Sustainable Electricity System Research Articles

Robustness of electricity systems with nearly 100% share of renewables: A worst-case study

Several research studies have shown that future sustainable electricity systems, mostly based on renewable generation and storage, are feasible with today's technologies and costs. However, recent episodes of extreme weather conditions, probably associated with climate change, cast shades of doubt on whether the resulting generation portfolios are sufficiently robust to assure, at all times, a suitable balance between generation and demand, when adverse conditions are faced. To address this issue, this work elaborates a methodology intended to determine a sustainable electricity generation system, that can endure extreme weather conditions which are likely to occur. First, using hourly production and demand data from the last decade, along with estimates of new uses of electricity, a worst-case scenario is constructed, including the storage capacity and additional photovoltaic power which are needed to serve the demand on an hourly basis. Next, several key parameters which may have a significant influence on the LCOE are considered, and a sensitivity analysis is carried out to determine their real impact, significance and potential trends. The proposed methodology is then applied to the Spanish system. The results show that, under the hypotheses and conditions considered in this paper, it is possible to design a decarbonized electricity system that, taking advantage of existing sustainable assets, satisfies the long-term needs by providing a reliable supply at an average cost significantly lower than current market prices.

Prioritization of renewable energy source for electricity generation through AHP-VIKOR integrated methodology

As the worldwide energy crisis worsens, renewable energy sources have undeniably opened new horizons for our society. It will offer an efficient solution to this severe energy crisis, environmental issues and fulfilling human energy needs. Therefore, six main criteria, social, economic, quality of energy, political, technical, environmental, and sixteen sub-criteria have been employed, and an assessment model is developed for prioritizing the most pertinent renewable energy sources for electricity generation in developing countries in which four major resources, solar energy, wind energy, hydropower, and biomass energy, are considered and their electricity generation potential. Furthermore, the integrated method with the analytical hierarchy process and VIekriterijumsko KOmpromisno Rangiranje are acquired for a comprehensive assessment. The results demonstrate that the economic criterion had the highest weight of (0.353) compared to the technical criterion, which took place second with a weight of (0.244) followed by environmental (0.205) and quality of energy with a weight (0.098), respectively. The political and social criteria have the lowest weights of (0.057) and (0.043). From the review, renewable resources seem to have sufficient potential to develop a sustainable electricity system. Likewise, the model priorities these resources, revealing that hydropower is the best renewable energy source option, followed by wind energy. Biomass energy and solar energy ranked third and fourth. The assessment performed in this study can help decision-makers in Pakistan to frame long-term energy policy directing for sustainability.

An integrated bifacial photovoltaic and supercritical geothermal driven copper-chlorine thermochemical cycle for multigeneration

This study thermodynamically investigates a newly developed supercritical geothermal and solar-based integrated energy system and applies to a local community which is near Kakkonda, WD-1a geothermal plant in Shinozaki, Japan. The proposed system produces useful outputs, such as electricity, heat for space heating and freshwater for self-consumption in the community and the auxiliary systems and hydrogen for commercial purposes. Thermochemical copper-chlorine cycle, bifacial photovoltaic plant, Rankine cycle, heat pump, and multi-effect water desalination subsystems are integrated into this unique system to employ solar, geothermal, and sea sources to produce useful outputs. The overall system and its components are analyzed thermodynamically using both energetic and exergetic approaches. The parametric studies and dynamic time-dependent simulations are carried out for performance assessment. The economic comparison methods are applied to determine feasibilities. According to the calculations, 2,144.45 tons of hydrogen is produced annually. A total of 204 households is considered to consume 1235 MWh electricity, 851 MWh thermal energy and 5,314.75 tons of freshwater annually. The overall energy and exergy efficiencies are 22.7% and 18.2%, respectively, for the average ambient conditions. The unit costs of useful commodities are found to be 2.73$/kg for the hydrogen, 0.023$/kWh for the electricity, 0.015$/kWh for the thermal energy, 0.47$/m3 for the freshwater. The overall system shows 5.15 years payback period with a 22% internal rate of return. The proposed subsystems and overall system possess environmentally benign, sustainable and reliable electricity, space heating, fresh water and hydrogen production system.

Design and analysis of double stator HE-FSM for aircraft applications

The main objective of aerospace industry is to produce all electric aircraft (AEA) equipped by electrical devices in coming developments. Electrical machines that provide higher torque densities are gaining more interest for researchers to obtain sustainable direct-drive electrical propulsion system for aircraft applications. In addition to lesser weight and higher torque density, a machine should be “fault tolerant” to applied in aerospace applications. A novel machine for high starting torque, identified as flux switching machine (FSM) was established over the last decade. FSMs comprise all effective sources on stator including robust rotor structure. These machines exhibited higher “torque-to-weight ratios” and reliability. Nonetheless, the challenge of developing a machine suitable for aircraft applications goes far beyond electromagnetic design and much deeper into the field of mechanical systems than traditional ones. Thus, a new double stator (DS) hybrid excitation (HE) FSM design employing segmented rotor is proposed and analyzed in this research work. The suggested design for DS HE-FSM comprises of six field excitation coils (FECs) and six permanent magnets (PMs) as their excitation sources. In this research, investigation of DS HE-FSM is accomplished with respect to flux linkage, back EMF, cogging torque and torque analysis based on 2D FEA.

Preliminary analysis of long‐term storage requirement in enabling high renewable energy penetration: A case of East Asia

Integrating a high penetration of renewable energy for developing sustainable and low-carbon electric energy system is becoming a common trend around the world. Many studies have evaluated the energy storage requirement for accommodating variable renewable energy (VRE). However, in the situation of high renewable penetration, there will be a huge potential requirement of long-term energy storage for addressing the seasonal energy imbalance between VRE and load demand. Thus, a key element of evaluating the storage demand in enabling high VRE penetration is identifying the timescales of storage needed and the economic combination of long-term and short-term energy storages. This is neglected in existing researches. In this study, we quantitatively analyse the role of long-term seasonal storage in enabling high VRE penetration. A generation expansion planning model is formulated to optimise the least-cost generation portfolio with a renewable penetration target. Based on the proposed model, an empirical analysis for East Asia in 2050 is performed. The results indicate that (1) long-term storage contributes to addressing the long-term energy imbalance issue, (2) the optimal duration time of long-term storage is around 720 h (a month), and (3) the long-term storage becomes economical when the renewable penetration is above 70% (54.2% VRE penetration).

Implications of renewable resource dynamics for energy system planning: The case of geothermal and hydropower in Kenya

Kenya's current electricity production is mainly relying on hydro and geothermal resources. Both of these resources are subject to complex dynamics that affect their sustainable utilization. Neither the current power expansion plan for Kenya, nor the existing electricity supply models address such effects. The research question in this paper is: What are the implications of hydro and geothermal resource dynamics for short- and long-term (sustainable) electricity system planning in Kenya? To answer this question a bottom-up system dynamics model representing the most prevalent technologies of Kenya's future electricity system, including the dynamics of geothermal and hydro resource utilization, is developed. The stock-flow system dynamics modelling allows to capture the resources characteristics and the link to electricity production. Due to the stock-like nature of geothermal resource, excessive utilization can lead to production capacity losses. In the case of hydro resources, climate change can reduce their availability significantly. A total of eight scenarios varying in demand size and consideration of resource dynamics are simulated and compared. The results indicate that when geothermal and hydro resource dynamics are considered, higher installed capacity will be required in the long-term to compensate production losses, which in turn leads to a higher electricity generation cost.

Making the sun shine at night: comparing the cost of dispatchable concentrating solar power and photovoltaics with storage

ABSTRACT Sustainable electricity systems need renewable and dispatchable energy sources. Solar energy is an abundant source of renewable energy globally which is, though, by nature only available during the day, and especially in clear weather conditions. We compare three technology configurations able to provide dispatchable solar power at times without sunshine: Photovoltaics (PV) combined with battery (BESS) or thermal energy storage (TES) and concentrating solar power (CSP) with TES. Modeling different periods without sunshine, we find that PV+BESS is competitive for shorter storage durations while CSP+TES gains economic advantages for longer storage periods (also over PV+TES). The corresponding tipping points lie at 2–3 hours (current cost), and 4–10 hours if expectations on future cost developments are taken into consideration. PV+TES becomes only more competitive than CSP+TES with immense additional cost reductions of PV. Hence, there remain distinct niches for two technologies: PV+BESS for short storage durations and CSP+TES for longer ones.

Sustainable Electrical Energy Supply Chain System With Hybrid Power Generation: An Inventory Approach

In this paper, we present a sustainable electrical energy supply chain system (SEESCS) where two supply chain parties are involved, namely a power plant and a transmission station. The power plant has two different types of power generation systems. The first power generation system (PG1) is more costly but it generates lower emissions than the second system (PG2). The model is developed based on a lot-sizing inventory problem to decide the load allocation between PG1 and PG2. The objective function is to minimize total costs that consist of energy generation cost and emission cost. The transmission station faces a stochastic demand and employs a continuous review policy to manage the electrical energy storage. An efficient procedure is developed to solve the model and a sensitivity analysis is carried out to explore the impact of changes in some key parameters on the model's behavior. The results show that the allocation of electricity generation is mostly influenced by the change in PG1's production cost parameter and PG2's emissions parameters. The amount of emissions generated from the system is significantly affected by the variation in PG1's production cost parameter, PG2's emissions parameters, and electricity demand. Furthermore, by adjusting the power supply rate of power generation, the supply chain can control the overall emissions produced and maintain the total cost.

Solar energy as a potential contributor to help bridge the gap between electricity supply and growing demand in Iraq: A review

<p><span>The pivotal role of electricity is as an enabler for every other sector in any economy. Adequate electricity supply is a vital input for the economic growth and in a range of key industries. Unfortunately, the electricity sector in Iraq has been an unsustainable fiscal burden on successive Iraqi governments yet it has not been able to meet the growing demand. Iraq’s electricity sector and government’s decision makers should look for a long-term solutions and strategies to meet the current and future demand, by taking important steps towards fostering a reliable, affordable, and sustainable electricity system in the years and decades to come. Also, Iraqi government and ministry of electricity in particular should understand that electricity is basic service and right of Iraqis, and many nations have overcome this kind of problem decades ago. Overcoming this problem will help refueling Iraqi economy and enable it to stand on its feet again. Renewable energy resources, and solar in particular could be part of the solution. This paper aims to highlight the importance of solar energy in Iraq as a potential contributor to help bridge the gap between electricity supply and growing demand. Also, it discusses the solar energy opportunities with challenges facing other renewable energy sources in Iraq.</span></p>

(Invited) Contribution of Organic Molecular Compounds to Electrochemical Energy Storage

Contribution of organic molecular compounds to electrochemical energy storage Dr. Matthieu Becuwe Laboratoire de Réactivité et Chimie des Solides (LRCS), UMR CNRS 7314, Université de Picardie Jules Verne (UPJV), Amiens, 33 rue Saint-leu, 80039 Amiens, France Matthieu.becuwe@u-picardie.fr We are currently facing global climate change caused by the worldwide rise of the average temperature. This increase is directly linked to the release of greenhouse gases by human activities, which is constantly increasing. To hamper this critical issue, a complete overhaul of our habits in terms of transport, energy production and consumption is required. This has already started with the growth of renewable energies. However, owing to the intermittency of these processes, it is essential to have efficient storage systems for delivering on-demand and transporting the energy thus produced. Electrochemical ion-based storage systems are currently the most efficient systems addressing these specifications. Nevertheless, the electroactive compounds used as an electrode in these systems are exclusively inorganic materials based on Co, Mn, Fe, Ni, V, W... which are exhaustible, difficult to recycle and sometimes toxic.[ 1 ] A promising solution to overcome these problems is to use renewable resources such as organic compounds, from inedible agro-resources and/or "green" synthesis processes taking into account the sourcing aspect and ecological durability, to create sustainable efficient easy recycling electrical energy storage systems.[ 2 ] With this aim, our attention was caught during the last years on the employment of electroactive and molecular compounds for faradic and capacitive electrode materials. Specific efforts were placed on the improvement of negative electrode materials for LiB, based on conjugated lithium carboxylate, with especially the enhancement of the power density and the tuning of the redox potential through molecular engineering. [3-6] Interest of molecular organic compounds resides also in the possibility to be strongly coupled with inorganic materials in order to improve their performances through an organic/inorganic hybrid approach. In this sense, a specific focus will be made on the surface modification of metal oxides, polyanionic framework or carbon-based materials by grafting and chemical adsorption techniques which lead to significant improvement of the storage capacity and conductive properties, for instance.[7-8] 1 D. Larcher, J.-M. Tarascon, Nat. Chem., 2015, 7, 1–12.2 P. Poizot, F. Dolhem, Energy Environ. Sci., 2011, 4, 2003–2019.3 L. Fédéle, F. Sauvage, J. Bois, J.-M. Tarascon, M. Bécuwe, J. Electrochem. Soc., 2014, 161, A46–A52.4 L. Fédèle, F. Sauvage, S. Gottis, C. Davoisne, E. Salager, J.-N. Chotard, M. Becuwe, Chem. Mater., 2017, 29, 546–554.5 A.E. Lakraychi, F. Dolhem, M. Becuwe, Electrochemistry Communications, 93, 71-75, 2018 . 6 A. E. Lakraychi, F. Dolhem, F. Djedaïni-Pilard, A. Thiam, C. Frayret, M. Becuwe, J. Power Sources, 2017, 359, 198–204.7 M. Boota, M. Becuwe, Y. Gogotsi, ACS Appl. Energy Mater., 3, 4, 3144-3149, 2020 . 8 M. Boota, C. Chen, M. Bécuwe, L. Miao, Y. Gogotsi, Energy and Environmental Science, 9, 2586-2594, 2016.

Incorporating new power system security paradigms into low-carbon electricity markets

Australian Electricity Markets are integrating variable renewable energy sources at rates faster than anywhere in the world. South Australia and Western Australia, in particular, are at the world’s forefront of the consequential new challenges in maintaining a secure electricity grid. These emerge primarily with respect to frequency and voltage instability, converter interoperability, and variability and forecasting issues. As a result, operating strategies that worked well in energy markets dominated by conventional generators must be transformed to take into account the physical characteristics and probabilistic capabilities of emerging energy conversion processes. In turn, these approaches must be incorporated into the mechanisms and rules that will govern new low-carbon electricity markets. This article summarises recent research work in the field and then considers how technical insights underpinning these new security services could be adopted into a competitive market construct to enable a smooth transition towards sustainable electricity systems.

Frequency and Voltage Regulation in Hybrid AC/DC Networks

Hybrid ac/dc networks are a key technology for sustainable electrical power systems, due to the increasing number of converter-based distributed energy resources such as solar or wind. In this article, we consider the design of control schemes for hybrid ac/dc networks, focusing especially on the control of the interlinking converters (ILCs). We present two control schemes: first for decentralized primary control and second a distributed controller to achieve secondary control objectives as well. In the primary case, the stability of the controlled system is proven in a general hybrid ac/dc network, which may include asynchronous ac subsystems. Furt hermore, it is demonstrated that power sharing across the ac/dc network is significantly improved compared to previously proposed dual-droop control. The proposed scheme for secondary control guarantees the convergence of the ac system frequencies and the average dc voltage of each dc subsystem to their nominal values. An optimal power allocation is also achieved at steady state. The applicability and effectiveness of the proposed algorithms are verified by advanced simulations on a test hybrid ac/dc network in Simscape Power Systems.

Evaluating critical barriers and pathways to implementation of e-waste formalization management systems in Ghana: a hybrid BWM and fuzzy TOPSIS approach

The majority of developing countries are facing enormous challenges in implementing sustainable waste electrical and electronic equipment (e-waste) management systems. Informal e-waste management practices in Ghana have become a critical challenge to the government and the various stakeholders owing to its environmental and health impacts. However, the effort to implement e-waste formalization management practices has been threatened with many barriers. This study aims to identify and evaluate barriers and pathways to the implementation of e-waste formalization management systems in Ghana. A three-phase methodology consisting of the Delphi method, the hybrid best-worst method and the fuzzy TOPSIS technique is employed. The first phase involves extensive literature review and the use of the Delphi method to identify barriers, pathways, and data collection for e-waste formalization. In the second phase, the best-worst method was employed to analyze the relative weight and ranking of the barriers. The third phase involves the application of fuzzy TOPSIS to rank and prioritize pathways to e-waste formalization systems. Fuzzy logic was applied to handle the subjectivity of decision-makers' preferences. A sensitivity analysis was carried out to check the robustness of the framework and address any effect of bias. The outcome of the study indicates that economic and financial limitations are the most significant barriers to e-waste formalization. "Setting up resourced environmental government agencies for effective monitoring and auditing at the regional levels for appropriate e-waste management practices" is the most prominent pathway. The present study can potentially inform policy makers to develop systematic and strategic policies for the implementation of e-waste formalization management systems.

Multiple roads ahead: How charging behavior can guide charging infrastructure roll-out policy

A key challenge for the roll-out of public charging infrastructure is that electric vehicles are needed to function both as a clean mode of transportation and as part of a sustainable electricity system, while being cost-effective. Translating these high-level policy goals to a coherent roll-out strategy is not trivial. We address this by analyzing local charging behavior and linking behavior indicators to specific policy measures through a decision tree. We analyze how policy measures for: (1) increasing the number of charge points, (2) reducing hogging, (3) vehicle-to-grid, (4) overnight charging, and (5) solar charging align with overall goals and characteristics of specific neighborhoods. More specifically, we analyze a dataset containing one million charging sessions in the Netherlands, and (1) link this data to neighborhood characteristics and (2) evaluate the coherency of policy mixes. Our analysis shows great spatial variation in charging behavior and consequently in the suitable policy mixes.

Role of the transmission grid and solar wind complementarity in mitigating the monsoon effect in a fully sustainable electricity system for India

Various assessments have shown abundant renewable energy (RE) potential for India, especially solar. For a fully sustainable power system, monsoon presents an obstacle with the resultant decrease in solar resource availability. In this study, India is subdivided into ten regions, and these regions are interconnected via power lines. A 100% RE transition pathway in hourly resolution, until 2050, is simulated. The results from this paper indicate that the power system can overcome the monsoon hurdle by solar–wind complementarity and grid utilisation. Wind energy output increases in regions that have the best wind conditions with 62% of the total wind energy generated in monsoon. Solar photovoltaic (PV) and grids can manage the unavailability of wind resources in some of the regions. There is a clear indication that imports increase during the monsoon period. The least affected regions such as India-Northwest (IN-NW) can transmit PV electricity to other regions via transmission grids. In the monsoon period, grid utilisation increases by 1.3% from the non-monsoon period to satisfy the respective demand. The two major exporters of electricity, IN-NW and India-South export about 43% of electricity in the monsoon period. These results indicate that no fossil-based balancing is required in the monsoon period.

A multi-criteria decision method for performance evaluation of public charging service quality

Public electric vehicle charging infrastructure provides an essential support for sustainable electric transportation systems. However, the current development model for such infrastructure tends to emphasize quantity over quality and cannot meet the charging needs of electric vehicle users. Addressing this situation requires further guidance from governments, which should be based on performance evaluation systems. This study therefore developed a multi-criteria evaluation framework to assess the performance of public charging infrastructure in terms of planning rationality, operational efficiency, service capacity, charging safety, and sustainable development. After defining individual charging station attributes through numerical data and user/expert input, a modified Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) model was used, with vague sets to standardize, weight, and process the data. The assessed stations were subsequently ranked. The model was applied to three public charging stations in Beijing, China to verify its effectiveness and robustness. The resulting rankings can facilitate regulatory assessment of these stations’ performance and guide improvements in the quality of their charging services. The results further indicated that the sustainable development value of charging facilities is often undervalued, and relevant incentive strategies should thus be implemented by policymakers.

Environmental analysis of a nano-grid: A Life Cycle Assessment

Renewable energy sources are fundamental to face the problem of climate changes. Unfortunately, some resources, such as wind and solar radiation, have fluctuations affecting the electrical grids stability. Energy storage systems can be used for a smart energy management to accumulate power from renewable sources. For such reason, these devices play a key role to achieve a sustainable electric system. On the other hand, they are affected by some environmental drawbacks mainly connected with the depletion of rare and expensive materials. Based on these considerations, in this study a nano-grid composed by a photovoltaic plant, a backup generator and an energy storage system is analysed by an environmental Life Cycle Assessment approach. A Solar Home System is designed, and its environmental profile is evaluated considering several Lithium-ion batteries. Among them, nickel-cobalt aluminium oxide cells resulted to be the most suitable solution for a Solar Home System (46.66 Pts/MWh). Moreover, a sensitivity analysis of the Solar Home System is performed and a hybrid energy storage plant integrating hydrogen and batteries is proposed to face the problem of seasonal solar radiation variability. Four scenarios having different gas pressure levels and lifespan of the devices are considered. Results show that currently the most sustainable configuration is represented by the Solar Home System, but in the future a hybrid nano-grid equipped with 700 bar hydrogen storage might be the best off-grid configuration for minimizing the impact on the environment (37.77 Pts/MWh). Extending the perspective of our analysis to future on-grid potential configurations, an efficient connection of the Solar Home System with a smart-grid is assessed as it looks more sustainable than other off-grid solutions (22.81 Pts/MWh).

Diagnostic challenges in dielectric loss assessment and interpretation: a review

In any sustainable electrical systems, various high-voltage (HV) power apparatuses such as electrical cable, transformer etc. play a pivotal role to transfer electrical energy from the generation end to the consumer end. The degradation due to electrical stress is very unlikely to avoid in operation. Prominently, the insulation system is mostly expected to be strong enough, and its degradation always provides a constant threat to the reliable operation. Moreover, the continual deterioration can gradually lead to the complete breakdown of HV equipment. To assess the overall dielectric properties, the regular monitoring/diagnosing of electrical insulation has a paramount importance in power systems. One of the potential tools for diagnostic assessment is the tan-delta (tan δ) measurement. Considering different aspects at various frequencies, this study elucidates a comprehensive review of tan δ measurement. First, a detailed review and explanation of multiple challenges associated with dielectric loss measurement are presented. Various dielectric losses, their contribution to tan δ, measurement techniques and their comparisons are also discussed. This study further reviews the analogy of different physical dipolar theories, modelling and a brief analysis of commercially available measurement instruments.

Smartening up while keeping safe? Advances in smart metering and data protection under EU law

Integrating increasing shares of renewable electricity generation within the European Union electricity market requires that the electricity system is capable of withstanding intermittency. One of the principal means of achieving this is by activating the demand side in such a way as to enable a more flexible balance between demand and supply. In practice, initiatives and technological solutions to activate the demand side are well exemplified by smart meters, which collect and communicate information on electricity consumption. The existing legal framework and the 2016 legislative proposals for the electricity sector recognise that significant opportunities exist to utilise consumer data collected via smart metering and that these are of fundamental importance in creating more flexibility in the electricity market. However, the extensive utilisation of this data also raises questions concerning data privacy and data protection. This article examines the interface between data protection and energy law in the EU. The focus of the legal analysis is on the General Data Protection Regulation (GDPR) and the proposed rules contained in the Winter Package, which are systematically analysed to determine the conditions under which smart metering data can be utilised to further the objectives of EU energy law. The underlying argument of the article is that there is an apparent conflict between the objectives embedded in EU data protection law and those embedded in EU energy law. EU energy law addresses smart metering and the resulting data as means of achieving a more sustainable electricity system that benefits the final consumer. Conversely, EU data protection rules focus on the protection of a fundamental right and perceive the collection and processing of data as a risk to the very same consumer that is considered to benefit from smart metering data under EU energy law. This article demonstrates how this apparent conflict can be reconciled through interpretation of the relevant rules of EU law.

Flexibility in Sustainable Electricity Systems: Multivector and Multisector Nexus Perspectives

As environmental concerns increase, researchers, policy makers, and the public in general are becoming more interested in options to make energy more sustainable while at the same time ensuring that energy systems are affordable, reliable, and resilient. This dynamic is bringing about challenges across the world, as established energy systems (such as those in cities) must be enhanced to integrate large volumes of renewable energy sources (RES), while new or evolving systems (for instance, in developing economies) must be planned to manage the increasingly extreme conditions associated with climate change. In these contexts, the flexibility to intelligently use and invest in resources that go beyond the power system (e.g., other energy vectors such as heat, gas, or water dams) can be extremely valuable from the perspective of sustainable development.