Field Of Clean Energy Research Articles

Engineering Single-Layer Hollow Structure of Transition Metal Dichalcogenides with High 1T-Phase Purity for Hydrogen Evolution Reaction.

Rational design and controllable synthesis of hollow structures based on transition metal dichalcogenides (TMDs) have gained tremendous attention in the field of clean energy. However, the general synthetic strategies to fabricate single-layer hollow structures of TMDs, especially with unconventional phases (e.g., 1T or 1T'), still pose significant challenges. Herein, a scalable method is reported for the synthesis of single-layer hollow spheres (SLHS) of TMDs with high 1T-phase purity by etching bismuth (Bi) cores from pre-synthesized Bi@TMDs core-shell heterostructures including SLHS-1T-MoS2 , SLHS-1T-MoSe2 , SLHS-1T-WS2 , and SLHS-1T-WSe2 . Additionally, the etched Bi ions can be adsorbed on the single-layer TMDs shells in the form of single atoms (SAs) via the Bi─S bond. Due to the benefits of the single-layer hollow structure, high conductivity of 1T phase, and synergistic effect of Bi SAs and TMDs supports, the fabricated SLHS-1T-MoS2 exhibits superior electrocatalytic performance for hydrogen production. This work provides a way to manufacture advanced functional materials based on the single-layer hollow structures of 1T-TMDs and to expand their applications.

Catalytic Activity of LnCo0.5Ni0.5O3-Δ (Ln = La, Pr, Nd) "Positrodes" on Ceramic Protonic Electrolytes

Proton-conducting solid-oxide electrolyzers and fuel cells represent viable, intermediate-temperature green energy conversion and storage technologies. Interest in this class of materials as electrolytes stems from their high ionic conductivity and inherent advantages in the gas flow configuration over traditional solid oxide cells in which the electrolyte is an oxygen ion conductor. However, their commercial viability has been hindered, in part, by the development of corresponding single-phase electrode components with mixed proton-electron conductivity and effective catalytic activity toward oxygen reduction and evolution reactions (ORR/OER). This paper investigates the origin of catalytic activity in LnCo0.5Ni0.5O3-δ (Ln=La, Pr and Nd) perovskites positrodes (positive electrode) by low energy-ion scattering (LEIS) and DFT studies. LEIS results reveal that La, Pr, and Pr cations dominate the outer atomic layer, with profound implications for catalytic activity. Whereas First principle calculations were performed using the plane-wave DFT method and hybrid HSE06 functional suggest, the catalytic activity and electronic properties depend on the valence shell structure of the Ln-site cation and their redox properties.AcknowledgmentsThe authors gratefully acknowledge financial support through JSPS KAKENHI Grant-in-Aid for Scientific Research (C), No. 19K05672, NEDO (International collaboration work in the field of clean energy) JPNP20005, the International Institute for Carbon-Neutral Energy Research (I2CNER) sponsored by the World Premier International Research Center Initiative (WPI),

Thermoforming, characterization, and in-house recycling of multi-layered laminated composites made with polyamide 6/recycled carbon fibers hybrid yarns-based plain weave fabrics

Carbon fiber reinforced plastics (CFRPs) in the form of laminated composites are widely used in various sectors, such as aeronautics and clean energy fields, due to their superior mechanical properties compared to traditional homogeneous composites. In this study, the authors developed a manufacturing process based on thermoforming a 7-layer stack of plain weave fabrics made from hybrid yarns (polyamide 6/recycled carbon fibers) to introduce a new method for reusing end-of-life (EoL) CFRPs and avoid landfilling. Several attempts were made to determine the optimal combination of process parameters, including forming temperature, forming pressure, and holding time. The manufactured multi-layered laminated composites underwent in-depth mechanical and thermal characterization tests to obtain information on their physical properties and identify potential applications for market exploitation. The developed materials exhibit very interesting mechanical properties, which are comparable to or greater than those of commercial carbon or glass fiber-reinforced polymers. Morphological analysis revealed good wettability of PA6 on rCFs and a very low degree of porosity. Finally, the re-use of yarn scraps and fabric remnants generated during the manufacturing process, as well as the recyclability of the manufactured composites once they reach the status of EoL materials, were studied through an in-house recycling process based on comminution and hot pressing of materials.

Boost of Gas Adsorption Kinetics of Covalent Organic Frameworks via Ionic Liquid Solution Process.

Adsorption, storage, and conversion of gases (e.g., carbon dioxide, hydrogen, and iodine) are the three critical topics in the field of clean energy and environmental mediation. Exploring new methods to prepare high-performance materials to improve gas adsorption is one of the most concerning topics in recent years. In this work, an ionic liquid solution process (ILSP), which can greatly improve the adsorption kinetic performance of covalent organic framework (COF) materials for gaseous iodine, is explored. Anionic COF TpPaSO3 H is modified by amino-triazolium cation through the ILSP method, which successfully makes the iodine adsorption kinetic performance (K80% rate) of ionic liquid (IL) modified COF AC4 tirmTpPaSO3 quintuple compared with the original COF. A series of experimental characterization and theoretical calculation results show that the improvement of adsorption kinetics is benefited from the increased weak interaction between the COF and iodine, due to the local charge separation of the COF skeleton caused by the substitution of protons by the bulky cations of ILs. This ILSP strategy has competitive help for COF materials in the field of gas adsorption, separation, or conversion, and is expected to expand and improve the application of COF materials in energy and environmental science.

Lignin-derived iron carbide/Mn, N, S-codoped carbon nanotubes as a high-efficiency catalyst for synergistically enhanced oxygen reduction reaction and rechargeable zinc-air battery

Design of efficient and durable oxygen reduction reaction (ORR) electrocatalysts still remains challenge in sustainable energy storage and conversion devices. To achieve sustainable development, it is of importance to prepare high-quality carbon-derived ORR catalysts from biomass. Herein, Fe5C2 nanoparticles (NPs) were facilely entrapped in Mn, N, S-codoped carbon nanotubes (Fe5C2/Mn, N, S-CNTs) by a one-step pyrolysis of the mixed lignin, metal precursors and dicyandiamide. The resulting Fe5C2/Mn, N, S-CNTs had open and tubular structures, which exhibited positive shifts in the onset potential (Eonset = 1.04 V) and high half-wave potential (E1/2 = 0.85 V), showing excellent ORR characteristics. Further, the typical catalyst-assembled Zn-air battery showed a high power density (153.19 mW cm−2) and good cycling performance as well as obvious cost advantage. The research provides some valuable insights for rational construction of low-cost and environmentally sustainable ORR catalysts in clean energy field, coupled by offering some valuable insights for reusing biomass wastes.

CLEAN ENERGY COOPERATION BETWEEN CHINA AND CENTRAL AND EASTERN EUROPE UNDER THE “BELT AND ROAD” FRAMEWORK: PROSPECTS AND COOPEARTIVE PATHS

Central and Eastern Europe, in the heartland of Eurasia, is an important region for the mutual construction of the “Belt and Road”, and also a key region for foreign cooperation of China’s energy industry. According to the renewable energy development goals of Central and Eastern European countries, the proportion of non-fossil energy consumption will increase to more than 25% by 2030. The renewable energy will become one of the important routes to achieve energy transformation and clean emissions in Central and Eastern Europe. At present, the proportion of renewable energy consumption in some Central and Eastern European countries is still significantly lower than the EU’s 2030 target; therefore, the pace of energy transformation will be further accelerated. Since China has advanced technology and rich experience in wind power, hydro-power, photovoltaic, nuclear power and other clean energy fields, it can cooperate with Central and Eastern European countries in green energy project development, smart grid, engineering construction, pipe network construction and other fields. The cooperation between the two sides is highly complementary, conforms to the theme of the era of global sustainable development, vigorously promoting the green development of the “Belt and Road”, and consolidating the people-to-people bond of jointly building the “Belt and Road”. This study focuses on the energy development trend of China and Central and Eastern European countries, explores the cooperation paths of the two sides in the energy field, and puts forward targeted reference suggestions for further deepening cooperation between the two sides.

The stability, mechanical, electronic and thermoelectric properties of unexplored monolayer Ca4Sb2O and Ca4Bi2O

Thermoelectric materials can directly convert heat gradient into electricity, thus have attracted much attention in the field of clean energy and ecological protection. In this work, we proposed two novel two−dimensional materials, Ca4Sb2O and Ca4Bi2O, and investigated their stability, mechanical, electronic and thermoelectric properties. We revealed that these two monolayers are direct semiconductors with bandgaps of 1.57 and 1.08 eV, respectively. Due to the lower electron effective mass, the electron mobilities (252.90–799.97 cm2/Vs) are significantly higher than those of hole (58.16–59.21 cm2/Vs), leading to high n-type conductivities (106–107 S/m), as well as high thermoelectric power factors of 28.80 and 10.83 mW K−2 m−1 at 300 K. Also, owing to the low phonon group velocities and high phonon-phonon scattering rates, the monolayers also possess low lattice thermal conductivities of 1.86 and 1.01 W/mK at room temperature, which are dominated by acoustic modes. As a result, Ca4Sb2O and Ca4Bi2O deliver high n-type thermoelectric figure of merit of 0.27 and 0.29 at 300 K, and increase even further to 1.50 and 1.67 at 700 K, suggesting that they are candidates for low - medium temperature thermoelectric appliances.

Research Advances in Amorphous-Crystalline Heterostructures Toward Efficient Electrochemical Applications.

Interface engineering of heterostructures has proven a promising strategy to effectively modulate their physicochemical properties and further improve the electrochemical performance for various applications. In this context related research of the newly proposed amorphous-crystalline heterostructures have lately surged since they combine the superior advantages of amorphous- and crystalline-phase structures, showing unusual atomic arrangements in heterointerfaces. Nonetheless, there has been much less efforts in systematic analysis and summary of the amorphous-crystalline heterostructures to examine their complicated interfacial interactions and elusory active sites. The critical structure-activity correlation and electrocatalytic mechanism remain rather elusive. In this review, the recent advances of amorphous-crystalline heterostructures in electrochemical energy conversion and storage fields are amply discussed and presented, along with remarks on the challenges and perspectives. Initially, the fundamental characteristics of amorphous-crystalline heterostructures are introduced to provide scientific viewpoints for structural understanding. Subsequently, the superiorities and current achievements of amorphous-crystalline heterostructures as highly efficient electrocatalysts/electrodes for hydrogen evolution reaction, oxygen evolution reaction, supercapacitor, lithium-ion battery, and lithium-sulfur battery applications are elaborated. At the end of this review, future outlooks and opportunities on amorphous-crystalline heterostructures are also put forward to promote their further development and application in the field of clean energy.

Thermodynamic analysis of Tesla turbine in Organic Rankine Cycle under two-phase flow conditions

In the field of clean energy, Organic Rankine Cycle (ORC) is considered a vital method to utilize low-grade waste heat effectively. Due to certain application advantages in low power level ORC systems, the Tesla turbine is considered one of the essential choices for the core components of ORC systems. Given the inadequacy of the current research on the performance of the Tesla turbine under two-phase flow conditions, a one-dimensional model of the Tesla turbine was constructed in this paper to make it equally applicable to the two-phase flow conditions of wet working fluids. A model of the Tesla turbine and ORC system was constructed from the thermodynamic point of view, and five typical wet working fluids (R22, R417a, R134a, R152a, and R290) were selected to study the effects of the five wet working fluids on the thermal performance of Tesla turbine and ORC system. The effects of the changes in key structural parameters of the Tesla turbine on the performance of the Tesla turbine and the ORC system were further analyzed when different wet working fluids were used in the ORC system. The results showed that the highest turbine efficiency of 42.0 % was achieved when the Tesla turbine used R22 as the working fluid under the design conditions, while the highest turbine output power and the highest system thermal efficiency of 1.19 kW and 3.96 % were achieved when R417a was used as the working fluid. The analysis of the key structural parameters of the system showed that for the five different wet working fluids, the turbine efficiency, turbine output power, and system thermal efficiency increased monotonically with increasing rotor inlet radius. For each of the five wet working fluids, an optimum rotor speed, rotor outlet radius, and rotor gap distance exist, resulting in optimal turbine efficiency and system performance. The related work provides an important reference for the optimal design of Tesla turbines with wet working fluids.

Application of Poly(ether sulfone)-Based Membranes in Clean Energy Technology.

Poly(ether sulfone) (PES) is a kind of polymer materials with excellent electrical insulation and acid/alkali stability. PES can be operated at high temperature continuously for a long time and still maintain excellent property stability in the environments with rapidly changed temperature, namely, great thermostability. Moreover, PES has low molding shrinkage, good dimensional stability and excellent film-forming characteristics. Compared with inorganic membranes, PES-based membranes have lower cost, which have received more attention and wide recognition in the field of clean energy technologies in recent years, such as flow batteries, fuel cells, water treatment, and gas separation. Therefore, this review summarizes the research status and prospect of the utilization of PES-based membranes in clean energy fields, in order to further promote their development and application.

Multiple active cobalt species embedded in microporous nitrogen-doped carbon network for the selective production of hydrogen peroxide

To obtain excellent electrocatalysts for improving H2O2 yield and selectivity, we formulated a novel method for embedding cobalt catalytic active sites in porous two-dimensional nitrogen-doped carbon network (CNy) network and employed them as excellent two-electron oxygen reduction reaction (2e−-ORR) electrocatalysts. The polymeric cobalt-based metal–organic framework (polyCo-MOF) and melamine–cyanuric acid–complex (MCA) hybrid (denoted as polyCo-MOF@MCA) was used as a precursor for preparing a series of electrocatalysts comprising multiple active sites such as metallic Co, CoOx, or Co-N, which are homogeneously embedded in the porous two-dimensional CNy network through pyrolysis at high temperatures (600 °C, 700 °C, and 800 °C) under N2 atmosphere. The obtained CoOx/Co@CNy,700 hybrid by pyrolyzing polyCo-MOF@MCA at 700 °C displayed remarkably high H2O2 production and large selectivity in an alkaline solution. The possible catalytic mechanism of CoOx/Co@CNy,700 toward 2e−-ORR was identified by determining the catalytic kinetics and control experiments. The cathode assembled with the CoOx/Co@CNy,700 hybrid showed the maximum H2O2 production of 405 mmol L−1gcat.−1h−1 with a high Faradaic efficiency of 88.9 % at 0.65 V. The present work demonstrated a novel strategy for identifying excellent electrocatalysts with homogeneously dispersed multiple active sites and high production and selectivity for H2O2 synthesis, extending the applications of porous organic frameworks to the field of clean energy.

Solid-state Z-scheme assisted hydrated tungsten trioxide/ZnIn2S4 photocatalyst for efficient photocatalytic H2 production

Efficient water splitting for H2 evolution over semiconductor photocatalysts is highly attractive in the field of clean energy. It is of great significance to construct heterojunctions, among which the direct Z-scheme nanocomposite photocatalyst provides effective separation of photo-generated carriers to boost the photocatalytic performance. Herein, Z-scheme hydrated tungsten trioxide/ZnIn2S4 is fabricated via an in-situ hydrothermal method where ZnIn2S4 nanosheets are grown on WO3⋅xH2O. The close contact between WO3⋅0.5H2O and WO3⋅0.33H2O as well as ZnIn2S4 improve the charge carrier separation and migration in the photocatalyst, where the strong reducing electrons in the conduction band of ZnIn2S4 and the strong oxidizing holes in the valence band of WO3⋅0.33H2O are retained, leading to enhanced photocatalytic hydrogen production. The obtained WO3⋅xH2O/ZnIn2S4 shows an excellent H2 production rate of 7200 μmol g−1 h−1, which is 11 times higher than pure ZnIn2S4. To the best of our knowledge, this value is higher than most of the WO3-based noble metal-free semiconductor photocatalysts. The improved stability and activity are attributed to the formation of the Z-scheme heterojunction, which can markedly accelerate the interfacial charge separation for surface reaction. This work offers a promising strategy towards the design of an efficient Z-scheme photocatalyst to suppress electron–hole recombination and optimize redox potential.

Phase-Controlled Synthesis of Nickel-Iron Nitride Nanocrystals Armored with Amorphous N-Doped Carbon Nanoparticles Nanocubes for Enhanced Overall Water Splitting.

Transition metal nitrides (TMNs) nanostructures possess distinctive electronic, optical, and catalytic properties, showing great promise to apply in clean energy, optoelectronics, and catalysis fields. Nonetheless, phase-regulation of NiFe-bimetallic nitrides nanocrystals or nanohybrid architectures confronts challenges and their electrocatalytic overall water splitting (OWS) performances are underexplored. Herein, novel pure-phase Ni2+ x Fe2- x N nanocrystals armored with amorphous N-doped carbon (NC) nanoparticles nanocubes (NPNCs) are obtained by controllable nitridation of NiFe-Prussian-blue analogues derived oxides/NC NPNCs under Ar/NH3 atmosphere. Such Ni2+ x Fe2- x N/NC NPNCs possess mesoporous structures and show enhanced electrocatalytic activity in 1m KOH electrolyte with the overpotential of 101 and 270mV to attain 10 and 50mAcm-2 current toward hydrogen and oxygen evolution reactions, outperforming their counterparts (mixed-phase NiFe2 O4 /Ni3 FeN/NC and NiFe oxides/NC NPNCs). Remarkably, utilizing them as bifunctional catalysts, the assembled Ni2+ x Fe2- x N/NC||Ni2+ x Fe2- x N/NC electrolyzer only needs 1.51V cell voltage for driving OWS to approach 10mAcm-2 water-splitting current, exceeding their counterparts and the-state-of-art reported bifunctional catalysts-based devices, and Pt/C||IrO2 couples. Additionally, the Ni2+ x Fe2- x N/NC||Ni2+ x Fe2- x N/NC manifests excellent durability for OWS. The findings presented here may spur the development of advanced TMNs nanostructures by combining phase, structure engineering, and hybridization strategies and stimulate their applications toward OWS or other clean energy fields.

Cover Feature: Piezodeposition of Metal Cocatalysts for Promoted Piezocatalytic Generation of Reactive Oxygen Species and Hydrogen in Water (ChemCatChem 16/2022)

The Cover Feature highlights the key role of noble metal as cocatalysts for piezoelectricity-driven oxygen reduction and hydrogen evolution reactions. In their Research Article, W. Wang, J. Li and co-workers synthesized BaTiO3@Metal (BTO@M, M=Pt, Pd and Au) hetero-nanostructures by using a piezodeposition method. The deposited metal cocatalysts significantly promote the separation and migration of piezogenerated charge, consequently enhancing the piezocatalytic reactions on different metal cocatalyst interfaces. Specifically, BTO@Au under ultrasonic vibrations exhibited most efficient generation of reactive oxidative species via a two-electron reduction pathway in the presence of dissolved oxygen, while BTO@Pt showed promoted hydrogen evolution in the absence of oxygen. This work could further advance piezocatalysis in the field of clean energy, water disinfection and biomedicine. More information can be found in the Research Article by W. Wang, J. Li and co-workers.

Syngas production from two-step CO2 gasification of low rank coal in an entrained flow reactor

Using CO2 as feedstock for syngas production is one hot topic in the field of clean energy due to the concern of global warming. Hence, two-step gasification (pyrolysis first and then subsequent char gasification) behaviour using CO2 as reactant was investigated under entrained flow conditions for one Inner Mongolia lignite and two Victorian brown coals (Maddingely and Morwell). The effects of CO2 concentration (5–30% CO2) and residence time(0–23 s) were assessed in the low temperature ranges of 700–1000 °C. High temperature improved H2 and CO yield in entrained flow pyrolysis. The higher CO2 concentration and longer residence time enhanced gasification syngas yield and carbon conversion. Three coal chars required around 23 s of residence time for 100% conversion under 20% CO2 and 1000 °C. It indicated that entrained flow gasification of the three chars was preferably performed above 1000 °C for industrial applications. Fe-rich Victorian brown coal achieved better pyrolysis performance than Inner Mongolia lignite because of the inherent catalytic effect of Fe oxides in coal. Morwell coal char achieved the best char-CO2 gasification performance due to higher gasification reactivity and better pore structure. This study provides essential information for the optimization of entrained flow gasifiers toward syngas production using CO2 as feedstock.

Piezodeposition of Metal Cocatalysts for Promoted Piezocatalytic Generation of Reactive Oxygen Species and Hydrogen in Water

AbstractPiezocatalysis in aqueous medium has shown great potential for various applications, however the efficiency of piezocatalytic nanoparticles is harmed by the limited utilization of piezoelectric charge and the lack of active catalytic interface. In this study, BaTiO3@Metal (BTO@M, M=Pt, Pd and Au) hetero‐nanostructures were synthesized by using a piezodeposition method. The deposited metal cocatalysts significantly promote the separation and migration of piezogenerated charge, consequently enhancing the piezocatalytic reactions on different metal cocatalyst interfaces. Specifically, BTO@Au under ultrasonic vibrations exhibited most efficient generation of reactive oxidative species via a two‐electron reduction pathway in the presence of dissolved oxygen, while BTO@Pt showed promoted hydrogen evolution in the absence of oxygen. The metal‐piezoelectric hetero‐nanostructures proposed in this work highlight the key role of noble metal as cocatalysts for piezoelectricity‐driven oxygen reduction and hydrogen evolution reactions, which could further advance piezocatalysis in the field of clean energy, water disinfection and biomedicine.

Peru’s energy policy in the context of energy transition

We examine the evolution of Peru’s energy strategy in the context of global energy transition trends. In the last decade, Peru’s energy sector has been actively developing due to an increase in domestic demand caused by the country’s economic growth. At the moment, the country is facing the task of expanding its energy system to ensure access to energy and at the same time its modernization in the context of the global climate agenda. The risks caused by climate change can have a significant negative impact on the ecosystem of Peru and pose serious threats to the future economic development of the country. Authors analyze the current state and prospects of the energy sector, which is the main engine of national economic growth and a significant factor for poverty eradication. We discuss the foundations of the state energy development strategy, the role of the climate agenda, and the specifics of renewable energy project regulation. Authors conclude that Peru has significant potential both in the field of traditional hydrocarbon energy, including LNGs, and in the field of clean energy. In addition to solar and wind power, Peru also has significant potential for the development of hydrogen and biomass energy. Of particular importance for the country is the gas industry, which has received a serious impetus for development in connection with the implementation of a major Camisea project. During the transition period, gas can partially replace the use of oil in industry, housing and electricity generation, thus contributing to the process of decarbonization. The choice of strategic priorities will determine the country’s energy architecture in the medium and long term.

Integrated CuO/Pd Nanospike Hydrogen Sensor on Silicon Substrate.

A large area of randomly distributed nanospike as nanostructured template was induced by femtosecond (fs) laser on a silicon substrate in water. Copper oxide (CuO) and palladium (Pd) heterostructured nanofilm were coated on the nanospikes by magnetron sputtering technology and vacuum thermal evaporation coating technology respectively for the construction of a p-type hydrogen sensor. Compared with the conventional gas sensor based on CuO working at high temperature, nanostructured CuO/Pd heterostructure exhibited promising detection capability to hydrogen at room temperature. The detection sensitivity to 1% H2 was 10.8%, the response time was 198 s, and the detection limit was as low as 40 ppm, presenting an important application prospect in the clean energy field. The excellent reusability and selectivity of the CuO/Pd heterostructure sensor toward H2 at room temperature were also demonstrated by a series of cyclic response characteristics. It is believed that our room-temperature hydrogen sensor fabricated with a waste-free green process, directly on silicon substrate, would greatly promote the future fabrication of a circuit-chip integrating hydrogen sensor.

Visible Light-Driven Highly Selective CO2 Reduction to CH4 Using Potassium-Doped g-C3N5.

Establishment of an efficient and robust artificial photocatalytic system to convert solar energy into chemical fuels through CO2 conversion is a cherished goal in the fields of clean energy and environmental protection. In this work, we have explored an emergent low-Z nitrogen-rich carbon nitride material g-C3N5 (analogue of g-C3N4) for CO2 conversion under visible light illumination. A significant enhancement of the CH4 production rate was detected for g-C3N5 in comparison to that of g-C3N4. Notably, g-C3N5 also showed a very impressive selectivity of 100% toward CH4 as compared to 21% for g-C3N4. The photocatalytic CO2 conversion was performed without using sacrificial reagents. We found that 1% K doping in g-C3N5 enhanced its performance even further without compromising the selectivity. Moreover, 1% K-doped g-C3N5 also exhibited better photostability than undoped g-C3N5. We have also employed density functional theory calculation-based analyses to understand and elucidate the possible reasons for the better photocatalytic performance of K-doped g-C3N5.

Application of Machine Learning to Accelerate Gas Condensate Reservoir Simulation

According to the roadmap toward clean energy, natural gas has been pronounced as the perfect transition fuel. Unlike usual dry gas reservoirs, gas condensates yield liquid which remains trapped in reservoir pores due to high capillarity, leading to the loss of an economically valuable product. To compensate, the gas produced on the surface is stripped from its heavy components and reinjected back to the reservoir as dry gas thus causing revaporization of the trapped condensate. To optimize this gas recycling process compositional reservoir simulation is utilized, which, however, takes very long to complete due to the complexity of the governing differential equations implicated. The calculations determining the prevailing k-values at every grid block and at each time step account for a great part of total CPU time. In this work machine learning (ML) is employed to accelerate thermodynamic calculations by providing the prevailing k-values in a tiny fraction of the time required by conventional methods. Regression tools such as artificial neural networks (ANNs) are trained against k-values that have been obtained beforehand by running sample simulations on small domains. Subsequently, the trained regression tools are embedded in the simulators acting thus as proxy models. The prediction error achieved is shown to be negligible for the needs of a real-world gas condensate reservoir simulation. The CPU time gain is at least one order of magnitude, thus rendering the proposed approach as yet another successful step toward the implementation of ML in the clean energy field.