the schedule accuracy achieved in the examined countries, secondly, to present the potentials for improvement in each of them (plausible even by the practical application of the methods available in 2021), and thirdly, to show the amount of regulation need resulting from PV electricity production forecasting error, the knowledge of which can help with the estimation of the size of the necessary storage capacities. This is the first work that analyzes the schedule accuracy from a practical perspective by examining the accuracy of the day-ahead and intraday PV forecasts of seventeen European countries, following the latest recommendations for verification. The results found significant differences between the forecast accuracy of different countries, which indicates a huge potential for imbalance reduction in most countries by improving their own algorithms or creating a uniform European PV power generation forecasting system. Overall, the intraday forecasts are less skillful than the day-ahead forecasts in all but one of the countries, which highlights the significance of further application-related studies in the intraday horizon. The aggregate regulatory need resulting from the discrepancies between the forecasted and actually produced amounts of energy of all studied countries is 4 TWh in the positive and 3 TWh in the negative direction, which calls for a large amount of energy storage capacity to provide carbon-free balancing power and reduce the regulation challenges of the increasing PV penetration.
... These benefits contribute to the development of the large-scale (50-1000 MW) CSP power plant [3]. In a multi-energy complementary system, the STP plant equipped with thermal storage can levelize the fluctuation of the power output [4]. The challenges to the STP come from two aspects-the volatility of the solar and wind and the unpredictability of the power load in demand. ...
Due to the change of direct normal irradiance (DNI) and the change of output power load, the receiver of the solar tower is in an unstable state in the actual operation. In this paper, a 100 MW external cylindric receiver is designed and modelled. The dynamic and comprehensive model is established for the receiver, including the thermal and mechanical equations. The temperature control strategy is applied to the receiver model. The validity of the control strategy is verified by disturbance experiments, including DNI, the inlet temperature of the heat transfer fluid (HTF), and the weather data on a cloudy day. The response characteristics of the receiver are demonstrated. Its thermal lag characteristics and restraining effect on the fluctuating environment are revealed. The dangerous occasion of the receiver during operation are detected, including the overheat of the local panel, and the dissociation point of the molten salt. Both the robustness and the deficiency of the control strategy of the receiver are pointed out. The research results will contribute to the control strategy formulation of the SPT (solar power tower) station.
Transition to a low-emission society requires radical emissions reductions in the electricity generation sector. Imposing that hourly load has to be served solely by wind power, solar PV and an energy storage technology, it is shown, using optimization and simulations of re-analysis data, how the EU can design a completely CO2 emission-free electricity generation sector. For such a system, the optimal battery energy capacity should be 32 times of average hourly consumption of electricity in the EU. However, total production of electricity over a 10 year period is as much as 43% above total consumption of electricity.
The practical operation of the receiver for solar power tower plant is under unsteady conditions because of the variation of direct normal irradiation, as well as the output power load. A 100 MW external receiver was designed and selected as the object. The unsteady one-dimensional model was established for the receiver and validated by comparing the simulation results with the published experimental data, aiming to launch the thermal, hydraulic and mechanical analysis. The heat transfer characteristics, thermal efficiency, as well as the thermal stress in the flow direction, are demonstrated by the static analysis. By comparison of different panels, the harsh working condition of the first and the last panels is discovered, including that of the highest temperature difference and tangential thermal stress along tubes. The tangential thermal stress is prominent at the light spot. The molten salt at the last panel is most likely to decompose. Dynamic simulation is carried out to analyze the thermal inertia and heat transport characteristics. The response curves and time constants of the receiver under step and periodical disturbances of different factors from the environment and load side are acquired. The thermal inertia of the receiver and its effect to dampen weather fluctuation are illustrated. These security problems and thermal performance will make demands on the control strategy and control accuracy. The results can provide a reference for the control strategy development of the solar power tower plant.
The energy storage requirement modelling tool outlined here uses an extension of the pinch methodology to quantify the network flexibility required due to greater variable renewable energy (VRE) integration. Quantifying this as the magnitude of energy storage required as a function of storage duration provides improved understanding of the fundamental balancing problem. Identification of the impact that key decision variables, such as location, VRE penetration and VRE that is supplied through wind have on these requirements has been enabled by condensing this dependence within two non-dimensional indices: the storage magnitude index and the storage duration index. These indices, in addition to the size of storage required, have enabled the tipping-points and VRE penetration levels beyond which short-term storage is not sufficient to be identified for the UK and Australian locations considered. In addition to how effective the provision of excess VRE is in the mitigation of the balancing requirements. This analysis shows that seasonal balancing is required at high levels of VRE penetration for all combinations of wind and solar sources, but can be needed with as low as 50% penetration at certain combinations and locations. The tipping-point is highly specific to location and VRE that is supplied through wind, varying between 30% and 50% of VRE penetration.
Electricity spot prices have shifted in response to increasing renewable energy infrastructure throughout the United States in recent decades. These shifts manifest as changes in the spot price mean and variance. One major factor influencing the variance of spot prices is the prevalence of price spikes. How renewables influence the magnitude and frequency of price spikes is not well understood. This study examines the influence of wind and additional determinants (load, nuclear generation, natural gas prices, as well as the load-to-capacity ratio) on electricity spot prices in the Electric Reliability Council of Texas system using a multiple regression mixture model framework. We focus on the influence of these determinants on the magnitude of spot prices within a low-price regime and a high-price regime, with the latter representative of price spikes. We also examine how system determinants influence the frequency of occurrence of each regime. We show that increases in wind generation drive average spot prices down in both the low and high price regime. However, system shortfalls of wind generation, particularly during times of high load, result in increased price magnitudes in both regimes, as well as more frequent price spike events.
In this work, novel proton-exchange membranes (PEMs) based on sulfonated poly(ether ether ketone) (SPEEK) and two-dimensional (2D) sulfonated niobium disulphide (S-NbS2) nanoflakes are synthesized by a solution-casting method and used in vanadium redox flow batteries (VRFBs). The NbS2 nanoflakes are produced by liquid-phase exfoliation of their bulk counterpart and chemically functionalized with terminal sulfonate groups to improve dimensional and chemical stabilities, proton conductivity (σ) and fuel barrier properties of the as-produced membranes. The addition of S-NbS2 nanoflakes to SPEEK decreases the vanadium ion permeability from 5.42 × 10-7 to 2.34 × 10-7 cm2 min-1. Meanwhile, it increases the membrane σ and selectivity up to 94.35 mS cm-2 and 40.32 × 104 S min cm-3, respectively. The cell assembled with the optimized membrane incorporating 2.5 wt% of S-NbS2 nanoflakes (SPEEK:2.5% S-NbS2) exhibits high efficiency metrics, i.e., coulombic efficiency between 98.7 and 99.0%, voltage efficiency between 90.2 and 73.2% and energy efficiency between 89.3 and 72.8% within the current density range of 100-300 mA cm-2, delivering a maximum power density of 0.83 W cm-2 at a current density of 870 mA cm-2. The SPEEK:2.5% S-NbS2 membrane-based VRFBs show a stable behavior over 200 cycles at 200 mA cm-2. This study opens up an effective avenue for the production of advanced SPEEK-based membranes for VRFBs.
The global energy markets of the last decade have been characterized by an ever-increasing share of electric power, more than half of which is projected to come from renewable energy sources by the year 2030. Such a remarkable rise in the quantity of renewable energy, of course, will induce a series of related changes as, without the successful integration of all that unconventional type of energy into the existing energy systems, the sustainability and security of the electricity supply cannot be maintained. As a result, new legislation and energy policies are required all over the world to accommodate not only the latest technological solutions but also a variety of previously unknown market actors. In the institutions, businesses and households of Hungary, the notion of sustainability has been gaining more and more importance lately, which is manifest in the efforts to reduce the use of electricity from the public grid, which is generated by burning fossil fuel. This endeavor is facilitated by the installation of photovoltaic (PV) household-sized power plant (HMKE) systems. Currently, the Hungarian electric energy system does not possess sufficiently flexible capacities; moreover, even this capacity is expected to decrease considerably in the future due to the phasing out fossil fuel power plants. Furthermore, dynamically growing HMKE penetration means an increasing frequency of technical problems in the macroenergy system (e.g., reverse energy flow in the local grid). It is such challenges that energy storage technologies can provide a solution for. Presently, there is insufficient information available on the recommended energy storage size necessary for the efficient integration of Hungarian HMKE systems into the electric energy system and the related investment needs. The innovative novelty of this study is that it examines the quantity and power of Hungarian HMKEs in the districts of the various electric companies over time with a view of exploring a possible way of their efficient integration into the electric energy system by determining the nominal energy storage power and energy capacity of the proposed energy storage systems. In addition, the paper also presents the expected investment needs associated with these energy storage systems.
In which way, and in which sectors, will renewable energy be integrated in the German Energy System by 2030, 2040, and 2050? How can the resulting energy system be characterised following a −95% greenhouse gas emission reduction scenario? Which role will hydrogen play? To address these research questions, techno-economic energy system modelling was performed. Evaluation of the resulting operation of energy technologies was carried out from a system and a business point of view. Special consideration of gas technologies, such as hydrogen production, transport, and storage, was taken as a large-scale and long-term energy storage option and key enabler for the decarbonisation of the non-electric sectors. The broad set of results gives insight into the entangled interactions of the future energy technology portfolio and its operation within a coupled energy system. Amongst other energy demands, CO2 emissions, hydrogen production, and future power plant capacities are presented. One main conclusion is that integrating the first elements of a large-scale hydrogen infrastructure into the German energy system, already, by 2030 is necessary for ensuring the supply of upscaling demands across all sectors. Within the regulatory regime of 2020, it seems that this decision may come too late, which jeopardises the achievement of transition targets within the horizon 2050.
Heating with wind and solar energy is an effective way to reduce carbon dioxide emissions. Vapor Compression Heat Pumps (VCHP) were generally used to improve the utilization rate of wind power. However, normal VCHP driven by wind power or solar energy has low performances in low temperature environment and low supply temperature of heating water, and it is also difficult to achieve continues and stable heating because of the intermittence of wind power. The present paper introduces a new integrated heat pump system, in which a VCHP absorbs heat from the environment and sends it to an Absorption Heat Pump (AHP) as its low temperature heat source after temperature lift. Thermal storage system is also equipped for continues heating and it serves as the driving force of the AHP. The results show that the integrated heat pump can produce heating water at 50 °C or even higher with a COP of about 1.42 when the environment temperature is as low as −30 °C. Also, the power consumption of the VCHP accounts for only 5%–18% of the total energy input. This indicates that the energy consumed by the integrated heat pump can be mainly from off-peak electricity produced by the wind turbine.
More utilities, energy providers, and governments are considering the transition to 100% renewable or carbon-free generation to satisfy electricity demand. This transition requires consideration of numerous factors including cost, resource adequacy, and geographical location, among others. Therefore, models that can explore the optimality of tradeoffs between multiple factors are crucial for planning this transition. An optimization problem formulation is proposed to analyze the amount of renewable generation and energy storage required to balance 100% of a utility's electricity demand on an hourly timescale over multiple years, while minimizing a desired cost. This formulation accounts for geographical location and accommodates regional energy trading, and it enables analysis of important metrics for planning, such as firm capacity, capacity factors, land area requirements, and amount of curtailed generation. This optimization-based approach is used to explore case studies in New Mexico, which is an area with significant potential for solar and wind generation in the United States. Considering multiple years of historical meteorological data and electricity demand data, results show that the amount of renewable generation required is an order of magnitude larger than the average demand, and that most of the generation is curtailed, which motivates a regional energy trading approach.
In this paper, the applicability of marine renewable energy (MRE) for potential grid applications is presented. We show that many of the unique value streams from marine-based electricity generation resources stem from their inherent temporal characteristics, especially when compared to wind and solar. Specifically, in this work, we evaluate the timing value for three types of MRE resources: (a) tidal, (b) wave, and (c) ocean currents. First, through a suite of novel metrics, such as resource availability, persistence, and versatility, we evaluate the temporal value characteristics of these resources. Second, through a more grid-oriented numerical study, we comment on the potential ramifications of those temporal characteristics in context of energy balancing and effective load carrying capability for one marine-based resource i.e., wave. Finally, we further our understanding of the relative advantages that may be leveraged by operating wave-based generation in tandem with more established renewable resources, such as wind and solar. Our results indicate that compared to wind and solar, MRE resources are consistently more available and persistent on an hourly level throughout an entire year of operation. In addition, wave resources are also seen to reduce the balancing requirements within the power system. Our work focuses on sites specific to the United States (US) and a parallel study for a location in Great Britain (GB). Results are found to be consistent for sites in both the US and GB, implying that the grid benefits discussed in this work could apply to a number of locations globally.
Supplying the increasing energy demand of communities both economically viable and environmentally friendly is among the primary challenges of the present century. In this regard, the current study aims to suggest a proper approach, in terms of economic and environment, to supply the energy demand of Eram Campus, Shiraz University. Pre-studies are carried out to realize the energy demand, primary energy potentials, and geographical constraints of Eram Campus. In the present study, simulations, optimizations and sensitivity analysis are performed to explore the feasibility of utilizing smart hybrid renewable energy system to meet the load demand of the Eram Campus. The results indicate that the suggested energy system consists of micro gas turbine (combined heat and power) power plant, thermal boiler, converter, photovoltaic panel, pumped hydro energy storage and predictive (smart) controller. To make use of the proposed power plant, 15$M is needed for initial capital cost. The levelized cost of energy and net present cost of the system is 0.09 $/kWh and 42.5 $M, respectively. Based on the obtained results, using the proposed energy system reduces the annual carbon dioxide production of the Eram Campus by 8000 megatonnes compared using the existing one. Moreover, the calculations reflect that the impacts of economic indexes variations, escalation of energy demand and energy consumption pattern change on the characteristics of the energy system are considerable. The optimum sizings of the gas turbine, thermal boiler, photovoltaic panel, converter and pumped hydro storage should be 2650 kW, 17 MW, 13754 kW, 4995 kW and 70 strings to meet the increase of 50 per cent in energy demand in the most economical strategy. It is worth mentioning that by reducing the energy consumption in specific time steps (1 per cent of the total energy demand), the net present cost and Levelized cost of energy would significantly decline 6 and 15 per cent, respectively.
The purpose of this study was to evaluate the costs and specifications of 100% VRE systems that consist of VRE and energy storage systems. For that purpose, a model was developed to comprehensively analyze the costs and the specifications of 100% VRE systems. Using the model, the following results were obtained: (1) A hybrid storage system of battery and hydrogen storage that are optimally combined, as well as the optimal combination of solar and wind power, could reduce supply costs of electric energy. Concerning the hybrid storage system, the battery that operates with a daily cycle cooperates with the hydrogen storage that operates with a multiple day cycle, and; (2) multi-production systems that supply electric energy as well as hydrogen energy could reduce energy supply costs when an optimal combination of electric energy and hydrogen energy is achieved. However, the supply costs of stable electric energy as well as hydrogen energy from the 100% VRE systems are more expensive than the target costs in 2030 in Japan. In order to reduce the energy supply costs, it is necessary to reduce the costs of elemental technologies such as solar, wind power, battery, and hydrogen-related technologies.
The increasing integration of renewable energy sources makes balancing an electricity grid challenging due to their intermittency. Renewable energy can be curtailed especially when production exceeds demand or when there are transmission and/or distribution network congestions within a grid. However, curtailment would become unnecessary with battery storage, provided the battery storage has enough available storage capacity, which can store energy during the time of excess generation and in turn discharge it to the grid once the demand is high during peak times. Hence, stored energy from batteries can potentially offset supply from expensive and environmentally harmful peak plants e.g. open/combined cycle gas turbine. We investigated the techno-economic prospects of the utilisation of curtailed energy from the wind with bulk battery storage to replace open and combined cycle gas turbine power plants, by taking the UK as a case study. A techno-economic model to size and optimise a Li-ion type battery was developed. The optimisation aimed to determine at what cost and size the storage can be commercially viable for grid-level energy applications. Results show that under base case assumptions of a 15% day to day curtailment from wind and £200/kWh battery cost, an optimised battery size of 1.25 GWh could supply 285 GWh peak demand per annum and its corresponding net present value of £22.4m, internal rate of return of 1.7% and a payback period of 14 years could be achieved. However, to achieve the internal rate of return of 8%, a minimum hurdle rate for investment, the cost of battery would need to be below £150/kWh. Sensitivity analysis with parameters such as curtailed wind, depth of discharge, battery efficiency, and cost and income of battery shows that all techno-economic parameters considered in this research have a significant impact on the commercial viability of battery storage for grid applications.
The use of dispatchable energy in a renewable power system plays an important role. Thus, it is of interest to explore the impact of the dispatchable energy price from both economic and environmental perspectives. In this work, we present a quantitative analysis using a fully electrified methanol process located in Kramer Junction, USA, and Norderney, Germany as two case studies to report the correlation between dispatchable energy price and renewable penetration in the methanol production. The correlation is governed by the optimal economic potential, which is optimised using nonlinear programming. It is found that the resulting renewable penetration exhibits a two-regime behaviour: it increases dramatically at the beginning and then slowly approaches 100% when the dispatchable energy price is above a critical point. The critical dispatchable energy price in Kramer Junction is found to be $220 per megawatt hour with a corresponding renewable penetration of 64%, whereas it is approximately $180 per megawatt hour and 86% for Norderney. There also exists a threshold price of $162 and $65 per megawatt hour respectively for Kramer Junction and Norderney, below which no renewable energy would be implemented due to a lack of economic incentive. The correlation suggests that the price of dispatchable energy can be used to predict or influence the renewable penetration in a renewable power system, provided that the system aims to achieve economic optimality.
Chemical production using renewable energies is an important element on the roadmap of industry decarbonisation. This work investigates the optimisation of renewable power supply for a fully electrified methanol process, with a focus on the interplay between renewable fix, storage sizing and the use of backup dispatchable power source. The analysis is performed using the meteorological data obtained from two locations, i.e. Kramer Junction (US) and Norderney (Germany), which have excellent solar and wind source, respectively. The minimum levelised energy cost, which is optimised in terms of renewable power generation, renewable mix and storage size, is found to be 106$/MWh and 103$/MWh for operations in Kramer Junction and Norderney, respectively, based on a dispatchable energy price of 230$/MWh. This leads to a levelised methanol cost of 1490$/tonne and 1459$/tonne with a respective renewable penetration of 81% and 96% in the production. The correlation between renewable penetration and dispatchable energy price in the most economical scenario exhibits a two-regime behaviour: the renewable penetration increases dramatically at the beginning and then slowly approaches 100% when the dispatchable energy price is above a critical point. For a fully renewable operation, the optimised levelised energy cost is found to increase to 167$/MWh and 114$/MWh for Kramer Junction and Norderney, respectively. The results show the importance of the dual functionality of hydrogen in the energy storage system, which improves the overall energy efficiency.
Three of the main challenges in achieving rapid decarbonization of the electric power sector in the near term are getting to net-zero while maintaining grid reliability and minimizing cost. In this policy analysis, we evaluate the performance of a variety of generation strategies using this "triple objective" including nuclear, renewables with different energy storage options, and carbon-emitting generation with carbon capture and storage (CCS) and direct air capture and storage (DACS) technologies. Given the current U.S. tax credits for carbon sequestration under Section 45Q of the Internal Revenue Code, we find that two options: (1) cofiring bioenergy in existing coal-fired assets equipped with CCS, and (2) coupling existing natural gas combined-cycle plants equipped with CCS and DACS, robustly dominate other generation strategies across many assumptions and uncertainties. As a result, capacity-expansion modelers, planners, and policymakers should consider such combinations of carbon-constrained fossil-fuel and negative emissions technologies, together with modifications of the current national incentives, when designing the pathways to a carbon-free economy.
This paper explores how the requirement for energy storage capacity will grow as the penetration of renewables increases. The UK’s electric grid is used as a case study. The paper aims to provide insight on what is the most economical solution to decarbonize the electric supply. A two-dimensional study varying the penetrations of wind and solar PV is carried out to identify the most appropriate generation mix for the country. The study is based on 9 years of demand and generation data with a 1hr resolution. It discusses the risk of underestimating the storage capacity needed, by failing to capture the inter-annual variability of renewables and analyzes the economic trade-off between over-generation (curtailment) and storage capacity. It also aims to determine the percentage of over-generation that minimizes the total cost of electricity. Results suggest that the UK could need a storage capacity of approximately 43TWh to decarbonize its electricity supply. This figure considers a generation mix of 84% wind + 16% solar PV, a roundtrip storage efficiency of 70%, and 15% of curtailment. Based on current costs of bulk energy storage technologies, this storage capacity translates into an investment of ∼£165.3 billion or approximately 7% of the country’s GDP.
The transition towards a sustainable, clean energy infrastructure is strongly dependent on the efficient integration of the fluctuating renewable power generation from wind and solar. With a focus on power flows, in this contribution we review complex renewable energy networks as a weather-data driven modelling approach to a highly renewable future electricity system. The benefit of cross-border transmission between the European countries in such a scenario is discussed, taking into account the role of spatial coarse-graining for the modelling results. Flow allocation methods are presented as a tool set to analyse the spatio-temporal flow patterns and to allocate both transmission and generation capacity costs.
Proposed emission reduction targets as well as the scarcity of fossil fuel resources make a transition of the energy system towards a carbon free electricity supply necessary. Promising energy resources are solar and wind energy. The high temporal and geographical variability of these resources is challenging for their integration. This study focuses on the subject of how a renewable-based energy system ideally should be designed. We investigated the optimal structure of a prospective renewable-based power supply system on two different scales: on the global and on a European level. This paper describes the applied simulation technique, based on linear optimization, employed to combine an adequately precise geographical coverage with high temporal resolution. As results we obtain ideal energy mixes, generation sites, storage and interregional power transmission capacities required for different scenarios of highly renewable supply.
The renewable power generation aggregated across Europe exhibits strong seasonal behaviors. Wind power generation is much stronger in winter than in summer. The opposite is true for solar power generation. In a future Europe with a very high share of renewable power generation those two opposite behaviors are able to counterbalance each other to a certain extent to follow the seasonal load curve. The best point of counterbalancing represents the seasonal optimal mix between wind and solar power generation. It leads to a pronounced minimum in required stored energy. For a 100% renewable Europe the seasonal optimal mix becomes 55% wind and 45% solar power generation. For less than 100% renewable scenarios the fraction of wind power generation increases and that of solar power generation decreases.
Einmal Fjord und zurück. Neue Energie
- K Wiedemann
Wiedemann K. Einmal Fjord und zurück. Neue Energie; 07 2010. pp. 24e31.
Energy storage in salt caverns e today and tomorrow
- S Donadei
- Crotogino
Donadei S, Crotogino F. Energy storage in salt caverns e today and tomorrow.