Gas Distribution Grid Research Articles

Optimal Resiliency‐Oriented Scheduling Framework for Integrated Power‐Gas‐Transportation Networks Based on Model Predictive Control Approach to Increase Electric Load Supply

Today’s societies need a sustainable supply of energy more than ever, whereas unseen events challenge the electric power supply. The coordinated operation of a power‐gas‐transportation system can decrease the effects of such faults in the distribution level. This paper proposes a model predictive control approach for dynamic load restoration in an integrated energy system. The coordination of electric and gas networks besides the mobile energy storage (MES) units provides a novel resilient alternative to serve active and reactive loads. First, the location and time of drastic events are identified as the initialization phase in this paper using a vulnerability analysis by a master–slave problem to find the weak points of the electric grid. Then, a rolling horizon model predictive control‐based approach is proposed to make corrective decisions to serve loads. Meanwhile, a new linearization approach for the Weymouth equation has been proposed based on the binary expansion method. The proposed linear resiliency‐oriented scheduling problem is tested on IEEE 33‐bus and IEEE 69‐bus integrated with a seven‐node gas distribution grid and a six‐station transportation railway. The analysis revealed that the coordination between electric and gas resources minimizes the not‐supplied load; MES units act as certain emergency tools to serve the critical loads.

Effectiveness of Water-Amine Combined Process for CO2 Extraction from Biogas

Abstract The EU countries are implementing biomethane production projects from biogas, supplying it to the natural gas distribution grid, or using it as motor fuel. It is also extremely relevant for Ukraine, supposing the problems with gas import due to Russian aggression. Biogas production from landfills, agriculture waste, and sewage is already implemented in Ukraine, so the next step must be biomethane production on an industrial scale and the selection of biogas separation technology is important. Using 11 years of industrial experience in biogas production from landfills, wide experience of the different methane-containing gases separations, and small companies’ industrial possibilities, the most applicable separation technologies for Ukraine were selected: amine, water, and combined water amine carbon dioxide separation. These technologies had compared using computer simulation with real landfill biogas flow rate debt. Results of a software simulation of the most applicable water-amine absorption technology were verified using a laboratory setup. For carbon dioxide concentration in biogas at 32–42 % vol., the specific energy consumption when using water absorption is on average 2 times less compared to amine absorption, but at the same time, the loss of methane due to its solubility in water during water absorption amounted to 7.1–7.6 %, with practically no losses in amine absorption, and minor losses at 0.17–2.8 % in combined water-amine technology. The energy consumption of combined water-amine absorption is comparable to that of water absorption due to: a) reduction of heat losses for the regeneration process of saturated amine absorbent, as part of carbon dioxide has already been removed with water technology; b) using the methane excess to compensate power consumption of the biogas compressor during the preliminary water absorption of carbon dioxide and/or to compensate heat costs of the saturated amine absorbent regeneration

FOR THE CALCULATION OF THE PARAMETERS OF THE VIBRATORY CONVEYOR OF THE DRYING INSTALLATION

The article deals with the theory of the movement of material in the vibrating conveyor of a drying installation developed at the National Technical University Dnipro Polytechnic, whose working surface has a stepped shape and the flow of coolant is directed at an angle to the horizontal plane. This constructive solution implements a method of creating a vibrating fluid layer in the working chamber, which significantly increases the drying speed of finely dispersed material. The working surface of the vibratory conveyor is made in the form of a step-shaped grid. Under the action of directional vibration excitation, the material entering drying moves along the grating surface and is blown through the slits with hot air. A feature of the vibro conveyor is the ability to move material with a wide granulometric composition, which includes fractions of grains from micrometers to tens of millimeters. When considering the movement of material along the working surface of the vibratory conveyor, it is possible to distinguish the loading zone and the transportation zone. In the loading area, the material is accepted into transport condition. In the transport zone, the material is subjected to an additional force from the coolant. For the efficient operation of the vibratory conveyor, the speed of movement of the material in the loading and transportation zone must be equal, which requires a comprehensive consideration of this issue. The mode with the separation of the material from the working surface of the vibrating conveyor with the assumption of the absence of air resistance is considered. Differential equations have been compiled and dependencies have been obtained that establish the relationship between the movement parameters of the material in the loading area of the vibrating conveyor, where there is no coolant flow, the angle of inclination of the working surface, width and angle of inclination of the plates forming the surface of the gas distribution grid. The conditions under which the contact of the material particles with the coolant flow is determined. Differential equations of particle motion taking into account the influence of the air flow on it are obtained, and dependences are obtained that determine the height of the gas distribution grid stage, the angle of inclination of the coolant flow to the horizontal plane, the motion parameters of the material particle with the additional effect of the heat carrier pressure on it. Thus, the proposed method of calculation allows obtaining initial data for designing the loading section of the transporting surface and the first stage of the gas distribution grid of the vibrating conveyor of the drying unit, as well as analyzing the influence of design parameters on the movement of a material particle.

Integration of storage technology oversight: power system and computer engineering analogy

Energy storage, analogous to data storage in a computer system, is one of the enabling technologies that has emerged alongside the widespread use of renewable energy sources in the nation's power grid. This article shows that the underlying platforms for storing data and energy are quite similar. Batteries and hydrogen storage offer significant energy potential, much like a hard disk for storing vast amounts of data in a computer's central processing unit (CPU). A supercapacitor or flywheel storage device can be used to have emergency power on hand, with access times as fast as random access memory (RAM) in modern computers. In this study, we propose an energy-control scheme for caches that is akin to computer engineering and is used to coordinate the operation of multilevel storage systems that incorporate both capacity and access-oriented storage. By supporting the energy-management system, which in turn provides modern plug-and-play functionality, cache energy control helps optimise the system as a whole. Such an integrated system calls for renewable energy generation, local loads, fueling stations, and connections to gas and electric distribution grids. Distribution energy concepts with various storage systems can be easily grasped by drawing parallels between computer engineering and power system integration.

Techno-economic assessment of H2 extraction from natural gas distribution grids: A novel simulation-based optimization framework for pressure swing adsorption processes

Green H2 plays an important role in the global energy transition. To improve its supply chain economics, the already existing gas grids can be an interim solution for its storage and transportation infrastructure. Injecting H2 into the gas networks seems straightforward from a process design standpoint. However, the extraction, at the other end of the supply chain, poses challenges, and its feasibility from the techno-economic viewpoint is crucial and can support the further development of such programs. This article presents a rigorous techno-economic and optimization model for this process developed in Aspen Adsorption V11 and MATLAB. This holistic model uses the cyclic steady-state approach of Aspen Adsorption V11, which avoids the redundant computations for achieving the steady-state performance in the dynamic simulation approach and allows for the development of a novel simulation-based optimization framework. The proposed optimization model can be used in other pressure swing adsorption applications to improve the rigorousness of the optimal solution and computational time. The results show that H2 extraction from a distribution grid with 30 mol% H2 and 70 mol% CH4 at 12 bar operating pressure costs $0.8064/kg-H2 and $0.9012/kg-H2 for product purities of 99.00 mol% and 99.97 mol%, respectively. Additionally, this study explores the impact of N2 and CO2 presence in natural gas on H2 separation costs. For natural gas containing CH4: CO2: N2 with a molar ratio of 95:2:3 mixed with 30 mol% H2, the separation cost of the 99.00 mol% pure H2 increases by 11.6% to $0.8998/kg-H2; however, based on the simulation, the purity of 99.97 mol% due to the presence of N2 is not technically achievable.

Determination of Energy-Saving Drying Modes in Vibrofluidized Bed Apparatus

The traditional pectin production technology is highly energy-intensive and environmentally unsafe. One of the possible ways to improve the technological process of pectin production is to dry directly the petine hydrolyzate before it is precipitated with ethyl alcohol. The most effective method of drying pectin hydrolyzate is drying in a vibrofluidized layer of an inert material, which provides high productivity in terms of evaporated moisture per unit volume of the chamber and the quality of the resulting dry product. This paper proposes a method for optimizing the drying process of pectin hydrolyzatein the apparatus of a vibrofluidized layer of an inert material, which makes it possible to determine the values of regime parame- ters at which the drying process proceeds with minimal costs for thermal and electrical energy. The technique is based on the experimentally obtained relationship between the specific productivity of the drying unit and the following operating parameters of the drying process: the air velocity in the drying chamber, the initial air temperature, the specific load related to the area of the gas distribution grid, the initial concentration for dry substances. On the basis of this experimental dependence, the criteria for assessing the reduced costs for heat and electric energy are formalized. A complex criterion for optimizing the drying process in a vibrofluidized bed is formulated, the minimization of which makes it possible to increase the efficiency of the drying process. Restrictions on the ranges of variation of the operating parameters of the drying process are formulated as well. The posed problem of optimization of the drying process in a vibrofluidized bed is solved numerically using the method of sequential quadratic programming and recommendations are formulated on the values of operating parameters for conducting the process in the optimal mode.

Comparative Analysis of the CO2 Extraction from Biogas Absorption Processes Effectiveness

Currently, the developed EU countries have implemented biomethane production projects from biogas, supply it to natural gas distribution grid with subsequent production of electricity or (and) heat, and use biomethane as motor fuel or supply to the gas network. It is also extremely relevant for Ukraine, supposing the problems with gas import due to Russian aggression and the presence of a large agricultural potential. The concern that arises is the rational choice of the technology for producing biomethane from biogas.The Gas Institute of the National Academy of Sciences of Ukraine has extensive experience in the development of technologies for the biogas collection, its direct usage, and CO2 extraction by the amine absorption method. Some of the technologies have been implemented at landfills in Ukraine. Data on other methods of CO2 extraction are widely available in world publications, so the authors compared the technologies from the point of view of their practical use possibility. Using computer modeling, the energy costs during the production of biomethane from biogas using the most advanced amine and water absorption processes for cleaning biogas from carbon dioxide were analysed. The combined water-amine absorption method of biogas purification from CO2 was included in the comparative analysis in which carbon dioxide was previously removed by water absorption at a pressure up to 0.3 MPa and output finally purified by amine absorption. Calculations for amine technology are verified in a pilot study.For a range of the CO2 concentration in biogas 32– 42 % vol., the specific energy consumption when using water absorption, the extraction of carbon dioxide from biogas is on average two times less compared to amine absorption, but at the same time the loss of CH4 due to its solubility during water absorption amounted to 7.1–7.6 %, with practically no losses of CH4 in amine absorption, and minor losses (0.17–2.8 %) in combined water-amine technology.The energy consumption of combined water-amine absorption is comparable to that of water absorption due to: a) reduction of heat losses for regeneration process of saturated amine absorbent, as part of CO2 has already been removed with water technology; b) using the CH4 excess to compensate power consumption of the biogas compressor during the preliminary water absorption of CO2 and/ or to compensate heat costs of the saturated amine absorbent regeneration.The results of extracting carbon dioxide from biogas processes modeling can be used to optimize technological absorption schemes for the production of biomethane, an analogue of natural gas.

Assessment of using hydrogen in gas distribution grids

Substantial changes in the energy system are necessary to achieve greenhouse gas neutrality. Green hydrogen is a key to defossilisation. Politicians frequently mention the use of hydrogen in the building sector to supply decentrally produced heat as a potential field of application. An advantage repeatedly mentioned is that the existing gas distribution network infrastructure is an important asset that could still be used in the future. However, there is a lack of analyses of the conversion of gas distribution networks to hydrogen focussing on the economic implications on the costs of the distribution network infrastructure. The paper provides insights using a techno-economic model network analysis (MNA) tool called gas Distribution grId modelliNg tOol (DINO). The analysis is carried out for Germany and considers hydrogen use in all counties. The results are compared to a synthetic methane and electrification scenario. In the hydrogen scenario, the total need for distribution grids is decreasing until 2050 by at least 130,000 km. The network length of the synthetic methane scenario is slightly lower and that of the electrification scenario drops to zero. The annual operation costs are lower in all scenarios as gas demand and infrastructure are reduced. Nevertheless, the total annual cost in the hydrogen scenario is potentially two times higher than in the case of the synthetic methane scenario and more than four times higher than in the electrification scenario. Based on the present results, it is questionable whether an advantage of the continued use of the existing gas distribution grid infrastructure in case of synthetic gas or hydrogen scenarios exists.

Challenges in part load operation of biogas-based power-to-gas processes (part I)

Direct methanation of biogas enables the storage of electrical energy in carbon-neutral (bio-)methane and subsequent injection into the national gas distribution grid. The intermittent availability of renewable electricity, as well as the varying nature of biogas production by e.g. anaerobic digestion, necessitate enhanced operational flexibility of such a Power-to-Gas process and intermediate buffer storage. This work provides experimental data of dynamic part load operation of a TRL 5 methanation plant with gas upgrading to grid-ready biomethane. Full recycling of unreacted H2 could be achieved by a commercial biogas upgrading membrane (Evonik SEPURAN® Green). Using real biogas, a sequence of load levels down to 45% of the full load capacity were tested. Stable operation of the plant could be demonstrated and grid injection limitations could be fulfilled after equilibration of the system. Additionally, an idealised PtG process chain was simulated with the focus on a sensitivity analysis of the H2 storage capacity on the methanation operation hours. It was shown that increasing the hydrogen storage capacity decreases the number of start-up and shut down procedures of the methanation plant. It could be shown that by using an equally sized electrolyser and methanation unit, allowing part load operation of the methanation only during the emptying of the H2 tank leads to longer activity phases of the methanation unit, while allowing part load operation of the methanation reactor during filling of the H2 storage tank had a negative effect.

Power-to-Gas in gas and electricity distribution systems: A comparison of different modeling approaches

Power-to-Gas (P2G) has been one of the most frequently discussed technologies in the last few years. Thanks to its high flexibility, it can offer services to power systems, thereby fostering Variable Renewable Energy Sources (VRES) and the electricity demand match, mitigating the issues related to VRES overproduction. The analysis of P2G systems used at the distribution level has only been dealt with in a few studies: however, at this level, critical operation conditions can easily arise, in both the electrical infrastructure and in the gas infrastructure. The choice of appropriate modeling approaches for a P2G plant, as well as for the electricity and gas distribution grids is necessary to avoid overestimating or underestimating the potential flexibility that P2G plants connected to distribution networks can offer. The study presents a methodological analysis on the impact of different simulation approaches when P2G is installed at a distribution system level. The aim of this paper has been to understand the impact of different modeling approaches in order to determine whether, and under what conditions, they could be adopted. An illustrative case study has been developed to perform this analysis. The results show that the flexibility of the P2G technology can also be used at the distribution level; nevertheless, a correct modeling approach is necessary to properly evaluate the potential of this solution. The placement of P2G systems within the electricity network can affect the performance of the plant to a great extent. Therefore, it is necessary to use a model that takes into account the topology and energy flows of the electrical network. It was found, in the analyzed case study, that the use of an inappropriate electricity network model can lead, depending on the conditions, to either an overestimation or an underestimation (of 50 % and 40 %, respectively) of the ability of P2G plants to absorb VRES over-generation. The accuracy of the gas network and of the P2G plant models also plays an important role. In conditions of low gas consumption, it is necessary to consider the gas flows and the line-pack potential of the gas network, as well as the interactions between the components of the P2G plant in order to avoid underestimating the flexibility of the entire system. In the analyzed case study, the use of a simplified model of the gas network led to an underestimation of the accumulation potential of the over-generations of VRES of about 30 %, while the use of a simplified model for the simulation of P2G plants led to a 10 % underestimation of the storage potential.

A provably secure data sharing scheme for smart gas distribution grid using fog computing

A provably secure data sharing scheme for smart gas distribution grid using fog computing

The potential of the natural gas grid to accommodate hydrogen as an energy vector in transition towards a fully renewable energy system

The temporal and geographical availability of renewable energy sources is highly variable, which imposes the importance of correct choices for energy storage and energy transport systems. This paper presents a smart strategy to utilize the natural gas distribution grid to transport and store the hydrogen. The goal is twofold: evaluating the capacity limits of the grid to accommodate “green hydrogen” for preset increasing shares of renewable energy sources (RESs) and determining at the same time the optimal mix of wind, photovoltaic (PV), biomethane and power-to-gas systems that minimizes the investment and operation costs. To this end, the energy supply system of an entire country is modelled and optimized considering the real characteristics and pressure levels of the gas grid, which is assumed to be the only storage mechanism of green hydrogen. The operational concept is to fill up the gas grid with hydrogen during the day and with natural gas during the night while always consuming the natural gas-hydrogen blend. Green hydrogen is generated by electrolysers powered by PVs, wind turbines and biomethane power systems. Results of the optimizations showed that: i) as long as the share of RES does not exceed 20%, there is no need to use the gas grid as RES storage system, ii) from 20 to 50% of RES share the gas grid receives the surplus of electricity in the peaks that would be necessary to “complete” the dispatchability of RES electricity, iii) above 50%, the excess of electricity in the peaks has to be used to generate the thermal energy required by the consumers. The gas grid can be used as unique renewable energy carrier and storage system up to 65% of RES share.

Estimation and simulation of gas losses in a city gas distribution grid: An Indian scenario

City Gas Distribution (CGD) projects are gas-pipeline networks which enable transport gas as piped natural gas (PNG) for domestic and industrial consumers. These networks have an impact in decreasing the footprint in transporting fuel. Several districts in India have been approved for CGD, with a portion of them being finished. Development of the distribution networks for accessible PNG involves commercial and safety requirements, and environmental regulations and designing them in developing metropolises have several obstacles like population and congestion on roads. The presented work was generated on basis of an existing PNG network of a metropolis. The network was studied with AVEVA PIPEPHASE Pipeline Simulator by adding the necessary inputs to the network architecture to observe for any unconformities.

On the equilibrium and stability of a fluidized bed as a thermodynamic system

The transfer of the dispersed layer into a fluidized state makes it possible to intensify the drying process. The small size of the particles leads to an increase in the surface of their contact with the coolant at a relatively low hydrodynamic resistance. Other positive qualities of fluidization are listed, which is very important when carrying out exothermic processes. We studied the behavior of the fluidized bed during the drying process. The curve of fluidization of beet chips is shown. The suspended state of the material began when the forces of the hydrodynamic layer were equal to the weight of all its particles per unit area of the cross-section of the working chamber. The region of existence of the fluidized bed is marked. In this area, the flow was relatively equilibrium (fluidized). On the surface of the layer, small waves were observed with different frequencies and amplitudes of oscillations, as well as with spontaneous fluctuations. This mode of operation was achieved as a result of the study of the structures of the support - gas distribution grid and the drying chamber. The flow velocity profile in the working chamber is investigated. An efficient equalization of velocities with the help of flat stamped grids has been established. The results were confirmed by the spectra of the flow in the drying chamber. Oscillations on the free surface of a fluidized bed are considered. The Euler equation was written, which made it possible, as a result of various transformations, to obtain a formula for calculating the oscillation frequency of the fluidized bed. The studies carried out made it possible to establish the regimes of pseudo-fluidization, to a certain extent minimizing the heterogeneity of the layer, which is of significant practical importance. However, the operating parameters need to be adjusted depending on the type of material to be dried and other indicators. The research results do not obscure the general provisions of nonequilibrium thermodynamics. The fluidized bed cannot be in an equilibrium state, since the transfer of substances is obvious: energy, mass and momentum. It is correct to regard the fluidized bed as unstable. Small and spontaneous fluctuations always exist in the layer. The absence of conditions for their decay becomes a condition for the instability of the process.

Demystifying natural gas distribution grid decommissioning: An open-source approach to local deep decarbonization of urban neighborhoods

In this paper, deep decarbonization in an urban neighborhood in Vienna, Austria is proposed focusing on decommissioning of the gas distribution grid for heat supply rather than trying to feed in “green” gas in the future. The core objective is to demonstrate that alternative network infrastructures and energy technologies ensure not only an adequate but also an even superior provision of local heat energy services. Two different deep decarbonization pathways are studied, namely, electrification of almost all energy services and expansion of the district heating network. In addition, future district cooling service supply is considered. The method applied couples and extends two open-source models offering a complete analysis toolkit covering a high spatial and temporal resolution. The results show that deep decarbonization of local multiple-energy carrier systems is possible, without being dependent on the existing distribution grid of natural gas. Possible stranded assets (also at the gas end-user level) must not play a decisive role, especially since the trade-off analyses in this work show that alternative scenarios of lower/zero-emission energy service provision are even more economical in the longer term since the CO2 price is expected to increase in the next decades. Future work may focus, among others, on the energy generation technology mix feeding into the district heating grid, the local mobility service needs, and a higher granularity to improve the assessment of the on-site (building-integrated) renewable generation potential associated with the emergence of energy community concepts.

An empirical-mathematical modelling approach to explore the drying kinetics of cereals under variable heat supply using the stitched method

ABSTRACT As reducing the energy consumption, as well as improving the quality of dried grain, is of great importance in the modern world, the present paper aims to develop an empirical-mathematical modelling approach for investigating the drying kinetics of cereals under variable heat supply. This approach is based on a stitching method and substantiates the layer height (or specific load) regulation of a product in different zones of a dryer. The proposed model made it possible to determine temperature distribution in the grain layer and substantiate the permissible range of thermal-humidity conditions for drying cereals in adjustable grain load conditions. A developed software-based algorithm for controlling the drying process of cereal grain under variable heat supply became a basis for designing a grain dryer changing the grain layer height from compartment to compartment. An original grain dryer design enables the adjustment of the specific grain load on the gas distribution grid, facilitating the occurrence of uniform drying and minimal energy consumption.

Classification of Gas-Distribution Grids of Fluidized Bed Apparatuses (Survey of Patents)

Classification of Gas-Distribution Grids of Fluidized Bed Apparatuses (Survey of Patents)

Making the TEN-E regulation compatible with the Green Deal: Eligibility, selection, and cost allocation for PCIs

The European Green Deal calls for a revision of the Regulation on guidelines for trans-European energy infrastructure (TEN-E Regulation). The focus of the TEN-E Regulation was on accelerating the development of strategically important projects linking energy networks across the EU, labelled as Projects of Common Interest (PCIs). We provide seven recommendations on how to revise the Regulation to align it with the new full decarbonisation objective. We split the analysis in three parts: the eligibility, selection and cost allocation of PCIs. Regarding eligibility, first, oil networks should be excluded, while the case of gas networks is debatable. Second, power-to-X technologies, electric charging infrastructure and (smart) gas distribution grids could be added to the scope. Regarding selection, first, the Ten-Year Network Development Plan (TYDNP) should be integrated over all energy vectors using an open-source model. Second and third, the scenarios used in the TYNDPs should be subject to the European Commission's approval, while the approval decision for cost-benefit analysis methodologies should be reallocated from the Commission to ACER. Finally, regarding cost allocation, first, cross-border cost allocation decisions should leave all involved jurisdictions with similar benefit-to-cost ratios to increase commitment. Second, affordability should be the only award criterion for European funding.

Plate-Type Gas Distribution Grids for Fluidized Bed Apparatuses (Survey of Patents)

A classification of plate-type gas distribution grids used with fluidized bed apparatuses is proposed. A critical review of the most characteristic designs of porous, perforated, slot-hole, shutter, grating, scaly, bubble-plate, valve, and composite-type fluidized-bed grids developed by designers and inventors in the leading countries around the world is presented.

Infrastructural coupling of the electricity and gas distribution grid to reduce renewable energy curtailment

Following the European Union’s emission reduction goals, the expansion of intermittent renewable energy sources is being pursued by numerous member states. This poses challenges especially to low-voltage electricity grids that are not designed for the volatile and unpredictable feed-in from renewable generation capacity. In addition to the expansion of renewable capacity, further measures, including the decarbonization of the transport, heating and industrial sectors are needed to achieve the environmental targets. Sector coupling refers to the electrification of end-user energy demand as well as the coupling of different energy infrastructures such as the electricity and gas networks through Power-to-Gas technology. In this paper, we address these issues by developing a methodology that enables distribution system operators to identify future grid constraints in advance and to address them using Power-to-Gas technology using geographical information systems. In further detail, we present a novel approach to identify sections of the distribution network that are likely to be congested in the future in order to locate congestion-induced potential sites for Power-to-Gas plants. We show the applicability of our approach in a case study for a municipality in the German state of Baden-Wurttemberg. We show the economic feasibility of a medium-sized Power-to-Gas plant that couples the gas and electricity distribution networks. Our findings offer insights into the possibility to use the existing gas infrastructure in order to integrate surplus electricity generation, avoid electricity grid congestion and to further decarbonize energy demand.