Hydrogen-natural Gas Mixture Research Articles

Extended Testing of the Auto-Ignition Characteristics of Hydrogen-Natural Gas Mixtures for the Safety of Power Plants

Extended Testing of the Auto-Ignition Characteristics of Hydrogen-Natural Gas Mixtures for the Safety of Power Plants

Purifying Hydrogen from Dilute Hydrogen–Natural Gas Mixtures Using HT-PEM Electrochemical Hydrogen Pumps

Purifying Hydrogen from Dilute Hydrogen–Natural Gas Mixtures Using HT-PEM Electrochemical Hydrogen Pumps

Machine learning models for the prediction of turbulent combustion speed for hydrogen-natural gas spark ignition engines

The work carried out in this paper focused on “Machine learning models for the prediction of turbulent combustion speed for hydrogen-natural gas spark ignition engines”. The aim of this work is to develop and verify the ability of machine learning models to solve the problem of estimating the turbulent flame speed for a spark-ignition internal combustion engine operating with a hydrogen-natural gas mixture, then evaluate the relevance of these models in relation to the usual approaches. The novelty of this work is the possibility of a direct calculation of turbulent combustion speed with a good precision, using only machine learning model. The obtained models are also compared to each other by considering in turn as a comparison criterion: the precision of the result, calculation time, and the ability to assimilate original data (which has not undergone preprocessing). An important particularity of this work is that the input variables of the machine learning models were chosen among the variables directly measurable experimentally, based on the opinion of experts in combustion in internal combustion engines and not on the usual approaches to dimensionality reduction on a dataset. The data used for this work was taken from a MINSEL 380, a 380-cc single-cylinder engine. The results show that all the machine learning models obtained are significantly faster than the usual approach and Random Forest (R2: R-squared = 0.9939 and RMSE: Root Mean Square Error = 0.4274) gives the best results. With a forecasting accuracy of over 90 %, both approaches can make reasonable predictions for most industrial applications such as designing engine monitoring and control systems, firefighting systems, simulation, and prototyping tools.

Investigation of Flow and Combustion Technology Changes in a Device Nozzle for Natural Gas as a Result of Mixing in Hydrogen

The efforts of the European Union (2021, EU Regulation on Gas and Hydrogen Networks) have been waiting for a solution to the problem of -even if only partial- independence from natural gas. The article shows the effects on the combustion technical parameters and equipment, if the 100% natural gas plant is replaced with a certain proportion of hydrogen. The article examines how it affects the combustion technical parameters of natural gas user equipment if the gas that feeds them is replaced by hydrogen-natural gas mixtures of different proportions. The results show that with the introduction of hydrogen, the Wobbe number decreases, and with this equipment, hydrogen can be added to the natural gas in an amount of 23 V/V% so that it meets the standards. When examining the flame propagation speed, we conclude that it is expected that the flame will not burn back at this ratio. The work promotes the progress of natural gas-hydrogen co-combustion technologies, as it examines a special part of the combustion equipment, the nozzle, and the flow engineering processes taking place in it. With the help of this model, we successfully investigated the excess air resulting from various natural gas-hydrogen mixtures in the case of a given geometry, but the model, with its mathematical additions, also proves that mixing in hydrogen generally reduces the amount of incoming air.

Experimental study of the performance of a SI-engine fueled with hydrogen-natural gas mixtures

Green hydrogen has become more attractive as a fuel for engines to reduce greenhouse gas emissions. By mixing it with natural gas (NG), the modification work on the engine can be minimized but the carbon dioxide emissions from combustion can still be decreased. In this paper, an experimental study was accomplished to investigate the performance of a spark-ignition engine fueled with hydrogen-natural gas blends by either keeping a constant ignition timing or changing it. Up to 25 mol-% hydrogen was mixed into natural gases with different compositions and the methane number and Wobbe index were calculated and compared to the requirements set by Euromot. The results show that up to 15 mol-% hydrogen can be blended into NG to meet the limits of Euromot. However, when 25 mol-% hydrogen was mixed into NG the methane number varied between 56 and 64 depending on the gas composition. This would most likely cause knock for a mixture consisting of higher hydrocarbons but during the executed tests knock was never a problem. Furthermore, it was detected that the methane number alone cannot tell the knock tendency of a gas in a certain engine and an additional condition is needed such as the hydrogen level. An adjusted ignition timing was also preferable compared to a constant one to keep the engine component temperature at a moderate level.

The role of gravity and temperature on hydrogen-containing mixtures in the subsurface

A model for thermal and gravity-induced compositional grading of hydrogen-containing gas mixtures using a cubic equation of state is presented. The theoretical background of compositional gradient modeling is reviewed, and the implementation of a thermal gradient model is used to predict the compositional variation of a hydrogen-natural gas mixture for both depleted gas reservoir and salt cavern applications. We show that near-uniform gas composition versus depth is expected during the storage of hydrogen mixed with natural gas over 100 m of vertical relief. Further study into the calculation and significance of the ideal portion of the component molar enthalpy is needed to increase confidence in model implementation and application.

Economic Modelling of Mixing Hydrogen with Natural Gas

As global efforts intensify to transition toward cleaner and more sustainable energy sources, the blending of hydrogen with natural gas emerges as a promising strategy to reduce carbon emissions and enhance energy security. This study employs a systematic approach to assess the economic viability of hydrogen blending, considering factors such as gas costs and heat values. Various hydrogen blending scenarios are analyzed to determine the optimal blend ratios, taking into account both technical feasibility and economic considerations. The study discusses potential economic benefits, challenges, and regulatory implications associated with the widespread adoption of hydrogen–natural gas mixtures. Furthermore, the study explores the impact of this integration on existing natural gas infrastructure, exploring the potential for enhanced energy storage and delivery. The findings of this research contribute valuable insights to policymakers, industry stakeholders, and researchers engaged in the ongoing energy transition, by providing a nuanced understanding of the economic dimensions of hydrogen blending within the natural gas sector.

Experimental investigation of various burner heads in residential gas stoves tested with hydrogen and natural gas blends

The current study is designed to investigate the effect of five different burner head geometries of gas stoves. The amounts of heat required for boiling 380 grams of water in a pot for a stove for these several burner heads are measured. The flow rates are set to be 3 L/min and 6 L/min for experimental tests. These experimental results show that the burner head with three lateral sets of holes and two circular sets of holes at the top gives the minimum heating time when burning natural gas alone. Once the hydrogen-natural gas mixture is used, the burner head with one lateral and three top circular sets of holes shows the best performance among others regarding heating time. The effect of the flow rate increase is also investigated. Once the flow rate doubles, the burner head with three lateral sets of holes offers the best performance. Based on the findings of the experiments, it can be said that burner heads with lateral sets of holes operate better than other geometries. When natural gas is utilized as fuel, it is observed that the burner head with three lateral sets of holes and two circular sets of holes at the top provided a 12% reduction in heating time compared to the conventional burner head. For the natural gas and hydrogen blends, the conventional burner head achieves the best in terms of heating time.

Effect of Fuel Reactivity and Operating Conditions on Flame Anchoring in the Premixing Zone of a Swirl Stabilized Gas Turbine Combustor

Abstract Flashback with subsequent flame anchoring (FA) is an inherent risk of lean premixed gas turbine combustors operated with highly reactive fuel. The present study has been performed to characterize flame stabilization in the premixing zone of a lean premixed swirl stabilized burner and to identify critical combustion characteristics. An optically accessible burner was used for experimental investigations under atmospheric pressure and elevated preheat temperatures. The air mass flowrate, global equivalence ratio and preheat temperature were systematically varied to identify critical operating parameters. Hydrogen-natural gas mixtures with hydrogen mass fractions from 15 to 100% were studied to evaluate the impact of fuel reactivity. The air-fuel mixture was ignited with a focused single laser pulse to trigger FA in the premixing zone during steady operation. High speed imaging with OH*-chemiluminescence were applied to observe flame characteristics and evaluate flame anchoring propensity. Flame anchoring limits (FAL) are reported in terms of the minimum global equivalence ratio at which the flame was blown out of the premixing zone within a critical time period. A comparison of characteristic time scales at FAL shows that the main impact during flame anchoring is given by the fuel reactivity and to some ex tent by preheat temperature. A Damköhler criterion is derived from the FAL that allows prediction of FA propensity based on operating conditions and 1-D reacting simulations.

Permeability measurement theory in case of natural gas and natural gas-hydrogen mixture

Green hydrogen, using renewable electricity that breaks down water molecules into hydrogen and oxygen, holds great promise for meeting global energy demand while contributing to climate policy goals. Interest in green hydrogen production technologies has increased considerably. This is because the potential uses of hydrogen cover many sectors, including power generation, manufacturing processes in steel and cement production, fuel cells for electric vehicles, and power grid stabilization. One possible use of green hydrogen is to blend it with natural gas and deliver it to end-users using existing natural gas pipeline storage and networks, thereby increasing performance and reducing emissions. In the case of underground storage of a hydrogen natural gas mixture, it is important to assess its impact on the reservoir beforehand, which rock permeability studies can do. This article deals with the theory of rock permeability testing for natural gas and natural gas-hydrogen mixtures.

Hydrogen–Natural Gas Mix—A Viable Perspective for Environment and Society

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.

Improving Ecological Efficiency of Gas Turbine Power System by Combusting Hydrogen and Hydrogen-Natural Gas Mixtures

Currently, the issue of creating decarbonized energy systems in various spheres of life is acute. Therefore, for gas turbine power systems including hybrid power plants with fuel cells, it is relevant to transfer the existing engines to pure hydrogen or mixtures of hydrogen with natural gas. However, significant problems arise associated with the possibility of the appearance of flashback zones and acoustic instability of combustion, an increase in the temperature of the walls of the flame tubes, and an increase in the emission of nitrogen oxides, in some cases. This work is devoted to improving the efficiency of gas turbine power systems by combusting pure hydrogen and mixtures of natural gas with hydrogen. The organization of working processes in the premixed combustion chamber and the combustion chamber with a sequential injection of ecological and energy steam for the “Aquarius” type power plant is considered. The conducted studies of the basic aerodynamic and energy parameters of a gas turbine combustor working on hydrogen-containing gases are based on solving the equations of conservation and transfer in a multicomponent reacting system. A four-stage chemical scheme for the burning of a mixture of natural gas and hydrogen was used, which allows for the rational parameters of environmentally friendly fuel burning devices to be calculated. The premixed combustion chamber can only be recommended for operations on mixtures of natural gas with hydrogen, with a hydrogen content not exceeding 20% (by volume). An increase in the content of hydrogen leads to the appearance of flashback zones and fuel combustion inside the channels of the swirlers. For the combustion chamber of the combined-cycle power plant “Vodoley”, when operating on pure hydrogen, the formation of flame flashback zones does not occur.

Impact of Hydrogen on Natural Gas Compositions to Meet Engine Gas Quality Requirements

To meet the target of reducing greenhouse gas emissions, hydrogen as a carbon-free fuel is expected to play a major role in future energy supplies. A challenge with hydrogen is its low density and volumetric energy value, meaning that large tanks are needed to store and transport it. By injecting hydrogen into the natural gas network, the transportation issue could be solved if the hydrogen–natural gas mixture satisfies the grid gas quality requirements set by legislation and standards. The end consumers usually have stricter limitations on the gas quality than the grid, where Euromot, the European association of internal combustion engine manufacturers, has specific requirements on the parameters: the methane number and Wobbe index. This paper analyses how much hydrogen can be added into the natural gas grid to fulfil Euromot’s requirements. An average gas composition was calculated based on the most common ones in Europe in 2021, and the results show that 13.4% hydrogen can be mixed with a gas consisting of 95.1% methane, 3.2% ethane, 0.7% propane, 0.3% butane, 0.3% carbon dioxide, and 0.5% nitrogen. The suggested gas composition indicates for engine manufacturers how much hydrogen can be added into the gas to be suitable for their engines.

Damage associated with interactions between microstructural characteristics and hydrogen/methane gas mixtures of pipeline steels

There is no common standard for blended hydrogen use in the natural gas grid; hydrogen content is generally based on delivery systems and end-use applications. The need for a quantitative evaluation of hydrogen-natural gas mixtures related to the mechanical performance of materials is becoming increasingly evident to obtain long lifetime, safe, and reliable pipeline structures. This study attempts to provide experimental data on the effect of H2 concentration in a methane/hydrogen (CH4/H2) gas mixture used in hydrogen transportation. The mechanical performance under various blended hydrogen concentrations was compared for three pipeline steels, API X42, X65, and X70. X65 exhibited the highest risk of hydrogen-assisted crack initiation in the CH4/H2 gas mixture in which brittle fractures were observed even at 1% H2. The X42 and X70 samples exhibited a significant change in their fracture mechanism in a 30% H2 gas mixture condition; however, their ductility remained unchanged. There was an insignificant difference in the hydrogen embrittlement indices of the three steels under 10 MPa of hydrogen gas. The coexistence of delamination along with the ferrite/pearlite interface, heterogeneous deformation in the radial direction, and abundance of nonmetallic MnS inclusions in the X65 sample may induce a high stress triaxiality at the gauge length at the beginning of the slow strain rate tensile process, thereby facilitating efficient hydrogen diffusion.

Influences of Hydrogen-Natural Gas Mixtures on The Performance of an Internal Reforming Solid Oxide Fuel Cell Unit: A Simulation Study

Blending hydrogen into natural gas grid can effectively reduce carbon emissions and promote the development of the hydrogen economy. Utilizing hydrogen-natural gas mixtures through internal reforming solid oxide fuel cells (SOFCs) can convert the chemical energy of the fuels direct into electricity, which is a promising technology for combined heat and power systems. In this study, a three-dimensional model for an internal reforming solid oxide fuel cell unit is developed coupling chemical and electrochemical reactions, mass, momentum and heat transfer processes. The model is validated by both the patterned anode experiments and the button cell experiments with porous electrodes. The distributions of temperature, gas compositions, and current density between pure methane and 30% hydrogen addition are simulated and compared. The influences of the hydrogen addition on the performance of the SOFC unit are further studied by changing the hydrogen blending ratio. The simulation results show that the addition of hydrogen affects the coupling of the endothermic reforming reactions and exothermic electrochemical reactions, which leads to improved temperature uniformity and higher current density of the SOFC unit compared with pure methane feeding.

Study of transportation prospects and safety regulations of hydrogen in Indian context: A green fuel for greener future

The transportation of huge quantities of Hydrogen to the consumption points is a herculean task and can only be economically viable through the pipeline route. The creation of a dedicated pipeline infrastructure for Hydrogen comes with huge investment requirements and time consuming. The transportation of Hydrogen in existing Natural Gas pipelines and the introduction of hydrogen into modern city gas distribution networks is the low hanging fruit even if it comes with technological challenges for maintaining pipelines integrity. The need of the hour is to develop the strategies and tools to identify 'hydrogen-ready' pipelines to enable a successful transition to economical and safe introduction of hydrogen into the natural gas network. The benefit would also be similar to the blending of hydrogen into the natural gas pipeline in term of providing renewable energy to distantly located consumers. The present chapter has given details about the prospect and challenges of conversion of natural gas pipelines made from 'standard' grades for hydrogen-natural gas mixture in Indian context.

Numerical Simulation of an Internal Reforming Solid Oxide Fuel Cell Unit Fueled with Hydrogen-Natural Gas Mixtures

Blending hydrogen into natural gas grid can effectively reduce carbon emissions and promote the development of the hydrogen economy. Utilizing hydrogen-natural gas mixtures through internal reforming solid oxide fuel cells (SOFCs) can convert the chemical energy of the fuels direct into electricity, which is a promising technology for combined heat and power systems. In this study, a three-dimensional model for an internal reforming solid oxide fuel cell unit is developed coupling chemical and electrochemical reactions, mass, momentum and heat transfer processes. The influences of the hydrogen addition on the distributions of temperature, gas compositions, and current density are studied by changing the hydrogen ratios in the inlet gas mixtures. The simulation results show that the addition of hydrogen affects the coupling of the endothermic reforming reactions and exothermic electrochemical reactions, which leads to improved temperature uniformity and lower fuel utilization of the SOFC unit compared with pure methane feeding. In order to further enhance the heat transfer between the exothermic and endothermic regions, a heat-pipe enhanced interconnect is introduced in the model. The introduction of the heat pipe is demonstrated to have the ability to decrease the temperature gradient and increase the electrochemical performance.

Numerical Simulation of an Internal Reforming Solid Oxide Fuel Cell Unit Fueled with Hydrogen-Natural Gas Mixtures

Blending hydrogen into natural gas grid can effectively reduce carbon emissions and promote the development of the hydrogen economy. Utilizing hydrogen-natural gas mixtures through internal reforming solid oxide fuel cells (SOFCs) can convert the chemical energy of the fuels direct into electricity, which is a promising technology for combined heat and power systems. In this study, a three-dimensional model for an internal reforming solid oxide fuel cell unit is developed coupling chemical and electrochemical reactions, mass, momentum, and heat transfer processes. The influences of the hydrogen addition on the distributions of temperature, gas compositions, and current density are studied by changing the hydrogen blending ratios in inlet gas mixtures. The simulation results show that the addition of hydrogen affects the coupling of the endothermic reforming reactions and exothermic electrochemical reactions, which leads to improved temperature uniformity and higher current density of the SOFC unit compared with pure methane feeding.

Pipeline durability and integrity issues at hydrogen transport via natural gas distribution network

Hydrogen will play a significant role in a decarbonised energy system in the coming decades. Extensive infrastructure exists for distribution of natural gas and it is an obvious step to assess it to be used for supply hydrogen or mixtures with natural gas. The durability and integrity issues in existing natural gas distribution steel pipelines associated with hydrogen embrittlement of steel at transporting hydrogen or mixtures natural gas with hydrogen are considered. Two mechanisms of steel hydrogenation from pipe internal surface are taken into account, namely, as a result of electrochemical corrosion due to presence of moisture in transported gas, and molecular hydrogen dissociation. Dissipated microdamaging in the bulk of the pipe wall is distinguished as the main factor of manifestation of hydrogen embrittlement of steel and its durability loss, increasing a risk of structural integrity violation. A sensitivity of some physico-mechanical properties of pipeline steels to hydrogen degradation is analysed. Some technological solutions are considered which should accompany experimental research on the assessment of the pipe serviceability at supply hydrogen or mixtures natural gas with hydrogen, including long-term exposing of pre-loaded specimens in hydrogen or hydrogen-natural gas mixture.

Possibilities of measuring hydrogen in natural gas

Green hydrogen produced by renewable energies is an innovative use of mixed with natural gas to deliver the mixture to end users using existing natural gas storage and networks, thereby achieving increased performance. In such a new technology, measuring the hydrogen content of a hydrogen natural gas mixture is essential. This paper provides an overview of hydrogen sensors.