Taking into account the international policies in the field of environmental protection in the world in general, and in the European Union in particular, the reduction of greenhouse gas (GHG) emissions, and primarily of carbon dioxide, has become one of the most important objectives. This can be obtained through various renewable energy sources and non-polluting technologies, such as the mixing of hydrogen and natural gas. Combining hydrogen with natural gas is an emerging trend in the energy industry and represents one of the most important changes in the efforts to achieve extensive decarbonisation. The importance of this article consists of carrying out a techno-economic study based on the simulation of annual consumptions regarding the construction and use of production capacities for hydrogen to be used in mixtures with natural gas in various percentages in the distribution network of an important operator in Romania. In order to obtain relevant results, natural gas was treated as a mixture of real gases with a known composition as defined in the chromatographic bulletin. The survey presents a case study for the injection of 5%, 10%, and 20% hydrogen in the natural gas distribution system of Bucharest, the largest city in Romania. In addition to conducting this techno-economic study, the implications for final consumers of this technical solution in reducing greenhouse gas emissions—mainly those of carbon dioxide from combustion—are also presented.

The increase in demand, and thus the need to lower its price, has kept C-based fuels as the main source. In this context, the use of oil and gas has led to increased climate change, resulting in greenhouse gases. The high percentage of eissions, over 40%, is due to the production of electricity, heat, or/and energy transport. This is the main reason for global warming and the extreme and increasingly common climate change occurrences, with all of nature being affected. Due to this reason, in more and more countries, there is an increased interest in renewable energies from sustainable sources, with a particular emphasis on decarbonisation. One of the energies analysed for decarbonisation that will play a role in future energy systems is hydrogen. The development of hydrogen–natural gas mixtures is a major challenge in the field of energy and fuel technology. This article aims to highlight the major challenges associated with researching hydrogen–natural gas blends. Meeting this challenge requires a comprehensive research and development effort, including exploring appropriate blending techniques, optimising performance, addressing infrastructure requirements, and considering regulatory considerations. Overcoming this challenge will enable the full potential of hydrogen–natural gas blends to be realised as a clean and sustainable energy source. This will contribute to the global transition to a greener and more sustainable future. Several international, European, and Romanian studies, projects, and legislative problems are being analysed. The mix between H2 and natural gas decreases fugitive emissions. In contrast, using hydrogen increases the risk of fire more than using natural gas because hydrogen is a light gas that easily escapes and ignites at almost any concentration in the air.

This study focuses on optimizing the storage capacity of an underground natural gas storage facility through numerical modeling and simulation techniques. The reservoir, characterized by an elongated dome structure, was discretized into approximately 16,000 cells. Simulations were conducted using key parameters such as permeability (10–70 mD) and porosity (12–26%) to assess the dynamics of gas injection and pressure distribution. The model incorporated core and petrophysical data to accurately represent the reservoir’s behavior. By integrating new wells in areas with storage deficits, the model demonstrated improvements in storage efficiency and pressure uniformity. The introduction of additional wells led to a significant increase in storage volume from 380 to 512 million Sm³ and optimized the injection process by reducing the storage period by 25%. The study concludes that reservoir performance can be enhanced with targeted well placement and customized flow rates, resulting in both increased storage capacity and economic benefits.

As air pollution has become a major issue in nowadays world, reducing methane emissions from the natural gas transmission systems is an issue that definitely has to be addressed. In order to do that, there are a few solutions available, such as the replacement of steel pipes with high-density polyethylene (HDPE) pipes. The main causes of these leaks are the corrosion defects and third-party interventions. The paper presents a new methodology for technological gas loss calculation from the natural gas transmission system. In order to obtain the most accurate calculation formulas, the flow coefficients for different cases were determined by experimental measurements. The paper presents the details regarding the construction and equipment of the experimental stand, as well as a new method for calculating the volumes of gas lost due to defects of this type. Thus, the aerial and buried defects were studied and the results obtained on statistical data were verified. Using the results of the study, the average emission of CH₄ per year in Romania was calculated, and it was proven to be about 30% bigger than the European average. The findings of this study can help for a better understanding of the level of the losses and the effect on the final costs for the population, as well as the negative impact on the environment, in case the transporter does not take any measures.

Water-based drilling fluids (WBDFs) are widely used due to their economic and environmental advantages; however, shale hydration remains a major limitation. This study evaluates Fe₂O₃, CuO, ZnO, and MgO nanocrystalline metal oxides synthesized via co-precipitation as inorganic shale inhibitors for WBDFs. Comprehensive characterization confirmed phase-pure nanocrystalline oxides (17–38 nm) with high thermal stability. Performance tests revealed that MgO-based WBDF exhibited the lowest plastic viscosity (17 cP), the highest pH (≈10.0), and the strongest shale inhibition (6.1% swelling), while Fe₂O₃ provided superior filtration control (6.0 mL). CuO showed balanced rheology, whereas ZnO displayed comparatively weaker inhibition. Compared with commercial inhibitors (Amine NF and Glycol), MgO- and Fe₂O₃-based systems achieved comparable or improved performance with enhanced thermal and environmental robustness. These results demonstrate the potential of nanocrystalline metal oxides as sustainable additives for improving WBDF performance under high-pressure, high-temperature (HPHT) conditions.

Underground hydrogen storage (UHS) in carbonate and siliceous formations presents a promising solution for managing intermittent renewable energy. However, experimental data on hydrogen–rock interactions under representative subsurface conditions remain limited. This study systematically investigates mineralogical and petrophysical alterations in dolomite, calcite-rich limestone, and quartz-dominant siliceous cores subjected to high-pressure hydrogen (100 bar, 70 °C, 100 days). Distinct from prior research focused on diffraction peak shifts, our analysis prioritizes quantitative changes in mineral concentration (%) as a direct metric of reactivity and structural integrity, offering more robust insights into long-term storage viability. Hydrogen exposure induced significant dolomite dissolution, evidenced by reduced crystalline content (from 12.20% to 10.53%) and accessory phase loss, indicative of partial decarbonation and ankerite-like formation via cation exchange. Conversely, limestone exhibited more pronounced carbonate reduction (vaterite from 6.05% to 4.82% and calcite from 2.35% to 0%), signaling high reactivity, mineral instability, and potential pore clogging from secondary precipitation. In contrast, quartz-rich cores demonstrated exceptional chemical inertness, maintaining consistent mineral concentrations. Furthermore, Brunauer–Emmett–Teller (BET) surface area and Barrett–Joyner–Halenda (BJH) pore distribution analyses revealed enhanced porosity and permeability in dolomite (pore volume increased >10×), while calcite showed declining properties and quartz showed negligible changes. SEM-EDS supported these trends, detailing Fe migration and textural evolution in dolomite, microfissuring in calcite, and structural preservation in quartz. This research establishes a unique experimental framework for understanding hydrogen–rock interactions under reservoir-relevant conditions. It provides crucial insights into mineralogical compatibility and structural resilience for UHS, identifying dolomite as a highly promising host and highlighting calcitic rocks’ limitations for long-term hydrogen containment.