Neutral Energy Research Articles

(Invited) Electric-Field Driven Selective Electrocatalytic CO2 Conversion

The efficient electrochemical conversion of CO2 to fuels or stock chemicals with high-energy density would be a major step forward in the introduction of a carbon neutral energy cycle. Especially, understanding the role of electrocatalysts, supports, and electrolytes that can efficiently reduce CO2 to fuels with high selectivity is a subject of significant interest.One of the achievements in electrochemical CO2 reduction is the clarification of the catalysts toward two-electron involved products such as CO and formate. For instance, CO is selectively generated on Au, Ag, and single-atom catalysts and formate has been selective on Hg, Pb, Sn or alloy catalysts. Interestingly, from our recent work, CO/formate ratio can be selectively controlled on formate selective catalyst by tuning the interfacial electric field.[1] On copper catalyst, the selection of alkali cations has direct influence on activity and product selectivity; increasing the size of mono-valent cations can increase the activity and selectivity toward C-C coupled products by modulating the interaction energy between adsorbates and electric fields at the interface.[2] In addition, copper catalyst with a specific atomic-scale gap accelerates the reaction kinetics and selectivity to C2+ products.[3] Therefore, understanding the roles of catalyst, support and electrolyte offers the design of efficient, yet cheap electrochemical CO2 reduction systems.[1] Y. Kwon et al., ACS Sustain. Chem. Eng. 2020, 8, 2117.[2] Y. Kwon et al., J. Am. Chem. Soc. 2016, 138, 13006.[3] Y. Kwon et al., Adv. Energy Mater. 2020, 1903423.

Structural Optimization of Metal Oxyhalide for CO2 Reduction with High Selectivity and Current Density

Summary of main observation and conclusionElectrochemical CO2 reduction into value‐added liquid fuels using CO2 neutral renewable energy sources is very promising to solve climatic issues. In order to realize their practical applications, highly active and inexpensive electrocatalysts are urgently required. In this study, we have experimentally achieved high electrocatalytic activity towards CO2 reduction for the synthesis of formate with an enhanced current density of 15.1 mA·cm–2 and significantly improved Faradaic efficiency of 98.4% upon electrochemical reduced ultrathin bismuth oxybromide nanosheets. Moreover, the stable performance during 24 h of operation is also obtained. Furthermore, by detecting the exposed crystal plane after surface reorganization and applying density functional theory calculations, the possible reaction pathways and catalytic active plane of the derived bismuth catalyst are put forward, which would offer basic and design principles to directly develop the optimized metal Bi catalysts for enhanced electrocatalytic CO2 conversion to formate.

Theoretical Analysis of the Formylmethylene Anion Photoelectron Spectrum: Importance of Wolff Rearrangement Dynamics.

Photoelectron spectroscopy of a molecular anion is very useful for investigating the transition state and intermediate regions on the reactive potential energy surfaces of a neutral system. In this work, we theoretically analyzed the previously measured photoelectron spectrum of the formylmethylene anion, HCCHO-. We simulated the photoelectron spectra for both the singlet and triplet states using the semiclassical method with quantum nuclear densities and Franck-Condon factor calculations with harmonic vibrational analysis. We also performed real-time quantum dynamics calculations to elucidate the importance of the Wolff rearrangement process, which leads to the stable product ketene from the carbene intermediate on the neutral singlet potential energy surface.

Anisotropic distributions of deuterium–deuterium nuclear fusion products in a compact tokamak

The paper is devoted to calculations of anisotropic spectra of nuclear fusion products in a compact tokamak. The knowledge of these spectra is essential for estimations of the first wall load by neutron radiation and other fast particle fluxes from the plasma, computations of the plasma heating profiles, and correct analysis of experimental data, obtained on the present-day and prospective tokamaks and other controlled fusion devices. Anisotropic analytical S- and L-formulae found earlier for nuclear fusion product distributions are computationally demanding. In this paper improved anisotropic S- and L-algorithms are introduced. The new simplified formulae retain the generality and reduce the calculation time without changing the results. Their application for the calculation of energetic and angular distributions of products of both neutron and proton branches of the deuterium–deuterium nuclear fusion reaction in the neutral beam heated plasma of the Globus-M2 spherical tokamak is described. Notwithstanding the low neutral beam energy, the obtained fusion product spectra are strongly anisotropic and may be observed experimentally.

Kinetic effects in parallel electron energy transport channels in the scrape-off layer

We present an analysis of parallel electron energy transport in the scrape-off layer (SOL), considering the convective and conductive channels, as well as the radiation and neutral inelastic energy transfer channels involving atomic deuterium. Kinetic effects in both equilibria and conductive transients are explored by utilizing the capability of the SOL-KiT code to treat electrons as either a fluid or kinetically. We find kinetic effects in multiple channels, with an emphasis on those occurring during the investigated conductive transients. Energetic electron effects in the heat flux, as well as a modification of ionization rates of up to 40% compared to Maxwellian rates during perturbations in detached conditions, are reported and discussed.

High-Voltage Rechargeable Alkali-Acid Zn-PbO2 Hybrid Battery.

Aqueous rechargeable batteries have attracted attention owning to their advantages of safety, low cost, and sustainability, while the limited electrochemical stability window (1.23 V) of water leads to their failure in competition with organic-based lithium-ion batteries. Herein, we report an alkali-acid Zn-PbO2 hybrid aqueous battery obtained by coupling an alkaline Zn anode with an acidic PbO2 cathode. It shows the capability to deliver an impressively high open-circuit voltage (Voc ) of 3.09 V and an operate voltage of 2.95 V at 5 mA cm-2 , thanks to the contribution of expanding the voltage window and the electrochemical neutralization energy from the alkali-acid asymmetric-electrolyte hybrid cell. The hybrid battery can potentially deliver a large area capacity over 2 mAh cm-2 or a high energy density of 252.39 Wh kg-1 and shows almost no fading in area capacity over 250 charge-discharge cycles.

High‐Voltage Rechargeable Alkali–Acid Zn–PbO2 Hybrid Battery

AbstractAqueous rechargeable batteries have attracted attention owning to their advantages of safety, low cost, and sustainability, while the limited electrochemical stability window (1.23 V) of water leads to their failure in competition with organic‐based lithium‐ion batteries. Herein, we report an alkali–acid Zn–PbO2 hybrid aqueous battery obtained by coupling an alkaline Zn anode with an acidic PbO2 cathode. It shows the capability to deliver an impressively high open‐circuit voltage (Voc) of 3.09 V and an operate voltage of 2.95 V at 5 mA cm−2, thanks to the contribution of expanding the voltage window and the electrochemical neutralization energy from the alkali–acid asymmetric‐electrolyte hybrid cell. The hybrid battery can potentially deliver a large area capacity over 2 mAh cm−2 or a high energy density of 252.39 Wh kg−1 and shows almost no fading in area capacity over 250 charge–discharge cycles.

Trends and progress in AnMBR for domestic wastewater treatment and their impacts on process efficiency and membrane fouling

Anaerobic membrane bioreactor has emerged as an innovative technology in treating domestic wastewater due to its excellent produced effluent quality and high potential of neutral or positive energy balance. One of the biggest challenges in positive energy objective is fouling mitigation which contributes towards 70% of the total energy requirement of MBR-based domestic wastewater treatment. Numerous studies were carried out to address this issue, utilizing various reactor design configurations and operating conditions for energy minimization as well as membrane performance enhancement. The latest research trend in this sector is the establishment of hybrid processes like Granular Anaerobic Membrane Bioreactors (G-AnMBR), Forward Osmosis Anaerobic Membrane Bioreactor (FO-AnMBR) and Microbial Electrolysis Cell-Anaerobic Membrane Bioreactor (MEC-AnMBR) for domestic wastewater treatment which not only provides efficiency in treatment but also improves fouling mitigation. Also, the application of techniques developed particularly for fouling mitigation like quorum quenching and sensing, cell entrapment and membrane module vibrations in AnMBRs were assessed. This paper reviews the latest trends in anaerobic membrane bioreactors research with regards to water quality produced, removal efficiencies and fouling mitigation. • AnMBR operation for domestic wastewater treatment at pilot-scale has been detailed. • Fouling mitigation accounts for largest energy requirement. • Hybrid processes can offer energy optimized fouling control. • Quorum Quenching and vibrations can reduce efficiently fouling in AnMBRs. • Research directions for fouling mitigation strategies in AnMBRs are identified.

Dutch Hybrid Neighbourhoods of 1860–1910 in Heat Transition: The Case Study of Zeeheldenkwartier in The Hague

This paper explores the typo-morphologic characteristics of late 19th century hybrid neighbourhoods in urban regions of The Netherlands and possibilities of a feasible climate neutral energy system in the future. The Zeeheldenkwartier neighbourhood in The Hague is used as a case study. Sustainable Development Goals (SDG) are involved to ensure access to affordable and clean energy (SDG 7) and make cities inclusive, safe, resilient and sustainable (SDG 11). With the 2019 Dutch-Climate-Agreement The Netherlands decided on a neighbourhood approach to the transition from natural gas to a climate neutral energy supply in buildings. Implicit homogeneity in most buildings of neighbourhoods is presupposed, in contrast to older neighbourhoods that were laid out before World War I. These are nowadays heterogenic, attractive, mixed and often protected neighbourhoods because of the quality of the architecture. Establishing a generic energy plan here is a challenge. The foremost important conclusion is the recognition of the architectural and urban quality and features of these kinds of neighbourhoods and to develop specific legislation and rules about insulation, service and energy systems. Another conclusion about the strategy is that one should not rely on a single generic solution but rather apply multiple forms of heat supply over a longer period of time. There is lack of heat and construction capacity. Box-in-box-renovation is best done when people are moving and the house is uninhabited. The tenants of a neighbourhood should oganise, not building owners, and implement legislation and framework for rental apartments. Insulation should be done to mandatory Energy Performance Certificate (EPC) label B or C, adding sound and energy production of heat pumps and district heating.

Can renewable generation, energy storage and energy efficient technologies enable carbon neutral energy transition?

Energy system decarbonization has been a critical measure to combat climate change, and an optimization framework modelling this process would facilitate designing cost-effective energy transition pathways. In this study, a bottom-up optimization framework for energy transitions is developed, which bridges the decarbonization processes for the power sector and the space heating sector, while considering energy system stability, climate targets and scheduled system changes. Our results show that the decarbonization goals of New York State are feasible for electricity and space heating energy system. By 2050, Offshore wind would be the main electricity source that generates 66% of power, while air source heat pumps and geothermal technologies would provide 47% and 41% of heat demands, respectively. It is also discussed how the results can facilitate developing energy transition policies regarding carbon price and geothermal technologies. Our findings reveal the feasibility of carbon neutral energy transition using renewable generation, energy storage, and energy-efficient technologies.

Multiscale Modeling of Lignocellulosic Biomass Thermochemical Conversion Technology: An Overview on the State-of-the-Art

Biomass is a kind of carbon neutral renewable energy source and considered as a potential alternative to fossil fuels. Thermochemical conversion technologies, including direct combustion, fast pyro...

Multiobjective Optimization Technique for Mitigating Unbalance and Improving Voltage Considering Higher Penetration of Electric Vehicles and Distributed Generation

The increasing penetration of distributed generations (DGs) and electric vehicles (EVs) offers not only several opportunities but also introduces many challenges for the distribution system operators (DSOs) regarding power quality. This article investigates the network performances due to uncoordinated DG and EV distribution. It also considers power quality-related performances such as the neutral current, energy loss, voltage imbalance, and bus voltage as a multiobjective optimization problem. The differential evolution optimization algorithm is employed to solve the multiobjective optimization problem to coordinate EV and DG in a distribution grid. This article proposed a method to coordinate EV and DG distribution. The proposed method allows DSOs to jointly optimize the phase sequence and optimal dispatch of DGs to improve the network's performance. If the network requires further improvement, the EV charging or discharging rate is coordinated for a particular location. The efficacy of the proposed method is tested in an Australian low-voltage distribution grid considering the amount of imbalance due to higher penetration of DG and EV. It is observed that the proposed method reduces voltage unbalance factor by up to 98.24%, neutral current up to 94%, and energy loss by 59.45%, and improve bus voltage by 10.42%.

Solving the Energy Transition Riddle: Renewable Gas for Transport and Renewable Electricity for Heating

An effective decision regarding the future energy mix must be based on multi-sectorial optimization that considers the key energy supply, carrier, conversion and storage options in an endogenous way, with high temporal resolution where positive and negative emissions are both internalized. The existing literature fails to meet all these conditions, leaving several open questions. To address the relative role of electricity and non-fossil gas in a cost-effective decarbonized energy system, we develop an integrated model including optimization of dispatch and investment for the whole energy sector, meeting all the necessary conditions. We apply this model to the French energy system for a wide range of social cost of carbon scenarios in 2050. Unlike most energy scenarios, which are nearly fully electrified, we find that renewable gas provides at least 22% of the energy supply in a carbon neutral energy system, where this carbon-neutrality can be achieved with a social cost of carbon of €200/tCO2. In such an energy system, renewables become the main component of the primary energy supply (up to 80%). A fully electrified heat sector and a highly gas-dependent transport sector fueled with renewable gas help to achieve carbon-neutrality at lowest cost.

Progress in modelling fast-ion D-alpha spectra and neutral particle analyzer fluxes using FIDASIM

FIDASIM is a code that models signals produced by charge-exchange reactions between neutrals and ions (both fast and thermal) in magnetically confined plasmas. With the ion distribution function as input, the code predicts the efflux to a neutral particle analyzer diagnostic and the photon radiance of Balmer-alpha light to a fast-ion D diagnostic, in addition to many other related quantities. A new, parallelized version of the Monte Carlo code FIDASIM has been developed in Fortran90 that is substantially faster than the original interactive data language version. Modified algorithms include more accurate treatments of the time dependent collisional-radiative equations that describe neutral energy levels, of the cloud of ‘halo’ neutrals that surround the injected neutral beam, and of finite Larmor radius effects. Enhanced physics capabilities include modelling ‘passive’ signals from cold edge neutrals, the ability to treat general three-dimensional magnetic confinement configurations, and calculations of diagnostic-specific weight functions that enable tomographic reconstructions of the fast-ion distribution function. Neutral beam attenuation, beam emission, and fast-ion birth profiles are also modelled. The new algorithms have been successfully validated against experimental data and new features have been tested through benchmarks between two independently developed versions of the code.

Composition-Tunable Antiperovskite Cux In1-x NNi3 as Superior Electrocatalysts for the Hydrogen Evolution Reaction.

A group of newly reported antiperovskite nitrides Cux In1-x NNi3 (0≤x≤1) with tunable composition are employed as electrocatalysts for the hydrogen evolution reaction (HER). Cu0.4 In0.6 NNi3 shows the highest intrinsic performance among all developed catalysts with an overpotential of merely 42 mV at 10 mA cmgeo -2 . Stability tests at a high current density of 100 mA cmgeo -2 show its super-stable performance with only 7 mV increase in overpotential after more than 60 hours of measurement, surpassing commercial Pt/C (increase of 170 mV). By partial substitution, the derived antiperovskite nitride achieves a smaller kinetic barrier of water dissociation compared to the unsubstituted InNNi3 and CuNNi3 , revealed by first-principle calculations. It is found that the partially substituted Cux In1-x NNi3 possesses a thermal neutral and desirable Gibbs free energy of hydrogen for HER, ascribed to the tailoring of the energy of d-band center arose by the A-site (A=Cu or In) substitution and a resulting optimization of adsorbate interactions.

Composition‐Tunable Antiperovskite CuxIn1−xNNi3 as Superior Electrocatalysts for the Hydrogen Evolution Reaction

AbstractA group of newly reported antiperovskite nitrides CuxIn1−xNNi3 (0≤x≤1) with tunable composition are employed as electrocatalysts for the hydrogen evolution reaction (HER). Cu0.4In0.6NNi3 shows the highest intrinsic performance among all developed catalysts with an overpotential of merely 42 mV at 10 mA cmgeo−2. Stability tests at a high current density of 100 mA cmgeo−2 show its super‐stable performance with only 7 mV increase in overpotential after more than 60 hours of measurement, surpassing commercial Pt/C (increase of 170 mV). By partial substitution, the derived antiperovskite nitride achieves a smaller kinetic barrier of water dissociation compared to the unsubstituted InNNi3 and CuNNi3, revealed by first‐principle calculations. It is found that the partially substituted CuxIn1−xNNi3 possesses a thermal neutral and desirable Gibbs free energy of hydrogen for HER, ascribed to the tailoring of the energy of d‐band center arose by the A‐site (A=Cu or In) substitution and a resulting optimization of adsorbate interactions.

Evaluating watershed health in Costa Rican national parks and protected areas

Although the biodiversity of Costa Rican national parks, forests, and wetlands has been extensively surveyed, there has not been a watershed assessment that reflects their baseline water quality. Undoubtedly, the influx of 3.1 million visitors annually can lead to deterioration. Additionally, the country’s movement toward 100% carbon neutral energy means reliance on capturing water for the production of hydroelectricity. The missing hydrologic data set is of immediate concern, as watershed health predicts total ecosystem health. This field-based project measures eight parameters (pH, temperature, fecal coliform, dissolved oxygen, biochemical oxygen demand, nitrates, total phosphates, turbidity) needed to assign a watershed quality index (WQI) value at nine national parks or protected areas. Overall, the WQI for the systems surveyed reflect good water quality. Results compared with US Environmental Protection Agency (EPA) and World Health Organization (WHO) drinking water standards indicate limited levels of contamination at most sites, with elevated signatures of nitrates, phosphates, turbidity, and/or fecal coliforms at few. The parks selected include coastal lowlands and central highlands; they also experience diverse tourist activities, degrees of use, and forest type that are challenges when managing land sustainably.

Experimentally validated computations of simultaneous ion and fast neutral energy and angular distributions in a capacitively coupled plasma reactor

Accurate predictions of the ion energy and angular distribution functions (IEADFs) and fast neutral energy and angular distribution functions (FNEADFs), are essential for a range of critical applications in the plasma processing of thin film etching and deposition. Computationally efficient methods that can be applied to industrial reactor systems that are also validated across a range of operating conditions are essential for prediction of IEADFs and FNEADFs. In this work, we present a hybrid model where a capacitively coupled plasma (CCP) solution was computed using a fluid model and the IEADF/FNEADF was generated using a particle transport model with a multi-species Monte Carlo Collision model. We first compare the computed IEADFs across a range of pressures with experimental measurements for a CCP reactor. We predict FNEADFs that are typically difficult to measure experimentally but are believed to have a significant effect on etch/deposition process phenomena. Across a large pressure range, we observe significant fast neutral bombardment of the electrode surface with at least half the energy of the most energetic ions as well as an angular spread that is larger than that of the ions.

An Electrochemical Neutralization Cell for Spontaneous Water Desalination

Summary We show that conversion of acid-base neutralization energy into electrical energy via reversible H2 redox can be used to spontaneously desalinate saline water while generating electric power and consuming ∼13.6 kJ for the removal of 1 mol of NaCl. This electrochemically driven neutralization pathway exhibits a positive temperature coefficient for the open circuit voltage (1.63 ± 0.11 mV/K), which, in turn, means it can harvest ∼24 kJ/mol of entropic heat, at room temperature, from the surroundings as electrical driving force. Our demonstration of desalination without the aid of an external power supply by performing reversible redox reactions and involving only gases, water, H+, and OH−, such that the products and the reactants of the reaction do not contaminate the desalinated water, opens up an unprecedented pathway for addressing the potable water crises looming over the 21st century.

RuS2-x quantum dots/rGO as bifunctional hydrogen electrocatalysts for harvesting electrochemical neutralization energy

It is crucially important and highly desirable, albeit remaining a grand challenge, to develop Pt-alternative electrocatalyst toward hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) that are indispensable for a variety of electrochemical energy initiatives. We herein reported a simple synthesis recipe to prepare nanohybrids of RuS2 quantum dots with abundant sulfur vacancies (Vs-RuS2QDs) supported on reduced graphene oxide (Vs-RuS2QDs/rGO), which exhibits impressively high electrocatalytic activity and durability toward HER in acidic medium and HOR in alkaline electrolyte, respectively, as evidenced by outperforming the state-of-the-art Pt/C catalysts with significantly promoting the catalytic kinetics. Comprehensive studies, by coupling systematic electrochemical investigation with density functional theory (DFT) calculation, signify that the synergistic effects of S vacancies, quantum size and robust 2D dimensional structure contribute to an optimized electronic structure for hydrogen bonding, leading to highly attractive catalytic performance as hydrogen electrocatalysts. We demonstrate the Vs-RuS2QDs/rGO hybrids perform superior performance to the commercial Pt/C as the bifunctional electrode in a proof-of-concept electrochemical device that can electrochemically harvest neutralization energy upon managing waste acid and alkali.