Potential Energy Research Articles

A Critical Analysis of Morocco’s Green Hydrogen Roadmap: A Modelling Approach to Assess Country Readiness from the Energy Trilemma Perspective

Morocco, despite its heavy reliance on imported fossil fuels, which made up 68% of electricity generation in 2020, has recognised its significant renewable energy potential. The Nationally Determined Contribution (NDC) commitment is to reduce emissions by 45.5% from baseline levels with international assistance and abstain from constructing new coal plants. Moreover, the Green Hydrogen Roadmap aims to export 10 TWh of green hydrogen by 2030, as well as use it for local electricity storage. This paper critically analyses this Roadmap and Morocco’s readiness to reach its ambitious targets, focusing specifically on an energy trilemma perspective and using OSeMOSYS (Open-Source energy Modelling System) for energy modelling. The results reveal that the NDC scenario is only marginally more expensive than the least-cost scenario, at around 1.3% (approximately USD 375 million), and facilitates a 23.32% emission reduction by 2050. An important note is the continued reliance on existing coal power plants across all scenarios, which challenges both energy security and emissions. The assessment of the Green Hydrogen Scenarios highlights that it could be too costly for the Moroccan government to fund the Green Hydrogen Roadmap at this scale, which leads to increased imports of polluting fossil fuels for cost reduction. In fact, the emission levels are 39% higher in the green hydrogen exports scenario than in the least-cost scenario. Given these findings, it is recommended that the Green Hydrogen Roadmap be re-evaluated, with a suggestion for a postponement and reduction in scope.

Quantifying state transfer strength on graphs with involution

AbstractThis paper discusses continuous-time quantum walks and asymptotic state transfer in graphs with an involution. By providing quantitative bounds on the components of the eigenvectors of the Hamiltonian, it provides an approach to achieving high-fidelity state transfer by strategically selecting energy potentials based on the maximum degrees of the graphs. The study also involves an analysis of the time necessary for quantum transfer to occur.

Study of Palm Oil Shell Utilization as Metallurgical Coke with Variation of Bondcrete Additive

Coke, an essential ingredient in the steel and metallurgical industries, is typically derived from bituminous coal. However, in Indonesia, where bituminous coal is rare, coke production is dependent on coal imports due to the high moisture content of local coal. An alternative approach is to use biomass, such as palm oil processing waste, for "biomass coke" to produce a more environmentally friendly coke with lower greenhouse gas emissions. Palm kernel shell waste rich in lignocellulose proved suitable for this purpose due to its compressive strength and carbon content. Pyrolysis, a technique for creating porous micro-structured carbon from palm kernel shells, was used to produce this coke substitute, offering a more sustainable energy source with a lower carbon footprint than fossil fuels. Bio-coke exhibits low moisture content (5.84%) and ash content (13.20%) due to the moisture and ash reduction effects of bondcrete adhesive during combustion. It also demonstrates substantial compressive strength (14 mPa), a high calorific value (6795 cal/g), and a favorable pore structure with a large surface area, indicating a positive influence of bondcrete adhesive on coke properties without compromising energy potential.

A Multi-Stage Approach to Assessing the Echo-Tech Feasibility of a Hybrid SAM-CREST Model for Solar PV Power Plants in Maryland, USA

Maryland is actively working towards doubling its Renewable Portfolio Standard (RPS) target, aiming to increase the share of renewable energy from 25% by 2020 to 50% by 2030. Furthermore, Maryland stands out as a state that strongly supports solar initiatives, offering incentives and specialized programs to assist residents in adopting solar energy solutions. The paper presents a multi-stage approach: Stage 1—Location Selection Process, Stage 2—Technical Feasibility Study, and Stage 3—Economical Feasibility Study. In Stage 1, the study focuses on three potential solar farm locations in Maryland: Westover, Princess Anne, and Eden. Stages 2 and 3 involve a feasibility assessment with detailed technical analysis using the NREL System Advisor Model (SAM) and PVWatts to determine monthly power to the grid and Energy Yield. Subsequently, economic feasibility is assessed using the NREL Clean Renewable Energy Estimation Simulation Tool (CREST), focusing on competitive levelized costs of energy (LCOE), payback time, and cumulative cash flows. Results indicate that all three locations exhibit promising solar irradiance levels, system outputs, and potential energy yields. Due to high solar irradiation, the Westover area has the highest energy yield at 1583.13 kWh/kW, while Princess Anne boasts the highest system output at 333.59 GWh. The economic evaluation suggests that all three locations become profitable within a two-year payback time, with competitive levelized costs of energy (LCOE). Westover emerges as the most cost-effective option at 5.99 cents/kWh, attributed to its higher solar irradiation values and energy yield compared to Princess Anne and Eden. Cumulative cash flows provide insights into long-term profitability, with Princess Anne, MD, having the highest Cumulative Cash Flow over 25 years at $183,383,304. By evaluating technical and economic aspects, this feasibility study offers quantitative insights to guide decision-making for the installation of Solar PV, considering both technological and economic feasibility.

Insights into the dynamic symphony: a comprehensive computational exploration of pure and fluorinated 6O.6 liquid crystals with the help of DFT analysis

ABSTRACT This article is based on the Density Functional Theory (DFT) simulations approach to examine the structural and vibrational behaviour of pure 6O.6 and fluorinated 6O.6 liquid crystalline compounds. The molecular interactions of the molecules were investigated by their optimised molecular structure. Identification of significant functional groups and their dynamic behaviours are made with the help of vibrational frequencies obtained through DFT calculations. Vibrational Energy Distribution Analysis (VEDA) software was used to perform the Potential Energy Distribution (PED) function of FT-IR and Raman spectra. Furthermore, changes in vibrational peaks provide insight into structural modifications. This investigation mainly focused on analysing the different reactivity, thermodynamic parameters and non-linear optical (NLO) properties of the compounds. This also helps to open a new path for further investigations into optoelectronic applications and molecular dynamics.

Formation of the oxyl's potential energy surface by the spectral kinetics of a vibrational mode.

One of the most reactive intermediates for oxidative reactions is the oxyl radical, an electron-deficient oxygen atom. The discovery of a new vibration upon photoexcitation of the oxygen evolution catalysis detected the oxyl radical at the SrTiO3 surface. The vibration was assigned to a motion of the sub-surface oxygen underneath the titanium oxyl (Ti-O●-) created upon hole transfer to (or electron extraction from) a hydroxylated surface site. Evidence for such an interfacial mode is derived from its spectral shape, which exhibited a Fano resonance-a coupling of a sharp normal mode to continuum excitations. Here, this Fano resonance is utilized to derive precise formation kinetics of the oxyl radical and its associated potential energy surface (PES). From the Fano lineshape, the formation kinetics are obtained from the anti-resonance (the kinetics of the coupling factor), the resonance (the kinetics of the coupled continuum excitations), and the frequency integrated spectrum (the kinetics of the normal mode's cross-section). All three perspectives yield logistic function growth with a half-rise of 2.3 ± 0.3ps and a time constant of 0.48 ± 0.09ps. A non-equilibrium transient associated with photoexcitation is separated from the rise of the equilibrated PES. The logistic function characterizes the oxyl coverage at the very initial stages (t ∼ 0) to have an exponential growth rate that quickly decreases toward zero as a limiting coverage is reached. Such time-dependent reaction kinetics identify a dynamic activation barrier associated with the formation of a PES and quantify it for oxyl radical coverage.

Evaluation of the effect of desliming and alternatives in iron ore reverse flotation circuits

Iron ore reverse flotation has been the main concentration process applied in iron ore processing plants since the 1970s. The performance of this process has been strongly affected by the control of the previous desliming stages. The presence of ultrafine particles promotes selectivity losses in the flotation circuits, in addition to a significant increase in the consumption of chemical reagents and pumping energy. The removal of ultrafine particles promotes metal losses, the need for additional dewatering steps, difficulties in handling and stacking together with flotation waste. This study focuses on investigating the feasibility of replacing desliming with high intensity vertical magnetic concentrators (VPHGMS). Pilot tests were carried out with this type of magnetic concentrator followed by flotation, the results show an increase in metal recovery of 4% when compared to the traditional desliming and flotation circuit, drastic possibility of reducing energy, chemical reagents and foot print and potential to reduce capex and opex by 22% and 24%, respectively, for new projects.

Quantum calculation of the pressure broadening of H and K lines of Ca+ calcium ion in a gaz of ground-state He helium atoms

In this theoretical study, we have conducted calculations to investigate the pressure broadening of the H ( 4 s 2 S 1 / 2 − 4 p 2 P 1 / 2 ) and the K ( 4 s 2 S 1 / 2 − 4 p 2 P 3 / 2 ) lines of the Ca + calcium ion in a gas of ground-state He helium atoms. The focus of our work is to determine the profiles of the pressure-broadened resonance lines and analyse their behaviour under the influence of binary collisions between Ca + ions and He atoms. To achieve this, we constructed accurate potential energy curves for the ground X 2 Σ 1 / 2 + and the excited D 2 Π 1 / 2 , D 2 Π 3 / 2 and E 2 Σ 1 / 2 + states. Additionally, we constructed the corresponding transition dipole moments based on the data obtained through high-level ab initio methods, including SA-CASSCF, MRCI, and SO coupling, with Davidson and BSSE corrections. The study spans a range of temperatures from 4000 K to 12,000 K and wavelengths from 200 nm to 500 nm . The theoretical profile is characterised by dominant free-free transitions. In the vicinity of the 436 nm wavelength position, there is a satellite peak in the red wing, attributed to the contribution of D 2 Π 1 / 2 ⟵ X 2 Σ 1 / 2 + and D 2 Π 3 / 2 ⟵ X 2 Σ 1 / 2 + transitions. Our findings are in good agreement with previous theoretical results.

Not fully twisted, not fully planar, but intermediate torsions for ideal chromophore design: A computational study on p‐phenylene bridged pyridinium phenolate betaines

AbstractThis contribution reports extensive studies on structure–property correlations of two isoelectronic betaine metamers (positional isomers). These zwitterions differ from each other with respect to bonding modes of pyridinium acceptors (Reichardt's mode: through N‐atom versus Brooker's mode: through C‐atom) with the p‐phenylene bridged phenolate donors. Various quantum chemical methodologies are used in this investigation, with time‐dependent (TD) and coupled perturbed (CPHF) theories for computations of many molecular response properties. Analysis of first hyperpolarizabilities (β) indicates that Reichardt's metamer (ωB97xD: β = 349.5 × 10−30 esu) is more efficient chromophore (~5‐fold enhanced) than Brooker's metamer (ωB97xD: β = 69.4 × 10−30 esu). The gyratory abilities of the bridge junctions resulted in a cohort of metastable conformations, in the rotational potential energy surfaces (PES) of the two metamers. Moreover, rotational PES establishes that intermediary torsions are suitable for optimal chromophore design strategies (Reichardt's metamer: β = 956.5 × 10−30 esu, and Brooker's metamer: β = 1104.7 × 10−30 esu), Thus suitable conformational manipulations, can be used to obtain more efficient zwitterionic molecular chromophores. Compared unbridged prototype molecules, p‐phenylene bridged zwitterions showed ~6–9 times enhanced values of β. In addition, important aspects of suitable chromophore design strategies are suggested.

Rovibrational calculations without model Hamiltonians: The infrared and microwave spectra of thiopropynal

AbstractRovibrational configuration interaction theory has been used to study the rotational spectrum and low lying rovibrational states of thiopropynal, a molecule, which has recently been detected in an interstellar cloud. Geometrical parameters, fundamental vibrational transitions and spectroscopic constants are also provided. All calculations rely on an ‐mode representation of the multidimensional potential energy surface, which has been obtained from explicitly correlated coupled‐cluster approaches including core correlation effects and an approximate treatment of high‐order coupled‐cluster terms. Comparison with experimental data is provided for several properties and the agreement was found to be excellent in most cases.

Numerical and experimental analysis of the combustion in a Single-Cylinder research engine with passive TJI pre-chamber operating with hydrated ethanol

Advanced ignition systems, such as turbulent jet ignition, have the capacity to improve the combustion process of internal combustion engines, increasing fuel conversion efficiency and reducing emissions, especially when applied with ethanol biofuel. Technologies that take advantage of the local energy potential, taking into account the geographic, demographic and social characteristics of each country, increase the diversity of solutions for the sustainable future of the transport sector. The present work aims to develop a system with a passive pre-chamber operating in turbulent jet ignition mode, applied to a single-cylinder research engine with a stoichiometric air–fuel mixture of ethanol. Numerical simulations were carried out and experimentally validated applying the commercial software CONVERGE CFD. The results showed that the optimized configuration presented higher fuel conversion efficiency, when compared to conventional spark ignition, thus producing greater savings per kilometer driven and lessing the dependence on fossil fuels. The pre-chambers with both lateral holes and a central hole showed a maximum NOx reduction of 5.9 g/kWh, reducing the second half of combustion by 6.2 crank angle degrees and the first half of combustion by up to 1.8 crank angle degrees compared to SI. This indicates a potential for increasing the compression ratio for pre-chamber configurations without the occurrence of knock. Furthermore, there is a direct relationship between the quenching of the jets after exiting the pre-chamber holes and turbulence, with quenching occurring when turbulent kinetic energy was greater than 15000 m2/s2.

Sustainable energy transition in Bangladeshi academic buildings: A techno-economic analysis of photovoltaic-based net zero energy systems

Bangladesh faces challenges with global carbon emissions and energy security due to its heavy reliance on imported fossil fuels. This paper investigates the techno-economic viability of photovoltaic (PV) systems for achieving net-zero energy in academic buildings as a sustainable alternative. The study evaluates the performance of PV systems based on factors including annual energy production, capacity factor, net-zero energy potential, self-consumption/sufficiency ratio, renewable fraction, levelized cost of energy (LCOE), net present value (NPV), payback period, profitability index (PI), and carbon emission reduction. The results indicate that optimally sized PV systems can generate net positive energy: 6.18 MWh for universities, 4.04 MWh for high schools, and 3.62 MWh for primary schools. Economic viability was assessed under two billing methods (net metering and all energy buy/sell), and all cases showed positive NPV and PI values greater than 1. Decarbonization analysis revealed significant reductions in CO2 emissions: 2026.5 tons for universities, 18.9 tons for high schools, and 9.7 tons for primary schools. Finally, a sensitivity analysis assessed the optimal PV system size for seven other regions in Bangladesh. These findings suggest that the widespread adoption of PV systems in academic buildings can play a crucial role in achieving net-zero energy, contributing significantly to the government and policymakers' pursuit of sustainable development goals.

Experimental Study on the Effect of Mixed Thermodynamic Inhibitors with Different Concentrations on Natural Gas Hydrate Synthesis

Natural gas hydrate (NGH) is a potential future energy resource. More than 90% of NGH resources exist in the pore medium of seafloor sediments. During the development of deep-sea oil and gas fields, wellbore pipelines are often clogged due to the synthesis of gas hydrates, and the addition of thermodynamic inhibitors is a common solution to prevent hydrate synthesis. In this paper, the effects of two single inhibitors, sodium chloride and ethylene glycol, as well as hybrid inhibitors combining these two inhibitors on the synthesis of methane hydrates were investigated using the self-developed one-dimensional gas hydrate exploitation simulation test apparatus. The effects of single and hybrid inhibitors were investigated in terms of the hydrate synthesis volume and gas–water two-phase conversion rate. The results show that the hybrid inhibitor has a better inhibitory effect on hydrate synthesis with the same initial synthesis driving force. When the concentration of inhibitors is low, salt inhibitors can have a better inhibitory effect than alcohol inhibitors. However, in the mixed inhibitor experiment, increasing the proportion of ethylene glycol in the mixed inhibitor can more effectively inhibit the synthesis of hydrates than increasing the proportion of sodium chloride in the mixed inhibitor.

Theoretical investigation on heats of formation, detonation properties and sensitivities of TANPy based energetic materials

A series of 2,4,6-triamino-3,5-dinitropyridine (TANPy) based energetic compounds were designed and optimized at the B3LYP/6-311G (d,p). The results show that all the designed compounds have high positive heats of formation, and the tetrazole ring/–N3 was an beneficial combination to increase the heats of formation. The introduction of furazan-furazan/-C(NO2)3/–CH(NO2)2 combination was effective to improve the densities and detonation properties while the furazan-furazan or furazan-tetrazine rings was beneficial to improving the values of heats of detonation. Considering the detonation properties and sensitivities, compounds D2, E2, F2 were finally screened as potential high energy density materials and their physicochemical properties were fully investigated.

Status and Development Perspectives of the Compressed Air Energy Storage (CAES) Technologies—A Literature Review

The potential energy of compressed air represents a multi-application source of power. Historically employed to drive certain manufacturing or transportation systems, it became a source of vehicle propulsion in the late 19th century. During the second half of the 20th century, significant efforts were directed towards harnessing pressurized air for the storage of electrical energy. Today’s systems, which are based on storing the air at a high pressure, are usually recognized as compressed air energy storage (CAES) installations. This paper aims to provide an overview of different technologies that take advantage of the energy accumulated in the compressed air. Particular attention is paid to the CAES installations that are working as electrical energy storage systems (EESs). These systems, developed originally as large capacity (>100 MWe) and fuel-based installations, may soon become fully scalable, highly efficient, and fuel-free electrical energy storage systems. To present this opportunity, a thorough review encompassing previous and up-to-date advancements in their development was carried out. In particular, CAES concepts, such as diabatic (D-CAES), adiabatic (A-CAES), and isothermal (I-CAES), are described in detail. This review also provides the detailed characteristics of the crucial elements of these configurations, including compressors, expanders, air storage chambers, and thermal storage tanks. Knowledge of these components and their role allows us to understand the main challenges behind the further development of the mentioned CAES setups. Apart from the CAES systems that are designed as EES systems, this paper describes other prospective technologies that utilize the energy of pressurized air. Accordingly, compressed air cars and their key elements are explained in detail. Moreover, the technology renowned as wave-driven compressed air energy storage (W-CAES) is described as well, indicating that the utilization of pressurized air represents a viable option for converting ocean energy into electrical power.

Influence of atomic electronegativity on ESIPT behaviour for the BTDI and its derivatives: Theoretical exploration

In this work, we theoretically explored the influence of atomic electronegativity on excited-state intramolecular proton transfer (ESIPT) behavior among novel fluorescent probes BTDI and its derivatives (BODI and BSeDI). A thorough examination of the optimized structural parameters and infrared vibrational spectra reveals an enhancement in intramolecular hydrogen bonding within BTDI and its derivatives upon light excitation. This finding is further reinforced by topological analysis and interaction region indicator scatter plots, which underscores the sensitivity of atomic electronegativity to variations in hydrogen bonding strength. With regards to absorption and fluorescence spectra, the decrease in atomic electronegativity leads to a pronounced redshift, primarily attributed to the narrowing of the energy gap. Additionally, an analysis of potential energy curves and the exploration of intrinsic reaction coordinate paths based on transition state structures afford a deeper understanding of the mechanism underlying ESIPT and being modulated through the manipulation of atomic electronegativity. We anticipate that this work on atomic electronegativity regulating ESIPT behavior will serve as a catalyst for novel fluorescent probes in the future, offering fresh perspectives and insights.

A hydrate reservoir renovation device and its application in nitrogen bubble fracturing

Abstract. Natural gas hydrate (GH) is a significant potential energy source due to its large reserves, wide distribution, high energy density, and low pollution. However, the gas production rate of past gas hydrate production tests is much lower than the requirement of commercial gas production. Reservoir stimulation technologies like hydraulic fractures provide one potential approach to enhance gas production from GH. The reservoir reformation behavior of the hydrate-bearing sediments (HBSs), particularly sediments with a high clay content, is a complex process during a hydraulic fracturing operation which has been poorly understood and thus hardly predictable. This paper presents an experimental facility that was developed to analyze the hydraulic fracture mechanism in synthesized HBSs. This facility can be used to form GH in sediments, conduct visual observation of hydraulic fracturing experiments, and measure the permeability of HBSs under high-pressure (up to 30 MPa) and low-temperature conditions (from 253.15 to 323.15 K). It is mainly composed of a pressure control and injection unit, a low temperature and cooling unit, a cavitation unit, a visual sapphire reactor, and a data acquisition and measurement unit. The hydraulic fracture module consists of a gas cylinder, fracturing pump, hopper, proppant warehouse, and valves. The sapphire reservoir chamber is applied to observe and measure the fracture of HBSs during hydraulic fracturing. The permeability test module is composed of a constant-flux pump and pressure sensors, which can evaluate the permeability performance before and after the hydraulic fracture in HBSs. The fundamental principles of this apparatus are discussed. Some tests were performed to verify hydraulic fracture tests, and permeability tests could be practically applied in the HBS exploitation.

Global Potential Energy Surfaces by Compressed-State Multistate Pair-Density Functional Theory for Hyperthermal Collisions in the O2+O2 System.

Interactions between oxygen molecules play an important role in atmospheric chemistry and hypersonic flow chemistry in atmospheric entries. Recently, high-quality ab initio potential energy surface (PES) of the quintet O4 was reported by Paukku et al. [J. Chem. Phys. 147, 034301 (2017)]. 10543 configurations were sampled and calculated at the level of MS-CASPT2/maug-cc-pVTZ with scaled external correlation. The PES was fitted to a many-body (MB) form with the many-body part described by the permutationally invariant polynomial approach (MB-PIP). In this work, the PIP-Neural Network (PIP-NN) and MB-PIP-NN methods were used to refit the PES based on the same data by Paukku et al. Three PESs were compared. It was found that the performances differ significantly in the O+O3 region as well as in the long-range region. Therefore, additional 1300 points were sampled, and the efficient compressed-state multistate pair-density functional theory (CMS-PDFT) was used to calculate the electronic structure of these 1300 points and 10543 points by Paukku et al. Then, a completely new quintet PES was fitted using the MB-PIP-NN method. Based on this PES, the quasi-classical trajectory (QCT) approach was used to reveal all possible reaction channels for hyperthermal O2-O2 collisions.

Resilient Si@C architecture fabricated by mechanochemical conjugation and thermal reduction for lithium storage: Simulation on interfacial state evolution

Synchronal comminution via high-energy bead milling not only efficiently pulverizes Si particles and exfoliates graphene oxide (GO) sheets but also facilitates Si surface functionalization and intensify Si-C conjugation. After a thermal reduction, a well-wrapped Si@C anode material can be fabricated for lithium storage. The discharge specific capacities of this Si@C composite sustain at 1110.3 mAh g−1 after 300 cycles at 1 A g−1 and 316.4 mAh g−1 for 800 cycles at 5 A g−1, which are respectively 1.35 and 2.07 times that of its random blended Si/C counterpart. By employing molecular dynamics (MD) simulations with ReaxFF reactive force field to investigate the mechanochemical reactions between Si and GO amidst high-energy milling, an atomic scale portrayal of Si crystal fragmentation and Si-C bonding can be depicted. Analyses focusing on the differential forces exerted on various Si crystal planes, coupled with potential energy (PE) trends, reveal a higher propensity for cleavage in (111) plane, with (311) plane followed. Radial distribution function (RDF) outcomes indicate that ball milling leads to substantial disruption of crystalline order in Si particles, generating a plethora of Si dangling bonds. This disruption stimulates the formation of SiOOC, SiOC and SiC bonds at the Si/C interface, thus enhancing the integration of GO with Si substrate. Subsequent thermal reduction processes not only restore the structural order of Si and GO but also consolidate Si/C bonding.

Potential Energy Optimization Approach in the Form-Finding of Tensegrities and Cable–Strut Systems

A form-finding process for tensegrities and cable–strut systems is determined as a minimum problem of potential energy that is constructed considering initial estimated pre-stress states. Both the Jacobian and Hessian matrices of a potential energy function are derived explicitly regarding free nodal coordinates. Based on these derivations, both the first-order geodesic dynamic relaxation optimization method and the second-order optimization method of Newton can be applied to solve form-finding problems involving tensegrities and cable–strut structures. It should be noted that both the pre-stress state and the configuration of the systems are adjusted during the optimization process to satisfy self-equilibrium conditions. The geometrical constraints are then included in the proposed work as equality constraint conditions to find the final forms satisfying not only the self-equilibrium states but also the designers’ demands. Two well-known and complex systems are investigated to assess the efficiency of the proposed method, i.e. free-standing truncated icosahedral tensegrity and the Kiewitt Dome.