Abstract

This study compares the techno-economic performance of on-site green hydrogen stations in Germany and Italy, with and without cogeneration from a standalone metal hydride system, respectively case 1 and 2. Results show that the major CAPEX contributors are the electrolyzer, compression system, and MH material, accounting for 51% and 67% of total investment costs for the electrolyzer and the compression – MH system, respectively. Levelized cost of hydrogen for the first case is 18.3 €/kgH₂‚‚ (Germany) and 15.06 €/kgH₂ (Italy), while Levelized cost of storage for the standalone MH station is 0.49 €/kWh (Germany) and 0.26 €/kWh (Italy). In the cogeneration scenario, the levelized cost rises to 21.49 €/kgH₂ (Germany) and 17.6 €/kgH₂ (Italy), but selling surplus electricity can reduce it to 3.1 €/kgH₂.

Abstract

To achieve China ‘dual carbon’ goals, the synergistic development of carbon capture, utilization, and storage (CCUS) and hydrogen energy has emerged as a critical pathway for deep emission reductions in hard-to-abate industrial sectors. This study focuses on the economic implications of integrating CCUS and hydrogen energy systems, and a multi-objective optimization model is developed, encompassing hydrogen production, carbon capture, pipeline transportation, underground hydrogen storage, and hydrogen refueling station deployment. The results indicate that the net present value of the integrated system reaches 19.992 billion CNY, demonstrating substantial economic feasibility. Enhanced oil recovery (EOR) constitutes the primary revenue source, generating 18.794 billion CNY, which accounts for 71.81% of the system’s total revenue. Cost analysis reveals that infrastructure investment represents approximately 32.86% of total costs, while operation and maintenance expenses related to CO₂ account for 47.84%. In contrast, the hydrogen subsystem contributes less than 1% to overall costs, highlighting the significant cost advantage of large-scale hydrogen utilization. Furthermore, the study finds that after 2037, hydrogen storage facilities are expected to play an increasingly pivotal role in hydrogen spatiotemporal allocation. Eventually, this research provides a theoretical foundation and decision-support framework for regional planning and policy formulation regarding CCUS–H₂ integrated systems.

Abstract

Large-scale underground hydrogen storage (UHS) in deep saline aquifers is a critical enabler for balancing seasonal energy disparities and decarbonizing heating systems. This study presents a comprehensive numerical investigation into optimizing well configuration and cushion gas selection to enhance the performance of UHS in a dome-shaped anticline structure. The results demonstrate that vertical wells significantly improve storage performance compared to horizontal wells by enhancing gas mobility control, which reduces water production during hydrogen recovery. An optimized seven-well pattern with a spacing of 350 meters achieves a storage capacity 6.5 times greater than a single-well system over long-term cyclic operation, with a hydrogen recovery efficiency exceeding 90%. Furthermore, using methane as cushion gas effectively maintains hydrogen purity above 98% during the recovery phase, outperforming carbon dioxide and nitrogen due to superior density-driven segregation. The findings underscore the critical interplay between well network design and cushion gas management in maximizing storage capacity, deliverability, and hydrogen recovery purity. This work provides essential technical guidelines for the efficient and reliable design of aquifer-based hydrogen storage, contributing significantly to the development of large-scale renewable energy integration.

Abstract

Addressing the low-carbon transformation of industrial park energy systems and the integration with carbon markets, this study develops an integrated optimization framework encompassing energy equipment configuration, risk-aware decision-making, and green certificate (TGC)-carbon trading. First, a mixed-integer linear programming model incorporating photovoltaics, energy storage, and other energy equipments is formulated. Price and load uncertainties are embedded through Conditional Value-at-Risk (CVaR) constraints, and the ε-constraint method is applied to derive the Pareto frontier across three objectives: economic cost, carbon emissions, and operational risk. The optimal solution along the Pareto frontier is subsequently selected using a fuzzy membership function. Second, three TGC-carbon conversion mechanismsare designed, and a joint trading model for park enterprises is established. A diminishing marginal substitution effect, modeled via an exponential decay factor, captures the declining efficiency of TGC offsets with increasing scale. Results demonstrate that the framework enables coordinated multi-enterprise energy and carbon decisions, enhances renewable energy utilization, and significantly reduces compliance pressure under carbon balance. By leveraging TGC conversion and internal trading, the compliance cost of deficit enterprises decreases by 39.53% compared to scenarios without trading, while surplus enterprises achieve higher revenue.

Abstract

This study addressed the research gap of lacking sensitivity analysis of component content to component number and target properties during biodiesel model construction. First, gas chromatography-mass spectrometry (GC-MS) and oil physicochemical property testing methods were employed to detect biodiesel’s components and properties, yielding 6 candidate components. Then, the Surrogate Blend Optimization module of CHEMKIN was used to construct 63 models, covering 3-component, 4-component, and 5-component types with 21 target property selection schemes. Results showed the higher the component number, the higher the proportion of sensitive models—rising from 28.27% (3-component) to 85.71% (5-component). Component sensitivity varied by model: in 4-component Model4-M4 (targets: H/C, vis, LHV, T90), n-tetradecane had the highest sensitivity (43.59%), and increasing its content reduced T90 error to 0.01%. Flexible component adjustment can thus guide accurate model fuel construction.

Abstract

Hydrogen injection strategy exerts a significant impact on the power performance, fuel economy, and emission characteristics of hydrogen-fueled internal combustion engines (HICEs). In this study, a heavy-duty six-cylinder port fuel injection (PFI) HICE wasselected as the research object. Through bench tests, the influence of injection pulse width (IPW) adjustment on engine torque, brake thermal efficiency (BTE), and nitrogen oxide (NOₓ) emissions was systematically investigated. The results show that undermost speed conditions, extending the hydrogen IPW leads to an upward trend in torque, with a slight decrease only at 1700 r/min. The maximum torque increase reaches 4.8% at a speed of 1900 r/min. At all speeds, increasing the IPW plays a positive role in improving BTE. When the speed is 1900 r/min and the IPW is expanded from 56 °CA to 68 °CA, the BTE increases by 4.35% cumulatively. In addition, under all speed conditions, a longer IPW causes varying degrees of increase in NOₓ emissions, and this trend isparticularly significant at 1900 r/min. Compared with the IPW of 56 °CA, the NOₓ emission increases by 45% when the IPW is 68 °CA. The research results can provide a reference for the optimization of injection parameters and the coordinated improvement ofperformance and emissions of HICEs.

Abstract

In this research, the evaluation and analyses of the application of compressed natural gas (CNG), liquified natural gas (LNG), and gas to liquid (GTL) technology to develop the stranded gas field was established based on economic evaluation. The evaluation is performed by calculating the unit cost (capital, operating, and transportation costs); then analyzing the economic aspects of Net Present Value (NPV) based on the fiscal cost recovery regime in Indonesia. The scenario applied is an alteration in production (range 1 – 25 MMSCFD) with constant transportation distance (100 km) and modifying transportation distance (range 100 – 2,000 km) with fixed production (5 MMSCFD). The infrastructure technology mapping was developed by evaluating the economics based on the applicable production sharing contracts and without minimum limits imposed by the government. Sensitivity analysis was applied to highlight the most dominant aspects in determining the economic utilization of the three technologies and to evaluate the mapping of infrastructure technology applications based on government revenue variations.

Abstract

In the late stage of waterflood development in oilfields, a significant amount of residual oil remains trapped due to factors such as limited sweep volume, increased heterogeneity, and elevated water cut. The use of chemical agents to improve waterflooding can effectively mobilize residual oil and enhance oil recovery. This research optimized chemical systems for enhanced water flooding through microvisual core oil displacement experiments. The results showed that: under the water-wet film displacement mode, an emulsified polymer-surfactant binary system with 0.01% polymer and 0.3% sodium dodecylbenzene sulfonate achieved a recovery rate of 72.68%; under the water-wet cluster displacement mode, a low-interfacial tension polymer-surfactant binary system with 0.01% polymer and 0.3% oleic acid amidopropyl betaine solution achieved a recovery rate of 59.21%; under the oil-wet film displacement mode, a low-interfacial tension polymer-surfactant binary system with 0.01% polymer and 0.3% oleic acid amidopropyl betaine solution achieved a recovery rate of 79.23%; and under the oil-wet cluster displacement mode, a low-interfacial tension polymer-surfactant binary system with 0.01% polymer and 0.3% oleic acid amidopropyl betaine solution achieved a recovery rate of 70.06%. These results identified four displacement modes for improved waterflooding with optimized polymer-surfactant binary chemical systems, providing new insights into enhancing oil recovery in the late stages of waterflooding.

Abstract

In this work, heavy oil was fractionated into pseudo-components with different boiling ranges via the true boiling point (TBP) distillation method. Kinetic Cell (KC) experiments were conducted to investigate the reaction behaviors of different pseudo-components in both bulk phase and porous media environments. Under bulk phase conditions, the high concentrations of oxygen and hydrocarbons result in intense oxidation reactions of pseudo-components, accompanied by significant changes in temperature and concentration. In porous media, however, the relatively low concentrations of both oxygen and hydrocarbons lead to a substantial reduction in the oxidation reaction rate. Additionally, the increased surface area of crude oil in porous media divides the entire reaction process into two distinct stages: low-temperature oxidation (LTO) and high-temperature oxidation (HTO). A lower heating rate extends the heating duration, facilitating the formation of more activated molecules and thereby decreasing the initial reaction temperature of LTO. Pseudo-components with higher boiling ranges exhibit weaker distillation effects, which means a greater number of hydrocarbon moles participate in the oxidation reaction, generating more COₓ molecules. Conversely, pseudo-components with lower boiling ranges show stronger distillation effects, resulting in smaller changes in the concentration of reactive hydrocarbons and consequently higher reaction activation energy. During the HTO stage, the gradual depletion of hydrocarbon concentrations hinders the reaction between hydrocarbons and oxygen molecules, leading to an increase in activation energy. This work holds significant implications for understanding the in-situ combustion (ISC) process.

Abstract

Charging electric vehicles (EV) causes a considerable energy demand. Varying renewable generation can be utilised by smart EV charging if congestion of the power distribution grid can be avoided. The presented work analyses the impact of voltage controlled photovoltaic (PV) production, flexible loads, and adjustable EV charging. The local grid voltage communicates every slight change in real time, which links the decentralised applied mechanisms. Achieved results show that, if applied in parallel, the peaks caused by PV generation and EV charging can be mitigated to the benefit of the distribution grid, the PV generation, and the EV charging.