Energy Research Community Research Articles

TorqTwin—An open-source reference multibody modeling framework for wind turbine structural dynamics

This paper presents an open-source multibody modeling framework for wind turbine structural dynamics, namely TorqTwin (Torque Towards wind). The multibody formulation includes both rigid and flexible bodies. For flexible bodies, such as towers and blades, the floating frame of reference formulation and modal reduction approaches are applied. The TorqTwin tool relies on Kane’s method and the symbolic Python library SymPy. The multibody formulation in TorqTwin is validated using the OpenFAST-ElastoDyn module and the commercial software Bladed. For both the fixed-bottom and floating IEA 15MW reference wind turbines, the rigid motions and flexible deflections calculated by TorqTwin are compared to those by ElastoDyn. Also, blade deflections predicted by TorqTwin are compared to those of the commercial software Bladed. The overall very good agreement between TorqTwin and other software validates the multibody formulation in TorqTwin. The strength of TorqTwin is that it contains the full functionality of the state-of-the-art open-source ElastoDyn module and includes other modeling capabilities of commercial software, such as the bend-twist coupling effect of blades and more flexible modes. TorqTwin is designed to benefit both the wind energy research community and industry, as it helps understand and verify the theory behind the ElastoDyn module, provides a reference for formulating more complicated configurations, such as multi-rotor turbines, and helps to develop aeroelastic simulation tools.

(Invited) Two-Dimensional Low-Toxicity Absorbers for Efficient and Air-Stable Indoor Photovoltaics

The toxicity and bioavailability of lead (Pb) in halide perovskites motivates the search of Pb-free perovskite-inspired materials (PIMs), which would replicate the great optoelectronic properties of the traditional Pb-based counterparts. Among them, pnictohalides employing antimony or bismuth are especially attractive due to their low toxicity and inherent air stability. Their wide bandgaps (⁓2 eV) can broaden the application scenario beyond single-junction solar cells, being specifically suitable for e.g., silicon-perovskite tandems, indoor photovoltaics (IPVs), and photocatalysis.Despite outstanding indoor power conversion efficiencies up to 60% have been theoretically predicted for PIM-based IPVs, this research is still in a very early stage. In this talk, I will highlight some of our key findings on two-dimensional Sb- and/or Bi- based two-dimensional pnictohalides for sustainable indoor light harvesting. The considerable presence of both intrinsic and surface defects in wide-bandgap PIMs is mostly responsible for the modest indoor power conversion efficiency (PCE(i)) reported so far up to ⁓5% at 1000 lux white LED illumination. I will discuss the effective defect mitigation strategies relying on compositional engineering that we proposed to significantly improve the PCE(i) up to nearly 10% (9.53%). Our extensive characterizations at both material and device level evidence the successful suppression of trap-assisted and interfacial charge recombination as the result of a reduced defect density within the PIM domains and/or at their surface.The importance of our findings for the energy research community (within and beyond halide perovskite) lies in promoting future compositional design effort to reduce the defects in the next-generation wide-bandgap absorbers for eco-friendly energy generation and consumption.

Current Insights From Task Area 1 in NFDI4Energy: Building and Serving the Energy Research Community

Energy system research has become increasingly reliant on modeling and simulation approaches. These endeavors are enabled by continuously improving tools and methods for developing, maintaining and sharing models and data. Knowledge of how to better conduct, share and archive one’s research has become increasingly complex and hard to manage for individual researchers or single research groups. Identifying and including relevant scientists from energy research, social sciences, and further disciplines is sometimes difficult. Furthermore, a plethora of best practices and guidelines exist on how to prepare data, models and results in ways that make them easier to discover, verify and build upon. To present a sustainable, problem-solving, technical solution for the energy research community, NFDI4Energy develops in Task Area 1 (TA1) two services of the NFDI4Energy platform. Consequentially, the intention of this abstract within the disciplinary track “Engineering” is to provide an overview of the development process with a special focus on Competence and Best Practices. In addition, it discusses interconnections with other Task Areas as well as the chances and challenges that are associated with those connections. The academic audience, e.g., from the Information Systems and (Software) Engineering domain at CoRDI 2023, can observe and discuss our proposed procedure with other community members. Furthermore, we expect interested individuals to compare the proposed procedures with their own, which can lead to meaningful discussions and knowledge-sharing situations within the Engineering domain.

Using human-centered design to develop a national research landscape for marine energy in the United States

In 2021, the United States Department of Energy (DOE) awarded the Pacific Ocean Energy Trust a grant to act as the coordinator of a foundational research network, ultimately named the University Marine Energy Research Community (UMERC). The community aims to facilitate connection between U.S. university researchers, industry, and government research laboratories to close common gaps in foundational research that are prohibiting the pathway to commercialization. To achieve this goal, UMERC held a series of workshops to create a Research Landscape (Landscape), which identified current challenges, gaps, research capabilities as well as uncovering additional questions about where the sector is headed. A human-centered design (HCD) approach was used throughout the three-workshop series. 
 HCD is a problem-solving and design technique that uses human perspective and emotion to develop solutions. The stages of human centered design include inspiration, ideation, implementation and validation, or testing, in an iterative, or cyclical process that results in ongoing refinement. HCD is carried out with the acknowledgement that values vary from context to context and are subject to change as people and technologies interact over time (Zachry and Spyridakis).
 It is through this approach that we are able to identify the current gaps and challenges and through the HCD approach, we will continue to refine the Landscape as current challenges and gaps are retired and new challenges and gaps arise. This will help account for the fast pace of innovation in the marine energy sector, where human-technology interactions are changing as the technology develops, and there are new entrants into the market. With the current state of fluidity in technology design and application, what works at one location may not work at another location. Using HCD methods and sensibilities, workshop participants, including individuals from universities, private sector companies and the national laboratories, we able to bring in their individual perspectives to develop the Landscape.
 Through the HCD process, the workshops revealed a set of values, tools, research interests and gaps and challenges. These were synthesized into what is now the current Landscape that can be found on the UMERC website. The values are themes that should be considered when designing marine energy projects. These include community, innovation and new technologies or applications, education, sustainability, equity, blue economy, and collaboration. The main challenges were condensed into four categories that include creating markets and a trained workforce, management and logistics, understanding and protecting the environment, and marine energy engineering, research and development. The tools are actions that can be carried out to overcome the main challenges. Finally, a list of common research areas was identified under each main challenge area.
 Following our HCD methodology, our cycle of iteration will soon start again. While the current Landscape serves as a benchmark, the next steps include a series of industry-academic brainstorming sessions, with the aim of creating collaborative projects to address challenges, as well as come up with a list of common technology agnostic challenges, in hopes to push future research funding.

Can data sharing really provide added value? Practical data sharing recommendations for the wind energy sector

The digital era offers many opportunities to the wind energy industry and research community and digitalisation is one of the key drivers for reducing project costs and risks. The WeDoWind framework has been developed in order to address one of the main challenges to a successful exploitation of digitalisation in wind energy - data sharing and collaboration. The main innovation of this framework is the way it creates tangible incentives to motivate different types of people to actually share data and knowledge in practice. In this work, we carry out a detailed analysis of the strengths and weaknesses of the WeDoWind framework based on a survey filled out by participants of two use case studies and observations from the WeDoWind development team. The results show that the framework successfully enhances collaboration and data sharing in the sector. The results allowed a set of practical data sharing recommendations for the wind energy sector to be developed, which are being continuously improved based on our experience with the WeDoWind framework. They can be applied by anyone wishing to share data effectively and efficiently.

Wind and solar resource complementarity and its viability in wind/PV hybrid energy systems in Machakos, Kenya

Integration of intermittent renewable energy resources provides the potential to mitigate the impact of the variability of independent sources. The intermittent nature creates stability, reliability and power quality problems in power grids. Wind and solar energies are the most viable resources whose complementarity could be deployed in the development of hybrid renewable energy systems to enhance their performance. In this study, wind-solar resource complementarity is investigated to establish its viability in hybrid energy systems in Machakos, a rural-urban town whose geographical location is 1°31′S, 37,016′E in the Eastern region of Kenya. The study findings could be fundamental in energy planning and developments in the area to provide more flexible and dependable hybrid energy systems which would supply energy services under constantly changing conditions. Ground measurements included PVGIS simulation and experimental tools installed at a height of 20 m. Weibull's distribution model and energy potential of wind resource are investigated to characterize wind resource for energy generation. The Wind distribution revealed a positively skewed profile with scale (c) and shape (k) parameter values of 2.68 m/s (≈ 3.0 m/s) and 1.9 at a mean wind speed of 2.47 m/s, respectively. The findings revealed a wind power density of 17 W/m2 at an average wind speed of 3.0 m/s. Further, an annual solar insolation of 2130 kWh/m2 with monthly average of 178 kWh/m2 translating to daily insolation of 5.8 kWh/m2 at an installation capacity of 1 kWp is reported. The months with minimum and maximum solar insolation were July and March which recorded monthly averages of 145 kWh/m2 and 213 kWh/m2 translating to a daily average of 4.7 kWh/m2 and 6.9 kWh/m2, respectively. The understanding gained from this study could be useful to the renewable energy research community and can be extended to stakeholders in PV and wind energy systems for micro grids and utility applications.

Enhancing the Bandwidth and Energy Production of Piezoelectric Energy Harvester Using Novel Multimode Bent Branched Beam Design for Human Motion Application.

In recent years, harvesting energy from ubiquitous ultralow-frequency vibration sources, such as biomechanical motions using piezoelectric materials to power wearable devices and wireless sensors (e.g., personalized assistive tools for monitoring human locomotion and physiological signals), has drawn considerable interest from the renewable energy research community. Conventional linear piezoelectric energy harvesters (PEHs) generally consist of a cantilever beam with a piezoelectric patch and a proof mass, and they are often inefficient in such practical applications due to their narrow operating bandwidth and low voltage generation. Multimodal harvesters with multiple resonances appear to be a viable solution, but most of the previously proposed designs are unsuitable for ultralow-frequency vibration. This study investigated a novel multimode design, which included a bent branched beam harvester (BBBH) to enhance PEHs' bandwidth output voltage and output power for ultralow-frequency applications. The study was conducted using finite element method (FEM) analysis to optimize the geometrical design of the BBBH on the basis of the targeted frequency spectrum of human motion. The selected design was then experimentally studied using a mechanical shaker and human motion as excitation sources. The performance was also compared to the previously proposed V-shaped bent beam harvester (VBH) and conventional cantilever beam harvester (CBH) designs. The results prove that the proposed BBBH could harness considerably higher output voltages and power with lower idle time. Its operating bandwidth was also remarkably widened as it achieved three close resonances in the ultralow-frequency range. It was concluded that the proposed BBBH outperformed the conventional counterparts when used to harvest energy from ultralow-frequency sources, such as human motion.

Analysis of heat transfer using Local thermal non‐equilibrium conditions for a non‐Newtonian fluid flow containing Ti6Al4V and AA7075 nanoparticles in a porous media

AbstractThe accurate forecasting of thermal processes is one of the primary concerns of those working in the area of heat transfer as well as those in the energy research community. The present investigation makes use of a simplified mathematical model as an illustration in order to investigate the properties of heat transport under the lack of local thermal equilibrium conditions. The LTNE model results in two distinct primary thermal gradients, one for the fluid phase and another for the solid phase. The non‐Newtonian fluid flow containing Ti6Al4V and AA7075 nanoparticles with a base fluid sodium alginate over a stretching sheet in a porous media with magnetic effect is studied here. The shooting approach is used to transform the resultant equations of boundary value problems into initial value problems, which are subsequently solved using Runge–Kutta–Fehlberg 45 process. The impact of pertinent parameters on the involved fields have been discussed graphically. Results reveal that the increase in porosity and magnetic parameters value decreases velocity and increases thermal performance. An upsurge in inter‐phase heat transfer parameter increases the heat transport rate of solid phase but, decreases the liquid phase heat transport rate.

Integration Opportunities of Power-to-Gas and Internet-of-Things Technical Advancements: A Systematic Literature Review

As renewable electricity integration generates grid-balancing challenges for network operators, new ways of grid resilience receive significant attention from the energy research community. Power-to-gas (P2G) applications could produce and use green hydrogen. Thus, they enable the integration of more renewable energy into the energy system. Meanwhile, Internet-of-things (IoT) solutions could optimize renewable energy applications in decentralized systems. Despite the strategic importance of both technologies in renewable-rich grid developments, opportunities for P2G advancements based on IoT and related solutions have not come to the forefront of renewable energy research. To fill in this research gap, this study presents a hybrid (thematic and critical) systematic literature review to explore how strategic co-specialization opportunities appear in recent publications. Findings suggest that P2G and IoT could be fundamentally linked within the proposed frameworks of multi-energy systems and energy internet, but further empirical research is needed regarding their operative and strategic integration (e.g., cost reduction, risk management and policy incentives).

Investigating the Performance of a Novel Multi-Element Airfoil Concept Using Numerical Analysis

Separation control is one of the trending topics recently for Vertical Axis Wind Turbine (VAWT) applications, flow separation that occur on the suction side of an airfoil is a major limitation for VAWTs starting and power coefficient; passive control of flow separation has been attracting wind energy research community recently. The principle objective of this paper is to investigate the effect of the multi-element airfoil on the aerodynamic characteristics at wide range of angles of attack at a Reynolds number of 140,000. The multi element airfoil modification has been implemented by replacing the baseline airfoil with two airfoil members within the same geometrical profile of the original baseline airfoil, cambered and symmetrical airfoil members were investigated in this work. The cambered airfoil sections were made of the NACA 4412 airfoil while the symmetrical airfoil sections consisted of the NACA 0015 airfoil. The baseline airfoil is a profile of NACA 0021. The numerical investigation was executed using computational fluid dynamics (CFD) by the usage of ANSYS FLUENT and the turbulence model used was the k-ε Standard. The results of the present research show that the optimized multi-element airfoil configurations have better performance than the baseline airfoil at high angles of attack. A significant delay of separation was observed using the multi element airfoil, resulted in an increase of 200% in the glide ratio using cambered airfoil members and of 100% using symmetric airfoil members. These results are expected to have a significant effect on the performance of low wind speed wind turbines. In addition, a potential benefit for vertical axis wind turbines, whereas the airfoil generates lift at wider range of angles of attack.

Recent Criterion on Stability Enhancement of Perovskite Solar Cells

Perovskite solar cells (PSCs) have captured the attention of the global energy research community in recent years by showing an exponential augmentation in their performance and stability. The supremacy of the light-harvesting efficiency and wider band gap of perovskite sensitizers have led to these devices being compared with the most outstanding rival silicon-based solar cells. Nevertheless, there are some issues such as their poor lifetime stability, considerable J–V hysteresis, and the toxicity of the conventional constituent materials which restrict their prevalence in the marketplace. The poor stability of PSCs with regard to humidity, UV radiation, oxygen and heat especially limits their industrial application. This review focuses on the in-depth studies of different direct and indirect parameters of PSC device instability. The mechanism for device degradation for several parameters and the complementary materials showing promising results are systematically analyzed. The main objective of this work is to review the effectual strategies of enhancing the stability of PSCs. Several important factors such as material engineering, novel device structure design, hole-transporting materials (HTMs), electron-transporting materials (ETMs), electrode materials preparation, and encapsulation methods that need to be taken care of in order to improve the stability of PSCs are discussed extensively. Conclusively, this review discusses some opportunities for the commercialization of PSCs with high efficiency and stability.

Heat extraction from hot dry rock by super-long gravity heat pipe: Selection of working fluid

The novel technical scheme of extracting the deep-earth hot dry rock heat by a super-long gravity heat pipe (SLGHP) system in a single-well has aroused widespread interest in the geothermal energy research and engineering community. Due to the unique characteristic of the SLGHP, i.e. the extremely large length-to-diameter ratio, the effect of working fluid on its thermal performance is different from that for the normal heat pipes, thus requiring careful evaluation in the working fluid selection. However, there is no unified evaluation standard, and consequently, it is not available an efficient preferred route for the working fluid selection. The present work proposes a selection criterion to guide the fast screening of the potential candidates for SLGHP working fluid. For this criterion, the temperature gradient of the working fluid along the SLGHP in operation is adopted as an index to evaluate the effect of working fluid on the SLGHP thermal performance. The thermal performance of SLGHP using several typical working fluids is also evaluated via numerical simulation. Comparison between the numerical predictions and the fast-screening evaluations presents good consistency, indicating the validity of the proposed working fluid selection criterion. Both approaches reveal that ammonia would be preferable to water and methanol as the SLGHP working fluid for low source (hot dry rock) temperature and small diameter heat pipe; while water would be the best choice when the source temperature is high and the heat pipe has a large diameter. This selection criterion can act as a convenient and reliable tool for the decision process on the best-suited working fluid for an SLGHP tailored for actual geothermal energy exploitation use.

Towards codes of practice for navigating the academic peer review process

Peer review is the bedrock of modern academic research and its lasting contributions to science and society. And yet, reviewers can submit “poor” peer review reports, authors can blatantly ignore referee advice, and editors can contravene and undermine the peer review process itself. In this paper, we, the Editors of Energy Research & Social Science (ER&SS), seek to establish peer review codes of practice for the general energy and social science research community. We include suggestions for three of the most important roles: peer reviewers or referees, editors, and authors. We base our 33 recommendations on a collective 60 years of editorial experience at ER&SS. Our hope is that such codes of practice can enable the academic community to navigate the peer review process more effectively, more meaningfully, and more efficiently.

Recent advances in wave energy conversion systems: From wave theory to devices and control strategies

Harnessing energy from ocean waves, although not a new concept, is beginning to gain traction in the renewable energy research community. This largely untapped energy resource has considerable potential; however, researchers are still seeking to understand how to make it economically viable. This paper presents an overview of wave energy conversion as follows. It identifies various advantages of wave energy conversion as well as challenges that researchers and industry developers must overcome before large-scale installations can be fully realized. This paper also reviews the devices that have been designed to achieve efficient energy conversion. Multiple studies concerning wave energy converters placed in an array are reviewed and discussed, focusing specifically on consistent trends concerning array performance. The paper also reviews recent control methods for wave energy conversion.

Challenging Carbon Lock-In: Insights From U.S. Governmental Energy Research and Development Expenditures With Advocacy Recommendations for the Energy Research Community

The United States relies heavily on fossil and nuclear energy to meet its burgeoning electricity generation demands. The incumbent institutional and industrial power dynamics may support a fossil and nuclear energy status quo and have shown signs of carbon lock-in. Government research and development (R&D) funding can either be a help or hinderance to institutional carbon lock-in. This analysis investigates the link between the Department of Energy's historical funding allocations for energy research programs in the fossil, nuclear, and renewable energy sector, and the federal government's tendency to support entrenched, carbon-based energy systems. While the Department of Energy's renewable energy programs have received more funding in recent years, this investment alone is not enough currently to thwart carbon lock-in. Thus, this article recommends suggestions for researchers to advocate for more renewable energy research and development resources through personal, professional, and institutional strategies to spur decarbonization.

FAIR Metadata Standards for Low Carbon Energy Research—A Review of Practices and How to Advance

The principles of Findability, Accessibility, Interoperability, and Reusability (FAIR) have been put forward to guide optimal sharing of data. The potential for industrial and social innovation is vast. Domain-specific metadata standards are crucial in this context, but are widely missing in the energy sector. This report provides a collaborative response from the low carbon energy research community for addressing the necessity of advancing FAIR metadata standards. We review and test existing metadata practices in the domain based on a series of community workshops. We reflect the perspectives of energy data stakeholders. The outcome is reported in terms of challenges and elicits recommendations for advancing FAIR metadata standards in the energy domain across a broad spectrum of stakeholders.

Implementing Smart City Technologies to Inspire Change in Consumer Energy Behaviour

One of the main challenges in smart city models is consumer behaviour, namely guiding the efforts to promote optimal use of energy in the dynamics of the developing cities, through lower energy consumption without impact on the comfort level. This relates to all energy vectors and can be done through different means. The uptake stage of smart metering and information and communication technologies (ICT) varies in different countries, creating the need for tailored innovative approaches in motivating behavioural change. This paper presents the work carried out within the joint research project ITCity (an ICT platform for sustainable energy ecosystem in smart cities) between the European Union and Latin American Countries. Cooperation of energy researchers and experts in ICT and application developers facilitates adoption of a multipurpose interdisciplinary approach. This work aims at providing the smart city and energy research and innovation community broader understanding of factors influencing adoption of energy efficiency technologies. Different ways of guiding optimal energy use are addressed elaborating on the building blocks for a smart city which consider load patterns based on high resolution, high reporting rate measurements, extensive consumer surveys, available communication solution analysis and end-user interaction with the ICT tool based on gamification principles.

Sub-seasonal forecasts of demand and wind power and solar power generation for 28 European countries

Abstract. Electricity systems are becoming increasingly exposed to weather. The need for high-quality meteorological forecasts for managing risk across all timescales has therefore never been greater. This paper seeks to extend the uptake of meteorological data in the power systems modelling community to include probabilistic meteorological forecasts at sub-seasonal lead times. Such forecasts are growing in skill and are receiving considerable attention in power system risk management and energy trading. Despite this interest, these forecasts are rarely evaluated in power system terms, and technical barriers frequently prohibit use by non-meteorological specialists. This paper therefore presents data produced through a new EU climate services programme Subseasonal-to-seasonal forecasting for Energy (S2S4E). The data correspond to a suite of well-documented, easy-to-use, self-consistent daily and nationally aggregated time series for wind power, solar power and electricity demand across 28 European countries. The data are accessible from https://doi.org/10.17864/1947.275 (Gonzalez et al., 2020). The data include a set of daily ensemble reforecasts from two leading forecast systems spanning 20 years (ECMWF, an 11-member ensemble, with twice-weekly starts for 1996–2016, totalling 22 880 forecasts) and 11 years (NCEP, a 12-member lagged-ensemble, constructed to match the start dates from the ECMWF forecast from 1999–2010, totalling 14 976 forecasts). The reforecasts contain multiple plausible realisations of daily weather and power data for up to 6 weeks in the future. To the authors’ knowledge, this is the first time a fully calibrated and post-processed daily power system forecast set has been published, and this is the primary purpose of this paper. A brief review of forecast skill in each of the individual primary power system properties and a composite property is presented, focusing on the winter season. The forecast systems contain additional skill over climatological expectation for weekly-average forecasts at extended lead times, though this skill depends on the nature of the forecast metric considered. This highlights the need for greater collaboration between the energy and meteorological research communities to develop applications, and it is hoped that publishing these data and tools will support this.

A survey of recommender systems for energy efficiency in buildings: Principles, challenges and prospects

Recommender systems have significantly developed in recent years in parallel with the witnessed advancements in both internet of things (IoT) and artificial intelligence (AI) technologies. Accordingly, as a consequence of IoT and AI, multiple forms of data are incorporated in these systems, e.g. social, implicit, local and personal information, which can help in improving recommender systems’ performance and widen their applicability to traverse different disciplines. On the other side, energy efficiency in the building sector is becoming a hot research topic, in which recommender systems play a major role by promoting energy saving behavior and reducing carbon emissions. However, the deployment of the recommendation frameworks in buildings still needs more investigations to identify the current challenges and issues, where their solutions are the keys to enable the pervasiveness of research findings, and therefore, ensure a large-scale adoption of this technology. Accordingly, this paper presents, to the best of the authors’ knowledge, the first timely and comprehensive reference for energy-efficiency recommendation systems through (i) surveying existing recommender systems for energy saving in buildings; (ii) discussing their evolution; (iii) providing an original taxonomy of these systems based on specified criteria, including the nature of the recommender engine, its objective, computing platforms, evaluation metrics and incentive measures; and (iv) conducting an in-depth, critical analysis to identify their limitations and unsolved issues. The derived challenges and areas of future implementation could effectively guide the energy research community to improve the energy-efficiency in buildings and reduce the cost of developed recommender systems-based solutions.

Land use and turbine technology influences on wind potential in the United States

As clean energy ambitions have expanded, critically evaluating renewable energy supply has become increasingly important to the energy research community and stakeholders. This study examines the onshore wind resource potential for the conterminous United States and its sensitivity to siting constraints and turbine technology innovation. We compile localized regulatory information and use high-resolution data to present multiple siting regimes covering relatively constrained to unconstrained potentials. Our efforts reveal high sensitivity to these variables and sizable uncertainty in the overall wind energy resource potential. Specifically, we find that siting constraints may shift the total capacity available to commercial wind energy by 2.3–15.1 TW. Furthermore, our results illustrate that technology advancement could require larger setbacks from buildings and infrastructure, reducing the total available capacity potential by 20% relative to estimates using current technology, but that this reduction is largely offset by increased generation such that the net effect on generation is 1%. The observed sensitivity to and uncertainty resulting from the variables we analyze suggest there is value in continued study and development of increasingly sophisticated approaches to characterizing wind resource potential.