Synthetic Natural Gas Production Research Articles

Co-feeding biomass and municipal solid waste for enhanced hydrogen and synthetic natural gas yields employing chemical looping process

Synthetic natural gas (SNG) is a promising alternative to conventional fossil natural gas. This study proposes a chemical looping hydrogen production (CLHP)-based route for SNG synthesis and elucidates the insights and necessities of appropriately co-feeding different types of feedstocks to maximize the yields of hydrogen and subsequent SNG. A study employing microalgae (MA) and refuse-derived fuel (RDF) as biomass and municipal solid waste representatives demonstrates that blending MA with RDF in a proportion of 40 %:60 % (0.4MA-0.6RDF) eradicates oxygen carrier splitting. This boosts fuel-to-hydrogen efficiency from 74.1 % to 77.8 %, as well as subsequent thermal and exergy efficiencies of SNG production from 59.07 % and 55.8 % to 61.3 % and 57.92 %, respectively, compared to the use of MA alone. Nonetheless, blending fuels does not yield substantial economic advantages, as evidenced by the levelized cost of SNG production using pure MA and the 0.4MA-0.6RDF blend remaining at approximately 0.63 USD/Nm3.

Life cycle assessment of synthetic natural gas production from captured cement’s CO2 and green H2

Research on the environmental benefits of carbon capture and utilization (CCU) in cement production so far, has predominantly emphasized energy efficiency enhancements and CO2 emission reductions at a CCU product level, neglecting broader environmental consequences for the sector. This research broadens this perspective by providing an extensive life cycle assessment (LCA) of a circular Portland cement (CPC) model. Synthesized methane is used as input fuel through green hydrogen and calcium-looping (CaL) post-combustion captured CO2 from cement flue gas. Comparative analysis with ordinary Portland cement (OPC) reveals significant reductions in climate change and fossil resource use environmental impact categories. However, trade-offs are evident in acidification, water use, and minerals and metals resource consumption. The electrolysis system is a critical contributor due to the high electricity demand for hydrogen production, and its environmental impact depends largely on the renewable electricity source. The wind-based electrolysis model yields the most favourable results, followed by mixed (50% solar – 50% wind) and solar scenarios. These findings offer valuable insights for the cement industry, supporting stakeholders decision making on the adoption of sustainable circular production methods.

Techno-economic and life cycle analysis of synthetic natural gas production from low-carbon H2 and point-source or atmospheric CO2 in the United States

Synthetic natural gas (SNG) is of great interest in reducing fossil energy consumption while maintaining compatibility with existing NG infrastructure and end-use applications equipment. SNG can be produced using clean H2 generated from renewable or nuclear energy and CO2 captured from stationary sources or the atmosphere. In this study, we develop an engineering process model of SNG production using Aspen Plus® and production scales reported by the industry. We examine the levelized cost and life cycle greenhouse gas (GHG) emissions of SNG production under various CO2 supply scenarios. Considering the higher cost of H2 transportation compared with CO2 transportation, we assume that CO2 feedstock is transported via pipeline to the H2 production location, which is collocated with the SNG plant. We also evaluate the cost of CO2 captured from the atmosphere, assuming the direct air capture process can occur near the SNG facility. Depending on the CO2 supply chain, the levelized cost of SNG is estimated to be in the range of $45–76 per million British thermal units (MMBtu) on a higher heating value (HHV) basis. The SNG production cost may be reduced to $27–57/MMBtu-HHV by applying a tax credit available in the United States for low-carbon H2 production (45 V). With a lower electricity price of 3ȼ/kWh for water electrolysis and accounting for a 45 V tax credit, the SNG cost reaches parity with the cost of fossil NG. Depending on the CO2 supply chain, SNG can reduce life cycle GHG emissions by 52–88 % compared with fossil NG.

Experimental demonstration of a sorption-enhanced methanation (SEM) cyclic process on a lab-scale TRL-3 fixed bed reactor

In this work, the scaling-up of the sorption-enhanced methanation (SEM) process to a TRL-3 fixed bed reactor has been demonstrated. The SEM process for synthetic natural gas (SNG) production consists mainly of two stages: in the first stage, the zeolite facilitates the removal of a product from the methanation reaction, thereby enhancing CO/CO2 conversion; in the second stage, zeolite regeneration takes place. The functional materials chosen were a zeolite 4A and a Nickel-based catalyst, selected for their high H2O adsorption capacity and high catalytic activity, respectively. Various operational variables, including temperature and pressure, were optimized during both SEM and regeneration stages to enhance the performance of the process. Optimum regeneration conditions consisted of pressure swing operation—from 10 bar during the SEM reaction to atmospheric pressure—while maintaining a constant temperature at 230°C. These operating conditions were tested for more than 20 SEM/regeneration cycles using a feed gas containing H2/CO/CO2. Stable performance throughout the cycles was fulfilled, reaching a CH4 purity of 100 % during 25 min during SEM for the operating conditions chosen. Finally, the number of reactors needed to obtain a continuous stream of CH4 was calculated resulting in a process productivity of 8.00×10-4 molCH4/kgcat·s.

Economy of scale for green hydrogen-derived fuel production in Nepal.

Opportunity for future green hydrogen development in Nepal comes with end-use infrastructural challenges. The heavy reliance of industries on fossil fuels (63.4%) despite the abundance of hydroelectricity poses an additional challenge to the green transition of Nepal. The presented work aims to study the possibility of storing and utilizing spilled hydroelectricity due to runoff rivers as a compatible alternative to imported petroleum fuels. This is achieved by converting green hydrogen from water electrolysis and carbon dioxide from carbon capture of hard-to-abate industries into synthetic methane for heating applications via the Sabatier process. An economy-of-scale study was conducted to identify the optimal scale for the reference case (Industries in Makwanpur District Nepal) for establishing the Synthetic Natural Gas (SNG) production industry. The techno-economic assessment was carried out for pilot scale and reference scale production unit individually. Uncertainty and sensitivity analyses were performed to study the project profitability and the sensitivity of the parameters influencing the feasibility of the production plant. The reference scale for the production of Synthetic Natural Gas was determined to be 40 Tons Per Day (TPD), with a total capital investment of around 72.15 Million USD. Electricity was identified as the most sensitive parameter affecting the levelized cost of production (LCOP). The 40 TPD plant was found to be price competitive to LPG when electricity price is subsidized below 3.55 NPR/unit (2.7c/unit) from 12 NPR/unit (9.2c/unit). In the case of the 2 TPD plant, for it to be profitable, the price of electricity must be subsidized to well below 2 NPR/kWh. The study concludes that the possibility of SNG production in Nepal is profitable and price-competitive at large scales and at the same time limited by the low round efficiency due to conversion losses. Additionally, it was observed that highly favorable conditions driven by government policies would be required for the pilot-scale SNG project to be feasible.

Carbon-neutral cement: The role of green hydrogen

Business-as-usual (BAU) cement production is associated with a linear model that contributes significantly to global warming and is dependent on volatile energy markets. A novel circular model is proposed, by adding three power-to-gas system components to current production systems: a calcium-looping (CaL) CO2 capture unit; water electrolysis for hydrogen and oxygen generation; and a methanation unit for synthetic natural gas (SNG) production. The paper presents the first analysis of the combined industrial-scale operation of these components in a closed loop, where the SNG fuels the cement kiln and the CaL unit, while the O2 produced feeds it. The circular, hybrid, and BAU models are compared in three feasibility scenarios. It is concluded that the circular model outperforms the other alternatives environmentally, opening a potential pathway for the cement industry to achieve near net-zero CO2 emissions, reduce energy dependence and improve economic efficiency.

Synthetic natural gas production using CO2-rich waste stream from hydrothermal carbonization of biomass: Effect of impurities on the catalytic activity

The utilization of biomass and bio-waste, particularly through hydrothermal processes, has shown promise as a technology for converting these materials into valuable products. While most research has traditionally focused on the solid and liquid byproducts of these hydrothermal treatments, the gaseous phase has often been overlooked. This study specifically investigates the conversion of off-gases produced during hydrothermal carbonation (HTC) into synthetic natural gas, offering a readily marketable product with economic potential. Although the methanation of conventional flue gases has been extensively studied, dealing with non-standard off-gases from processes like HTC presents challenges due to the presence of minor impurities like CO and CH4. This novel research seeks to experimentally evaluate the methanation of HTC off-gases using nickel-based catalysts and analyze how these impurities affect the catalytic performance. The studied catalysts include nickel supported by ceria and alumina, as well as alumina supported nickel-cobalt systems. The results demonstrate that these catalysts exhibit high CO2 conversion and CH4 selectivity under ideal gas conditions. However, when real gas compositions with impurities are considered, CO2 conversion decreases at lower temperatures (ca. 20% lower conversion for real gas vs. ideal), probably due to side reactions such as CH4 cracking. This difference becomes less pronounced at higher temperatures. Nevertheless, the catalysts perform satisfactorily, especially at temperatures exceeding 350 °C. In conclusion, this study sheds light on the methanation of HTC off-gases and underscores the significance of understanding how impurities in real gases impact the process, providing potential directions for future research.

Model-based techno–economic analysis of an integrated synthetic natural gas production system with direct air capture and water electrolysis

In this study, a techno-economic analysis is performed for an integrated system of carbon capture and utilization (CCU). The proposed system utilizes CO2 captured by a direct air capture (DAC) process using a metal–organic framework adsorbent. The captured CO2 is converted into a methane product, or synthetic natural gas (SNG), using hydrogen produced by water electrolysis. Rigorous mathematical models are used for the mass and energy balances in the major components of the proposed integrated system, allowing us to estimate the capital and operating costs and energy consumption. A sensitivity analysis is also performed to identify model parameters that significantly affect the SNG cost. Our analysis indicates that the thermal and electrical energies required to produce SNG are 0.409 MJ/Nm3-SNG and 19.6 kWh/Nm3-SNG, respectively, and the cost of SNG is within the range of 1.43–2.60 $/Nm3-SNG.

An econometric analysis of the sawmill by-product market to explore bioeconomy options in Austria

Bioeconomy strategies promote higher shares of biomass products in material and energy sectors. Deploying by-products from sawmills is therefore of major interest. This study aims at analyzing market characteristics and implications of bioeconomy strategies by combining three methods: First, an econometric supply and demand model for sawmill by-products (SBP) was estimated based on data from 2001 to 2020. Second, the model was used to analyze a reference and a bioeconomy scenario. Third, a use case was analyzed dealing with the integration of wood gasification and BioSNG (Synthetic Natural Gas) production into Austrian flows of SBP. The results indicate that SBP supply reacts unit-elastic to sawnwood exports, while both supply and demand respond inelastic to SBP prices. Demand is positively inelastic related to SBP as input in panel and pellet production. In a bioeconomy scenario, long-term supply would exceed demand, resulting in additional SBP to be used for gasification. A 100 MW BioSNG plant converting these SBP could provide 528 MWh BioSNG per year. This is a 11 % share of the Austrian target value of 5 TWh green gas.

Innovative synthetic natural gas production from biomass and renewable hydrogen: Evaluation and optimization with sustainability perspective

Synthetic natural gas has a promising potential to contribute in sustainable supply of the natural gas and mitigating the intermittence issue of renewable energy sources. This study presents a novel system for synthetic natural gas production from biomass and renewable electrolytic hydrogen. A novel biomass and renewable electricity driven synthetic natural gas production system is presented. Hydrogen, an important input of the system, is supplied by biomass gasification and water electrolysis driven by renewable energy. Integrated system of photovoltaic panels and wind turbines supplies the required electricity of the system. An oxygen-steam mix is utilized as the gasification agent. An ion transport membrane is employed for oxygen production as an alternative to an expensive and complicated air separation unit. A comprehensive thermodynamic and economic analysis of the system is carried out. All equipment and ancillary costs are considered. Since solid carbon generation can lead to deactivation of the methanation reactor catalysts, the potential for solid carbon generation is considered for practicality. Multi-objective optimizations of different scenarios, are performed to determine the optimal economical and technical performance of the system. The optimization results indicate that the minimum cost for producing synthetic natural gas is 0.28 $/kWh. Furthermore, the heating value of synthetic natural gas is 41,500 kJ/kg, which closely approximates that of natural gas. Additionally, the price of the produced synthetic natural gas is lower than the price of natural gas in certain countries. In Sweden and the Netherlands, synthetic natural gas costs are notably 36% and 10% lower than conventional natural gas. However, in Germany, Austria, and Denmark, synthetic natural gas prices closely align with conventional natural gas rates, reflecting regional market variations.

Synthetic natural gas (SNG) production with higher carbon recovery from biomass: Techno-economic assessment

Due to the growth in the share of renewable energy sources (RES) in the power generation sector worldwide and their intermittency, storage of surplus electricity is needed. The technology known as Power to X (PtX) facilitates the extended storage of excess electricity by converting it into gaseous or liquid fuels such as hydrogen, methane, ammonia, or methanol. This study examines the potential of synthetic natural gas (SNG) technology as a viable energy storage solution. The paper introduces three distinct SNG production systems, all of which are based onthe processes of biomass gasification and methanation. Case 1 assumes further CO2 capture from generated SNG, and Cases 2 and 3 additionally assume hydrogen production and almost complete CO2 utilization by syngas hydrogenation via the methanation process. The methanation process converts syngas and hydrogen into SNG with a high methane content (>90 vol% dry), that can be injected into the natural gas grid. The thermodynamic and economic potential of SNG production systems is presented in this work. The simulations were conducted using the AspenONE software. The methanation process was analyzed for various design conditions such as methanation temperature and pressure, and different H2:CO, and H2:CO2 ratios. The estimated cold gas efficiency of proposed SNG production systems varies from 63.27% to 77.10% and can be increased up to about 69.10–75.58% when the recovery of heat from methanation is considered. A sensitivity analysis was conducted to determine the break-even price of SNG, considering different scenarios for the costs of feedstock, specifically biomass and electricity. The results indicate that under the most optimistic conditions, the break-even price of SNG is estimated to be 115 €/MWhSNG, 58€/MWhSNG and 67 €/MWhSNG for Cases 1, 2, and 3, respectively.

Carbon recovery from biogas through upgrading and methanation: A techno-economic and environmental assessment

Reducing the use of fossil fuels is an essential measure to counteract the rise in greenhouse gas emissions. In this context, biofuels and e-fuels make an important contribution to achieving climate neutrality targets, especially if their distribution can take place within existing infrastructure, as in the case of methane.The aim of this work is to carry out a techno-economic and environmental assessment of the combined production of biological and synthetic methane in a wastewater treatment plant (WWTP). Methane yield from biogas, usually associated only with biogas upgrading, is enhanced by recovering CO2 to produce additional synthetic natural gas (SNG) through a methanation process. The analysis is applied to a medium-sized WWTP in Italy, whose biogas production profile is known throughout the year.In the current scenario, SNG is not competitive on the gas market. The investment costs of the technologies and the electricity price are then varied in order to better investigate the profitability of SNG production. The results show that, considering long-term cost projections and an electricity price of about 50 €/MWh, SNG can become competitive, with a production cost of 1.4 €/Sm3. Finally, the environmental competitiveness of SNG (direct and indirect CO2 emissions) with respect to fossil natural gas is investigated: results are shown as a function of the carbon intensity of grid electricity and the share of local renewable energy. To make SNG environmentally sustainable, the renewable share must increase to 46% or, alternatively, the carbon intensity of grid electricity must decrease to 187 gCO2eq/kWh.

Synthetic natural gas production through biogas methanation using a sorption-enhanced reaction process

Using CO2 from biogenic sources to produce fuels is one of the most attractive applications in climate change mitigation, as it leads to the replacement of fossil fuels and contributes to the circular economy. By this means, the primary purpose of this paper is to design a biogas methanation process to produce synthetic natural gas (SNG) suitable to be fed into the gas grid. In this way, a SERP process was proposed in which the equilibrium is overcome by eliminating the co-produced water using a selective adsorbent, such as zeolite 3A. For this purpose, two different catalysts were (NiAl2O3 and Ni5A) and compared with a commercial catalyst. First, the catalytic performance of the three catalysts was studied in an experimental setup, discarding the Ni5A catalyst due to its lower reaction yields. Subsequently, a sorption-enhanced reaction process (SERP) was designed by simulation using the experimental kinetic data obtained and a theoretical model of reaction/adsorption cycles design. The PSASIM software, previously registered by the research group, was used for the simulation. The proposed process consisted of three main stages: a first reaction/adsorption stage where the biogas was upgraded to SNG with the corresponding water adsorption by the catalyst/adsorbent, and a second and third stages (purge and rinse) where the retained water in the adsorbent is desorbed and eliminated from the process. The process variables studied were temperature and biogas composition fed to the process. Finally, at 488 K and a residual waste biogas composition (55–60 % CH4), CO2 conversions of 99.55 % and selectivities towards methane of 99.99 % were achieved using NiAl2O3-zeolite3A mixture. In addition, the purity of the methane produced was 98.6 % molar in the product.

Comparative cost analysis of Synthetic Natural Gas distribution pathways in the context of Nepal

Synthetic Natural Gas (SNG) produced using Green Hydrogen, and carbon dioxide not only helps to reduce the harmful greenhouse gas emission but also can help Nepal to reduce its dependency on imports for fuel used in the industrial sector. For Nepal to utilize its full potential in Green Hydrogen for industries and household cooking, SNG can be an attractive alternative due to its storage, transmission, and controlled combustion advantages. Europe has been a frontier in SNG production, relying on its already-built Natural Gas network for distribution. Unlike Europe, Nepal doesn’t have any previously built gas pipeline network. Large biogas plants distribute the produced gaseous bio-CNG in cylinders. But unlike LPG, which can be liquified through pressurization (836 kPa at 20°C) only, SNG can only be liquified cryogenically (-162°C at 20 kPa), which requires a tremendous amount of energy. This study compares the costs of the distribution of SNG in gaseous form through gas pipelines and cylinders. A case study is performed in the Butwal Industrial Area of Nepal, in which data is gathered from primary and secondary sources to design the gas pipeline network and estimate the costs associated with distributing SNG using both pipelines and cylinders. It has been found that the capital cost (CAPEX) and the annual operating cost (OPEX) are significantly lower for pipeline distribution compared to the distribution using cylinders. The Net Present Value (NPV) of total costs for pipeline distribution was found to be NPR 12,002,821 compared to NPV of NPR 35,417,390 for cylinder distribution. Hence, distributing produced SNG using pipelines is more cost-effective than distributing using cylinders inside the industrial area of Nepal.

Process modeling and integration of hydrogen and synthetic natural gas production in a kraft pulp mill via black liquor gasification

The black liquor gasification integrated to chemical plants has shown potential for reducing the process irreversibility and promoting the decarbonization of this industrial sector. In the integrated chemical plants proposed in this work, the purpose is co-producing pulp and gaseous fuels, either hydrogen or synthetic natural gas, in order to expand the biorefinery product portfolio and, consequently, increase the plant revenues. However, due to additional equipment and utility demands, along with the uncertainty about the prices of the commodities; the benefits of the integrated setups must be thoroughly weighed by considering thermodynamic, economic and environmental indicators before the retrofit of the existing configuration is implemented. The exergy method is used along with the energy integration technique and other financial indicators to determine whether and in which scenarios the integrated biorefineries would be more attractive. The average exergy efficiency of the integrated chemical production plants is 44%, which is higher than that of the conventional case (40%). The balance of the overall CO2 emissions vary from 1.97 to −0.56 tCO2/tPulp, for the conventional and integrated setups, respectively. An incremental financial analysis under uncertainty also shows that the hydrogen production route with partial import of electricity and carbon taxations above 60 EUR/tCO2 outperforms the other scenarios. Therefore, the import of electricity from low-carbon grids and the upgrade of biorefinery residues arise as key factors for ensuring the sustainable production of traditionally fossil-based chemicals under more stringent environmental regulations.

Utilisation of Renewable Electricity to Produce Synthetic Methane

This study demonstrates the production of synthetic methane or synthetic natural gas via methanation of carbon dioxide (CO2), which could replace natural gas. For the power-to-methane (P2M) process, a simulation of two-stage methanation with simultaneous power generation was carried out in Aspen Plus. The process is based on an assumed production capacity of 1 t/h of synthetic methane and is also capable of simultaneous methanation of CO2 and biogas. The biogas flow rate was estimated from industry data. When co-methanation is carried out, it is possible to produce up to 1.3 t/h of synthetic methane. After the production of synthetic methane, compression of the product was added to the process scheme, followed by dehydration. The dehydration of the synthetic methane was carried out via dynamic simulation in Aspen Adsorption. The steady-state operation was determined. The final dehydrated product contained on average only about 4.85 × 10−4 mol.% water (H2O) and the methane (CH4) contents were above 97 mol.%, providing a composition suitable for injection into the pipelines of many European countries.

Validation of and Simulations using a High-Temperature Electrolysis Model

Efforts for increasing the share of renewable power generation are dramatically boosted since electrical power from fossil fuels has been used as weapon [1]. Therefore, efficient conversion systems are of great importance to conserve most of the delivered power by nature. High-temperature electrolysis is such an efficient type of energy conversion system compared to similar technologies [2-4]. To bridge the gap to an industrial scale application, the electrochemical and chemical processes have to be understood in detail which is enlightened by some publications from our group [5-8]. In this contribution, a multiphysics model for three types of electrolysis processes (steam, CO2 and co-electrolysis) is presented and evaluated. Relevant parameters like the exchange current density or the anodic / cathodic transfer coefficient including parameter variations for the inlet gas stream, flow rate of the gas, temperature and applied current are investigated. For the microscale properties in the functional layer, Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) is used with the “Slice and View” technique [9,10]. Extracting information like the Triple Phase Boundary Length (TPBL), the fraction of electronic and ionic phase in mixed ionic-electronic conducting (MIEC) materials or the porosity and tortuosity of the (La,Sr)CoO3-δ (LSC) air electrode and the Ni / 8 mol% yttria stabilized zirconia (Ni-8YSZ) fuel electrode help in enhancing the modeling quality of high-temperature SOC model. A conversion from the TPBL (s. Figure 1) to an active area to volume ratio for the computation is needed.Calculated iV-characteristics and experimental curves are compared and serve as a validation for (I,V) data points at higher currents. Depending on the degree of agreement, the (missing) main contributions to loss mechanisms can be identified and initiate a feedback loop for material optimization. Sensitivity analyses are carried out for parameters that are difficult to vary in experiments (e.g. porosity). Porosity and tortuosity parametrize the porous structure for a homogeneously distributed property assumption across the material layers. The ratio between electronic and ionic phase fine-tunes the positioning of iV-characteristics within the potential regime of Ohmic and polarization losses. Calculated electrochemical impedance spectra (EIS) enhance the insight into the theoretical system and may be compared to experimental spectroscopy data via Equivalent Circuit Models (ECM). Calculated data from the model are acquired as in the used experimental setup. As an example, calculated EIS data from steam electrolysis show good agreement with a R-(RQ)4 ECM which as well describes most of the corresponding experimental data in our group. Effects of degradation are envisioned to be incorporated into the model as well.[1] Hosp, G.; Höltschi, R.; Keusch, N.; Schürpf, T.: https://www.nzz.ch/wirtschaft/rohstoffe-als-waffen-die-neusten-entwicklungen-ld.1681268 (28th October 2022, 2.13 pm)[2] Foit, S.R.; Dittrich, L.; Duyster, T.; Vinke, I.; Eichel, R.-A.; de Haart, L.G.J. (2020): Direct Solid Oxide Electrolysis of Carbon Dioxide: Analysis of Performance and Processes. In: Processes 8 (11), 1390[3] Foit, S.R.; Vinke, I.C.; de Haart, L.G.J.; Eichel, R.-A. (2017): Power-to-Syngas: An Enabling Technology for the Transition of the Energy System? In: Angew. Chem. Int. Edit. 56 (20), 5402–5411[4] Tanaka, Y.; Hoerlein, M.P.; Schiller, G. (2016): Numerical simulation of steam electrolysis with a solid oxide cell for proper evaluation of cell performances. In: Int. J. Hydrogen Energ. 41, 752–763[5] Wolf, S.E.; Dittrich, L.; Nohl, M.; Duyster, T.; Vinke, I.C.; Eichel, R.-A.; de Haart, L.G.J. (2022): Boundary Investigation of High-Temperature Co-Electrolysis Towards Direct CO2 Electrolysis. In: J. Electrochem. Soc. 169, 034531[6] Unachukwu, I.D.; Vibhu, V.; Vinke, I.C.; Eichel, R.-A.; de Haart, L.G.J. (2022): Sr Substituted La2-xSrxNi0.8Co0.2O4+ d (0 ≤ x ≤ 0.8): Impact on Oxygen Stoichiometry and Electrochemical Properties.In: Energies 15, 2136[7] Mebrahtu, C.+; Nohl, M.+; Dittrich, L.; Foit, S.R.; de Haart, L.G.J.; Eichel, R.-A.; Palkovits, R. (2021): Integrated Co-Electrolysis and Syngas Methanation for the Direct Production of Synthetic Natural Gas from CO2 and H2O. In: ChemSusChem 14, 2295 – 2302[8] Dittrich, L.; Nohl, M.; Jaekel, E.E.; Foit, S.R.; de Haart, L.G.J. (Bert), Eichel, R.-A. (2019): High-Temperature Co-Electrolysis: A Versatile Method to Sustainably Produce Tailored Syngas Compositions. In: J. Electrochem. Soc. 166 (13), F971 – F975[9] Wilson, J.R.; Kobsiriphat, W.; Mendoza, R.; Chen, H.; Hiller, J.M.; Miller, D.J.; Thornton, K.; Voorhees, P.W.; Adler, S.B.; Barnett, S.A. (2006): Three-dimensional reconstruction of a solid-oxide fuel-cell anode. In: Nat. Mater. 5, 541–544[10] Gostovic, D.; Smith, J.R.; Kundinger, D.P.; Jones, K.S.; Wachsman, E.D. (2007): Three-Dimensional Reconstruction of Porous LSCF Cathodes. In: Electrochem. Solid St. 10 (12), B214–B217Figure 1: Histogram of the TPBL from a 400 image sample set of a FIB-SEM cut of a Ni-8YSZ electrode. Figure 1

Deployment of integrated Power-to-X and CO2 utilization systems: Techno-economic assessment of synthetic natural gas and methanol cases

Achieving the climate neutrality requires decisive actions in curbing CO2 emissions. Various possible strategies can be exploited for this target such as boosting renewable sources, increasing energy efficiency for both conversion and utilisation steps, deploying Carbon Capture, Utilization and Storage (CCUS) applications. Power-to-X (P2X) and CO2 utilization technologies got significant attention as options to reduce fossil CO2 emissions and produce sustainable chemicals. This work assesses large-scale synthetic natural gas (SNG) and methanol production from renewable H2 and captured CO2 from a techno-economic perspective. Sizes of investigated systems are 500 MWth for the SNG case and 100000 t/y for the methanol case to be relevant from an industrial perspective. The assessed concepts were modelled and simulated in a thermally integrated design for optimization of the overall energy utilization. The key performance indicators were calculated based on overall mass & energy balances. As results show, the SNG and methanol production systems from green H2 and captured CO2 have high energy efficiency (e.g., about 54–58 %) and very high CO2 conversion yields (about 96–99 %). From an economic point of view, these solutions are not yet competitive to existing fossil-based systems (e.g., production costs are about 16 €/GJ for SNG and about 755 €/t for renewable methanol compared to average 10 €/GJ for natural gas and 450–500 €/t for fossil methanol).

Experimental investigation of hydrogen-intensified synthetic natural gas production via biomass gasification: a technical comparison of different production pathways

AbstractA sustainable and secure energy supply requires alternative concepts for energy generation. Utilizing biomass to produce synthetic natural gas (SNG) allows the synthesis of a currently widely used energy carrier on a renewable basis. The additional integration of hydrogen increases the carbon utilization of the biomass. This study experimentally investigates and compares the production of raw-SNG in three novel process chain configurations combining the advanced dual fluidized bed (DFB) gasification technology, gas cleaning units, and a fluidized bed methanation reactor. The three process chains comprise the direct methanation of DFB product gas, a hybrid route with hydrogen addition to the DFB product gas, and the methanation of a hydrogen-enriched product gas generated through DFB gasification with in situ CO2 removal (SER process). The direct methanation of the DFB product gas yielded a raw-SNG CH4 content of 40 vol.-%db at 360 °C and atmospheric pressure conditions. Through the integration of external hydrogen in a hybrid process, the carbon utilization of the biomass could be increased from 37% to around 70% at an unchanged cold gas efficiency of 58–59%. Via the SER process, a high raw-SNG CH4 content of 70 vol.-%db was achieved at an increased cold gas efficiency of 66% without the need for external hydrogen. Finally, a comparison points out the main advantages of the process configurations and provides a decision basis for novel SNG production pathways.

Systematic Determination of Optimal Design-Points of Fully Integrated Power-to-SNG Process Chains Via Detailed Simulation of SOEC Stacks

The denomination Power-to-SNG covers technologies for the production of synthetic natural gas (SNG) through methanation of electrolytic hydrogen and captured carbon, enabling long-term storage of electrical energy from intermittent renewable sources. A methodology leveraging the pinch method for the optimization of the operating conditions of power-to-SNG plants is presented and applied to a system layout comprising a series of fixed-bed methanation reactors, a biomass gasification process and solid oxide electrolysis cell (SOEC) stacks, which recover the heat produced by the exothermic methanation process. For the system optimization, a rapid SOEC stack model is built from an underlying detailed multi-physics 3D model whilst maintaining its accuracy. Simulations reveal a maximum system HHV efficiency of 85.2% while identifying optimal operating conditions for all plant components. Moreover, the necessity of integrated system optimization strategies is showcased, as the predicted ideal conditions in the system strongly differ from the optimal conditions of the isolated components.