Feed Gas Research Articles

Tuning the two phases ratio by nonmetal ion doping in dual‐phase mixed‐conductive ceramic membranes

AbstractThe mixed protonic–electronic conductor of BaCe0.5Fe0.5O3−δ can be automatically decomposed into a dual‐phase material of the cerium‐rich oxide BaCe0.85Fe0.15O3−δ (BCFe8515) and the iron‐rich oxide BaCe0.15Fe0.85O3−δ (BCFe1585). The BaCe0.5Fe0.5O3−δ membrane possessed an extremely high hydrogen (H2) permeation flux, but poor stability. Therefore, in this work, for the first time, the nonmetal P is doped to increase the proportion of the BaCe0.85Fe0.15O3−δ (P‐doped Ce‐rich) phase to improve the stability of the dual‐phase membrane. The developed dual‐phasic ceramic membranes of BaCe0.5Fe0.5−xPxO3−δ (BCFePx) (x = 0, 0.025, 0.05, 0.1) exhibit enhanced stability compared to their parent oxides. Under the condition of 950°C, feed gas with dry 50% H2‐50% He and sweep gas with wet Ar, the H2 permeation flux of BCFeP0.05 membrane stabilized at 1.56 mL min−1 cm−2 after the long‐term stability test for 480 h. The enhanced stability resulted from the increase of the P‐doped Ce‐rich phase content and the inhibition of Fe2O3 phase precipitation from the BaCe0.15Fe0.85O3−δ (P‐doped Fe‐rich) phase in the reducing atmosphere by doping non‐metal P element.

Molecular dynamics study of carbon dioxide and nitrogen selectivity through poly[bis((methoxyethoxy)ethoxy)phosphazene] (MEEP) membrane

A molecular dynamics simulation model was developed to comprehensively understand carbon dioxide over nitrogen (CO2/N2) selectivity through polyphosphazene-based membrane comprising of poly[bis((methoxyethoxy)ethoxy)phosphazene] (MEEP) selective layer at the molecular level. The effects of temperature, pressure, and initial feed gas composition on the CO2 transport on a polymer membrane were studied. The computed free energy and density profile of the permeating gas mixture exhibited that CO2 molecules express higher interactions with the membrane than N2 molecules, resulting in higher CO2/N2 selectivity. Statistical analysis of gas molecules (CO2, water (H2O), and N2) transportation suggested that hydro- and CO2-philic functional groups in the membrane significantly impact CO2 permeability and CO2/N2 selectivity. This study suggested that Lewis acid–base and hydrogen bonding combinations contribute to CO2 permeation and CO2/N2 selectivity. An equal CO2/N2 selectivity was observed with and without water vapor in the feed gas suggesting that water does not hinder CO2 transport through the membrane.

Exploring the Role of Various Feed Gases in Cold Plasma Technology: A Comprehensive Review

Exploring the Role of Various Feed Gases in Cold Plasma Technology: A Comprehensive Review

Evaluation of Characteristics of Plasma Created by an Electron-Beam Generator with Gas Feeding into the Discharge Channel

Evaluation of Characteristics of Plasma Created by an Electron-Beam Generator with Gas Feeding into the Discharge Channel

Ion concentration ratio measurements of ion beams generated by a commercial microwave electron cyclotron resonance plasma source.

A commercially available electron cyclotron resonance (ECR) plasma source (GenII Plasma Source, tectra GmbH) is widely used for surface processing. This plasma source is compatible with ultrahigh vacuum systems, and its working pressure is relatively low, around 10-6-10-4 Torr even without differential pumping. Here, we report ion flux concentration ratios for each ion species in an ion beam from this source, as measured by a mass/energy analyzer that is a combination of a quadrupole mass spectrometer, an electrostatic energy analyzer, and focusing ion optics. The examined beams were those arising from plasmas produced from feed gases of H2, D2, N2, O2, Ar, and dry air over a range of input power and working pressures. H2(D2) plasmas are widely used for nuclear fusion applications and, hence, the ion concentration ratios of H+, H2+, and H3+ reported here will be useful information for research that applies this plasma source to well-controlled plasma-material interaction studies. Ion energy distributions, stability of operation, and impurity concentrations were also assessed for each of the plasma species investigated.

The spatial density distribution of H2O2 in the effluent of the COST-Jet and the kINPen-sci operated with a humidified helium feed gas

Abstract Cold atmospheric plasma jets operated with a helium feed gas containing small admixtures of water vapour are excellent sources of H2O2 for direct biomedical applications. However, H2O2 is typically distributed non-uniformly throughout the effluent region, meaning the dosage received by a patient or substrate is dependent on their positioning relative to the plasma source. This study presents the spatial distribution of absolute H2O2 number densities in the effluent of two popular plasma jets, the COST-Jet and the kINPen-sci plasma jet, when operated with a humidified helium feed gas. The measurements were performed using continuous wave cavity ring-down spectroscopy with a tunable, mid-infrared laser. The H2O2 number density measured close to the jet nozzle is 2.3 × 1014 cm−3 for the kINPen-sci plasma jet and 1.4 × 1014 cm−3 for the COST-Jet. The average number density of H2O2 in the effluent of the kINPen-sci plasma jet is a factor of two higher than in the effluent of the COST-Jet. The distribution of H2O2 in the COST-Jet effluent is initially highly uniform and suggests negligible mixing of H2O2 with the ambient air up to 15 mm from the jet nozzle, although it is rapidly diluted at further distances. In the case of the kINPen-sci plasma jet, the number density of H2O2 has a more pronounced radial distribution close to the nozzle, while the mixing with the ambient air is more gradual at further distances from the nozzle. It is evident that a detailed understanding of the H2O2 production in the plasma source, as well as of the transport of H2O2 to the substrate through the effluent, is required in order to optimise the intended effects. This work serves to highlight the difference of the distinct spatial distribution of H2O2 in the effluent of both types of plasma jets when considering their direct application in biomedicine.

Surface-engineered PIM-1 membranes for facile CO2 capture

Polymers of intrinsic microporosity (PIMs) are promising candidates for carbon dioxide (CO2) separation and capture from flue gas or natural gas. PIM-1, which has excellent gas permeation properties over the Robeson upper bound (1991), has been widely functionalized to further enhance the CO2 permeability or selectivity. In this work, a simple and readily processive surface modification method has been proposed via hydrolysis of the PIM-1 membrane. The two hydrolysis processes by the acid method, amidation and carboxylation processes, have been conducted to functionalize the surface of PIM-1 membranes forming NA-PIM-1 and CA-PIM-1 membranes. The TGA, FT-IR spectra and NMR results verify that the composition and structure inside the PIM-1 membrane remain unchanged. XPS and NMR spectra demonstrate that the nitrile group at the surface was successfully functionalized with an amine group or carboxyl group. The CO2 permeability and CO2/N2 selectivity of the NA-PIM-1 membrane both increased to 4593.2 Barrer and 28.5, respectively. Another advantage of NA-PIM-1 membranes is the coordination site from introduced nitrogen atoms with zinc ions to form NA-PIM-1-Zn, which could further react with PEI to introduce amine-rich groups on the surface of the PIM-1 membrane. The CO2/N2 selectivity of the NA-PIM-1-Zn-PEI membrane coated with PEI on the surface increases 45.4% compared to the unmodified PIM-1 membranes, with CO2 permeability decreasing only 15.5% compared to the unmodified PIM-1 membrane. The NA-PIM-1 and NA-PIM-1-Zn-PEI membranes both surpass the Robeson upper bound (2008) even under mixed gas feeding, suggesting that surface modification of PIM-1 is a promising approach for CO2 capture from natural gas and flue gas.

Pore-optimized MOF-808 made through a facile method using for fabrication of high-performance mixed matrix composite CO2 capture membranes

Mixed matrix composite membranes (MMCMs) are considered as one of the potential directions for the development of CO2 capture membranes. Nevertheless, the high cost and the challenging nature of improving separation performance are significant obstacles that prevent MMCMs from being widely applied in practice. In this study, we developed a cost-effective modified pore-optimized MOF-808 (MOF-808@PVAm) and utilized it to fabricate high-performance CO2 capture MMCMs. Specifically, MOF-808 and polyvinylamine (PVAm) were cross-linked by γ-(2,3-epoxypropoxy) propytrimethoxysilane (KH-560), which improved the pore structure characteristics of MOF-808 and led to high-performance MMCMs. For 2 bar feed gas (CO2/N2, 15/85), the MMCM with 33.33 wt.% MOF-808@PVAm loading displayed remarkable CO2 permeance of 2753 GPU and selectivity of 181. The prepared MMCM demonstrated good operational stability in simulated flue gas and exhibited potential for application in various gas purification fields (CO2/CH4, CO2/H2) through gas permeation tests.

Activation by O2 of AgxPd1-x Alloy Catalysts for Ethylene Hydrogenation.

A composition spread alloy film (CSAF) spanning all of AgxPd1-x composition space, xPd = 0 → 1, was used to study catalytic ethylene hydrogenation with and without the presence of O2 in the feed gas. High-throughput measurements of the ethylene hydrogenation activity of AgxPd1-x alloys were performed at 100 Pd compositions spanning xPd = 0 → 1. The extent of ethylene hydrogenation was measured versus xPd at reaction temperatures spanning T = 300 → 405 K and inlet hydrogen partial pressures spanning PH2in = 70 → 690 Torr. The inlet ethylene partial pressure was constant at PC2H4in = 25 Torr, and the O2 inlet partial pressure was either PO2in = 0 or 15 Torr. When PO2in = 0 Torr, only those alloys with xPd ≥ 0.90 displayed observable ethylene hydrogenation activity. As expected, the most active catalyst was pure Pd, which yielded a maximum conversion of ∼0.4 at T = 405 K and PH2in = 690 Torr. Adding a constant O2 partial pressure of PO2in = 15 Torr to the feed stream dramatically increased the catalytic activity across the CSAF at all experimental conditions and catalyst compositions without inducing catalytic ethylene combustion and without measurable O2 consumption. The presence of PO2in = 15 Torr more than doubled the maximum achievable conversion on Pd to ∼0.9 and activated alloys with as little as xPd = 0.6 for ethylene hydrogenation. Measurement of the reaction order with respect to hydrogen, nH2, showed that nH2 ≈ 0 when PO2in = 15 Torr on high xPd alloys but that nH2 increases to values between 0.5 and 1 as xPd decreases or when PO2in = 0 Torr. We attribute this PO2in-induced change in nH2 to a change in the reaction mechanism resulting from different functional catalyst surfaces: one that is O2-activated and Pd-rich and one that is Ag-capped with low activity. Both are extremely sensitive to the bulk alloy composition, xPd, and the reaction temperature, T. These results show that the activity of AgPd catalysts for ethylene hydrogenation depends strongly on the operational conditions. Furthermore, we demonstrate that the exposure of AgPd catalysts to 15 Torr of O2 at moderate temperatures leads to enhanced catalyst performance, presumably by stimulating both Pd segregation to the topmost surface and Pd activation for ethylene hydrogenation.

PSV-12 Effects of Diet on Feed Intake, Weight Change, and Gas Emissions in Beef Cows

Abstract The objective of this study was to examine the effects of diet energy density on ranking for dry matter intake (DMI), residual feed intake (RFI), and greenhouse gas emissions. Forty-two mature, gestating Angus cows [600 ± 69 kg body weight (BW); body condition score (BCS) 5.3 ± 1.1] with a wide range in DMI expected progeny difference (−1.38 to 2.91) were randomly assigned to two diet sequences; forage then concentrate (FC) or concentrate then forage (CF). The forage diet consisted of long-stem native grass hay plus protein supplement (HAY; 1.96 Mcal ME/kg DM). The concentrate diet consisted of 35% chopped grass hay and 65% concentrate feeds on a dry matter basis (MIX; 2.5 Mcal ME/kg DM). The GreenFeed Emission Monitoring system was used to determine carbon dioxide (CO2), oxygen (O2), and methane (CH4) flux. Cow performance traits, ultrasound back fat and rump fat, feed DMI, and gas flux data were analyzed in a crossover design using a mixed model including diet, period, and sequence as fixed effects and pen and cow within sequence as random effects. For all measured traits excluding DMI, there was a diet × sequence interaction (P < 0.05). The correlation between MIX and HAY DMI was 0.41 (P = 0.067) and 0.47 (P = 0.03) for FC and CF sequences, respectively. There was no relationship (P > 0.66) between HAY and MIX average daily gain (ADG), regardless of sequence. Fifty-seven percent of the variation in DMI was explained by metabolic BW, ADG, and BCS for both diets during the first period. During the second period, the same three explanatory variables accounted for 38% and 37% of the variation in DMI for MIX and HAY diets, respectively. The negative relationship between BCS and DMI was more pronounced when cows consumed the MIX diet. There was no relationship between MIX and HAY RFI, regardless of sequence (P > 0.18). During the first period, correlations for CO2, CH4, and O2 with MIX DMI were 0.69, 0.81, and 0.56 (P ≤ 0.015), respectively, and 0.76, 0.74, and 0.64 (P < 0.01) with HAY DMI. During the second period, correlations for CO2, CH4, and O2 with MIX DMI were 0.62, 0.47, and 0.56 (P ≤ 0.11), respectively. However, HAY DMI during the second period was not related to gas flux (P > 0.47). Results from this experiment indicate that feed intake of two energy-diverse diets is moderately correlated while ADG while consuming the two diets is not related. Further experimentation is necessary to determine if gas flux data can be used to predict feed intake in beef cows.

Selection and optimisation of a zeolite/catalyst mixture for sorption-enhanced CO2 methanation (SEM) process

The sorption-enhanced methanation (SEM) process has emerged as a promising technology to produce high quality synthetic natural gas (SNG) from renewable sources under milder conditions than conventional methanation technologies. During the SEM process developed in this paper, an H2O adsorbent is combined with a Rhodium-based catalyst to remove the H2O generated during the CO2 methanation reaction, shifting the equilibrium towards CH4 formation. In this work, several commercial zeolites (3A, 4A, 5A and 13X) were studied as H2O adsorbents under SEM conditions. Based on the study performed, zeolite 4A demonstrated to be the most suitable zeolite which, combined with the proposed catalyst, allowed maximising the production and purity of the obtained CH4. The influence of gas space velocity, H2/CO2 ratio in the feed gas, zeolite/catalyst proportion and cyclic stability were analysed and optimized to maximise CH4 production. When the process was run under SEM conditions using zeolite 4A as sorbent at 275 °C and a gas space velocity of 230 Nml/h·gcat, the CH4 content increased from 10.6 vol% in conventional methanation up to 85 vol% in the SEM conditions. Thus, the enhanced performance of the SEM process was demonstrated.

MT-CVD Ti(C,N,O) coatings controlled by CO: Microstructure evolution and its effect on the hardness

Incorporation of oxygen into Ti(C,N) coating by CO doping during moderate temperature chemical vapor deposition (MT-CVD) process is a promising strategy for enhancing the performance of cutting tools. In this work, Ti(C,N,O) coatings were prepared by MT-CVD in a hot-wall industrial-scale CVD reactor with increased CO volume fraction from 0 % to 8.0 % in the feed gas mixture. Microstructure evolution is revealed by high-resolution scanning electron microscopy, electron backscatter diffraction detector, and high-resolution transmission electron microscopy. Its effect on the hardness is investigated. The results show that as the CO fraction increases, the microstructure changes from columnar and large faceted grains to equilateral and nanoscale grains. An increasing density of plane defects including twins, especially Σ3 twin boundaries and stacking faults are identified in Ti(C,N,O) coatings with increasing CO fraction. The hardness of Ti(C,N,O) coatings increase from 26 GPa at 0 % CO to 34 GPa at 8.0 % CO, due to the grain refinement, solution strengthening, increased stacking faults, twins and {111} texture. A considerably lower rate of hardness increase is observed at CO fractions above 4.0 %, which is hypothesized to be related to grain boundary sliding, residual chlorine and excessive density stacking faults.

A comparative study on the influence of potential 4th period promoters in Ni-bimetallic catalysts for CO2 methanation

Because of their simplicity, bimetallic nickel catalysts are a rational step to further develop improved CO2-methanation catalysts suitable for specific applications and feed gas situations. In this study, hydrotalcite-based catalysts incorporating a second metal from the 4th period (chromium, manganese, iron, cobalt, copper, zinc and gallium) were synthesized, characterized (ICP-OES, XRD, BET, XPS) and performance tested under comparable conditions. The study aims at the clarification of inconsistencies regarding these additives found in the literature by ensuring comparability as good as possible. To achieve this goal the catalysts were tested using the same reactor, were prepared by the same type of synthesis possessing the same atomic ratio of Ni to the potential promoter element. In catalytic tests, performed at atmospheric pressure and at 20 bar, all catalysts were active in respect to CO2 hydrogenation. While Cu, Zn, and Ga acted as inhibitors, reducing the activity approximately by half, Fe and Mn proved to be very active promotors. The catalyst without promotor shows 80 % yield at 400 °C whereas the iron containing catalyst reaches this value already at 320 °C, but undergoes a irreversible loss at high temperatures (20 % loss after being exposed to 480 °C). In contrast, the manganese containing catalyst possesses a significantly improved activity without showing such a deactivation process, indicating a high level of stability.

Recent Advances in Bimetallic Catalysts for Methane Steam Reforming in Hydrogen Production: Current Trends, Challenges, and Future Prospects.

As energy demand continues to rise and the global population steadily grows, there is a growing interest in exploring alternative, clean, and renewable energy sources. The search for alternatives, such as green hydrogen, as both a fuel and an industrial feedstock, is intensifying. Methane steam reforming (MSR) has long been considered a primary method for hydrogen production, despite its numerous advantages, the activity and stability of the conventional Ni catalysts are major concerns due to carbon formation and metal sintering at high temperatures, posing significant drawbacks to the process. In recent years, significant attention has been given to bimetallic catalysts as a potential solution to overcome the challenges associated with methane steam reforming. Thus, this review focuses on the recent advancements in bimetallic catalysts for hydrogen production through methane steam reforming. The review explores various aspects including reactor type, catalyst selection, and the impact of different operating parameters such as reaction temperature, pressure, feed composition, reactor configuration, and feed and sweep gas flow rates. The analysis and discussion revolve around key performance indicators such as methane conversion, hydrogen recovery, and hydrogen yield.

Understanding the performance of membrane for direct air capture of CO2

AbstractDirect air capture (DAC) of CO2 is becoming increasingly important for reducing greenhouse gas concentrations in the atmosphere. However, the cost and energy requirements associated with DAC make it less economically feasible than carbon capture from flue gases. While various methods like solid sorbents and gas–liquid absorption have been explored for DAC, membrane processes have only recently been investigated. The objective of this study is to examine the separation performance of a membrane unit for capturing CO2 from ambient air. The performance of a membrane depends on several factors, including the composition of the feed gas, pressure ratio, material selectivity, and membrane area. The single‐stage separation process with the co‐current flow and constant permeability flux model is evaluated using a commercial module integrated with a process simulator to separate a binary mixture of carbon dioxide and nitrogen to assess the sensitivity of selectivity on purity and recovery of CO2 in permeate, and power requirement. Additionally, three levels of CO2 reduction from the feed stream to the retentate stream (25%, 50%, and 75%) are studied. A trade‐off between purity and recovery factor is observed, and achieving high purity in permeate requires high concentration in the retentate.

Thermodynamic design and experimental study of a condensation recovery system for VOCs

During the storage and transportation process of crude oil on tankers, the light hydrocarbon components in liquid form have the tendency to evaporate and vaporize easily, resulting in wasted resources and environmental pollution. The current petroleum volatile organic compounds (VOCs) recovery system such as absorption and membrane separation applied to crude oil tankers is unable to fulfil the requirements of existing VOCs emission standards. In contrast, the condensation method of VOCs recovery technology has the benefit of a straightforward process principle, and the recovered liquid hydrocarbons can be utilized directly. It is thus vital to develop a condensation recovery system for petroleum VOCs that is compatible with crude oil tankers. To attain the condensation and recovery of the non-azeotropic gases, such as CH4, C2H6, C3H8, and N2 in the feed gas, this paper proposes a low-temperature VOCs condensation recovery system with graded cooling and liquefaction separation for crude oil tankers. The proposed system initially utilizes a R404A/R23 double-stage cascade refrigeration cycle to cool the VOCs below −75 ℃ to liquefy most heavy hydrocarbons. Then, a low-temperature nitrogen expansion cooling cycle is utilized to cool the VOCs to approximately −160 °C to recover the remaining light hydrocarbons. The condensation process is simulated by Aspen HYSYS to study the variable operating conditions. The recovery of total hydrocarbons in the outlet tail gas in the simulation results is analyzed and found to be up to 95.50 %. Under identical refrigeration capacity circumstances, decreasing the inlet pressure, increasing the inlet flow rate, and increasing the methane mole fraction in VOCs component, all lead to declining trends of total hydrocarbon recovery and methane recovery rate. Specifically, the effects of four different hydrocarbon component ratios on total hydrocarbon recovery and total cooling load are investigated at a constant nitrogen content and refrigeration capacity. Furthermore, the optimal design and analysis process for the flow path section of the turbine expander under the cryogenic conditions is discussed. The results demonstrate that the outlet temperature through the turbine expander is at least −172.1 °C, and the cooling capacity can be up to 4.5 kW with a margin of 80 %. Finally, through the comprehensive VOCs condensation recovery experiments, the proposed system successfully achieves the liquefied separation and recovery of CH4, C2H6, and other hydrocarbons. The recovery rate of the total hydrocarbons in the outlet tail gas reaches 96.21 %, conforming to the VOCs emission standards and regulations. The findings of this study provide a viable technical resolution in the field of petroleum VOCs recovery from crude oil tankers.

An SDBD plasma-based source for efficient degradation of VOCs in an enclosed environment

In this work, a surface dielectric barrier discharge (SDBD) plasma-based source powered by a bipolar pulsed power supply is reported. This source has been tested for the decomposition of toluene and benzene in an enclosed environment of size 12 ft3. Study has been performed to compare decomposition of toluene and benzene on various combinations of the applied voltages and frequencies. For about 60 min of continuous operation of the SDBD source, a decomposition efficiency of 99.7% (toluene) and 74.8% (benzene) has been achieved. For the effective generation of reactive species, the ground electrode of the SDBD source is coated with TiO2 nanoparticles. Optical emission spectroscopy diagnostic has also been used to estimate the electron temperature, which is found to be in the range of 3–6 eV. Consequently, the high energetic electrons produced via the SDBD source are the primary reason to activate the catalyst instead of ultra-violet (UV) light. The results further showed that the developed SDBD source produces powerful, immediate discharge and energetic electrons, which could be efficiently used for volatile organic compounds (VOCs) degradation. The need for feed gas, pellets and/or differential pressure has been eliminated by the developed SDBD source from the known conventional methods for VOCs decomposition.

La0.6Sr0.4MnO3-Based Fuel Electrode Materials for Solid Oxide Electrolysis Cells Operating under Steam, CO2, and Co-Electrolysis Conditions

The conventional Ni–YSZ (yttria-stabilized zirconia) fuel electrode experiences severe degradation due to Ni- agglomeration and migration away from the electrolyte. Therefore, herein, we have considered Ni free electrodes, i.e., La0.6Sr0.4MnO3-δ (LSM)-based perovskite oxides as fuel electrodes. The LSM perovskite phase transforms into a Ruddlesden–Popper LSM (RP-LSM) phase with exsolved MnOx under reducing atmospheres. The RP-LSM is mainly interesting due to its good electrical conductivity, redox stability, and acceptable electrochemical behaviour. In this work, we synthesized the LSM powder and characterized it using several methods including X-ray diffraction (XRD), thermogravimetry analyses (TGA), four-probe conductivity, and scanning electron microscope with energy-dispersive X-ray spectroscopy (SEM-EDX). Finally, the electrolyte-supported single cells were fabricated and electrochemically characterized using AC and DC techniques under electrolysis conditions. In addition to pure LSM fuel electrodes, we have also investigated the electrochemical behaviour of LSM + YSZ (50:50) and LSM + GDC (50:50) composite fuel electrodes. The single cells containing LSM and LSM + GDC fuel electrodes show higher cell performance than LSM + YSZ. For instance, current densities of 1, 1.03, and 0.51 A·cm−2 at 1.5 V are obtained for LSM, LSM + GDC, and LSM + YSZ fuel electrodes containing single cells, respectively, with a 50% N2 and 50% H2O feed gas mixture. Moreover, the performance of the cell was also investigated under co-electrolysis with 50% CO2 and 50% H2O and under direct CO2 electrolysis conditions with 100% CO2 fuel gas.

Economic modelling of flexible carbon capture and storage in a decarbonised electricity system

This research provides new techno-economic insights into integrating flexible combined-cycle gas turbines with post-combustion carbon capture and storage (CCGT-CCS) for low-carbon power systems. This study developed a versatile unit-commitment optimisation model of CCGT-CCS. This research highlights the model’s adaptability, accommodating diverse techno-economic configurations, feed gases (e.g., biomethane or fossil natural gas), carbon capture rates, and policy instruments. This generalisation empowers seamless application in various policy and market contexts, making the model a potent tool for researchers and policymakers. While the case study focuses on the UK, the findings are relevant for most low-carbon power systems with variable renewable supplies. Analysing the UK’s net-zero scenarios from 2030 to 2050, the economic viability of flexible CCGT-CCS was highlighted. Intertemporal flexibility proves highly valuable with greater electricity price volatility, with a total ROI range of 81–246 %, surpassing the CCGT-CCS plant’s ROI (7–64 %). A flexible solvent storage solution should be seen in the context of the overall system ‘flexibility’ requirements of a low-carbon power system. On a cost basis, solvent storage represents just a fraction of the capital costs of more “mainstream” energy storage technologies, such as lithium-ion batteries or hydro-pumped storage, while CCGT-CCS offers firm power. Overall, while seen as a rather technical solution, if abated fossil fuel generation is to be part of a future low-carbon power system, having this flexibility adds economic benefits not just to operators but also improves overall system security and complements high shares of variable renewables on the grid.

Process Considerations for the Production of Hydrogen via Steam Reforming of Oxygenated Gases from Biomass Pyrolysis and Other Conversion Processes

AbstractIn 2021, average CO2 emissions was 9.7 g CO2/g H2 produced, primarily based on steam methane reforming (SMR) technology that currently dominates hydrogen production. The substitution of natural gas (NG) and other fossil feedstocks in SMRs with renewable gases may be considered as an option for reducing greenhouse gas emissions. This analysis explores process impacts and constraints associated with the potential introduction of biogenic gases into SMRs. The results indicate that replacing NG in the fuel train of the SMR, followed by partial replacement of NG in the feed train may be a feasible approach. For the CO‐ and CO2‐rich gas compositions assumed in this analysis the results indicate that feed train may accommodate up to 25 mole % of biogenic gases using allowances in existing designs and/or with small modifications, while maintaining similar hydrogen output. NG substitution in higher proportions require more major changes because of increased flow rates and heat exchange requirements in the system. Biogenic gases with lower CO2 and higher calorific values are advantageous for NG substitution, and dry reforming using the CO2 present in the feed gas can reduce steam consumption and increase process efficiency within limits where coking does not become a new constraint.