Sorption-enhanced Gasification Research Articles

Isothermal CO2 separation Enabled by redox-active mixed oxide sorbents

This study reports an isothermal CO2 capture strategy using redox-active perovskite oxides and demonstrates its application in sorption-enhanced hydrogen production. Using a thermodynamic analysis, we investigated the relationship between the equilibrium oxygen partial pressure and the extent of CO2 sorption as well as the theoretical hydrogen purity. To validate the concept, calcium and cobalt co-doped SrFeO3 (SrxCa1-xFeyCo1-yO3-δ) samples were screened experimentally to assess their (isothermal) CO2 sorption capacity and reducibility. The optimal sorbent, Sr0.6Ca0.4Fe0.7Co0.3O3-δ (SCFC-6473), underwent further characterizations and was used for isothermal sorption-enhanced steam reforming (iSESR) of glycerol to produce H2, achieving 93 vol% H2 purity. In addition, we present iSESR of biogas and isothermal sorption-enhanced gasification (iSEG) of pulverized pine by Sr0.875Ba0.125MnO3-δ (SBM 718) to validate the generalizability of the proposed concept for a variety of applications. Nearly 90 % syngas efficiency was demonstrated for iSEG of biomass while producing a hydrogen enriched (73 vol%) syngas product.

Techno-economic analysis of small-scale ammonia production via sorption-enhanced gasification of biomass

Biomass gasification is a green and efficient pathway for lowering the carbon footprint of ammonia production. Decentralized, small-scale biomass gasification plants (<150 t NH3/day output) are more practical than large plants due to sustainable large-scale biomass supply constraints. Small-scale biomass gasification for ammonia production faces the challenges of high energy consumption and production costs. Process intensification through sorption-enhanced gasification (SEG) integrates steam gasification and in-situ CO2 separation using regenerable CaO sorbents, directly producing hydrogen-rich syngas (∼70 vol%), which streamlines syngas conditioning and increases cost-effectiveness. Two SEG process configurations for small-scale biomass-to-ammonia (∼45000 t of agricultural residues/year) were proposed: SEG process A, which produced low-carbon ammonia without air separation, and SEG process B, which employed an air separation unit to deliver carbon-negative ammonia by capturing CO2. The two processes were compared against a dual fluidized bed gasification (DFBG) process, which generated green ammonia without an air separation, like SEG process A. Of the three cases, SEG process B showed the lowest biomass (2.14 t biomass/t NH3) and water consumption (0.47 t H2O/t NH3) and avoided 2.8 t CO2/t NH3, making it carbon-negative. While the DFBG process and SEG process A had higher energy efficiencies, SEG process B posted the lowest net energy consumption (36.6 GJ/t NH3). Furthermore, SEG process B had the lowest ammonia production cost ($692/t NH3) and payback time (9.4 years), making it the most economically viable. Sensitivity analysis showed that favorable carbon credit policies could boost the economics of SEG process B to match large-scale plants.

AspenPlus-based techno-economic analysis of solar-assisted sorption-enhanced gasification for hydrogen and chemicals recovery from polyethylene terephthalate waste

Although the recycling of polyethylene terephthalate (PET) bottles is well-operating in several countries, less than 10% of PET plastic waste was recycled in a closed loop globally, and the rest was discarded as leakage. A process to recover hydrogen and valuable chemicals through solar-assisted PET sorption-enhanced gasification was analyzed. PET steam gasification with CaO and solar-assisted calcium looping processes were already experimentally studied in our previous work to obtain optimized processing conditions. In this paper, the integrated process with product purification, steam power plant, and LiBr-H2O absorption chiller was simulated with Aspen Plus based on previous experimental results to investigate the techno-economic performance. Material flows, energy balance, exergy destruction, and economics were analyzed. Day and night mode operations at different seasons were evaluated based on energy balance and the weather conditions of Naples, Italy. The energy and exergy efficiencies of day and night modes varied between 62%–72%. The annual production yields of hydrogen and benzene were 684 t and 6286 t, respectively. Due to the high production of benzene, its higher price (>1092 €/t) would make the project feasible with a larger than 12% internal rate of return value and competitive break-even hydrogen price (less than 4 €/kg). The results show that this integrated process could be technically and economically feasible. It has the potential to be implemented for hydrogen and benzene recovery from PET plastic waste with sustainable solar heat source and zero fossil CO2 emissions.

Investigating the behavior of six limestones in presence of steam in dual interconnected fluidized beds, under operating conditions relevant for sorption-enhanced gasification

This paper presents results on the behavior, in terms of CO2 capture capacity and attrition/fragmentation tendency, for six limestones processed in a dual interconnected fluidized beds system under operating conditions simulating those of sorption-enhanced gasification in presence of water vapor. Ten calcination/carbonation cycles have been carried out for each sorbent; in particular, carbonation has been carried out at two temperature levels (650 °C and 700 °C), with a CO2 and H2O inlet concentration of 10% for both gases. Degree of CaO carbonation (with related modelling) along the cycles, and particle size distribution at the end of the cycles, have been analyzed and discussed, together with results coming from ex situ impact fragmentation tests carried out in a specifically devoted apparatus. The discussion has been extended to particular cases in which the system was operated in the absence of steam, to analyze the role of this species on the sorbent behavior.

Pilot-scale study of sorption-enhanced gasification of sewage sludge

Sustainable management and disposal alternatives for sewage sludge (SS) should be pursued due to the substantial increment in its global production, as well as due to the raising interest in the renewable energy and synthetic fuels deployment. Since SS present high moisture (>95 % wt.), drying would play an essential role in SS management. In this work, SS pre-treated in a solar-drying facility has been successfully used as feedstock in a 30 kWth bubbling fluidised-bed (BFB) gasification pilot plant operating under Sorption Enhanced Gasification (SEG) conditions, i.e. using CaO as bed material and steam as gasifying agent. The influence of key operating SEG parameters (such as temperature, steam-to-carbon ratio and sorbent-to biomass proportion) in the syngas yield and composition (H2, CO, CO2, CH4, CxHy, H2S, COS, NH3 and tars) has been carefully assessed. As a matter of comparison, steam-oxygen gasification conditions have been also tested in the facility using solar-dried SS as feedstock. The results obtained demonstrate the possibility of producing a syngas with high H2 contents of 70–73 vol% and relatively low CO and CO2 contents (i.e. 2–3 vol% and 8 vol% respectively).

Gasification kinetics of chars from diverse residues under suitable conditions for the Sorption Enhanced Gasification process

Gasification kinetics for six chars from residual origin have been determined in a relatively low temperature range, low CO2 and high H2O partial pressures, typical from Sorption Enhanced Gasification (SEG) processes. In general, models based on the Random Pore Model (RPM) are the best fitting experimental results, but ash composition (in terms of alkali and alkaline earth metals) was crucial for the selection of the reaction model to be applied. Char conversion from biogenic waste with ash content higher than 30 % wt. was modelled with RPM model, but reaction rate for chars with the highest K/Si ratio was better described with modified versions of the RPM capable of predicting maximum reaction rates at high char conversion. For chars with similar ash content and composition, textural properties determined the pre-exponential factor and the activation energy for the gasification reaction (with both CO2 and H2O), while identical fitting parameters for the semi-empirical model were capable of predicting char conversion with time.

Towards an environmentally friendly power and hydrogen co-generation system: Integration of solar-based sorption enhanced gasification with in-situ CO2 capture and liquefaction process

The sorption-enhanced gasification systems, which integrate the gasification process with an in-situ CO2 capture system, have emerged as environmentally friendly solutions. This study proposes an innovative solar-based SEG system aimed at co-generating power and hydrogen while ensuring environmental sustainability. The suggested system comprises municipal solid waste gasification, in-situ calcium looping CO2 capture process, steam and humid air gas turbine secondary power cycles, and a CO2 liquefaction system. Comprehensive analysis including energy, exergy, and exergoeconomic evaluations are conducted to assess the overall system performance. The annual electrical energy efficiency of the system is calculated to be 11.9%, resulting in a net electrical power generation of 19.48 MW. The annual total energy efficiency is determined to be 54.8%. To convert the captured CO2 into a liquid form, a dual-pressure Linde-Hampson cycle with a coefficient of performance of 1.9 is employed. Among the system components, the carbonator reactor exhibits the highest exergy efficiency at 88.7%, while the sorption-enhanced gasifier, calciner, and combustion chamber show relatively higher exergy destruction. The heliostat field is identified as the most expensive component in the SEG system. The levelized cost of electricity (LCOE) for the produced electricity is calculated to be 60.1$/MWh.

Hydrogen production through two-stage sorption-enhanced biomass gasification: process design and thermodynamic analysis

This study presents process design and thermodynamic analysis of hydrogen production through a novel two-stage sorption-enhanced gasification (SEG) process. The SEG process integrates decoupled gasification with calcium looping to convert solid fuels such as biomass. The proposed two-stage SEG process employs a fluidized bed gasifier and a countercurrent moving bed reformer. The first stage involves high-temperature sorption-enhanced gasification in a fluidized bed. Then the product gas from the first stage undergoes sorption-enhanced reforming at relatively lower temperatures to further improve the hydrogen purity. This study employs an autothermal multistage model based on Gibbs free energy minimization to analyze and optimize the calcium looping ratio, steam-to-carbon ratio and feed temperatures of the moving bed reformer. The product gas distribution and temperature profile along the moving bed are discussed. Under optimal conditions, the two-stage SEG process can directly produce 99% H2 (dry basis), and the overall energy efficiency of the two-stage SEG is 58.7%, which is nearly 10% higher than the conventional process. Therefore, two-stage sorption-enhanced biomass gasification shows the potential to significantly improve green hydrogen production.

Thermodynamic analysis of a sorption-enhanced gasification process of municipal solid waste, integrated with concentrated solar power and thermal energy storage systems for co-generation of power and hydrogen

A system of coupled CO2 capture and gasification has led to a new concept entitled sorption-enhanced gasification (SEG) which can increase H2 concentration in the syngas composition. This study proposed a novel configuration of the SEG system comprising concentrated solar power and thermal energy storage systems. Calcium looping (CaL) is utilized as the CO2 capture process. Unlike conventional SEG systems in which calcination heat demand is supplied by an oxy-combustion process, this study considers a heliostat field to provide heat for sorbent regeneration. The solar and thermal energy storage systems are simulated dynamically to achieve accurate results. A steam Rankine cycle is also designed to recover the released heat sources through the SEG system. The overall system performance is explored through energy and exergy analyses. Based on the results, the proposed system managed to produce 0.58 kg/s pure hydrogen in addition to 13.96 MW of net electrical power. Meanwhile, CO2 is captured from syngas composition with capturing efficiency of 95%. The energy analysis shows cold gas efficiency and the annual total energy efficiency of 87.76 and 70.74%, respectively. Based on exergy analysis results, the carbonator reactor exhibits the highest permeance compared to the gasifier and calciner reactors, with an exergy efficiency of 88.74%. Parametric study results show an increase in the cold gas efficiency, hydrogen production rate, and electrical energy efficiency with enhancing steam-to-biomass ratio. An increase in CO2 capture efficiency also improves both the electrical energy efficiency and H2 concentration of the syngas composition. CO2 capture efficiency and S/B ratio are inversely related to the exergy efficiency of the system.

Modelling and assessment of a sorption enhanced gasification system coupled with hydrothermal carbonization, hot gas cleaning, and plasma to produce pure H2 from biomass

Concerns about energy security, energy prices and climate change led scientific research towards sustainable solutions to fossil fuel as renewable energy sources coupled to hydrogen as energy vector and carbon capture and conversion technologies. Among the technologies investigated in the last decades, biomass gasification acquired great interest owing to the possibility to obtain low cost and CO2 negative emission hydrogen production from a large variety of everywhere available organic wastes. Upstream and downstream treatment were then studied in order to maximize hydrogen yield, reduce the content of organic and inorganic contaminants under the admissible levels for the technologies which are coupled with, capture, and convert carbon dioxide. However, studies which analyse a whole process made of all those technologies is still missing. In order to fill this lack, the present paper investigated the coexistence of Hydrothermal Carbonization (HTC), Sorption Enhance Gasification (SEG), Hot Gas Cleaning (HGC), and CO2 conversion by Dielectric Barrier Discharge (DBD) plasma reactor for H2 production from biomass waste by means of Aspen Plus software. The proposed model aimed to identify and optimise the performance of the plant by varying operating parameters (such as temperature, CaO/biomass ratio, separation efficiency, etc.). The carbon footprint of the global plant is 2.3 kg CO2/kg H2, lower than the latest limit value imposed by the European Commission to consider hydrogen as “clean”, that was set to 3 kg CO2/kg H2. The hydrogen yield referred to the whole plant is 250 gH2/kgBIOMASS.

Analysis of the behaviour of limestone sorbents for sorption-enhanced gasification in dual interconnected fluidised bed reactor

Sorption-Enhanced Gasification (SEG) is a promising technology based on the use of Ca-based sorbents (like limestone) to selectively remove CO2 from the gasification environment, for production of hydrogen rich syngas. This process benefits from the extensive understanding of “calcium looping”, a post-combustion technique aimed at removing CO2 from flue gas. Calcium looping is most typically carried out in Dual Interconnected Fluidised Bed (DIFB) reactors. The correct design of sorbent looping processes in DIFB reactors must consider: 1) sorbent deactivation (i.e., decay of CO2 capture performance) over repeated cycling; 2) the loss of sorbent material due to elutriation, that may be enhanced by attrition and fragmentation. The aim of this study is to investigate six different commercial limestones in terms of sorbent performance and attrition/fragmentation tendency under simulated SEG conditions.The experimental campaign was carried out in a lab-scale DIFB reactor, electrically heated. The six sorbents were limestones coming from different parts of Europe. A synthetic gas including air, CO2 and N2 was used to simulate SEG conditions. A “test” consisted of ten complete cycles of calcination/carbonation. Calcination was performed at 850 °C, fluidising the bed with a stream of 10 % CO2 (balance air) to simulate oxidising conditions typical of the combustor-calciner. In the carbonation stage, the temperature was kept at 650 °C and the CO2 concentration was set at 10 % (balance nitrogen) to account for reducing conditions typical of the gasifier-carbonator.During each carbonation stage, the CO2 concentration at the exhaust was continuously monitored to calculate the CO2 specific capture performance. The sorbent attrition rate was determined by working out the mass of fines elutriated at the exhaust and collected in filters, for each calcination and carbonation stage. After a test, each exhaust sorbent sample was sieve-analysed to obtain the particle size distribution and the fraction of generated fragments. Moreover, the characterisation was extended by carrying out, in an ex situ apparatus, impact fragmentation tests on samples preprocessed in DIFB.Results were critically analysed in the light of the adopted operating conditions, by also including: (a) a fitting equation of conversion data, able to give indications on the sorbent resistance to sintering; (b) a carbonation reaction model, that allowed the estimation of the decrease in the sorbent specific surface area as long as the number of cycles increases.

Simulation of sorption-enhanced gasification: H[formula omitted]O staging to a circulating fluidised bed gasifier to tailor the producer gas composition

Sorption-enhanced gasification (SEG) is an advanced gasification technology for biofuel and biochemical synthesis processes. The SEG process allows tailoring of the producer gas composition for different synthesis processes by adjusting the temperature of the gasifier. Conventionally, the solids circulation rate from the combustor to the gasifier has been used to tailor producer gas composition. In this study, H2O staging is investigated in a circulating fluidised bed (CFB) gasifier as an alternative approach. The H2O staging can be used to decrease the riser temperature locally to enhance the main chemical reactions. The H2O staging as gas and liquid phases were considered in this study. Also, reactor cooling was combined with the staging. A validated one-dimensional CFB gasifier model was used to investigate the process. The simulation results indicate that H2O staging and cooling enhance the gasifier’s limestone carbonation and water-gas shift reactions. Thus, allowing to tailor the producer gas composition directly by adjusting the gasifier’s operating parameters. The methods investigated increase flexibility for operating the SEG CFB gasifier and the reactor system. Understanding different operation methods of the process and their impact on the system’s operation enables more flexible use and design of the gasification process.

Non-catalytic partial oxidation of methane in biomass-derived syngas with high steam and hydrogen content optimal for subsequent synthesis process

Methane is present in biomass gasification syngas but cannot be directly utilized in the synthesis of fuels or chemicals. As a result, a method for converting methane into useable gases such as H2 and CO for synthesis processes is required. This study thus investigated the non-catalytic partial oxidation of methane in sorption enhanced gasification (SEG) environments composed mainly of steam and hydrogen at atmospheric pressure using a non-premixed burner system. The results indicated that the oxygen to fuel ratio had a strong impact on CH4 conversion, whereas the effects of preheating temperature and steam were insignificant. The highest CH4 conversion of 67% was achieved at the highest oxygen to fuel ratio of 0.77. Through the oxidation process, not only hydrocarbons but also H2 were reduced with increasing oxygen to fuel ratios. Nevertheless, the desired CO was improved in SEG environments with 60% steam. While CH4 and H2 concentrations decreased by 23% and 10%, respectively, CO concentration increased by 39% in relation to the inlet syngas at an oxygen to fuel ratio of 0.24. This condition allows for a target module M of roughly 2 for methanol synthesis. Taken together, the non-catalytic partial oxidation method could be used to upgrade methane in syngas for downstream synthesis applications. To attain complete hydrocarbon conversion, combining partial oxidation and catalytic reforming is suggested, with oxidation supplying heat for reforming reactions.

Sorption-enhanced steam gasification of fine coal waste for fuel producing

Improving the quality of syngas from fine coal waste using the sorption-enhanced gasification process is a novel technology in the production of H2. The effect of CaO on CO2 absorption and H2 increase in the steam fine coal gasification process was determined in a fixed bed gasifier. The steam gasification process took place at 650 °C using bentonite and CaO as catalysts and absorbents. Steam increased the H2 concentration in the syngas to 58 vol%. In-situ CO2 absorption is more effective with the addition of CaO. The maximum percentage of CO2 was absorbed when the Ca/C ratio 2 was 78.33 %. The H2 content in the syngas after the CO2 was absorbed increased rapidly to 75.80 vol% at a Ca-to-carbon-mole ratio (Ca/C) of 1.5 and a steam-to-feedstock ratio (S/F) of 1.5. CaO did not produce significant results for low heating value (LHV) or cold gas efficiency (CGE), with results of 12 MJ/Nm3 and 44.53 %. The dominant water gas shift reaction due to the influence of steam and CaO increased H2/CO up to 9.11, which made the syngas from this work suitable for Fischer–Tropsch synthesis.

Hydrogen and power co-production from autothermal biomass sorption enhanced chemical looping gasification: Thermodynamic modeling and comparative study

Calcium looping and chemical looping technologies envisage advanced solutions for H2 production. This study compared the H2 and power co-production from biomass sorption enhanced gasification (SEG) and sorption enhanced chemical looping gasification (SECLG) under autothermal conditions with thermodynamic simulation. The thermal self-sufficiency of calcination was achieved by splitting biomass for combustion and oxidizing the reduced oxygen carrier, respectively. It was found that SECLG was able to achieve higher energy efficiency (64.6%) than SEG (55.7%) at the optimized carbonator temperature. In both processes, parametric analysis illustrates that under the autothermal-available carbonator temperature range, higher carbonator temperature and fixed carbon conversion are recommended to achieve higher H2 yields and energy efficiencies, owing to lower energy penalty leading to lower requirement of combusted biomass content or Ni/C molar ratio for thermal self-sufficiency. Elevating carbonator pressure slightly improved the energy performance. Regarding CO2 capture through oxyfuel combustion in SEG and SECLG processes, the energy penalty from higher calcination temperature greatly degraded the energy performance, which was even higher than the power consumption of air separation unit. According to exergy analysis, the main exergy destruction occurred at the syngas production section (∼49%). From the view of energy performance, SECLG is a promising autothermal strategy for SEG upgrade.

Sorption-enhanced gasification of municipal solid waste for hydrogen production: a comparative techno-economic analysis using limestone, dolomite and doped limestone

Sorption-enhanced gasification has been shown as a viable low-carbon alternative to conventional gasification, as it enables simultaneous gasification with in-situ CO2 capture to enhance the production of H2. CaO-based sorbents have been a preferred choice due to their low cost and wide availability. This work assessed the technical and economic viability of sorption-enhanced gasification using natural limestone, doped limestone with seawater and dolomite. The techno-economic performance of the sorption-enhanced gasification using different sorbents was compared with that of conventional gasification. Regarding the thermodynamic performance, dolomite presented the worst performance (46.0% of H2 production efficiency), whereas doped limestone presented the highest H2 production efficiency (50.0%). The use of dolomite also resulted in the highest levelised cost of hydrogen (5.4 €/kg against 5.0 €/kg when limestone is used as sorbent), which translates into a CO2 avoided cost ranging between 114.9 €/tCO2 (natural limestone) and 130.4 €/tCO2 (dolomite). Although doped limestone has shown a CO2 avoided cost of 117.7 €/tCO2, this can be reduced if the production cost of doped limestone is lower than 42.6 €/t. The production costs of new sorbents for CO2 capture and H2 production need to be similar to that of natural limestone to become an attractive alternative to natural limestone.

Chemical looping gasification and sorption enhanced gasification of biomass: A perspective

Chemical looping gasification (CLG) and sorption enhanced gasification (SEG) of biomass are promising technologies to improve the energy efficiency and simplify the processes for producing renewable hydrogen, synthetic fuels, and chemicals. In terms of process intensification, CLG achieves inherent air separation through the use of oxygen carriers, eliminating the need of air separation units. With inherent CO2 separation enabled by CO2 sorbents, SEG can directly generate hydrogen-rich syngas (>70 vol.% H2) without individual water-gas shift and CO2 separation units. The state-of-the-art of the reactors, functional materials, and modeling works for CLG and SEG is reviewed in this paper. The impact of essential process parameters, including temperature, solid circulation rate, and steam-to-biomass ratio, is summarized. The research needs and outlook of CLG and SEG are discussed. Combining the perspectives of both basic research and practical application, this paper is expected to serve as a valuable guide for academic research groups, industry stakeholders, and policy makers seeking to research, invest in, or evaluate biomass CLG and SEG.

Influence of gas atmosphere and role of tar on catalytic reforming of methane and tar model compounds: Special focus on syngas produced by sorption enhanced gasification

Combining sorption enhanced gasification (SEG) of biomass with a downstream reformer leads to high-quality syngas for hydrogen production and synthesis applications. Reforming of methane and tar model compounds (toluene and naphthalene) at various parameters and in simulated SEG environments was thus examined for reaching maximum conversion of hydrocarbons to enhance H2/CO production. This was studied by means of thermodynamic analyses and experiments using a Ni-based catalyst in a fixed bed reformer. Simulation and experimentation indicate that the high steam-to-carbon ratio of SEG syngas promotes the high conversion of hydrocarbons. The high hydrogen concentration inhibits the methane-steam reaction but improves CO yield. Experimentally, the presence of tar model compounds at 600 °C reduced methane conversion by approximately 30%, and deactivation of catalysts by carbon formation was detected. The deactivation resulted in significant drops in toluene and naphthalene conversions over time, while methane conversion remained almost stable. Furthermore, the heavier tar compound, naphthalene, showed an inhibition effect on toluene and methane reforming. The results implicate the significance of studying different hydrocarbons in the reforming process. Overall, to completely convert all hydrocarbons in the SEG syngas for more H2/CO production, a high reforming temperature of 800 °C for the applied Ni-based catalyst is recommended. No additional steam is required in a reformer due to the typical composition of SEG syngas.

Performance of limestone‐based sorbent for sorption‐enhanced gasification in dual interconnected fluidized bed reactors

AbstractA possibility to carry out sorption‐enhanced gasification (SEG) is represented by its integration with the calcium looping concept in dual interconnected fluidized beds (DIFB). This article is focused on the sorbent CO2 uptake performance and attrition/fragmentation tendency when operating conditions simulating those of a DIFB‐SEG process are adopted. Experiments were carried out on a commercial Italian limestone in a laboratory‐scale DIFB reactor. Carbonation was carried out in a range of test conditions, including variable temperature (600–700°C) and absence/presence of steam (10% by volume); CO2 concentration was set at 10% by volume. The characterization is extended by investigating the behavior of preprocessed DIFB‐SEG samples on impact fragmentation tests, conducted in an ex situ apparatus. Tests were carried out for impact velocities in the range 17–45 m/s. Results were discussed considering both the impact velocity value and the operating conditions under which the sample was preprocessed in the fluidized bed.

Flexible Power and Biomass-To-Methanol Plants With Different Gasification Technologies

The competitiveness of biofuels may be increased by integrating biomass gasification plants with electrolysis units, which generate hydrogen to be combined with carbon-rich syngas. This option allows increasing the yield of the final product by retaining a higher amount of biogenic carbon and improving the resilience of the energy sector by favoring electric grid services and sector coupling. This article illustrates a techno-economic comparative analysis of three flexible power and biomass to methanol plants based on different gasification technologies: direct gasification, indirect gasification, and sorption-enhanced gasification. The design and operational criteria of each plant are conceived to operate both without green hydrogen addition (baseline mode) and with hydrogen addition (enhanced mode), following an intermittent use of the electrolysis system, which is turned on when the electricity price allows an economically viable hydrogen production. The methanol production plants include a gasification section, syngas cleaning, conditioning and compression section, methanol synthesis and purification, and heat recovery steam cycle to be flexibly operated. Due to the high oxygen demand in the gasifier, the direct gasification-based plant obtains a great advantage to be operated between a minimum load to satisfy the oxygen demand at high electricity prices and a maximum load to maximize methanol production at low electricity prices. This allows avoiding large oxygen storages with significant benefits for Capex and safety issues. The analysis reports specific fixed-capital investments between 1823 and 2048 €/kW of methanol output in the enhanced operation and LCOFs between 29.7 and 31.7 €/GJLHV. Economic advantages may be derived from a decrease in the electrolysis capital investment, especially for the direct gasification-based plants, which employ the greatest sized electrolyzer. Methanol breakeven selling prices range between 545 and 582 €/t with the 2019 reference Denmark electricity price curve and between 484 and 535 €/t with an assumed modified electricity price curve of a future energy mix with increased penetration of intermittent renewables.