SINTEF Energy Research

Abstract Much effort has been devoted to developing, constructing and refining fish passage facilities to enable target species to pass barriers on fluvial systems, and yet, fishway science, engineering and practice remain imperfect. In this review, 17 experts from different fish passage research fields (i.e., biology, ecology, physiology, ecohydraulics, engineering) and from different continents (i.e., North and South America, Europe, Africa, Australia) identified knowledge gaps and provided a roadmap for research priorities and technical developments. Once dominated by an engineering‐focused approach, fishway science today involves a wide range of disciplines from fish behaviour to socioeconomics to complex modelling of passage prioritization options in river networks. River barrier impacts on fish migration and dispersal are currently better understood than historically, but basic ecological knowledge underpinning the need for effective fish passage in many regions of the world, including in biodiversity hotspots (e.g., equatorial Africa, South‐East Asia), remains largely unknown. Designing efficient fishways, with minimal passage delay and post‐passage impacts, requires adaptive management and continued innovation. While the use of fishways in river restoration demands a transition towards fish passage at the community scale, advances in selective fishways are also needed to manage invasive fish colonization. Because of the erroneous view in some literature and communities of practice that fish passage is largely a proven technology, improved international collaboration, information sharing, method standardization and multidisciplinary training are needed. Further development of regional expertise is needed in South America, Asia and Africa where hydropower dams are currently being planned and constructed.

The demand for low carbon energy calls for close to 100% renewable power systems, with decarbonization of other energy sectors adding to the anticipated paradigm shift. Rising levels of variable inverter-based renewable energy sources (VIBRES) are prompting questions about how such systems will be planned and operated when variable renewable generation becomes the dominant technology. Here, we examine the implications of this paradigm shift with respect to planning, operation and system stability, also addressing the need for integration with other energy vectors, including heat, transport and Power-to-X. We highlight the knowledge gaps and provide recommendations for improved methods and models needed as power systems transform towards 100% VIBRES.

Chemical-kinetic combustion mechanisms for hydrogen-oxygen-nitrogen systems, motivated originally by concerns about NOx emissions during hydrogen burning, have recently acquired renewed interest as a result of the possibility of employing ammonia-hydrogen mixtures in gas turbines and reciprocating engines as drop-in fuel to replace the use of natural gas. Specifically, this is of relevance to the implementation of engineering approaches for economical power generation with carbon sequestration or to large-scale energy-storage schemes, based on hydrogen or efficient hydrogen carriers such as ammonia. Because computational investigations are facilitated by short mechanisms (since the use of large mechanisms is often prohibitively expensive in reactive flow simulations), in response to the original concerns, a short nitrogen mechanism was developed in San Diego in the 1990s (not updated since 2004), without consideration of ammonia combustion. In view of the renewed interest in this topic, that mechanism has now been expanded to encompass 60 elementary steps among 19 reactive chemical species, including ammonia burning and NOx production, as reported herein, greatly improving predictions. With particular attention to high reactant temperatures and high-pressure conditions, relevant to industrial applications, it is shown that the present short mechanism retains satisfactory accuracy, exhibiting deviations that in most cases are within acceptable bounds (±20%). The revisions maintain the shortness of the original mechanism, adding only one more reactive species and six more elementary steps (while updating values of rate parameters of nine other steps, on the basis of newly available information). In addition, the short mechanism is applied herein to the analysis of fundamental combustion properties of ammonia/hydrogen/nitrogen-air laminar premixed flames, at unstrained and strained conditions, for comparison with methane-air flames as a reference gas-turbine fuel. It is found by comparing carbon-free and hydrocarbon laminar flames that these reactive mixtures, even if characterized by nearly identical adiabatic flame temperature and laminar flame speeds, nevertheless exhibit substantially different resistance to strain, with the ammonia/hydrogen flames exceeding the strain limit of methane flames by a factor of 5.

Abstract Wind farm control design is a recently new area of research that has rapidly become a key enabler for the development of large wind farm projects and their safe and efficient connection to the power grid. A comprehensive review of the intense research conducted in this area over the last 10 years is presented. Part I reviews control system concepts and structures and classifies them depending on their main objective (i.e. to maximise power production or to provide grid services. The work and key findings in each paper are discussed in detail with particular emphasis on the turbine side. Additionally, the review contributes to the existing reviews on the area by providing an elegant classification between model testing and control approaches. Areas where significant work is still needed are also discussed. In Part II, a thorough review on aerodynamic wind farm models for control design purposes is provided.

The way to produce and use energy is undergoing deep changes with the fast-pace introduction of renewables and the electrification of transportation and heating systems. As a consequence, the electrical grid sees much higher power variability than in the past, challenging its frequency and voltage regulation. Energy storage systems will be fundamental for ensuring the energy supply and the voltage power quality to customers. This survey paper offers an overview on potential energy storage solutions for addressing grid challenges following a ”system-component-system” approach. Starting from system challenges, the energy storage technologies and their power electronics integration in the grid are described at component level considering the last scientific trends, including the hybrid energy storage concept. The impact of the energy storage technologies on the power systems are then described by exemplary large-scale projects and realistic laboratory assessment with Power Hardware In the Loop techniques, returning at system level. Finally, this work addresses some of the most important challenges for a sustainable and safe integration of energy storage systems, such as the circular economy and the safety aspects.

Plans to build a large number of offshore wind farms have created a need for decision support in the planning process to choose the most cost-efficient alternatives. This paper gives an overview of existing commercial as well as non-commercial decision support models along with their main characteristics. It focuses mainly on operation and maintenance, but also covers offshore logistics, power production and total project cost to a limited extent. The models were found through an extensive search of published literature, research organizations, research projects, and consulting companies. The search detected 49 models that address parts of the life cycle or the whole life cycle of an offshore wind farm.

Hydro power is one of the most flexible sources of electricity production. Power systems with considerable amounts of flexible hydro power potentially offer easier integration of variable generation, e.g., wind and solar. However, there exist operational constraints to ensure mid‐/long‐term security of supply while keeping river flows and reservoirs levels within permitted limits. In order to properly assess the effective available hydro power flexibility and its value for storage, a detailed assessment of hydro power is essential. Due to the inherent uncertainty of the weather‐dependent hydrological cycle, regulation constraints on the hydro system, and uncertainty of internal load as well as variable generation (wind and solar), this assessment is complex. Hence, it requires proper modeling of all the underlying interactions between hydro power and the power system, with a large share of other variable renewables. A summary of existing experience of wind integration in hydro‐dominated power systems clearly points to strict simulation methodologies. Recommendations include requirements for techno‐economic models to correctly assess strategies for hydro power and pumped storage dispatch. These models are based not only on seasonal water inflow variations but also on variable generation, and all these are in time horizons from very short term up to multiple years, depending on the studied system. Another important recommendation is to include a geographically detailed description of hydro power systems, rivers’ flows, and reservoirs as well as grid topology and congestion. WIREs Energy Environ 2017, 6:e220. doi: 10.1002/wene.220 This article is categorized under: Wind Power > Science and Materials Wind Power > Systems and Infrastructure

A method for comparing the levelized cost of energy (LCoE) of different superconducting drive trains is introduced. The properties of a 10-MW MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> superconducting direct-drive generator and the cost break down of the nacelle components are presented and scaled up to a turbine with a rotor diameter of up to 280 m. The partial load efficiency of the generator is evaluated for a constant cooling power of 0, 50, and 100 kW, and the annual energy production is used to determine the impact on the LCoE.

This article reviews dc transmission technologies for future power grids. The article emphasises the attributes that each technology offers in terms of enhance controllability and stability, resiliency to ac and dc faults, and encourages increased exploitations of renewable energy resources (RERs) for electricity generation. Discussions of ac/dc and dc/dc converters reveal that the self‐commutated dc transmission technologies are critical for better utilisation of large RERs which tend to be dispersed over wide geographical areas, and offer much needed controllability for operation of centralised and decentralised power grids. It is concluded that the series power flow controllers have potential to restrict the expensive isolated dc/dc converters to few applications, in which the prevention of dc fault propagation is paramount. Cheaper non‐isolated dc/dc converters offer dc voltage tapping and matching and power regulation but they are unable to prevent pole‐shifting during pole‐to‐ground dc fault. To date hybrid dc circuit breakers target dc fault isolation times ranging from 3 to 5 ms; while the resonance‐based dc circuit breakers with forced current zeros target dc fault clearance times from 8 to 12.5 ms.

Abstract Numerical calculations of a lifted H2/N2 turbulent jet flame in a vitiated coflow of hot gases are presented. The calculations are performed using Magnussen's Eddy Dissipation Concept (EDC) for turbulent combustion, and are an extension to previously reported EDC modeling results presented by Cabra et al. (Citation2002). Four different turbulence models are employed to investigate in more detail the turbulence modeling effect on the EDC combustion model with detailed chemistry. A series of simulations are presented that indicate the extent to which turbulence models influence the predicted lift-off height with the EDC combustion model. Several flow conditions were tested. For all calculations, EDC predicts more lift-off by using the standard k-ϵ model than by using Reynolds-stress-equation (RSE) models, whereas a modified k-ϵ model predicts less lift-off than the RSE models. The reason for the lower predicted lift-off with the modified k-ϵ model is because a modified turbulence Prandtl or Schmidt number in the scalar equations in the modified k-ϵ model allows an earlier mixing of the hot coflow with the fuel jet. All models overpredict the lift-off height for the standard flow conditions. Recent experiments and numerical calculations by others have shown that the vitiated coflow flame is extremely sensitive to variations in the coflow temperature. The present calculations show that this sensitivity is captured by the EDC combustion model, however to a smaller degree than that previously reported. Calculations with variations in coflow temperature and jet flow velocity indicate that for each flow condition, the various turbulence models predict the same percentage increase or decrease in lift-off height. These EDC calculations show that the turbulence model effect on the EDC predicted lift-off height is important and that a better flame structure is predicted with the RSE model by Jones and Musonge than with the other turbulence models. Keywords: turbulentnonpremixedmodeling This work was supported by the Research Council of Norway and Gassnova (Climit Programme). The research by R. Cabra and J.-Y. Chen was part of a project supported by NASA Glenn Research Center Contract NAG3-2103 (USA). Notes The second row shows the lift-off heights for the standard conditions described in Table 1. The left column describes what is changed compared to the standard conditions.

Smart energy solutions aim to modify and optimise the operation of existing energy infrastructure. Such cyber-physical technology must be mature before deployment to the actual infrastructure, and competitive solutions will have to be compliant to standards still under development. Achieving this technology readiness and harmonisation requires reproducible experiments and appropriately realistic testing environments. Such testbeds for multi-domain cyber-physical experiments are complex in and of themselves. This work addresses a method for the scoping and design of experiments where both testbed and solution each require detailed expertise. This empirical work first revisited present test description approaches, developed a newdescription method for cyber-physical energy systems testing, and matured it by means of user involvement. The new Holistic Test Description (HTD) method facilitates the conception, deconstruction and reproduction of complex experimental designs in the domains of cyber-physical energy systems. This work develops the background and motivation, offers a guideline and examples to the proposed approach, and summarises experience from three years of its application.

Abstract Lifetime models of high‐power Insulated Gate Bipolar Transistors modules express the number of cycles to end of life as a function of stress parameters. These models are normally developed based on experimental data from accelerated power‐cycling tests performed at predefined temperature stress conditions as, for example, with temperature swings above 60 °C. However, in real power converters applications, the power modules are usually stressed at temperature cycles not exceeding 40 °C. Thus, extrapolating the parameters of lifetime models developed using data from high‐temperature stress cycles experiments might result in erroneous lifetime estimations. This paper presents experimental results from power cycling tests on high‐power Insulated Gate Bipolar Transistors modules subjected to low temperature stress cycles of 30 and 40 °C. Therefore, devices experience still accelerated aging but with stress conditions much closer to the real application. Post‐mortem failure analysis has been performed on the modules reaching end‐of‐life in order to identify the failure mechanism. Finally, the number of cycles to end‐of‐life obtained experimentally is fit with a state‐of‐the‐art lifetime model to assess its validity at low temperature stress cycles. Challenges and limitations on data fitting to this lifetime model and the impact of various stress parameters on the anticipated failure are also presented.

The transition of the manufacturing industry towards carbon neutrality requires a reduction of the emissions from combustion for the supply of process heat. Heat pumps are an efficient alternative technology for supplying heat while improving the overall efficiency and shifting to potentially carbon neutral electricity. The state-of-the-art technology is limited to supply temperatures between 100 °C and 150 °C because of lower efficiency and component limitations. This paper has therefore analyzed two promising concepts for higher supply temperatures and found technically and economically feasible solutions for process heat supply of up to 280 °C. These solutions are using large-scale equipment from oil and gas industries for applications in energy-intensive industries. The suggested systems benefitted from the economy of scale and access to low electricity prices. The concepts outperformed a biogas-based solution, and they were competitive with biomass or natural gas systems with respect to economic performance. It was concluded that an electricity-based heat supply is possible for a wide range of industrial applications and accordingly represents an important contribution to fulfilling the objectives of lower climate impact of energy supply in industry. Keywords: Electrification, R-718, R-744, Reversed Brayton cycle, Process heat, Steam compression

The world's largest Chemical Looping Combustion (CLC) demonstration unit is being built close to the city of Chengdu in China. The design and construction of the unit, as well as the coming testing, is done within the CHEERS project, which is a collaborative project between Europe and China. The funding (∼25M€) comes from several of the project partners, in addition to EU's Horizon2020 and China's Ministry of Science and Technology (MOST). TotalEnergies has been responsible for the Front-End Engineering Design (FEED) study. The investment decision from December 2021 marks the transition from the R&D studies and design phases to Engineering, Procurement, Construction (EPC) and testing phase. The EPC phase has been led by Dongfang Boiler Co.,Ltd, and the demonstration unit is located at their technology development site in Deyang City, outside Chengdu in China. It is designed for a thermal input of 2–4 MW and includes two different reactor configurations. The first configuration is optimized for conversion of pet-coke, while the second one is tuned towards conversion of lignite. The oxygen carrier (OC) that will be used for the demonstration unit (ilmenite) will be presented, together with an overview of the various OC materials that were tested at various scales (up to 150 kWth) during the first part of the project. In addition, results from testing of a cold mock-up of the unit is presented. Finally, an overview of plans for the rest of the project is given, together with some thoughts related to intercontinental collaboration in highly collaborative projects, such as CHEERS.

In May of 2004, the IEA Wind Implementing Agreement (IA) established R&amp;D Task 24, “Integration of Wind and Hydropower Systems.” Australia, Canada, Finland, Norway, Sweden, Switzerland, and the United States joined Task 24 with the goal of collaborating in the study of wind integration in a variety of electrical system configurations (load, generation, and transmission); hydro system configurations and characteristics; and market and operational configurations. Representing these countries were utilities and research organizations with the intent to understand the potential for and limiting factors in integrating wind into systems with hydropower. Case studies that analyze the feasibility, benefits, detriments, and costs of specific wind-hydro integration projects were the mechanism through which the goals of the task were addressed. The purpose of this article is to summarize the framework within which these studies were performed, and to present the key results and the general conclusions of the Task.

The use of wind power has grown strongly in recent years and is expected to continue to increase in the coming decades. Solar power is also expected to increase significantly. In a power system, a continuous balance is maintained between total production and demand. This balancing is currently mainly managed with conventional power plants, but with larger amounts of wind and solar power, other sources will also be needed. Interesting possibilities include continuous control of wind and solar power, battery storage, electric vehicles, hydrogen production, and other demand resources with flexibility potential. The aim of this article is to describe and compare the different challenges and future possibilities in six systems concerning how to keep a continuous balance in the future with significantly larger amounts of variable renewable power production. A realistic understanding of how these systems plan to handle continuous balancing is central to effectively develop a carbon-dioxide-free electricity system of the future. The systems included in the overview are the Nordic synchronous area, the island of Ireland, the Iberian Peninsula, Texas (ERCOT), the central European system, and Great Britain.

Abstract Fluxes of carbon dioxide (CO 2 ) and methane (CH 4 ) from hydroelectric and water supply reservoirs are receiving increasing attention around the world with a number of research groups having undertaken measurements of these emissions across a range of lakes and reservoirs located in different climates and landscapes. The use of floating chambers (aka flux chambers) is the most common technique for direct measurement of these fluxes. However, the relative performance of different measurement systems, especially different chamber designs, is not well documented. We report the results of an international workshop held in June 2012 at Three Gorges Dam, China, to compare measurements performed by four groups with extensive chamber monitoring experience: the Chinese Academy of Science (China), CSIRO (Australia), SINTEF (Norway), Hydro‐Québec/Environnement Illimité (Canada). A fifth group, Eawag (Switzerland), performed hydroacoustic surveys to detect ebullition in the water column. We recommend CH 4 as a more suitable trace gas for comparing methodologies due to its relative stability in the surface layer of the water column, for example, it is not subject to significant diurnal changes due to photosynthesis and respiration. Measured fluxes agreed to within 20% between the four teams suggesting that the shape and dimensions of the floating chambers and the chamber gas flow rates (i.e., chamber residence time) did not have an appreciable systematic effect on the measured fluxes for the relatively low wind speeds prevalent at the reservoir. The CO 2 and CH 4 fluxes measured during the workshop agree well with previous measurements in Three Gorges Reservoir.

In this paper, we investigate the extent to which the use of in-home displays affects daily practices and electricity consumption. Through two pilot projects, in-home displays were installed in 33 Norwegian homes, and we provide a qualitative analysis of the effects. The results point to the potential differences in the ways households interact with the in-home displays. The effects differed among various groups according to people’s previous experiences with monitoring and their level of affluence. In the sample, affluent respondents living in detached houses tended to be accustomed to monitoring consumption before the display was introduced. These families used the display for controlling that “nothing was wrong”, but they did not use the information provided by the display to initiate new energy saving measures. In contrast, among less affluent flat owners the notion of “control” was specifically linked to the family’s management of finances, and in this sense the displays empowered them. In addition, the results indicate that the in-home display for this group resulted in electricity savings. The study adds to earlier research on the effects of in-home displays by showing the importance of previous experience with monitoring electricity for the effects of feedback and by highlighting not only energy savings but also social effects of displays.

Interconnecting offshore wind power plants with oil and gas installations (O&G) can create a positive symbiosis for both installations. An O&G installation may reduce the emissions generated by gas turbines installed on platforms and the wind farm may reduce the investment costs by removing expensive transmission links to the shore. The power demand of an O&G-installation lies in the same range as a small to medium sized wind power plant. This paper analyzes methods of maintaining secure operation of such offshore interconnected power systems. The combination of high reliability requirements and low system inertia is challenging. Hence, an adequate overall control strategy is of major importance. As such interconnected systems are not yet implemented, this paper is based on a system with typical ratings. The first and main part demonstrates how wind turbines can contribute to an improved robustness and stability of the system. This is realized through a control concept called inertia emulation. The second part of the paper quantifies the impact on O&G operations in terms of fuel saving and wind variability issues.

Modular multilevel converters with embedded battery cells are suitable candidates to improve the energy conversion efficiency of battery electric vehicles. In this new topology, the series connection of the battery cells is obtained by means of H-bridge modules, allowing the highest flexibility for the discharge and recharge of each individual battery cell. This objective can be achieved in practice only when a suitable control algorithm is designed to control at the same time the generation of the desired output voltages and the state of charge of cells. This paper discusses some aspects of the balancing algorithm of the battery cells including the cross-balancing between the converter's arms and the design of the control loop for symmetric three-phase output voltages. Simulations results applied to a city car confirm the theoretical considerations and illustrate the main features of the proposed control algorithm.