Showing papers on "Substitute natural gas published in 2019"

Power-to-Gas: Electrolysis and methanation status review

Abstract: This review gives a worldwide overview on Power-to-Gas projects producing hydrogen or renewable substitute natural gas focusing projects in central Europe. It deepens and completes the content of previous reviews by including hitherto unreviewed projects and by combining project names with details such as plant location. It is based on data from 153 completed, recent and planned projects since 1988 which were evaluated with regards to plant allocation, installed power development, plant size, shares and amounts of hydrogen or substitute natural gas producing examinations and product utilization phases. Cost development for electrolysis and carbon dioxide methanation was analyzed and a projection until 2030 is given with an outlook to 2050. The results show substantial cost reductions for electrolysis as well as for methanation during the recent years and a further price decline to less than 500 euro per kilowatt electric power input for both technologies until 2050 is estimated if cost projection follows the current trend. Most of the projects examined are located in Germany, Denmark, the United States of America and Canada. Following an exponential global trend to increase installed power, today's Power-to-Gas applications are operated at about 39 megawatt. Hydrogen and substitute natural gas were investigated on equal terms concerning the number of projects.

Enhanced low-temperature performance of CO2 methanation over mesoporous Ni/Al2O3-ZrO2 catalysts

Abstract: Converting carbon dioxide to value-added chemicals has been attracted much attention, whereas direct hydrogenation of CO2 to synthetic natural gas (SNG) at a lower temperature remains a big challenge. Mesoporous Al2O3-ZrO2 modified Ni catalysts were prepared via a single-step epoxide-driven sol-gel method for CO2 methanation. Almost 100% selectivity of CH4 with 77% CO2 conversion were obtained at a lower temperature of 300 °C, and no catalyst deactivation was observed in 100 h. Different characterization methods including N2 adsorption-desorption, H2-TPR, H2-TPD, XRD, XPS, and TEM were combined together to explore the interaction of Ni-ZrO2 and Al2O3-ZrO2. Incorporation of ZrO2 into Ni/Al2O3 weakened the Ni-Al2O3 interaction via the combination of Al2O3-ZrO2 solid solution, promoting the reduction and dispersion of NiO phase. The adding of higher Zr loading increased the amount of active metallic nickel sites and oxygen vacancies on the composite support, improving obviously the lower temperature catalytic activity and CH4 selectivity. Higher Ni species loading further resulted in the formation of active Ni sites and improved the low-temperature CO2 methanation performance. Moreover, the enhanced stability of the Al2O3-ZrO2 support and oxygen vacancies provided by the ZrO2 promoter could help to promote the catalytic stability.

Metal-oxide promoted Ni/Al2O3 as CO2 methanation micro-size catalysts

Abstract: The Power-to-Gas concept has the challenge to convert the excess of renewable electricity to synthetic natural gas, composed mainly by methane, through CO2 methanation. The superior heat transfer capacity of micro-structured reactors offers a suitable alternative for an efficient control of the reaction temperature. In the present work, the strategy of adding large amount of metal oxide promoters (15 wt.%) to nickel supported on micro-size catalysts (dp = 400–500 μm) is presented. The addition of CeO2, La2O3, Sm2O3, Y2O3 and ZrO2 was clearly beneficial, as the corresponding metal-oxide promoted catalysts exhibited higher catalytic performance than Ni/Al2O3 and the commercial reference Meth® 134 (T = 200–300 °C, P = 5 bar·g). This increase of catalytic activity is attributed to the higher amount of CO2 adsorbed on the catalyst. Among the selected promoters, La2O3 showed the highest catalytic activity (XCO2=+20% at 300 °C) due to the enhancement of nickel reducibility, nickel dispersion and the presence of moderate basic sites. In addition, Ni-La2O3/Al2O3 was stable for one week, while the unpromoted catalyst exhibited a slight decline in its activity. Accordingly, the technical catalyst proposed in this study could be used directly in compact reactors for CO2 methanation with much higher activity than the commercial reference.

Production of Synthetic Natural Gas From Carbon Dioxide and Renewably Generated Hydrogen: A Techno-Economic Analysis of a Power-to-Gas Strategy

Abstract: Power-to-gas to energy systems are of increasing interest for low carbon fuels production and as a low-cost grid-balancing solution for renewables penetration. However, such gas generation systems are typically focused on hydrogen production, which has compatibility issues with the existing natural gas pipeline infrastructures. This study presents a power-to-synthetic natural gas (SNG) plant design and a techno-economic analysis of its performance for producing SNG by reacting renewably generated hydrogen from low-temperature electrolysis with captured carbon dioxide. The study presents a “bulk” methanation process that is unique due to the high concentration of carbon oxides and hydrogen. Carbon dioxide, as the only carbon feedstock, has much different reaction characteristics than carbon monoxide. Thermodynamic and kinetic considerations of the methanation reaction are explored to design a system of multistaged reactors for the conversion of hydrogen and carbon dioxide to SNG. Heat recuperation from the methanation reaction is accomplished using organic Rankine cycle (ORC) units to generate electricity. The product SNG has a Wobbe index of 47.5 MJ/m3 and the overall plant efficiency (H2/CO2 to SNG) is shown to be 78.1% LHV (83.2% HHV). The nominal production cost for SNG is estimated at 132 $/MWh (38.8 $/MMBTU) with 3 $/kg hydrogen and a 65% capacity factor. At U.S. DOE target hydrogen production costs (2.2 $/kg), SNG cost is estimated to be as low as 97.6 $/MWh (28.6 $/MMBtu or 1.46 $/kgSNG).

CO2 Methanation: Principles and Challenges

Abstract: The power to gas (P2G) process has the potential to solve long-term and large-scale energy storage problems as well as reduce CO2 emissions. P2G involves CO2 methanation as a pillar of the process for the production of synthetic natural gas. Therefore, this chapter focuses on the principles and fundamental challenges of the CO2 methanation. In CO2 methanation, a catalyst facilitating high CO2 conversion and selectivity to CH4 needs to be utilized due to kinetic limitations. Ni-based catalysts are mostly studied for CO2 methanation because of their high activity and low cost. However, conventional alumina-supported Ni catalysts are easily deactivated as a result of sintering of Ni particles and coke deposition during the exothermic methanation reaction. Hence, a rational design of Ni-based catalysts with tailored properties is required. Subsequently, a brief explanation on hydrotalcite-derived materials and bimetallic catalysts as advanced Ni-based catalysts for CO2 methanation is presented.

Parametric Study of CO2 Methanation for Synthetic Natural Gas Production

Abstract: The production of methane by carbon dioxide hydrogenation through optimization of the operating parameters to enhance methane yield and carbon dioxide conversion in a two‐stage fixed bed reactor is investigated. The influence of temperature, gas hourly space velocity (GHSV), and H2:CO2 ratio on the production of methane is studied. In addition, different methanation catalysts in terms of metal promoters and support materials are investigated to maximize methane production. The results show that the maximum methane yield and maximum carbon dioxide conversion are obtained at a catalyst temperature of 360 °C with a H2:CO2 ratio of 4:1 and total GHSV of 6000 mL h−1 g−1catalyst and reactant GHSV of 3000 mL h−1 g−1catalyst. The optimum metal‐alumina catalyst investigated for CO2 conversion and methane yield is the 10 wt%‐Ni‐Al2O3 catalyst. However, reduction in the methane yield is observed with the addition of Fe and Co promoters because of catalyst sintering and nonuniform dispersion of metals on the support. Among the different catalyst support materials studied, i.e., Al2O3, SiO2 and MCM‐41, the highest catalytic activity is shown by the Al2O3 catalyst with 83 mol% CO2 conversion, producing 81 mol% CH4 with 98% CH4 selectivity.

Waste gasification processes for SNG production

Abstract: Gasification is the conversion of solid or liquid feedstock into useful and convenient synthetic gas (or syngas) that can be burned to release energy or used for production of high-value chemicals and fuels, including synthetic natural gas (SNG). When biomass or waste are used as gasification feedstock, large part of the biogenic carbon is retained in the final product, making it a perfect renewable (i.e., “bio”) alternative to fossil fuels. Bio-SNG, for example, is a product which can be fed into an already existing and also well-functioning infrastructure all over Europe and also in many other parts in the world. Therefore, bio-SNG is one of these products that has a large distribution potential and also allows a fast transition from a fossil-based to a renewable-based energy carrier. The production technology for SNG from syngas is also well known since decades and available in large scale which makes this process a possible candidate for frontrunner. The question is only, whether the reliable technologies for waste gasification and gas upgrading for supply of a suitable syngas ready for bio-SNG production can be established in the near future. This chapter will give an overview of the state of the art of waste gasification and will present promising technologies for further development.

Cost optimisation and life cycle analysis of SOEC based Power to Gas systems used for seasonal energy storage in decentral systems

Abstract: Chemical energy carriers and storage mechanisms will play a significant role in future energy systems. Apart from stabilising network fluctuations caused by renewable energy supply, chemical energy carriers also serve multiple sectors like electricity generation, chemical industry, transportation and shipping. Power to Gas (PtG) is a method that can be adapted for energy storage using chemical energy carriers produced from reserve electricity. This study contains the evaluation of long term energy storage in a decentral energy hub using a high temperature Power to Gas (PtG) plant. The Power to Gas process in this study uses surplus electricity for high temperature SOEC electrolysis. The resulting H2 undergoes methanation to generate Substitute Natural Gas (SNG) which has the same properties of natural gas and can be distributed using existing infrastructure. Compared to PtG processes using PEM or alkaline electrolysis, better overall process efficiencies up to 85% have been estimated for the high temperature PtG process. A pilot plant with thermally coupled SOEC-Electrolysis and Methanation was constructed as a part of the HELMETH project and is used in this study. Based on the experiments conducted in the pilot plant, the technical feasibility of long term energy storage and transient operations were evaluated. It was observed that short term energy storage with transient plant operation resulted in more operational costs when compared to long term storage with continuous plant operation. Novel methods to minimise the operational costs of the plant were also investigated using a dynamic pricing model and numerical optimisation of PtG plant. The numerical optimisation shows that if the duration of plant operation is adapted to target surplus renewable energy production, the concept could also be economically viable. Further, a life cycle analysis (LCA) of the PtG process was performed to evaluate the global warming potential (GWP) of the PtG plant configured with various input feeds. From the LCA, it was determined that if the input electricity is generated from sources with a global warming potential of less than 150 g CO2-eq/kWh, and carbon dioxide used for methanation is derived from biogenic sources, the PtG plant could act as a carbon sink.

Enhanced low-temperature catalytic carbon monoxide methanation performance via vermiculite-derived silicon carbide-supported nickel nanoparticles

Abstract: The methanation process is renowned worldwide and effectually employed for synthetic natural gas (SNG) production. It involves a highly exothermic reaction that can induce severe sintering of the catalyst and heavy carbon deposition, leading to catalyst deactivation. Thus, this process requires well-dispersed active metal catalyst components, improved thermal conductivity of the catalyst supports, and the lowest possible reaction temperature. Consequently, we successfully synthesized SiC ceramics with high specific surface areas and large pore volumes using vermiculite (VMT), and methanation catalysts comprising small Ni nanoparticles with mean diameter of 7.8 nm were produced on VMT-SiC supports by a conventional impregnation method. Contrastingly, Ni catalysts similarly prepared on commercially obtained SiC supports (Ni/VMT-SiC) demonstrated higher catalytic activity (CO conversion of 83.2% at 250 °C, pressure of 0.1 MPa, and gas hourly space velocity of 18 000 mL g−1 h−1) and stronger sintering resistance during long-term (50 h) low-temperature CO methanation experiments. Concisely, these improvements can be attributed to the superior thermal conductivity of SiC, high Ni dispersion and smaller Ni particle size, and strong metal–support interactions in the Ni/VMT-SiC catalysts. Moreover, we believe that this new insight will be worthy for future studies of CO methanation.

Techno-economic performance of sustainable international bio-SNG production and supply chains on short and longer term

Abstract: Synthetic natural gas (SNG) derived from biomass gasification is a potential transport fuel and natural gas substitute. Using the Netherlands as a case study, this paper evaluates the most economic and environmentally optimal supply chain for the production of biomass based SNG (so-called bio-SNG) for different biomass production regions and location of final conversion facilities, with final delivery of compressed natural gas at refueling stations servicing the transport sector. At a scale of 100 MWth, in, delivered bioSNG costs range from 18.6 to 25.9$/GJ(delivered CNG) while energy efficiency ranges from 46.8-61.9%. If production capacities are scaled up to 1000 MWth, in, SNG costs decrease by about 30% to 12.6-17.4$ GJ(delivered CNG)(-1). BioSNG production in Ukraine and transportation of the gas by pipeline to the Netherlands results in the lowest delivered cost in all cases and the highest energy efficiency pathway (61.9%). This is mainly due to low pipeline transport costs and energy losses compared to long-distance Liquefied Natural Gas (LNG) transport. However, synthetic natural gas production from torrefied pellets (TOPs) results in the lowest GHG emissions (17 kg CO(2)e GJ(CNG)(-1)) while the Ukraine routes results in 25 kg CO(2)e GJ(CNG)(-1). Production costs at 100 MWth are higher than the current natural gas price range, but lower than the oil prices and biodiesel prices. BioSNG costs could converge with natural gas market prices in the coming decades, estimated to be 18.2$ GJ(-1). At 1000 MWth, bioSNG becomes competitive with natural gas (especially if attractive CO2 prices are considered) and very competitive with oil and biodiesel. It is clear that scaling of SNG production to the GW(th) scale is key to cost reduction and could result in competitive SNG costs. For regions like Brazil, it is more cost-effective to densify biomass into pellets or TOPS and undertake final conversion near the import harbor. (c) 2018 Society of Chemical Industry and John Wiley & Sons, Ltd

Gas cleaning for waste applications (syngas cleaning for catalytic synthetic natural gas synthesis)

Abstract: In order to achieve the stringent requirements on syngas quality for synthetic natural gas (SNG) production, conventional and advanced gas-cleaning technologies are presented, grouping them in two main categories: cold and hot gas cleaning. Particular attention was directed at tars, representing one of the major drawbacks of gasification processes: these heavy hydrocarbons should be avoided by primary treatments or eliminated by secondary treatments. The former include the optimization of gasification conditions such as the choice of reactor type, operating conditions, use of bed additives, and modifications in the gasifier design. The secondary treatments consist of physical methods, thermal and catalytic conversion of tar. Each contaminant (sulfur, chlorine, alkali, etc.) has to be deeply removed to protect the catalyst used for downstream reaction. After gas cleaning, a gas-conditioning step is needed before methanation reaction to adjust the H2/CO ratio close to 3 (stoichiometry of methanation reaction) and to avoid carbon formation.