Gases

The LNG maritime industry started to anticipate offshore LNG production in tandem with increasing demand for FLNG platforms as offshore gas resources were developed further. The rapid expansion of FLNG deployment demands equipment and procedures that handle challenges associated with weight and space constraints. The chemical composition of LNG will result in slightly fewer CO₂ emissions. While not significant, another crucial aspect is that LNG predominantly comprises methane, which is acknowledged as a greenhouse gas and is more harmful than CO₂. This requires investigation into clean energy fuel supply for power generation systems, carbon emissions from the process, and thermodynamic analysis and optimisation. Focus on supplying fuel for FLNG power generation to reduce the essential management of boil-off fuel gas, which can be researched on the direct reforming method of hydrogen as a marine fuel gas to support the power generation system. The principal reason for choosing hydrogen over other energy sources is its exceptional energy-to-mass ratio (H/C ratio). The most effective method for hydrogen production is the methane reforming process, recognised for generating significant quantities of hydrogen. To optimise the small-scale plant with a carbon capture system (CCS) as integrated into the reforming process to produce blue hydrogen fuel with zero carbon emissions, this research selection focuses on two alternative processes: steam methane reforming (SMR) and autothermal reforming (ATR). Furthermore, the research article will contribute to other floating production platforms, such as FPSOs and FSRUs, and will be committed to clean energy policies that mandate the support of green alternatives in substitution of hydrocarbon fuel utilisation. Full article

The total quantity and energy delivered through a gas grid is calculated using simple formulæ that sum the increments measured at regular time intervals. These calculations are described in international standards (e.g., ISO 15112 and EN 1776) and guidelines (e.g., OIML R140). These guidelines recommend that the associated measurement uncertainty is evaluated assuming the measurement results to be mutually independent. This assumption leads to the underestimation of the measurement uncertainty. To address the growing concern among transmission and distribution system operators, the underlying assumptions of these uncertainty evaluations are revisited and reworked to be more adequate. The dependence of measurement results coming from, e.g., the same flow meter and gas chromatograph will be assessed for correlations, as well as other effects, such as the effect of the chosen mathematical approximation of the totalisation integral and fluctuations in the flow rate and gas quality. In this paper, an outline is given for improvements that can be implemented in the measurement models to render them more responsive to the error structure of the measurement data, temporal effects in these data, and the fluctuations in the gas quality and gas quantity. By impact assessment using a simple scenario involving the injection of (renewable) hydrogen into a natural gas grid, it is shown that these improvements lead to a substantive difference. This preliminary work demonstrates that correlations occur both in the instrumental measurement uncertainty and due to temporal effects in the gas grid. To obtain a fit-for-purpose uncertainty budget for custody transfer and grid balancing, it is key to enhance the current models and standards accordingly. Full article

This study assesses the potential for biogas production from wastewater treatment plants (WWTPs) in Adana, Türkiye, and evaluates the feasibility of transitioning a fleet of 83 municipal buses (ranging from 15 to 24 years old) to operate exclusively on biogas generated from these WWTPs. Biogas production data from three distinct WWTPs in Adana were analyzed, revealing a total annual biogas production of 5,394,346 Nm³. Replacing the diesel fleet with biogas-powered buses was found to yield a significant reduction in environmental impacts. CO₂ emissions were reduced by 84%, particulate matter emissions decreased by 84.4%, and nitrogen oxides (NO_X) dropped by 80%. These findings highlight the substantial potential of wastewater-derived biogas as a renewable energy source in public transportation, not only reducing reliance on non-renewable fuels but also contributing to improved air quality and energy efficiency. Transitioning to biogas-powered buses presents a promising model for sustainable public transportation, with broader implications for reducing the environmental footprint of urban transit systems. Full article

The central Mediterranean and nearby regions were affected by extreme wildfires during the summer of 2021. During the crisis, Türkiye, Greece, Italy, and other countries faced numerous challenges ranging from the near-complete destruction of landscapes to human losses. The crisis also resulted in reduced air quality levels due to increased emissions of pollutants linked to biomass-burning processes. In the Mediterranean Basin, observation sites perform continuous measurements of chemical and meteorological parameters meant to track and evaluate greenhouse gas and pollutant emissions in the area. In the case of wildfires, CO (carbon monoxide) and formaldehyde (HCHO) are effective tracers of this phenomenon, and the integration of satellite data on tropospheric column densities with surface measurements can provide additional insights on the transport of air masses originating from wildfires. At the Lamezia Terme (code: LMT) World Meteorological Organization–Global Atmosphere Watch (WMO/GAW) observation site in Calabria, Southern Italy, a new multiparameter approach combining different methodologies has been used to further evaluate the effects of the 2021 wildfires on atmospheric measurements. A previous study focused on wildfires that affected the Aspromonte Massif area in Calabria; in this study, the integration of surface data, tropospheric columns, and backtrajectories has allowed pinpointing additional contributions from other southern Italian regions, as well as North Africa and Greece. CO data were available for both surface and column assessments, while continuous HCHO data at the site were only available through satellite. In order to correlate the observed peaks with wildfires, surface BC (black carbon) was also analyzed. The analysis, which focused on July and August 2021, has allowed the definition of three case studies, each highlighting distinct sources of emission in the Mediterranean; the case studies were further evaluated using HYSPLIT backtrajectories and CAMS products. The LMT site and its peculiar local wind patterns have been demonstrated to play a significant role in the detection of wildfire outputs in the context of the Mediterranean Basin. The findings of this study further stress the importance of assessing the effects of wildfire emissions over wide areas. Full article

The increase in atmospheric CO₂ caused by human activities has driven the development of technologies to capture this gas before it reaches the atmosphere. This study analyzed CO₂ sorption using amine-based solvents, such as methyldiethanolamine (MDEA), diethylenetriamine (DETA), triethanolamine (TEA), and monoethanolamine (MEA) in 40 wt.% aqueous solutions, under high-pressure conditions (initial pressure: 500 psia) and room temperature (30 °C), in both non-stirred and stirred systems. Piperazine (PZ), a heterocyclic compound, was tested as an additive to improve the kinetics of the CO₂ sorption process. Kinetic and thermodynamic analyses were conducted to evaluate the efficiency of each amine-based solution in terms of reaction rate and CO₂ loading capacity. MEA and TEA exhibited higher reaction rates, while DETA and MDEA were the most thermodynamically efficient due to the highest CO₂ loading capacity. The PZ kinetic behavior depended on the equipment used; in the non-stirred system, no kinetic effect was observed, while in the stirred system, this effect was appreciable. Additionally, a corrosivity study revealed that MEA, a primary amine, was the most corrosive, whereas TEA, a tertiary amine, was the least corrosive. Full article

Biogas usually contains volatile organic compounds such as terpenes, siloxanes, halogenated hydrocarbons, ketones, alcohols, furans and esters whose presence in the biogas is highly dependent on the feedstock. These trace components can affect the integrity of the materials they come into contact with, e.g., equipment, pipelines and engines, and their presence in the gas may pose health, safety and environmental risks. Understanding the composition of gases is a prerequisite to ensure the correct function of gas infrastructure, appliances and vehicles. This study examined how volatile organic compound (VOC) content in biogas varies depending on the feedstock and evaluated the efficiency of different upgrading processes in removing VOCs. The data, primarily collected in Sweden, include biogases produced in digesters and landfills. The selection of VOCs included in this study was based on extensive analysis of samples collected from numerous biogas and biomethane industrial facilities over an extended period, providing a comprehensive overview of VOC composition. The conducted research is intended to serve as a basis for more systematic studies on the influence of process parameters and feedstock composition on the formation of VOCs. The data have multiple potential uses, including predicting which VOCs would be found in biomethane for a given feedstock and upgrading techniques. Additionally, these data can also be used in standardization discussions to assess the plausibility of the proposed limit values and the need to regulate additional compounds. Full article

This article investigates how safety culture impacts the safety performance of blue hydrogen projects. Blue hydrogen refers to decarbonized hydrogen, produced through natural gas reforming with carbon capture and storage (CCS) technology. It is crucial to decide on a suitable safety policy to avoid potential injuries, financial losses, and loss of public goodwill. The system dynamics approach is a suitable tool for studying the impact of factors controlling safety culture. This study examines the interactions between influencing factors and implications of various strategies using what-if analyses. The conventional risk and safety assessments fail to consider the interconnectedness between the technical system and its social envelope. After identifying the key factors influencing safety culture, a system dynamics model will be developed to evaluate the impact of those factors on the safety performance of the facility. The emphasis on safety culture is directed by the necessity to prevent major disasters that could threaten a company’s survival, as well as to prevent minor yet disruptive incidents that may occur during day-to-day operations. Enhanced focus on safety culture is essential for maintaining an organization’s long-term viability. H₂-CCS is a complex socio-technical system comprising interconnected subsystems and sub-subsystems. This study focuses on the safety culture sub-subsystem, illustrating how human factors within the system contribute to the occurrence of incidents. The findings from this research study can assist in creating effective strategies to improve the sustainability of the operation. By doing so, strategies can be formulated that not only enhance the integrity and reliability of an installation, as well as its availability within the energy networks, but also contribute to earning a good reputation in the community that it serves. Full article

This study presents a comparative analysis of CO₂-EOR and water flooding scenarios to optimize oil recovery in a geologically heterogeneous reservoir with a dome structure and partial aquifer support. Using production data from twelve production and three monitoring wells, a dynamic reservoir model was built and successfully history-matched with a 1% deviation from actual field data. Three main recovery methods were evaluated: water flooding, continuous CO₂ injection, and water-alternating-gas (WAG) injection. Water flooding resulted in a four-fold increase from primary recovery, while continuous CO₂ injection provided up to 40% additional oil recovery compared to water flooding. WAG injection further increased recovery by 20% following water flooding. The minimum miscibility pressure (MMP) was determined using a 1D slim-tube simulation to ensure effective CO₂ performance. A sensitivity analysis on CO₂/WAG ratios (1:1, 2:1, 3:1) revealed that continuous CO₂ injection, particularly in high permeability zones, offered the most efficient recovery. An economic evaluation indicated that the optimal development strategy is 15 years of water flooding followed by 15 years of continuous CO₂ injection, resulting in a net present value (NPV) of USD 1 billion. This study highlights the benefits of CO₂-EOR for maximizing oil recovery and suggests further work on hybrid EOR techniques and carbon sequestration in depleted reservoirs. Full article

Excessive emissions of greenhouse gases, primarily carbon dioxide (CO₂), have garnered worldwide attention due to their significant environmental impacts. Carbon capture, utilization, and storage (CCUS) techniques have emerged as effective solutions to address CO₂ emissions. Recently, direct air capture (DAC) and bioenergy with carbon capture and storage (BECCS) have been advanced within the CCUS framework as negative emission technologies. BECCS, which involves cultivating biomass for energy production, then capturing and storing the resultant CO₂ emissions, offers cost advantages over DAC. Algae-based CCUS is integral to the BECCS framework, leveraging algae’s biological processes to capture and sequester CO₂ while simultaneously contributing to energy production and potentially achieving net negative carbon emissions. Algae’s high photosynthetic efficiency, rapid growth rates, and ability to grow in non-arable environments provide significant advantages over other BECCS methods. This comprehensive review explores recent innovations in algae-based CCUS technologies, focusing on the mechanisms of carbon capture, utilization, and storage through algae. It highlights advancements in algae cultivation for efficient carbon capture, algae-based biofuel production, and algae-based dual carbon storage materials, as well as key challenges that need to be addressed for further optimization. This review provides valuable insights into the potential of algae-based CCUS as a key component of global carbon reduction strategies. Full article

This article reports on field tests devoted to the emissions of particles from gas turbines (GT) and more particularly to the formation of soot and its suppression by fuel additives. These field tests involved four heavy-duty gas turbines used as power generators and equipped with air atomization systems. These machines were running on natural gas, No. 2 distillate oil, heavy crude oil and heavy fuel oil, respectively. The GT running on natural gas produced no soot or ash and its upstream air filtration system in fact allowed lower concentrations of exhaust particles than those found in ambient air. Soot emitted when burning the three liquid fuels (No. 2 distillate; heavy crude oil; and heavy oil) was effectively reduced using fuel additives based on iron(III), cerium(III) and cerium(IV). Cerium was found to be very effective as a soot suppressant and gave rise to two surprising effects: cerium(III) performed better than cerium(IV) and a “memory effect” was observed in the presence of heat recovery boilers due to the deposition of active cerium species. All of the reported results, both regarding natural gas emissions and soot reduction, are original. A review of the soot formation mechanisms and a detailed interpretation of the test results are provided. Full article

Hydrocarbon fields that contain non-associated gas, such as gas condensate, are highly valuable in terms of production. They yield significant amounts of condensate alongside the gas, but their unique behavior presents challenges. These reservoirs experience constant changes in composition and phases during production, which can lead to condensate blockage near wells. This blockage forms condensate bridges that hinder flow and potentially decrease gas production. To address these challenges, engineers rely on numerical simulation as a crucial tool to determine the most effective project management strategy for producing these reservoirs. In particular, relative permeability curves are used in these simulations to represent the physical phenomenon of interest. However, the representativeness of these curves in industry laboratory tests has limitations. To obtain more accurate inputs, simulations at the pore network level are performed. These simulations incorporate models that consider alterations in interfacial tension and flow velocity throughout the reservoir. The validation process involves reproducing a pore network flow simulation as close as possible to a commercial finite difference simulation. A scale-up methodology is then proposed, utilizing an optimization process to ensure fidelity to the original relative permeability curve at a microporous scale. This curve is obtained by simulating the condensation process in the reservoir phenomenologically, using a model that captures the dependence on velocity. To evaluate the effectiveness of the proposed methodology, three relative permeability curves are compared based on field-scale productivities and the evolution of condensate saturation near the wells. The results demonstrate that the methodology accurately captures the influence of condensation on well productivity compared to the relative permeability curve generated from laboratory tests, which assumes greater condensate mobility. This highlights the importance of incorporating more realistic inputs into numerical simulations to improve decision-making in project management strategies for reservoir development. Full article

Many governments around the world have taken action to utilise carbon capture (CC) technologies to reduce CO₂ emissions. This technology is particularly important to reduce unavoidable emissions from industries like cement plants, oil refineries, etc. The available literature in the public domain explores this theme from two distinct perspectives. The first category of papers focuses only on modelling the CC plants by investigating the details of the processes to separate CO₂ from other gas components without considering the industrial applications and synergies between sectors. On the other hand, the second category investigates the required infrastructure that must be put in place to allow a suitable integration without considering the specific particularities of each carbon capture technology. This review gives a comprehensive guideline for the implementation of CC technologies for any given application while also considering the coupling between different energy sectors such as heating, power generation, etc. It also identifies the research gaps within this field, based on the existing literature. Moreover, it delves into various aspects and characteristics of these technologies, while comparing their energy penalties with the minimum work required for CO₂ separation. Additionally, this review investigates the main industrial sectors with CC potential, the necessary transportation infrastructure from the point sources to the end users, and the needs and characteristics of storage facilities, as well as the utilisation of CO₂ as a feedstock. Finally, an overview of the computation tools for CC processes and guidelines for their utilisation is given. The guidelines presented in this paper are the first attempt to provide a comprehensive overview of the technologies, and their requirements, needed to achieve the cross-sector coupling of CC plants for a wide range of applications. It is strongly believed that these guidelines will benefit all stakeholders in the value chain while enabling an accelerated deployment of these technologies. Full article

This work presents a diagnosis of greenhouse gas (GHG) emissions for floating production storage and offloading (FPSO) platforms for oil and gas production offshore, using calculation methodologies from the American Petroleum Institute (API) and U.S. Environmental Protection Agency (EPA). To carry out this analysis, design data of an FPSO platform is used for the GHG emissions estimation, considering operations under steady conditions and oil and gas processing system simulations in the Aspen HYSYS^® software. The main direct emission sources of GHG are identified, including the main combustion processes (gas turbines for electric generation and gas turbine-driven CO₂ compressors), flaring and venting, as well as fugitive emissions. The study assesses a high CO₂ content in molar composition of the associated gas, an important factor that is considered in estimating fugitive emissions during the processes of primary separation and main gas compression. The resulting information indicates that, on average, 95% of total emissions are produced by combustion sources. In the latest production stages of the oil and gas field, it consumes 2 times more energy and emits 2.3 times CO₂ in terms of produced hydrocarbons. This diagnosis provides a baseline and starting point for the implementation of energy efficiency measures and/or carbon capture and storage (CCS) technologies on the FPSO in order to reduce CO₂ and CH₄ emissions, as well as identify the major sources of emissions in the production process. Full article

At the Group of Seven (G7) summit held on 13–15 June in 2024, the Group’s leaders committed to establishing a collective cyber security framework and reinforcing the work of the cyber security working group to manage the risks targeting energy systems. Likewise, oil and electricity, and natural gas rely on complex and interdependent technologies and communication networks from production to consumption. The preparedness to handle cyber security threats in the energy infrastructures among decision makers, planners, and the industry in a concerted manner signifies that cyber security is becoming more appreciated. Therefore, considering the ambition and achievement of the G7 countries towards energy and cyber sovereignty, this paper’s focus and research question aims to explore the potential existence of the cyber governance alliance in the gas subsector within the G7. The objective of this paper is twofold. First, it explores the potential of the G7, the world’s seven largest advanced economies, to lead on a nascent cyber governance for risk management in the gas sector. The qualitative analysis conducted through the institutional analysis and design method examines up-to-date data involving mainly state actors. Second, by drawing on LNG, one of the world’s fastest growing energy types in the coming decades, the paper points out the need for further research on the transnational governance operating through public–private engagement to address the cyber risks to gas systems. While the paper makes an empirical contribution to the field of security governance and a practical contribution to security consulting, its limitations rely on the necessity to also conduct a quantitative enquiry, which would necessitate, among others, a review of the literature in the G7 countries, and a group of researchers from academia and practitioners to obtain a sense of the cyberspace in the energy reality. Full article

Since retrofitting existing natural gas-fired (NGF) power plants is an essential strategy for enhancing their efficiency and controlling greenhouse gas emissions, this paper compares the carbon footprint of natural gas-fired power generation from an NGF power plant in Brazil (BR-NGF) with and without retrofitting. The former scenario entails retrofitting the BR-NGF power plant with combined-cycle gas turbine (CCGT) technology. In contrast, the latter involves continuing the BR-NGF power plant operation with open-cycle gas turbine (OCGT) technology. Our analysis considers the BR-NGF power plant’s life cycle (construction, operation, and decommissioning) and the natural gas’ life cycle (natural gas extraction and processing, liquefaction, liquefied natural gas transportation, regasification, and combustion). Moreover, it is based on data from primary and secondary sources, mainly the Ecoinvent database and the ReCiPe 2016 method. For OCGT, the results showed that the BR-NGF power plant and the natural gas life cycles are responsible for 620.87 gCO₂eq./kWh and 178.58 gCO₂eq./kWh, respectively. For CCGT, these values are 450.04 gCO₂eq./kWh and 129.30 gCO₂eq./kWh. Our findings highlight the relevance of the natural gas’ life cycle, signaling additional opportunities for reducing the overall carbon footprint of natural gas-fired power generation. Full article

This paper investigates the operating benefits and limitations of utilizing carbon dioxide in hydro-pneumatic energy storage systems, a form of compressed gas energy storage technology, when the systems are deployed offshore. Allowing the carbon dioxide to transition into a two-phase fluid will improve the storage density for long-duration energy storage. A preliminary comparative study between an air-based and a carbon dioxide-based subsea hydro-pneumatic energy storage system is first presented. The analysis is based on thermodynamic calculations assuming ideal isothermal conditions to quantify the potential augmentation in energy storage capacity for a given volume of pressure containment when operating with carbon dioxide in lieu of air. This is followed by a transient thermal analysis of the carbon dioxide-based hydro-pneumatic energy storage system, taking into account the real scenario of a finite thermal resistance for heat exchange between the gas and the surrounding seawater. Results from numerical modelling revealed that the energy storage capacity of a carbon dioxide-based subsea hydro-pneumatic energy storage system operating under ideal isothermal conditions can be theoretically increased by a factor of 2.17 compared to an identical air-based solution. The numerical modelling revealed that, under real conditions under which transient effects resulting from a finite thermal resistance are accounted for, the achievable factor is lower, depending on the charging and discharging time, the initial temperature, and whether a polyethene liner for corrosion prevention is considered or not. Full article

This paper presents an analysis of NO₂ emissions in Mashhad City utilizing statistical evaluations and the Cisco Network Model. The present study begins by evaluating NO₂ emissions through statistical analysis, followed by the application of histograms and radar statistical appraisals. Subsequently, a model execution logic is developed using the Cisco Network Model to further understand the distribution and sources of NO₂ emissions in the city. Additionally, the research incorporates managerial insights by employing Petri Net modeling, which enables a deeper understanding of the dynamic interactions within the air quality management system. This approach aids in identifying critical control points and optimizing response strategies, thus enhancing the overall effectiveness of urban air pollution mitigation efforts. The findings of this study provide valuable insights into the levels of NO₂ pollution in Mashhad City and offer a structured approach to modeling NO₂ emissions for effective air quality management strategies which can be extended to the other megacities as well. Full article

In this work, we analyze non-Darcy two-component single-phase isothermal flow in naturally fractured tight gas reservoirs. The model is applied in a scenario of enhanced gas recovery (EGR) with the possibility of carbon dioxide storage. The properties of the gases are obtained via the Peng–Robinson equation of state. The finite volume method is used to solve the governing partial differential equations. This process leads to two subsystems of algebraic equations, which, after linearization and use of an operator splitting method, are solved by the conjugate gradient (CG) and biconjugate gradient stabilized (BiCGSTAB) methods for determining the pressure and fraction molar, respectively. We include inertial effects using the Barree and Conway model and gas slippage via a more recent model than Klinkenberg’s, and we use a simplified model for the effects of effective stress. We also utilize a mesh refinement technique to represent the discrete fractures. Finally, several simulations show the influence of inertial, slippage and stress effects on production in fractured tight gas reservoirs. Full article

Methane is a powerful greenhouse gas with a 25 times higher 100-year warming potential than carbon dioxide and is a target for mitigation to achieve climate goals. To control and curb methane emissions, estimates are required from the sources and sectors which are typically generated using bottom-up methods. However, recent studies have shown that national and international bottom-up approaches can significantly underestimate emissions. In this study, we present three bottom-up approaches used to estimate methane emissions from all emission sectors in the Denver-Julesburg basin, CO, USA. Our data show emissions generated from all three methods are lower than historic measurements. A Tier 1/2 approach using IPCC emission factors estimated 2022 methane emissions of 358 Gg (0.8% of produced methane lost by the energy sector), while a Tier 3 EPA-based approach estimated emissions of 269 Gg (0.2%). Using emission factors informed by contemporary and region-specific measurement studies, emissions of 212 Gg (0.2%) were calculated. The largest difference in emissions estimates were a result of using the Mechanistic Air Emissions Simulator (MAES) for the production and transport of oil and gas in the DJ basin. The MAES accounts for changes to regulatory practice in the DJ basin, which include comprehensive requirements for compressors, pneumatics, equipment leaks, and fugitive emissions, which were implemented to reduce emissions starting in 2014. The measurement revealed that normalized gas loss is predicted to have been reduced by a factor of 20 when compared to 10-year-old normalization loss measurements and a factor of 10 less than a nearby oil and production area (Delaware basin, TX); however, we suggest that more measurements should be made to ensure that the long-tail emission distribution has been captured by the modeling. This study suggests that regulations implemented by the Colorado Department of Public Health and Environment could have reduced emissions by a factor of 20, but contemporary regional measurements should be made to ensure these bottom-up calculations are realistic. Full article