Greenhouse Gases: Science and Technology最新文献

Acid gas injection is one of the most effective strategies to deal with waste gas generated during the development of sour oil and gas reservoirs. This study numerically investigates the effect of H₂S content on the acid gas migration and storage in shale reservoirs. The results indicate that the variations of acid gas density, viscosity, solubility, relative permeability, and capillary pressure caused by different H₂S contents have great influence on the acid gas plume migration. When acid gas is in gas state, the maximum horizontal flow appears at the lower part of the reservoir after 5 years, and the horizontal migration distance first decreases and then remains unchanged with the increase of H₂S content. Hereafter, the maximum horizontal migration distance appears at the top of the reservoir, and the horizontal migration distance first increases and then remains unchanged with the increase of H₂S content. When acid gas is in liquid state, the maximum horizontal migration distance appears at the lower part of the reservoir in the early stage of injection. The horizontal migration distance decreases with the increase of H₂S content. Subsequently, the maximum horizontal migration distance first decreases and then increases. The vertical migration distance increases gradually with the increase of H₂S content until the acid gas reaches the top of the reservoir, and then the vertical migration distance remains unchanged. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

This study evaluates greenhouse gas (GHG) emissions and reduction potential from municipal solid waste management (MSWM) following the IPCC 2006 guidelines. Under different MSWM scenarios of Phnom Penh municipality, this study quantifies GHG emissions from transportation, open burning, composting, recycling, anaerobic digestion (AD), incineration, and landfilling municipal solid waste. The study also considers the GHG emissions avoided as a benefit of recycling and electricity generation from incineration and AD. Various waste separation rates are used to evaluate the effectiveness of source segregation in GHG mitigation. The results show that the most significant net GHG emission saving is under scenario 5, avoiding about 1.15 M kg CO₂-eq/day with treatment affords 389 t/day of organic waste, 714 t/day of mixed recyclables, 777 t/day of digestible food waste, and 1,280 t/day of commingled waste via composting, recycling, AD, and incineration, respectively. The worst-case scenario represents the current MSWM method, which generates the highest GHG emissions of 3.13 M kg CO₂-eq/day. This is due to the open burning of uncollected waste (211 t/day) and landfilling (2,835 t/day). Based on the analysis, an integrated MSWM system along with source separation for recycling and resource recovery purposes is highly recommended as it leads to the most significant reduction in environmental impacts. The findings of this study provide valuable insights into the practical implications of policy frameworks for MSWM, specifically in terms of GHG emissions reduction. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Mitigation of nitrous oxide (N₂O) emissions is of primary importance to meet the targets of reducing carbon footprints of wastewater treatment plants (WWTPs). This paper takes the N₂O discharged from a case study of wastewater treatment plants as the main research object, and then develops a novel algorithm, which can accurately estimate the amount of N₂O release, and then applies it to the local wastewater treatment plants. According to the results, the nitrous oxide emission flux and the emission factors (EFs) are discussed. The results include the following: (1) The total amount of N₂O discharged from Xiamen wastewater treatment plants between 2018 and 2019 was 3881.29 kg and 3642.97 kg, respectively; (2) the production of N₂O emissions based on the total nitrogen (TN) algorithm in the existing wastewater treatment factories in Xiamen was obtained based on the research EFs; and (3) by controlling other factors of WWTPs process such as chemical oxygen demand /nitrogen (COD)/ (N) ratio, dissolved oxygen (DO) concentration, pH value (the degree of concentration of hydrogen ions), and solids retention time (SRT) in the wastewater treatment process, selecting a secondary wastewater treatment process with an economical and reasonable approach can reduce N₂O emissions in the wastewater treatment process. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

The conversion of CO₂ into valuable chemicals to reduce greenhouse gas emissions has received extensive attention. Converting CO₂ into pharmaceutical intermediates via graphitic carbon nitride (CN) at atmospheric pressure is a challenge. In this work, a series of novel graphitic carbon nitrides (K-CN) catalysts with different doping ratios of K were synthesized by post-treatment of CN with KOH as a dopant under magnetic stirring. Herein, substrates of o-phenylenediamine with different electron-donating/withdrawing groups were employed to convert CO₂ into high-value heterocyclic benzimidazoles. The optimal reaction conditions were determined by a single factor optimization approach. A series of benzimidazole derivatives were synthesized with a yield of up to 96% under atmospheric pressure, indicating that the catalyst can efficiently fix CO₂. This work not only designs a simple and low-cost K-CN catalyst but also provides a new pathway for converting CO₂ into valuable benzimidazole derivatives at atmospheric pressure. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

In this paper five bimetallic Fe₂O₃-MnO₂ oxygen carriers supported on TiO₂ were evaluated for direct hard coal combustion via chemical looping path. The oxygen carriers were obtained via mechanical mixing and high-temperature calcination. The samples contained varying amounts of Fe₂O₃ (20–50 wt.%) and MnO₂ (65–30 wt.%) but an identical amount of inert material (15 wt.%). Both the impact of the oxygen carrier's composition and the process temperature on their reactivity with the selected hard coal were evaluated. The amount of manganese in the oxygen carriers correlated positively with their reactivity toward the fuel. It was concluded that after eight reaction cycles the oxygen carriers remained resilient for side reactions with the ash residue. Thus, the physicochemical stability of the presented oxygen carriers was proved. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Chemical looping applications offer a variety of options to decarbonise different industrial sectors, such as iron and steel and hydrogen production. Chemical looping with water splitting (CLWS) is a chemical looping technology, which produces H₂ while simultaneously capturing CO₂. The selection of oxygen carriers (OCs) available to be used in CLWS is finite, due to the thermodynamic limitations of the oxidation with steam for different materials at the relevant process temperatures. Iron-based materials are one of the most widely studied options for chemical looping combustion (CLC), touted for their relative abundance and low cost; likewise, for CLWS, iron is the most promising option. However, when the reduction of iron oxide (Fe₂O₃) is extended to wüstite (FeO) and iron (Fe), agglomeration and sintering problems are the main challenge for fluidisation.

This work presents iron and tungsten mixed oxides as the OCs for a family of chemical looping applications. The OCs were produced via co-precipitation; performance assessment was conducted in a thermogravimetric analyser and a lab-scale fluidised bed reactor over continuous redox cycles. The use of tungsten combined with iron results in a solid solution of tungsten within the Fe₂O₃ matrix that produced a more mechanically stable material during operation, which performed well during multiple redox cycles with no apparent decrease in the oxygen transport capacity and showed no apparent agglomeration. Furthermore, materials containing tungsten showed a resistance to carbon deposition, whereas the reference Fe₂O₃ showed peaks of CO and CO₂ during the oxidation period, thus indicating carbon deposition. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Geologic carbon storage (GCS) is an increasingly important technology for reducing carbon dioxide (CO₂) emissions to the atmosphere. The leakage risks associated with GCS are an environmental and human health concern, however, and site operators must develop contingency plans that thoroughly consider leakage risks and identify potential mitigation strategies. Here, we use a GCS system model (the National Risk Assessment Partnership's Open-Source Integrated Assessment Model, NRAP-Open-IAM) to evaluate different contingency plans for a hypothetical GCS site. In the scenario considered, an unplugged legacy well is discovered near the site after 5 years of CO₂ injection. Our simulations show that the planned operation has a relatively high chance of causing brine leakage through the legacy well and into the two overlying aquifers, the shallower of which has potable water—an unacceptable outcome. To reduce this risk, we consider five remedial response scenarios that manipulate reservoir pressures through brine extraction, injection rate reduction, and early injection stopping. NRAP-Open-IAM is used to quantify the degree to which each scenario reduces the probability of brine leakage at the site amidst reservoir uncertainty. Evaluation of the different scenarios suggests that reduction of injection rates effectively reduces leakage risks while maintaining a substantial fraction of the initially intended cumulative CO₂ storage. In the event of an emergency, the reservoir pressure management strategies considered here can provide operators more time while they pursue a more permanent solution. The analyses demonstrated here fit into a larger workflow we propose for evaluating the contingency plans of GCS sites. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Carbon dioxide capture and geologic storage (CCS; geologic sequestration) is a promising technology for reducing anthropogenic greenhouse gas emissions to the atmosphere from industrial point sources. Aspects of CCS have been investigated for over two decades, and many large- and small-scale geologic storage field demonstration projects are now underway globally. Interest in offshore CCS has been increasing in recent years (e.g., European Union, Australia, Japan, and the United States). Deep geologic storage in offshore settings is analogous to onshore CCS activities in many respects (i.e., geologic and geotechnical aspects), but is distinct from previously explored seabed sediment CO₂ storage) or deep marine dissolution). Given the large subsurface geologic storage volumes available in offshore settings, much discussion of offshore CCS is focused on the benefits and risks of such activity compared to onshore settings. Similar to onshore settings, existing (legacy) wells likely present the most direct migration pathway and largest risk of noncontainment in offshore settings. As part of current studies to evaluate geologic storage options in offshore settings along the Texas coast and greater Gulf of Mexico (GoM), mapping of the geographic distribution and ages of wells in a region containing coastal counties and extending 30 miles offshore Texas indicates that both well spatial density and well age decrease moving from onshore to offshore. Results suggest reduced risk of leakage owing to more rigorous and documented well completion and abandonment practices for these generally younger wells (although many are decades old). A result of decreased well density is that larger areas are available for leasing for CCS projects that avoid legacy wells altogether (> 1 mile from any existing well). The one-mile designation is used as an arbitrary convention, and while it is recognized that this is smaller than a typical area of review (AoR) for permitting, each site will have a different AoR radius for consideration. The combination of large subsurface storage volumes under control of a single landowner and reduced risks from legacy wells makes offshore CCS attractive in the GoM. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.