Current Energy System Research Articles

New York State Climate Impacts Assessment Chapter 06: Energy.

Energy plays an integral role in New Yorkers' lives. It powers the economy, moves people and goods, keeps homes and workplaces at a livable temperature, and runs critical infrastructure that keeps people healthy and safe. Reliable energy systems are easy to take for granted, but many aspects of these systems are vulnerable to weather and climate hazards. This chapter discusses how climate change is affecting and will increasingly affect New York State's energy supply, delivery, and end uses. It provides insights into current and future climate vulnerabilities as New York's energy system transitions to clean energy sources. This assessment also highlights opportunities to adapt current and future energy systems and to build resilience to climate impacts.

Control strategy of the novel stator free speed regulating wind turbine generation system.

Building a high-proportion renewable energy power system is a key measure to address the challenges of the energy revolution and climate change. However, current high-proportion renewable energy systems face issues of frequency instability and voltage fluctuations. To address these challenges, this paper proposes a novel topology for a stator free speed regulating wind turbine generation system. The stator free speed regulating machine connects a gearbox and a synchronous generator, forming a flexible drive chain that increases system inertia and enhances frequency stability in high-proportion renewable energy power systems. The synchronous generator at the end of the drive chain can be directly connected to the grid without the converter, thanks to the speed regulation provided by the stator free speed regulating machine, thus avoiding harmonic pollution caused by power electronic devices in traditional wind turbines, enhancing the reactive power support capability, and improving voltage stability in high-proportion renewable energy systems. Given that the proposed stator free speed regulating machine consists solely of a rotating inner and outer rotor without a stator, traditional motor control strategies are not applicable. Therefore, this paper focuses on developing control strategies for the stator free speed regulating machine, employing a dual closed-loop PI control strategy with an outer loop for speed and an inner loop for current, based on flux orientation of the outer rotor. Simulation experiments will validate the feasibility of the proposed stator free speed regulating wind turbine generation system topology and the effectiveness of the control strategy.

Reevaluating fair carbon emissions for households in Japan: basic energy needs and subsistence CO2 emissions

ABSTRACT Substantial inequalities in per capita carbon emissions have recently been highlighted. Given the diversity of people’s energy needs and extant differences in access to low-carbon energy, a fair emissions benchmark would not be equal CO2 emissions for all, but the CO2 emissions needed to enjoy a decent life ('subsistence emissions’). This study investigates the relationship between people’s basic energy needs and associated CO2 emissions, and illustrates the distribution of subsistence emissions among households in Japan, employing a unique and high-visibility technique. It finds that approximately 20% of households cannot meet their basic energy needs with one tonne of CO2 emissions per capita, and that an additional 1.56 million t-CO2 is required for all households to be able to meet their basic energy needs; this additional amount needs to be offset by further emissions reduction by households that consume a lot of domestic energy ('energy extravagant’) or non-residential sectors. With an equal-per-capita distribution of CO2 emissions in line with Japan’s 2030 target, approximately two-thirds of households would not be able to meet their basic energy needs, given the current energy mix and systems. In this context, low-carbon energy and technologies must be made more accessible for vulnerable populations to achieve both decarbonization and satisfaction of basic needs.

Simulation of PSDF (Photovoltaic, Storage, Direct Current and Flexibility) Energy System for Rural Buildings

The PSDF (photovoltaic, storage, direct current, and flexibility) energy system represents an innovative approach aimed at achieving carbon neutrality. This study focused on rural buildings and utilized Modelica to develop a dynamic simulation model of the PSDF system. The research introduced a framework for direct current distribution microgrid systems with flexible regulatory mechanisms, employing a virtual inertia control strategy to provide stable adjustments for flexible operations and support integration with local grids. Case simulation results indicated that the system equipped with a water tank saved 3.15 kWh compared to the system without a water tank, resulting in an energy savings rate of 22.14%. Compared to traditional photovoltaic systems, the PSDF system significantly enhanced energy management flexibility and system reliability through the integration of thermal storage and battery management. This research made significant contributions to the fields of renewable energy and building energy systems by offering a scalable and practical solution suitable for rural contexts.

Investigation of Ammonia/Hydrogen Mixtures and Pilot-Split Strategies in a Laboratory-Scale Radial Swirl Combustor

Abstract The transition to a decarbonized energy future relies on identifying the most suitable alternative fuels that can meet the needs of various energy sectors. While both ammonia and hydrogen are zero-carbon energy vectors, their physical properties and burning characteristics sit on either side of that of natural gas. Hence, mixtures of ammonia and hydrogen are being increasingly looked at as having the potential to fuel current energy systems without requiring significant combustor redesign. However, the combustion characteristics and operation limits for different ammonia/hydrogen mixtures still need to be evaluated. For gas turbine applications in particular, the effect of ammonia/hydrogen mixture composition and operating condition on flame behavior and stability is not well understood. The current work was carried out in a laboratory scale, radial swirl-stabilized turbulent combustor. A systematic study of two ammonia/hydrogen blend ratios (70:30 and 80:20 by volume) and a range of equivalence ratios were tested for different pilot-split ratios, to understand the effect on flame shape, stability and dynamics. Time-resolved pressure and integrated heat release fluctuations were measured to evaluate combustor dynamics, and NH2* chemiluminescence flame images were captured to understand spatial differences in flame structure. When comparing blend ratios, differences were observed in flame macrostructures and combustor dynamics, which could be largely attributed to the considerable difference in the laminar flame speeds of the blends. The addition of pilot generally improved the stability and lean operation for both blend ratios.

System friendliness of distributed resources in sustainable energy systems

The increasing share of volatile renewable energy generation in current and future energy systems which does not follow the demand, makes it necessary to shift the synchronization tasks to the system and demand level. The intended demand side consumption management is usually incentivized via financial mechanisms. However, the optimum design of related incentives is still unclear. It is usually discussed under the term “system friendliness” which in turn still lacks a broadly accepted definition. In this article we introduce a new technical definition of “system friendliness” and develop comprehensive and holistic related indicators. For that, we introduce the burden concept for energy systems which represents the amount of technical infrastructure required for stable operation. We use the concept of a hypothetical system energy storage to derive indicators that are capable of quantifying the system friendliness of a given point-of-interest. The developed indicators are independent of regulations or market environments which enables comparability of results between studies and different systems. In a case study we demonstrate our newly developed methodology and exemplary examine decentral district energy storages. Our findings demonstrate that today’s regulatory environments that usually support residential self-consumption maximization are counterproductive. Instead, we show that dynamic end-user prices coupled with dynamic feed in tariffs are able to incentivize an almost 100% system friendly behavior of distributed prosumers.

THE ROLE OF RENEWABLE ENERGY IN REDUCING CO2 EMISSIONS IN UZBEKISTAN

The transition to renewable energy is a key strategy for reducing CO2 emissions and promoting green growth in Uzbekistan. This paper explores the role of renewable energy sources, including solar, wind, and hydropower, in reducing carbon emissions within the country’s energy mix. Uzbekistan’s current energy system remains heavily reliant on fossil fuels, particularly natural gas, which is a significant contributor to CO2 emissions. By analyzing the potential of renewable energy and government initiatives to support its growth, this study assesses the progress made and identifies challenges that hinder the transition. The findings suggest that increasing the share of renewable energy will play a vital role in reducing emissions and promoting sustainable development in Uzbekistan

Are we on the same page? Understanding value similarity and its impact on public trust in institutions of the energy sector

Value similarity – the extent to which people think institutions managing risks hold different or similar values to themselves, affects trust in those institutions and as such, plays a critical role in the public acceptability of energy projects and policies. Yet, we do not know what constitutes value similarity. How do people judge the level of similarity between their own values and the values of an institution? What role do different values play in theses judgments? And to what extent can these perceived similarities actually increase trust in institutions? To explore this, we decomposed the construct of value similarity into one's personal values and the perceived values of an institution, and explored if their congruence led to higher ratings of perceived value similarity and trust in institutions. We studied these relationships for three institutions playing important roles in the energy sector in the Netherlands, in current and future energy systems. Overall, response surface analyses (RSA) showed that people see their own values and the values of an institution as more similar and trust the institution more when they both endorse biospheric values more strongly. Further, perceived value similarity and trust in institutions are higher when people perceive institutions to have stronger biospheric values than themselves and when they expect institutions to be less egoistic than themselves. We discuss these findings reflecting on what they suggest regarding the role of shared values in increasing trust in relevant institutions and acceptability of energy risks.

Analysis on integration of heat pumps and thermal energy storage in current energy system: From research outputs to energy policies

This paper presents a comprehensive examination of the integration of heat pumps and thermal energy storage (TES) within the current energy system. Utilizing bibliometric analysis, recent research trends and gaps are identified, shedding light on the evolving landscape of this dynamic field. The study delves into the research outputs since 1969, offering insights into the global scholarly contributions shaping the discourse. Furthermore, an extensive policy analysis is conducted, focusing on seven countries with the highest research output. The interplay between research advancements and energy policies is explored, providing an understanding of the practical implications of the integration of heat pumps and TES. An understanding is tried to reach as how research and policy sector influence each other. This analysis contributes not only to the academic understanding of the subject but also informs policymakers about potential pathways for enhancing energy efficiency and sustainability in heating and cooling sector.

Status and Challenges of Marine Current Turbines: A Global Review

Over the past few decades, marine current energy utilization has transitioned from conceptual demonstrations to industrial-scale prototypes. This progression now approaches a crucial phase emphasizing the need for industrialization and commercialization. This paper provides an in-depth examination of the developmental status of large-scale marine current turbines and arrays, underscoring the promising prospects for marine current energy systems. Despite the significant advancements, the deployment of these systems has revealed several challenges, including blade design optimization, transmission system selection, and the establishment of appropriate test sites. Addressing these issues is essential for technological maturity and economic feasibility, which will foster the next wave of innovation in marine energy systems. Furthermore, the paper offers various perspectives for future applications.

Unraveling the complexity: A taxonomy for characterizing and structuring smart energy services in the building sector

Achieving climate goals requires restructuring the current energy systems, which, among other things, involves decentralizing energy systems. This entails new challenges, e.g., a high degree of coordination and information exchange. Especially the building sector, being the largest energy consumer, offers great improvement potential to reduce emissions. Smart energy services promise various benefits in overcoming these challenges, e.g., through optimized energy generation, demand control, and more efficient energy control systems. Although smart energy services are crucial to transitioning to a more sustainable, reliable, and intelligent energy (eco)system, research lacks a holistic perspective of their essential characteristics and configuration options due to their novelty and heterogeneity. Nevertheless, this perspective is crucial as service providers, service innovators (e.g., business development and start-ups), and researchers face problems developing and deploying value-adding and sustaining smart energy services. Consequently, this work identifies the essential characteristics of building-related smart energy services by reviewing scientific and practitioner literature. It structures them by developing a taxonomy and organizing them in 15 dimensions and 54 characteristics, along smart energy service structure, value creation, delivery, and energy-related data input. The taxonomy and the derived theoretical and managerial implications support researchers and practitioners in designing and conceptualizing future smart energy service innovations.

106 Net energy of soybean meal

Abstract Our current net energy (NE) systems were developed based on work conducted around 40 yr ago. At that time, it was normal that pigs deposited no more than 40% of the protein they were fed. However, modern genetic lines are much leaner than older genetics and they deposit more protein than earlier. It is, therefore, not uncommon that protein deposition in modern genotypes exceeds 60% of dietary protein intake. This means that more of the amino acids in the protein-rich ingredients are used for protein deposition and less are being deaminated with a subsequent reduced energetic cost of deamination associated with feeding protein-rich ingredients. As a consequence, the theoretical energy value of protein rich ingredients such as soybean meal (SBM) is greater when fed to modern pigs than to older genotypes that were used when our current NE systems were developed. Indeed, in several recent experiments it was demonstrated that the ME and NE of SBM is greater than indicated in current feed ingredient tables. A greater NE than predicted has also been demonstrated for field peas, whereas corn does not seem to have increased energy value compared with previous estimates, which is consistent with the hypothesis that it is the increased protein efficiency of modern pigs that is the reason for the greater NE value in SBM. As a consequence of the greater NE value of SBM, less added fat need to be used to reach a certain NE level in the diet, which will reduce overall diet costs. However, because of the greater genetic capacity for protein deposition in modern pigs, there is a need to upgrade the NE system and to develop new equations to predict NE in diets and ingredients based on the protein deposition capacity of modern pigs. It can also be argued that because commercially fed pigs always are group housed and allowed ad libitum intake of feed, pigs fed to generate prediction equations for NE also need to be group housed and allowed ad libitum intake of feed because both animal behavior and level of feed intake may affect the NE value of diets. In conclusion, because of the increased ability of modern genotypes of pigs to retain dietary protein in the body, there is reduced deamination of amino acids and therefore reduced energy loss in modern pigs than in older genotypes, which results in greater NE of protein rich ingredients including SBM. There is, therefore, a need for developing a new NE system that preferably uses group-housed pigs that are allowed ad libitum access to feed.

Patenting for profitability: green energy innovations and firm performance in BRICS countries

Introduction:Despite the significant advancements in renewable energy technologies, the current energy system remains heavily reliant on fossil fuels. However, an increasing number of studies have demonstrated that the proliferation of “green” patents is contributing to the transition towards a more sustainable energy future, with important implications for both environmental sustainability and corporate financial performance.Methods:Utilizing panel data sourced from 63 of the most prominent energy sector companies within the BRICS countries during the period between 2011 and 2020, we conducted a comprehensive analysis with the objective of uncovering the distinct impacts of various types of patents in renewable energy technologies on the firm’s financial performance indicators (ROA, ROIC, and market capitalization) by using multiple regression modeling.Results:The feasible generalized least squares estimations reveal that higher CO2 emissions correlate with lower return on assets, ROIC, and market capitalization of energy companies, significant at the 5% level. Additionally, while renewable energy technologies (Y02E10) did not impact ROA, they contributed significantly to ROIC at the 1% level. Combustion technologies with mitigation potential (Y02E20) positively influence all financial performance indicators, and nuclear energy technologies (Y02E30) significantly contribute to both ROA and ROIC at the 10% level.Discussion:Our research demonstrates that technological advancements in national economies are not consistent and that disparities exist in specific data segments. Advancements are observed in certain areas, highlighting the significance of national legislation in promoting green finance and renewable energy development. This emphasizes the need for BRICS countries to prioritize renewable energy technologies and adopt legislative initiatives from developed nations as a model for achieving clean technological growth and renewable energy targets.

Citizen-led decentralised energy futures: Emerging rationales of energy system organisation

The current energy systems are undergoing fundamental changes driven by the climate crisis, unfolding digitalisation and increasing calls for a more active citizens' engagement. The impact of these ongoing trends on the future energy system, however, is far from straightforward. Although there is an increasing shift towards a decentralisation, it is not clear yet how exactly this new decentralised configuration will unfold and materialise. In this article we explore the rationales behind current trends towards a more decentralised electricity system. Given the developments in the electricity system, our study centres on emerging initiatives led by citizens and their values. Theoretically, we first mobilise the notion of socio-technical system as constituted and reproduced by actors, institutions, and technology, operating based on certain shared principles. We use this lens to describe the past and current energy system organisation. Secondly, based on two dimensions of value orientation and steering direction we define four emerging ideal-types socio-technical decentralisation configurations. We examine possible pathways of change, and the institutional, actor and technological preconditions they require, to become predominant forms of decentralisation. We conclude that although all forms of decentralisation may potentially contribute to low carbon objectives, they are likely to co-evolve catering to diverse system needs and the citizen requirements simultaneously.

Identification of typical district configurations: A two-step global sensitivity analysis framework

The recent geopolitical conflicts in Europe have underscored the vulnerability of the current energy system to the volatility of energy carrier prices. In the prospect of defining robust energy systems ensuring sustainable energy supply in the future, the imperative of leveraging renewable indigenous energy sources becomes evident. However, as such technologies are integrated into the existing system, it is necessary to shift from the current centralized infrastructure to a decentralized production strategy. This paper presents a method to identify a panel of technological solutions at the district level, intended to reduce complexity for the integration of decentralized models into a national-scale model. The framework’s novelty lies in combining a global sensitivity analysis for solution generation with clustering to identify typical configurations. The global sensitivity analysis is performed on a mixed integer linear programming model, which optimally sizes and operates district energy systems. The sensitivity analysis determines the most influential parameters of the model using the Morris method and provides a representative sampling of the solution space by leveraging the Sobol sampling strategy. The latter is then clustered using a density-based algorithm to identify typical solutions. The framework is applied to a suburban and residential Swiss neighborhood. The first outcome of the research is the high sensitivity of the model to energy carrier prices. As a result, Sobol’s sampling space separates itself into two system types: those based on a natural gas boiler and those relying on a combination of electrical heaters and heat pumps. For both types, the electricity demand is either fulfilled by PV panels or electricity imports. The identified configurations showcase that the framework successfully generates a panel of solutions composed of various system configurations and operations being representative of the overall solution space.

Institutional investor behaviour and the energy transition: A complexity framework for accelerating sustainable finance from UK investors

Despite sustainable investment flows having increased significantly over the past decade for transforming the current energy system, a large investment gap remains. This research explores the complex links between institutional investors' expectations on the speed of the energy transition and their sustainability-related investment behaviours. Through in-depth semi-structured interviews with institutional investors, we construct a complex system model using a causal mapping approach, illustrating complex relationships within the sustainable investment system. Our contribution involves the development of multi-layer cognitive maps for different types of institutional investors, followed by a composite causal map that dissects key investment behaviours and investor expectations. Results reveal interlinked concepts influencing investment behaviour and highlight feedback loops with potential amplifying effects on investor expectations and investment behaviour. Two critical feedback loops emerge: 1) the interplay between political and financial support for the energy transition and the associated cost, and 2) the intricate relationship between sustainability factors and asset valuation. Addressing these interconnected issues simultaneously and monitor negative feedback loops that may curtail sustainable finance flows are vital. The results reveal heterogeneities amongst institutional investors such as fiduciary duties, stranded assets, the importance of fossil fuels in the energy system. In sum, our insights provide a foundation for holistic energy policies and a reference system for evaluating policies aimed at accelerating green finance.

Implementation of Positive Energy Districts in European Cities: A Systematic Literature Review to Identify the Effective Integration of the Concept into the Existing Energy Systems

The positive energy district (PED) is a rather recent concept that aims to contribute to the main objectives of the Energy Union strategy. It is based on an integrated multi-sectoral approach in response to Europe’s most complex challenges. But to what extent have its development and implementation been supported by research and innovation programs? And what is the state of the art of its implementation and effective penetration into the current energy systems of European cities, according to the evidence provided by the scientific literature? This study aims to investigate these issues, providing a critical overview of the PED situation by means of a systematic literature review based on the use of open-access bibliometric software supplemented with content analysis. The results show that less than half of the documents analyzed refer to actual case studies, 80% of which were funded as part of research projects. This seems to lead to the conclusion that although PEDs have been strongly encouraged by the scientific community and policy initiatives at the European level, their implementation in cities is still limited. Moreover, an uneven distribution among countries can be observed. To overcome the existing barriers to PED diffusion and implementation, it would be useful to provide more ad hoc funding and, above all, facilitate its accessibility also by municipalities not yet well integrated into European projects, initiatives, and networks.

Hybrid AC/DC architecture in the CE.D.E.R.-CIEMAT microgrid: demonstration of the TIGON project.

This article presents the demonstrative development of the Towards Intelligent DC-based hybrid Grids Optimizing the Network performance (TIGON) project at the Centre for the Development of Renewable Energy - Centre for Energy, Environmental and Technological Research (CE.D.E.R.-CIEMAT), as well as the established objectives to be achieved with the implementation of a microgrid with smart grid architecture based on direct current (DC) and integrated into the current energy system. This type of architecture is proposed as a future solution to reduce energy losses caused by DC-alternating current (AC) conversions, increasing the overall performance and profitability of hybrid grids. All this without forgetting to ensure the supply, stability and reliability of the system with the development of all the necessary equipment and protections to make this approach a reality. The microgrid design and process of implementation start from a transformation centre, from which the medium voltage direct current (MVDC) grid will be created by the Solid State Transformer (SST). In the MVDC grid, we will find a bank of lead-acid batteries and other essential equipment in the microgrid, a DC/DC converter that will create the low voltage direct current (LVDC) grid. On the LVDC side, several branches have been designed to connect the rest of the systems; generation (mini-wind and photovoltaic), storage (LFP batteries) and loads (AC and DC loads). Each of the equipment will have a connection to the DC grid through converters made exclusively for this equipment and connexion to the AC grid, which will allow us to obtain all the necessary data to carry out the required studies to achieve the established objectives of the project.

Development of Floating Tidal Current Energy Systems to Support Energy Independence in Island Areas

Development of Floating Tidal Current Energy Systems to Support Energy Independence in Island Areas

Design and Assessment of a solar collector system for low-cost, pollution-free cooking and grilling applications

Recently, using solar energy for several purposes has become very important to preserve the environment, reduce pollution, and reduce consumption. Examples of these applications are cooking, barbecuing, desalination, and generating electrical power. Solar oomph is extremely important in providing the energy used in cooking. In the current work, a solar collector consisting of six flexible reflective panels was designed and assembled for solar cooking and grilling operations in the city of Jazan, southwestern Saudi Arabia. Pots of different sizes have been prepared for cooking operations, as well as a grid for grilling operations. They are installed at the center of the collection of reflected rays from the solar center, in addition to a movable stand and a manual system for directing the direction of the falling sunlight. The current solar energy system provides an estimated power of about 2,300 watts from 9 a.m. to 5 p.m. It took 16 minutes to cook 2700 grams of vegetables with the current system and less than two minutes to boil 2 liters of water. Grilling a whole chicken weighing 800 grams, cut in half, takes about ten minutes. Cooking was also done inside the kitchen using a solar energy source by transferring heat from the solar concentrator's absorber to a 35-diameter pipe filled with vegetable oil as a heat transfer fluid. The absorber temperature reached 321 degrees Celsius, while the internal cooking stove registered 129 degrees. The storage of collected heat and how it is transferred to indoor cooking processes were also studied.