Neutral Energy Research Articles

Factors Governing Oxygen Vacancy Formation in Oxide Perovskites

The control of oxygen vacancy (VO) formation is critical to advancing multiple metal-oxide-perovskite-based technologies. We report the construction of a compact linear model for the neutral VO formation energy in ABO3 perovskites that reproduces, with reasonable fidelity, Hubbard-U-corrected density functional theory calculations based on the state-of-the-art, strongly constrained and appropriately normed exchange-correlation functional. We obtain a mean absolute error of 0.45 eV for perovskites stable at 298 K, an accuracy that holds across a large, electronically diverse set of ABO3 perovskites. Our model considers perovskites containing alkaline-earth metals (Ca, Sr, and Ba) and lanthanides (La and Ce) on the A-site and 3d transition metals (Ti, V, Cr, Mn, Fe, Co, and Ni) on the B-site in six different crystal systems (cubic, tetragonal, orthorhombic, hexagonal, rhombohedral, and monoclinic) common to perovskites. Physically intuitive metrics easily extracted from existing experimental thermochemical data or via inexpensive quantum mechanical calculations, including crystal bond dissociation energies and (solid phase) reduction potentials, are key components of the model. Beyond validation of the model against known experimental trends in materials used in solid oxide fuel cells, the model yields new candidate perovskites not contained in our training data set, such as (Bi,Y)(Fe,Co)O3, which we predict may have favorable thermochemical water-splitting properties. The confluence of sufficient accuracy, efficiency, and interpretability afforded by our model not only facilitates high-throughput computational screening for any application that requires the precise control of VO concentrations but also provides a clear picture of the dominant physics governing VO formation in metal-oxide perovskites.

Hydrogen Technology towards the Solution of Environment-Friendly New Energy Vehicles

The popularity of climate neutral new energy vehicles for reduced emissions and improved air quality has been raising great attention for many years. World-wide, a strong commitment continues to drive the demand for zero-emission through alternative energy sources and propulsion systems. Despite the fact that 71.27% of hydrogen is produced from natural gas, green hydrogen is a promising clean way to contribute to and maintain a climate neutral ecosystem. Thereby, reaching CO2 targets for 2030 and beyond requires cross-sectoral changes. However, the strong motivation of governments for climate neutrality is challenging many sectors. One of them is the transport sector, as it is challenged to find viable all-in solutions that satisfy social, economic, and sustainable requirements. Currently, the use of new energy vehicles operating on green sustainable hydrogen technologies, such as batteries or fuel cells, has been the focus for reducing the mobility induced emissions. In Europe, 50% of the total emissions result from mobility. The following article reviews the background, ongoing challenges and potentials of new energy vehicles towards the development of an environmentally friendly hydrogen economy. A change management process mindset has been adapted to discuss the key scientific and commercial challenges for a successful transition.

Superconducting critical temperature in the extended diffusive Sachdev-Ye-Kitaev model

Models for strongly interacting fermions in disordered clusters forming an array, with electron hopping between sites, reproduce the linear dependence on temperature of the resistivity, typical of the strange metal phase of high temperature superconducting materials [extended Sachdev-Ye-Kitaev (SYK) models]. We identify the low energy collective excitations as neutral energy excitations, diffusing in the lattice of the thermalized non-Fermi liquid phase. However, the diffusion is heavily hindered by coupling to the pseudo-Goldstone modes of the conformal broken symmetry SYK phase, which are local in space. The imaginary time evolution of the extended model in the strong interaction and $1/N$ expansion limit is presented in the incoherent nonchaotic regime. On the other hand, a Fermi electronic liquid at low energy becomes marginal when perturbed by the SYK dots. A critical temperature for superconductivity is derived, which is not BCS-like, in case the collective excitations are assumed to mediate an attractive Cooper pairing.

Three-level market optimization model of virtual power plant with carbon capture equipment considering copula–CVaR theory

To achieve carbon neutrality, promoting clean and renewable energy consumption and reducing CO2 emissions have become important measures. Therefore, virtual power plants (VPPs) containing carbon capture devices have become a research focus. This study first builds a VPP model containing carbon capture devices, analyzes the cooperative operation mode of a carbon capture system and power-to-gas, and develops a comprehensive demand response mechanism for the VPP. Second, owing to the uncertainty of the electricity market clearing price and the natural gas market price, a risk dependence model between electricity price and gas price based on the copula–conditional value-at-risk theory is constructed. Then, a VPP three-level market optimization model considering risk dependence and carbon trading mechanisms is proposed, and an improved collaborative evolutionary algorithm that combines the NSGAII and AGE-MOEA algorithms is used to solve multi-objective problems. Finally, an example of a VPP is used to verify the effectiveness of the model.

Critical implications of ion-surface energy accommodation and neutralization mechanism in hollow cathode physics

Self-heating thermionic hollow cathodes are essential components in modern plasma thrusters. To fully understand their operation, three interdependent physical domains must be considered: plasma discharge physics, thermal response of the cathode structure, and chemical evolution of plasma exposed surfaces. In this work, we develop the first self-consistently coupled plasma–thermal–chemical simulation platform for hollow cathode operation using lanthanum hexaboride (LaB6) and Xe and study its performance against our experimentally determined temperature measurements. Results show that the customary assumptions of single-step resonant neutralization and full energy accommodation in ion-surface collisions fail to reproduce our empirical observations. We propose a two-step neutralization mechanism that consists of resonant neutralization to the first excited state of xenon followed by Auger de-excitation to the ground state, along with system specific accommodation factors. In this way, the agreement between the results of the simulations and experiments was achieved. These fundamental processes could govern neutralization in other cathode technologies where low work function emitters are employed and should therefore be accounted for in physical models. In addition, the new simulation platform allows us to better estimate the equilibrium work function of LaB6 hollow cathode emitters. In the cathode studied here, we found that the effective work function is 2.25 eV, which is significantly lower than previous estimates, and leads to better than expected cathode material performance with important implications for space missions.

Resilience, reliability and gas to power systems in the USA: an energy policy outlook in the era of decarbonization

Abstract This article examines the requirements of resilience and reliability for gas to power systems planning in an era of decarbonization. It recongizes that energy transitions and decarbonization portend an increasing competition between various traditional and emerging net-zero, carbon neutral and low-carbon energy sources and technologies. Likewise, energy policy development has traditionally focused on the dimensions of affordability, sustainability, cost-efficiency through viable markets and security of supply. Recent disruptive events that may or may not be attributable to climate change have tested the resiliency of energy networks. Thus, energy policy and planning now require a more comprehensive outlook that includes the dimension of resilience. Also, there is the need to prevent or effectively manage the aftermath of disruptive events, rather than a piecemeal focus on hardening infrastructure against one or more issues such as cyber-security and functionality of energy networks in adverse conditions. This article discusses resilience and reliability as key dimensions of US energy policy from a public choice law and economics purview. It builds on the premise that politicians, administrative agencies and other stakeholders in the energy sector can be irrational and therefore unable to identify and implement the policy package that is in the public interest if not properly guided. It considers the role of investments in resilience and systems planning. It also underscores the need for developing a more efficient framework that would enable relevant stakeholders to avoid the risk of opportunity cost neglect, informational gaps and fragmented institutional coordination that could escalate the social, health, safety and economic impacts of future disruptive events such as the February 2021 winter storm Uri that tested the resilience of energy supply infrastructure in the US.

Sustainable Second-Generation Ethanol Production from Switchgrass Biomass via Co-fermentation of Pentoses and Hexoses Using Novel Wild Yeasts

The production of second-generation (2G) ethanol remains an interesting proposition for the implementation of sustainable and net carbon–neutral energy systems. To be economically viable, 2G biorefineries must make use of all processing streams, including the less desirable pentose (C5) sugar stream. In this work, a strategy of sequential dilute acid and alkaline pretreatment of the lignocellulosic feedstock, switchgrass, was implemented for improving the fermentable sugar yield. The hemicellulose-enriched hydrolysate obtained after dilute acid pretreatment was fermented by a newly isolated wild Scheffersomyces parashehatae strain—UFMG-HM-60.1b; the corresponding ethanol yield (YPS) and volumetric productivity (QP) were 0.19 g/g and 0.16 g/L h, respectively. The remaining switchgrass cellulignin fraction was subjected to optimized alkaline delignification at 152 ºC for 30 min. Then, the delignified solid fraction was subjected to contiguous enzymatic saccharification and fermentation releasing a glucose (C6) sugar stream. The control yeast strain, Saccharomyces cerevisiae 174, displayed an ethanol YPS of 0.46 g/g and QP of 0.70 g/L h for the C6 sugar stream, whereas the above-mentioned wild strain presented YPS and QP of 0.29 g/g and 0.38 g/L h, respectively. Upon combining the conversion of hemicellulose (37%) and cellulose-derived sugars (57%), the wild S. parashehatae strain provided higher yield (94%) than the generic S. cerevisiae (90%). Henceforth, our sequential two-stage pretreatment and fermentation of C5 and C6 sugar streams provides a pathway for maximum utilization of switchgrass carbohydrates for 2G ethanol production.

Economic analysis and business model exploration of hydrogen transport – Case study of heavy-duty FCV demonstration in China

Hydrogen is considered an important future energy to achieve a carbon neutral energy system, and transport is the most mature area to start a hydrogen economy. China proposed new policies in 2020 to encourage the development of FCV especially in heavy-duty transport, however little research can provide appropriate framework and practical data for the economic analysis of such demonstration, to provide important and rational support for the decision making of local government. This paper introduces a planned heavy-duty FCV demonstration project in city A, provides a framework for its economic analysis as well as practical data from FCV manufacturers, hydrogen producers and suppliers. Results show comprehensive investment required for such demonstration project, cash flow for the planning period and key impacting factors considering the whole circle of hydrogen production-transmission-refilling-utility. Findings show that FCV application shows better profitability than the hydrogen supply business, and long-term FCV planning targets are crucial to all practical business models; Capex reduction is the common and crucial element to realize commercial application of hydrogen transport, and hydrogen supply chain should be integrated to reduce the overall hydrogen cost.

Conceptual modeling of energy storage systems

AbstractConceptual models are explicit representations of complex systems that help people understand and communicate the system and its behavior in its actual context. The stable energy systems that we rely on in our daily life require a balance between energy production and consumption. Energy systems, particularly those that include renewable energy sources, have inherent dynamic behavior due to the intermittence of energy sources such as solar and wind. We use conceptual models to understand this behavior.The transition towards a carbon neutral energy system requires energy storage to ensure a supply of renewable energy when needed. The sizing strategy for energy storage systems is challenging because both the supply side and the demand side varies with time. In this paper, we investigate how energy storage technologies can provide seasonal storage for an existing energy system with excess electric power production during the summer months. We use conceptual models to review pumped hydro energy storage, hydrogen storage, and brine technology.The conceptual models simplify the selection process and help in choosing the most suitable energy storage solution from technical and economic criteria. The conceptual models are effective in communicating the constraints and opportunities of the system. However, we find it difficult to balance between comprehension that requires simplification, and accuracy that requires details.

Neutrino energy estimation in neutral current interactions and prospects for sterile neutrino searches

Modern neutrino detectors, particularly the large liquid argon time projection chambers (LAr TPCs) at SBN and DUNE, provide an unprecedented amount of information about GeV-scale interactions. By taking advantage of the excellent spatial and calorimetric resolution as well as the low tracking thresholds provided by LAr TPCs, we present a novel method of estimating the neutrino energy in neutral current interactions. This method has potential implications for the search for a sterile neutrino; it allows for the potential observation of spectral distortions due to sterile neutrino-induced oscillations in the neutral current neutrino energy spectrum. As an example, we use this method to perform an analysis of the statistics-only sensitivity to sterile neutrinos in the neutral current channel at SBN under a 3+1 model.

The beet sugar factory of the future

The beet sugar industry is facing several challenges for the future. The climate change is requiring a transition from the traditional fossil fuel to a greenhouse gas neutral energy source. The available possibilities for this purpose will be outlined in this paper. The recent EU sugar market reform has markedly increased the competition between sugar companies and the resulting lower sugar price has a significant impact on the profit margin of sugar production. In order to keep up with these challenges it is key to make an appropriate use of the available opportunities to improve the cost-efficiency of sugar beet processing. The different means to advance the sugar business are better asset utilization, continuous process improvement, introducing innovative process technologies and further developing a sugar factory into a biorefinery with a further valorisation of (co-)products and wherein synergy is obtained between different on-site process operations. Why and how these different available tools can improve the competitiveness of sugar factories will be discussed in detail. A proper combination and choice of the suggested changes and opportunities will enable sugar factories to get prepared for the future.

Estimating storage needs for renewables in Europe: The correlation between renewable energy sources and heating and cooling demand

The inexhaustible availability of solar irradiance and wind speed makes these natural resources major contributors to a CO2 neutral energy system. Since these natural resources interact with temperatures, this paper aims at determining their correlation with temperature derived heating and cooling degree-hours (HDH and CDH) historically and based on climate projections towards 2100. The case study investigates demand and supply balancing requirements in three European climate regions Spain, Austria and northern Europe. Two approaches are used to analyse the hourly correlation on different time scales and the relationship of daily and weekly totals assuming storage. Understanding these interrelations provides a basis for appropriate planning and forecasting in smart energy systems. While solar irradiance does correlate strongly with CDH on hourly basis, achieving 0.80 in Spanish locations and 0.60 in Austria, the relation between wind speed and heating demand is more complex only reaching moderate (0.40–0.59) correlation with monthly storage in all regions. The relationship between solar irradiance and heating needs, by contrast, seems promising in central and southern Europe by applying daily storage to reach moderate to strong (0.40–0.79) results. While HDH will lose importance mostly in Madrid, but also in Vienna and Stockholm, CDH will increase. The implications for final energy demand, however, require consideration of additional parameters, such as energy efficiency measures on building insulation. Smart energy systems, therefore, should embrace the positive correlation between solar irradiance and CDH, and account for at least monthly storage of potential wind power to use VRE for heating and cooling efficiently.

Measurements of neutral particle energy spectrum on EAST using a time-of-flight low-energy neutral particle analyzer.

The neutral particles generated by charge exchange reactions can play an important role in erosion of first wall materials in fusion devices. In order to measure the flux and energy of neutral particles to the first wall, a low-energy neutral particle analyzer (LENPA) based on the time-of-flight method has been developed and successfully applied on the Experimental Advanced Superconducting Tokamak (EAST)' to measure the neutrals with an energy of 20-3000eV. The LENPA works in the counting mode, and the signal of photons is used as the reference for the flight time of neutrals. The energy spectrum of low-energy neutral particles on EAST has been obtained for the first time. The new diagnostics can help in understanding the neutral particle generation and deposition on the first wall materials in tokamaks under different plasma conditions.

Heat Pump Optimization Strategies for Participation in Price-Controlled Demand Response in the Latvian Electricity Market

Abstract Improved end-user engagement is considered to be a key factor in decarbonization efforts towards climate neutral energy systems. While first adopters are already actively seeking ways how to optimize their energy consumption, a true shift in consumer behaviour can only be achieved if the financial benefits are well established and presented. The study aims at estimating the economic performance of end-user engagement in provision of demand response services using air-to-air heat pumps as the underlying technology. The results of the paper help evaluate in a real data setting whether the existing market framework provides sufficient incentives to facilitate end-user participation in the demand response service.

An augmented food strategy leads to complete energy compensation during a 15-day military training expedition in the cold.

Soldiers on military expeditions usually fail to compensate for the increase in energy expenditure, with potential deleterious consequences. We therefore analyzed the characteristics of energy compensation in 12 male soldiers, during a 15‐day expedition in the cold, while alleviating some of the contextual limitations of food intake (~20‐MJ daily bags of easy‐to‐use, highly palatable and familiar foods with multiple and long breaks allowed during the day). Body and fat mass losses were low and moderate, respectively (−1.13 ± 1.42% and −19.5 ± 15.6%, respectively, p < .021). Mean energy intake (EI) was high (~16.3 MJ) and increased at each third of the expedition (15.3 ± 2.1, 16.1 ± 2.1, and 17.6 ± 2.0 for D1–5, D6–10 and D11–15, respectively, p < .012). This resulted in reaching a neutral energy balance as soon as the D6 to 10 period and reaching normal energy availability during D11 to 15. Participants only increased their EI during the mid‐day (10:00–14:00) period (p = .002) whereas hunger and thirst only increased in the morning, with higher scores during D11–15 than D1–5 (p < .009). Last, the reward value of sweet foods was also higher during D11–15 than during D1–5 (p = .026). The changes in body mass were positively associated with EI (r = 0.598, p = .040) and carbohydrate intake (r = 0.622, p = .031). This study indicates that complete energy compensation can be reached in challenging field conditions when food intake is facilitated, offering some guidelines to limit energy deficit during operational missions.

Agriculture Residue: A Potential Source for Biogas Production

To achieve energy security and to address energy related environmental issues attempts have been made to find out such energy resources that are economically viable and environmentally friendly. Biogas appears as a sustainable, renewable and carbon neutral energy source, a substitute to reduce the global fossil fuels dependency. Agricultural activities generate huge amounts of organic residues annually worldwide. Microbial conversion of agriculture residue and organic wastes to produce biogas offers an attractive way for energy supply, resource recovery and waste treatment. Energy generated is renewable can have positive impact on environment, replacing fossil fuels and mitigating greenhouse gases emissions. In addition to a clean and cost effective energy source, it improves the management of manure and organic wastes and replaces inorganic fertilizer. Biogas production in the agricultural sector is a fast growing market particularly in many European countries. This article is aimed to review and investigate the potential contribution of biogas from agricultural residues. Techniques for quantitative assessment of the residue from different crops that can be recovered sustainably as a potential resource for biogas production are discussed.

Velocity effect on the nanostructure creation at a solid surface by the impact of slow highly charged ions

The energy necessary for the nanostructure creation by the impact of highly charged ions (charge Z ≫ 1) on solid surface consists of the neutralization energy and the deposited kinetic energy. We analyze the relative importance of these two contributions for very low to moderate ionic velocities and introduce the critical velocity as a measure of interplay of these two energies. In the study of the velocity effect on the neutralization energy, we employ the recently developed micro-staircase model based on the quantum two-state vector model of the ionic Rydberg states population. The final ionic charges after the neutralization cascade in front of the surface are used for the calculation of the (nuclear) stopping power and the deposited kinetic energy below the surface. We discuss the nanohillocks and nanocraters formation by the impact of XeZ + ions on titanium and gold nanolayers, and formation of the nanorings on gold surface, from the standpoint of the required energy.

The effect of increased coupling strength between electricity and heating systems in different climate scenarios for Europe

Over the last two centuries, the growth of fossil fuel combustion is the dominant cause of the increasing concentration of CO2 in the atmosphere. Timely mitigation strategies are therefore important and can be achieved through energy system transformation, but time is limited. We investigate into sector coupling as a first step towards a carbon neutral energy economy by imposing additional synergy between the European electricity and heating systems. Because future climate change is unpredictable, we follow three reconstructed concentration pathways (RCP2.6, RCP4.5 and RCP8.5) from the IPCC AR5 covering the years 2000–2100. Three-hourly time series of the national wind and solar capacity factors, electricity and space heat consumption, and coefficient of performance of heat pumps were generated from climate change affected weather data from an ensemble of nine climate models. By using a greenfield cost-optimisation approach, we find that net zero-emission scenarios as, e.g., by the end-century of RCP26 result in extremely electrified energy systems, which almost doubles the system costs compared to historical levels. Carbon intensive pathways as, e.g., the end-century of RCP8.5 result in fossil-fuel dominated energy systems with significant cost reductions. Independent of the climate outcome, the cost of a strongly coupled system is comparable to that of a weakly coupled system. This result states the importance of transforming energy systems towards higher electrification even if strong coupling technologies such as heat pumps and combined heat and power plants are not implemented at large scale.

Comparative environmental benefits of power generation from underground and surface coal gasification with carbon capture and storage

Underground gasification combined cycle (UGCC), when combined with carbon capture and storage (CCS), is widely judged to be a promising approach for clean coal utilization especially in the context of carbon neutral energy pathways. Nevertheless, the overall operation processes may consume a multiple of energy and inevitably trigger environmental concerns. Hence, a careful evaluation of the potential environmental impacts associated with UGCC is needed. In this study, we assessed environmental impacts of UGCC with and without CCS by the life cycle assessment method, and compared the results with those of surface integrated gasification combined cycle (IGCC) to gain better insight into tradeoffs of two coal gasification technologies and lighten the environmental burden by design optimizations. The results demonstrated that most mid-point impact values of UGCC power plants, which reflect pollution emissions and corresponding damage degree, were lower. Inversely, the global warming potential was 16.9% higher than those of IGCC power plants. Furthermore, UGCC power plants have superior end-point environmental benefits, which represent the damage of ecosystem quality, human health and resources. As demonstrated by the fact that the value of above three impact types were 23%, 15% and 4%, lower than those of IGCC power plants, respectively. In addition, the implement of CCS in two types of power plants decreased human health damage due to reduced greenhouse gas emissions, but notable environmental trade-offs are the increase in ecosystem quality damage and resource damage. The aggregated results show that UGCC with or without CCS has a more outstanding environmental performance with exception of global warming potential than IGCC with or without CCS. Enhancing UCG process control, improving syngas heating value and decreasing the energy in gasification agent preparation are effective methods to further reduce the GHG emissions. Approached in an improved way, UGCC-CCS stands to provide a low-carbon and self-contained solution for power production and energy provision.

Selective atomic layer reaction between GaN and SiN in HBr neutral beam etching

We investigated higher selective etching between SiN and GaN using an HBr neutral beam (NB) and found that it exhibited a more selective reaction compared to Cl2 NB. The etching rate of GaN mainly depended on the desorption rate of the etching product (GaClx or GaBrx) assisted by the bombardment of NB. As a result, in the case of the HBr neutral beam, the GaN etching rate was drastically decreased at the atomic layer level because the vapor pressure of the etching product, GaBrx, was much lower than that of GaClx. On the other hand, the dominant etching progression of SiN was mainly caused by neutral beam bombardment energy, and the desorption of the etching products (SiClx or SiBrx) was almost the same in both cases because the vapor pressures of the etching product, SiClx and SiBrx. In particular, in the case of the HBr neutral beam, the neutral beam energy dependence of the surface reaction layer of SiN was larger than that of Cl2 NB. As a result, the etching selectivity between SiN and GaN in HBr NB improved to 2.1 at 10 W of bias power, whereas that with Cl2 NB was saturated at 0.41 at more than 10 W of bias power. We found that the surface atomic layer etching reaction could precisely control the desorption rate of the etching product by optimizing the neutral beam bombardment energy and gas chemistry. The HBr neutral beam process can achieve atomic layer level selective reactions on the SiN/GaN structure.