There is an unprecedented need to expand the toolbox of solutions to boost the scalability of clean power and energy systems. Amidst this challenge, nuclear energy is increasingly recognized as an important player in the path toward deep decarbonization of the global energy mix. This paper presents a technology review of small modular reactor (SMR) concepts currently under development and deployment. Both conventional and next-generation reactor technologies are evaluated with a focus on potential power system integration benefits, added system values, and provision of system-bearing services. Nevertheless, there are currently some uncertainties in the techno-economic competitiveness of SMRs, whether they can leverage economics of mass production over their inherent lack of economics of scale. To address this challenge, our paper provides some basic cost analysis of SMRs, taking into account their expected learning curves to evaluate the cost of future deployments and give insights into their economic competitiveness and potential role as a disruptive solution in the energy transition.

Ten years ago, the concept of the hyperloop vacuum train promised to revolutionize transportation by offering a fast, inexpensive, and eco-friendly alternative to traditional modes of travel. The key components of the hyperloop are a vacuum tube, magnetic levitation, and linear electric propulsion technology, which is envisaged to achieve surface velocities approaching the speed of sound. This paper presents the functionalities of an ideal hyperloop transportation system (HTS) with a low-cost track and a lightweight hyperloop capsule. We show how this ideal system is indeed difficult to achieve in reality. Despite the potential benefits, hyperloop technology still lacks experimental evidence at subsonic speeds to reach a higher level of technological readiness. Taking one step back, hyperloop has lessons to learn from the maglev research and experiments in the 1970s. In fact, there are many unresolved challenges associated with maglev technologies, even at moderate speeds, which need to be recognized before reaching the whole way into the subsonic speed domain. This paper will provide a status update after ten years of hyperloop research and development.

A document by Markus Aasen Anker . Click on the document to view its contents.

A document by Peder A. Tyvand . Click on the document to view its contents.

This paper presents a homogenized electro-thermal model for high-temperature superconductor (HTS) stacks made of multiple REBCO tapes, which reduces the computational complexity of their thermal analysis. The electromagnetic analysis is performed in both the H- and Tâ\euro“A-formulation. An average heat capacity and an orthotropic heat conductivity are derived for the equivalent thermal properties of the HTS coil. The proposed homogenization method is verified to produce the same results as the full model with an error below 5% for a range of scenarios, including transport losses, magnetization losses, AC frequencies from 50 to 300 Hz and a temperature range from 25 to 80 K. Finally, the model is applied to study a permanent magnet motor with HTS armature windings, and is verified to produce accurate results as long as the stabilizer eddy current losses are low. Compared to the full multilayer model, the newly proposed model allows for the use of a significantly coarser mesh, which reduces the computation time by an order of magnitude.

As a result of the worldwide energy transition, reactive power generation has started to become a more scarce resource in the power grid. Until recently, reactive power has been an auxiliary grid service that classical power generation facilities have provided without necessarily allocating any cost for this valuable service. In this paper, a new approach for predicting the additional costs of reactive power services delivered by large hydrogenerators is proposed. We derive the optimal reactive power with minimal losses as a function of the active power level within the generator’s capability diagram. This pathway can then be used to calculate additional losses from operational regimes deviating from the optimal reactive power for each active power level. To back up the analysis, a dedicated population study was handpicked consisting of four real-world generators scaled in terms of power rating, i.e., 15 MVA, 47 MVA, 103 MVA, and 160 MVA. The objective was to identify how the optimal reactive power scale from smaller to larger MVA-sized generators. Moreover, a sensitivity analysis explores the link between the standard parameters, the stator losses, the rotor losses, the optimal reactive power, and the optimal efficiency. We find the ratio between the rotor and stator losses as the determining factor. Finally, the operational pathway introduces a new way to allocate the power producer’s cost associated with their reactive power services and can be used to justify potential profit for this service, especially considering that the intermittent reactive power needs are projected to increase in the future.

Pumped-storage hydropower is seen as a promising solution for efficient, large-scale energy storage. One competitive technical solution is the variable-speed hydropower plant (VSHP) configured with a converter-fed synchronous machine (CFSM). These machines are operated with one extra degree of freedom that is not usually optimized, where the CFSM’s rotor-side DC excitation interacts with the stator-side AC excitation. Depending on machine loading, the CFSM will be utilized in conditions far from its original design. In order to deal with this issue, this paper presents a stator flux control (SFC) method for regulating VSHPs in a more efficient way by adjusting the field current to prevent the machine from operating with over-magnetization independent of loading condition, as well as better utilizing the stator-fed converter current, maximizing the utilization of the CFSM. The derived first-principle analytical equations for the proposed SFC have been validated and analyzed in the Matlab/Simulink environment for a large 45 MVA, 375 rpm CFSM, with the measured saturation curve as input. Finally, dynamic transitions between different levels of pumping power reveal the SFC’s ability to help to maintain a unity stator flux in the machine, enabling optimal operation independent of loading level.

This paper presents a homogenized electrothermal model for high-temperature superconductor (HTS) stacks made of multiple REBCO tapes, which reduces the computational complexity of their thermal analysis. An average heat capacity and an orthotropic heat conductivity are derived for the equivalent thermal properties of the HTS coil. The proposed homogenization method is verified to produce the same results as the full model with an error below 5% for a range of scenarios, including transport losses, magnetization losses, AC frequencies from 50 to 300 Hz and a temperature range from 25 to 80 K. This new model allows for the use of a significantly coarser mesh, which reduces the computation time by an order of magnitude compared to the full model.

This article describes the design and analysis of a 2.5-MW, 5000-rpm electric motor with a slotted armature employing REBCO high-temperature superconductors (HTS). The alternating current and field in the armature induces AC losses in the superconductors, requiring cryogenic cooling. Therefore, the aim is to design a machine with sufficiently low losses to make this cooling realistic, which simultaneously outperforms the state-of-the-art. The reasoning behind the key design choices is presented before the model used for two-dimensional (2-D) finite element analysis (FEA) is described. Then, HTS AC losses are studied with the T-A-formulation, examining the impact of various operating conditions. Aligning the HTS tapes with the field was found to successfully reduce AC losses, while filamentization was only successful for more than 10 filaments. The final design had an estimated efficiency of 99.8%, an active torque density of 50.9 Nm/kg, and a cryogenic cooling power requirement of 0.05% of the output power.

Macroscopic superconductivity models have improved significantly over the last decades. Formulations and methods have been developed to faster solve problems involving high-temperature superconductors (HTS). Despite these developments, finite element analysis (FEA) of AC superconducting machines (SCMs) with HTS coils still remains time-consuming. The combined burden from the HTS models and the moving mesh makes the models complex and slow. To deal with this challenge, a new framework for FEA of AC superconducting SCMs with surface-mounted permanent magnet (PM) rotors and HTS armature windings is proposed in this paper. In this approach, the rotating rotor geometry is emulated with a stationary array of small PM segments excited with time-varying boundary sources. The major benefit of this approach is that the models can be realized without moving meshes, which increases the computation speed by more than one order of magnitude. In our dedicated case study of a complete SCM design, the speedup factors are 17.4x and 38.5x for the H-A and T-A formulations, respectively. Over a large parametric space of 18 design permutations, the highest relative error in calculated HTS loss was 4.12 percent. As a result, this work enables the designer to perform much more comprehensive performance studies of SCMs.

This paper aims to shed light on the possibility of first-generation electric aviation in Norway by looking at both the potential and the limitations of today’s technology while emphasizing Norway’s geographical opportunities and unique regional network as a pioneer in this field. Operating a flight distance up to 400 km would cover around 77 % of all domestic flights in Norway. In this work, the key factors influencing the scalability of electric flight are investigated and critically discussed, including battery technologies, propulsion systems, aircraft designs, and important aspects of the flight profile. A case study is presented based on five different flight distances in Norway (from 77 km to 392 km) and two different aircraft bodies. Our proposed framework is used to make detailed-level calculations for the required power, energy, and battery state of charge. The results show that slight energy density improvements in the battery technology would facilitate the implementation of electric aircraft, rendering the possibility of retrofitting already existing planes. However, other alternatives, such as novel aircraft design and adjusted mission profiles, are also viable options for complying with weight and power capability requirements to scale up all-electric aircraft for distances up to 400 km.

Hydrogen-powered airplanes have recently attracted a revitalized push in the aviation sector to combat CO2 emissions. However, to also reduce, or even eliminate, non-CO2 emissions and contrails, the combination of hydrogen with all-electric solutions is undoubtedly the best option to move toward the ambitious goal of climate-neutral aviation. Another important design choice is to store hydrogen cryogenically in its liquid form (LH2) to reduce space occupation compared to storage as compressed gas. However, the LH2 fuels cannot be utilized directly in fuel cells. It needs to be brought from liquid to a gas at about 350 K, where large amounts of heat must be added. Thus, a synergy can be made from this otherwise wasted cryogenic refrigeration power where superconducting machines (SCMs) and cold power electronics (CPE) are low-hanging fruits that could lead to radical space and weight reductions onboard the aircraft. These opportunities can be realized without having to pay the price, nor the volume occupation and mass needed for the cooling ability usually needed to achieve these extraordinary performances. In fact, this ground-breaking synergy makes cryogenic energy conversion relevant in a whole new way for aviation. The SCMs’ more than five times higher power densities than their conventional counterparts are exceptionally significant. This article introduces the recently proposed cryo-electric drivetrain initiatives and explores the opportunities of using direct hydrogen cooling as a potential heating solution to enhance the overall performance and scalability of zero-emission propulsion systems in future regional aircraft.