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Advanced Fossil Fuel Power Systems
Published in D. Yogi Goswami, Frank Kreith, Energy Conversion, 2017
One can, however, take the coal gasification one step further and add one more process to convert syngas to nearly pure methane. This process is called methanation, which converts H2, CO, and CO2 into methane and water/steam. The resulting substitute natural gas (SNG) can then be burned in a local gas turbine–based power plant or can be transported to a power plant in a distant location via an existing natural gas pipeline. The basic process thermodynamics can be found in [48].
Biorefineries
Published in M.R. Riazi, David Chiaramonti, Biofuels Production and Processing Technology, 2017
Isabella De Bari, Daniela Cuna, Nicola Di Fidio, M.R. Riazi, David Chiaramonti
In addition to liquid biofuels, syngas can be converted to natural gas. The process is known as SNG, or substitute natural gas. SNG is rich in methane and can be distributed into the grid. The conversion of biomass into SNG takes place in several steps: gasification of biomass, water-shift conversion to adjust the ratio between CO and H2, and methanation over suitable catalysts. Haldor Topsøe offers cost-efficient technologies to produce SNG from cheap carbonaceous feedstocks.
Feedstock Preparation by Gasification
Published in James G. Speight, Handbook of Petrochemical Processes, 2019
The kinetics of the rapid-rate reaction between gaseous hydrogen and the active intermediate depends on hydrogen partial pressure (PH2). Greatly increased gaseous hydrocarbon derivatives produced during the initial feedstock gasification stage are extremely important in processes to convert feedstock into methane (synthetic natural gas, substitute natural gas (SNG)).
Power sector asset stranding effects of climate policies
Published in Energy Sources, Part B: Economics, Planning, and Policy, 2019
Deger Saygin, Jasper Rigter, Ben Caldecott, Nicholas Wagner, Dolf Gielen
This study presents the first assessment of the stranded asset value in the global power sector between 2015 and 2050 under a decarbonization scenario driven by accelerated renewable energy and energy efficiency. By applying a simplified bottom-up methodology to analyze stranded assets on a country-basis, we estimate that globally more than 2,000 GW fossil fuel-fired electricity generation capacity would be stranded in this period in the REmap Case. The high-end value related to this stranded capacity is estimated at USD 927 billion. If climate policy action to meet the Paris Climate Agreement goals is delayed until 2030, the stranded asset value doubles. Stranded coal assets would represent around three-quarters of the total stranded assets in both cases and China would account for 45% of stranded assets in the REmap Case. Results depend on assumptions on asset lifetime and the timing of emission reductions objectives. Countries’ short-term actions in relation to their long-term objectives should depend on the age of their assets as shown by the example of China. The annual average stranded assets volume between now and 2050 equals 20–40% of the current annual investment volume in thermal power generation. This comparison suggests that the utility sector may be affected significantly. This highlights the critical role of early action and development of alternative investment strategies that minimize stranded asset risks in the power sector. These findings provide a new aspect of the economics of energy transition and should therefore be accounted for in the design of new energy and climate policies. There are several technology and policy strategies to reduce the value of stranded assets in the power sector while still achieving energy sector decarbonization, for example hydrogen that can substitute natural gas in existing gas pipeline system with limited investment needs or biomass combustion in coal power plant. The trade-offs between these strategies should be assessed in line with the findings of this paper.
Progress and utilization of biomass gasification for decentralized energy generation: an outlook & critical review
Published in Environmental Technology Reviews, 2023
Deepak Kumar Singh, Reetu Raj, Jeewan Vachan Tirkey, Priyaranjan Jena, Prakash Parthasarathy, Gordon Mckay, Tareq Al-Ansari
Entrained flow gasifiers are a type of gasification system used to convert solid or liquid feedstocks into gaseous fuel called syngas (synthesis gas). In an entrained flow gasifier, the feedstock is suspended in a high-velocity stream of gas, typically oxygen or air, and undergoes rapid combustion and gasification. Entrained flow gasifiers can process a wide range of feedstocks, including coal, petroleum coke, biomass, and waste materials. This flexibility allows for the utilization of diverse carbonaceous resources. The feedstock is typically ground into a fine powder or atomized as a liquid to facilitate suspension and thorough mixing with the gasifying agents. The small particle size enables rapid reaction rates and efficient conversion of the feedstock. Entrained flow gasifiers operate at high temperatures, typically ranging from 1,200 to 1,600 °C [105]. These elevated temperatures ensure the complete gasification of the feedstock and promote the breakdown of complex organic molecules into syngas components. In entrained flow gasifiers, the gasifying agent can be pure oxygen or air. Pure oxygen gasifiers offer higher syngas quality and increased process efficiency, while air gasifiers are more common and cost-effective. The gasifier typically consists of a vertical cylindrical vessel with a burner at the bottom and a syngas outlet at the top. The feedstock is injected near the burner and quickly entrained in the high-velocity gas stream, resulting in a plug flow pattern. The residence time of the feedstock in the gasifier is relatively short. The feedstock particles are rapidly heated and gasified in the oxygen-rich environment. The high temperatures and short residence time promote the conversion of the feedstock into syngas, which mainly comprises carbon monoxide (CO) and hydrogen (H2). The syngas may also contain small amounts of methane (CH4) and other trace gases. The high temperatures in entrained flow gasifiers lead to the melting of inorganic constituents in the feedstock, forming a molten slag. The slag flows downward and is collected at the bottom of the gasifier, aiding in the removal of impurities and protecting the gasifier walls. Entrained flow gasifiers are known for their high gasification efficiency, with the ability to convert a large portion of the carbon in the feedstock into syngas [106]. The rapid and thorough mixing of the feedstock with the gasifying agents and the high temperatures contribute to this efficiency. The syngas produced in entrained flow gasifiers typically requires cleanup processes to remove impurities, such as particulate matter, tar, sulfur compounds, and trace metals. These impurities can be detrimental to downstream applications or equipment and need to be eliminated or reduced. Entrained flow gasifiers are commonly used in large-scale industrial applications, including coal gasification for power generation, syngas production for chemical synthesis, and the production of substitute natural gas from various feedstocks. They offer high conversion efficiencies and are suitable for handling a wide range of feedstock types [107].