Greenhouse Gases: Science and Technology最新文献

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.

Carbon dioxide-enhanced water recovery (CO₂-EWR) is a promising strategy for managing reservoir pressure build-up and mitigating the risk of fault activation resulting from CO₂ injection in deep saline aquifers. CO₂-EWR can also be employed for supplying the required water for different applications after a treatment stage for the produced saline water. In this study, a brief review on CO₂-EWR technology and its necessities are first carried out. After that, the feasibilities, advantages, and challenges of various available treatment technologies that can potentially be used to treat high total dissolved solids (TDS) brine are comprehensively assessed. Based on comprehensive evaluation on technologies, a chain desalination process, consisting of pretreatment, main treatment, and post treatment, is proposed as a strategic path for the treatment of high TDS brine extracted from the Shenhua CCS site. It is concluded that coagulation-flocculation and gravity filtration are needed as primary stages to remove suspended particles, while membrane distillation (MD) is selected as a suitable main treatment technology for high TDS Shenhua brine. Then, MD treatment is comprehensively discussed for a small-scale treatment of extracted Shenhua brine assuming that the pretreated brine is free of suspended solids. After presenting the heat and mass transfer equations for direct contact membrane distillation (DCMD), a mathematical thermodynamic model is programmed in EES (Engineering Equation Solver) software to briefly analyze the performance parameters of DCMD. The results indicate that the designed DCMD, in the absence of auxiliary systems and considering the inherent temperature of extracted brine from different formations, has the capability of producing 15.1 kg m⁻²hr of freshwater from the extracted brine of the Shihezi formation layer. In the case of employing the auxiliary system of flat-plate collector (FPC) combined with heat exchanger (HX) to heat up the extracted Shenhua brine to the desired temperature of 80°C, the amounts of produced flux are enhanced by 133%, 72%, and 45% for the brine extracted from Liujiagou, Shiqianfeng, and Shihezi formations, respectively. Using the yearly solar radiation model in TRNSYS software, the maximum solar radiation on the tilted surface at the location of Shenhua project in Inner Mongolia Autonomous Region of China reaches 3800 kJ m⁻²hr at 1 PM on April 1. Considering maximum solar radiation on the tilted surface, it is proved that a small-surface FPC can supply the required energy to heat up the extracted brine from its inherent temperature to the desired temperature of 80°C. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Biomass conversion with carbon capture and storage (Bio-Energy CCS; BECCS) is one of the options considered for mitigating climate change. In this paper, the carbon capture technology chemical-looping combustion (CLC) is examined in which the CO₂ is produced in a stream separate from the combustion air. A central research topic for CLC is oxygen carriers; solid metal oxides that provide oxygen for the conversion process. Biomass and waste-derived fuels contain reactive ash compounds, such as potassium, and interactions between the oxygen carrier and the ash species are critical for the lifetime and performance of the oxygen carrier. This work develops and demonstrates an improved method for studying the interactions between ash species and oxygen carriers. The method uses a lab-scale reactor operating under fluidized conditions, simulating CLC batch-wise by switching between feed gas. The novelty of the setup is the integrated system for feeding solid particles of ash model compounds, enabling the simulation of ash species accumulating in the bed. Ilmenite is a benchmark oxygen carrier for solid fuel conversion and was used in this study to evaluate the method using K₂CO₃ as a model ash compound. Experiments were done at 850 and 950°C. Methane conversion in CLC cycles and fluidization was evaluated with gas analysis and pressure drop measurements. Scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD) analysis of bed particles were done after the experiments to establish changes in the morphology and composition of the ilmenite. The method for feeding the ash model compound was concluded to be satisfactory. At 950°C, K accumulated in the particles forming K-titanates and agglomeration was enhanced with K₂CO₃ addition. The agglomeration mechanism was solid-state sintering between the Fe-oxides forming on the particle surfaces. The bed defluidized at 950°C, but no such effect was seen at 850°C. The method is suitable for studying the Fe-Ti-K system with ilmenite and potassium without the influence of other ash species. © 2023 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd.

Electrostatic precipitator (ESP) is the main equipment for flue dust control of coal-fired power plants in China, accounting for about 70% of the total currently. In this paper, energy efficiency data of ESP, including 202 sets before ultra-low emission and 45 sets after ultra-low emission are systematically studied and analyzed by using the research method of field testing and technical investigation. The results showed that after ultra-low emission, the energy consumption and converted CO₂ emission of ESP in coal-fired power plants increased significantly, and the specific power consumption and energy consumption corresponding to unit mass particulate matter (PM) removal increased by 49.61% and 139%, respectively, and the converted CO₂ emission increased by 1.67 × 10⁻⁴ kg CO₂/m³ and 31.12 kg CO₂/t PM on average. The energy consumption of low-low-temperature ESP (LLT-ESP) was positively correlated with its emission reduction range. Before and after the gas cooler operation, the power consumption, specific power consumption and energy consumption corresponding to unit mass PM removal increased by 8.06%–38.68%, 10.66%–60.14% and 7.23%–62.98%, respectively, and the CO₂ emissions corresponded increased by 26.29–691.81 kg CO₂/h, 0.46–2.18×10⁻⁴ kg CO₂/m³, 1.10–23.62 kg CO₂/t PM, respectively. LLT-ESP had a great possibility to optimize the operation for energy-saving and carbon-reduction, because when the high voltage power supply operated on the maximum output mode and the energy-saving mode, the drop of power consumption and specific power consumption was around 52.00%–58.23%, 52.02%–58.29%, respectively, and the CO₂ emission reductions corresponded was 1,039.25–1,359.35 kg CO₂/h, 2.71–3.58×10⁻⁴ kg CO₂/m³, respectively. LLT-ESP also had the great optimizing possibility for energy-saving and carbon-reduction during low load operation, as when the load reduced from 100% to 50%, the specific power consumption and energy consumption corresponding to unit mass PM removal increased by 5.05%–45.50%, 6.59%–63.90%, respectively, and the CO₂ emissions corresponded increased by 0.38–2.44×10⁻⁴ kg CO₂/m³, 6.76–45.98 kg CO₂/h, respectively. The operation energy consumption can be effectively reduced by integrated use of multiple electric dust removal technologies, such as compared with LLT-ESP technology, the power consumption, specific power consumption and energy consumption corresponding to unit mass PM removal of “low-low-temperature + moving electrode+ electrostatic agglomeration” decreased by 37.88%, 30.08% and 45.29% respectively, and the corresponding CO₂ emission decreased by 697.22 kg CO₂/h, 1.87×10⁻⁴ kg CO₂/m³ and 32.98 kg CO₂/t PM, respectively.

Circular economy is beneficial to solve the conflict between the environment and development. The study combines the material flow in human society with the evaluation of the regional circular economy. Through the evaluation method combining DEA and rank-sum ratio, the development level of circular economy in this area is evaluated from both vertical and horizontal perspectives (time level and space level). The result shows: (1) from the point of view of material input, direct material input, total material demand and total material consumption all show an upward trend. The overall resource input is relatively large. (2) In terms of material output, the emission is increasing. But the growth rate is relatively slow. The emission reduction effect is outstanding. The resource output rate showed a continuous growth trend. Economic development is less dependent on the massive consumption of natural resources. (3) In terms of material circulation, the import volume of natural resources outside the province in the southwest region increased. Solid waste recycling is not high. (4) Judging from the evaluation results, the development level of Sichuan's circular economy is relatively stable. Followed by Chongqing and Guizhou. However, the level of development in Yunnan fluctuates greatly. The material consumption rate in Southwest China is higher than the economic growth rate. Resource input and resource consumption are still relatively large. Although some environmental indicators have improved, there are still serious resource and environmental problems in the future economic development of the western region that need to be paid attention. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Adsorption using bio-based adsorbents has been pointed out as an economical and environmentally benign technology for CO₂ gas separation and storage. A bio-based adsorbent can be fabricated from low-cost worldwide available biomass feedstock and bio-wastes from different industries (e.g., dairy manure, forestry, agriculture). As a result, it is a carbon rich material of hydrophobic nature, activated to gain high porosity development, and requires mild regeneration conditions. However, large-scale deployment of bio-based adsorption processes remains challenging. Our group has been intensively developing biomass-based adsorbents in conjunction with the design of tailored CO₂ adsorption-based cyclic processes for the envisioned application. Herein, key concepts on adsorption technology, biomass waste management, and different activation techniques for biomass-based adsorbent precursors are discussed. This review addresses the most relevant studies in the literature, from lab experimentation on a milligram scale (volumetric and gravimetric tests) to dynamic tests in bench or large-scale cyclic adsorption processes (i.e., pressure swing adsorption, temperature swing adsorption, vacuum swing adsorption). Therefore, the main target is to give a holistic view of the industrial applications where CO₂ separations with these materials are more suitable. Finally, concluding remarks and future perspectives of bio-based adsorbents in carbon capture are presented. © 2023 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd.

Chemical looping with oxygen uncoupling, a variant of chemical looping combustion, requires chemically and physically stable oxygen carriers over long-term redox cycling. Copper-based oxygen carriers are characterised by high oxygen release rates but experience sintering at high temperatures. The use of layered double hydroxides (LDHs), prepared via co-precipitation, as oxygen carrier precursors has been shown to effectively limit deactivation of copper-based mixed metal oxides (MMOs) over extended redox cycling. The LDH-derived MMOs have highly dispersed metal oxide within a stable support; the high dispersion of metals is due to the LDH precursor structure. In this work, a fluidised bed reactor (FBR) was used to study the intrinsic kinetics of oxygen release from CuO/MgAl₂O₄ oxygen carriers synthesised via the LDH-MMO design strategy. The long-term performance of MMOs with higher loadings of CuO, calcined from LDHs with higher Cu contents, was also investigated using an FBR. The intrinsic kinetics were determined using a kinetic model incorporating an effectiveness factor. By minimising the effects of intra- and inter-particle mass transfer, the activation energy and the pre-exponential factor of the lower loading MMOs were determined to be 51 ± 3 kJ mol⁻¹ and 0.0567 s⁻¹, respectively. All MMOs showed excellent stability over 100 redox cycles in a thermogravimetric analyser. However, the pH during co-precipitation of the LDHs affected the stability of the MMOs in an FBR. The MMOs calcined from LDHs synthesised at pH 9.5 disintegrated during operation, whilst those produced from LDHs synthesised at pH 11 maintained high conversion and physical integrity over 100 redox cycles. © 2023 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd.

Carbon dioxide has been proved an effective agent to enhance recovery for relatively light crude oil, but its applications in heavy oil are very limited. This short communication presents field trials of CO₂ huff and puff at Dagang, a heavy oil field in Northeast China. Two wells received CO₂ injection, and both wells saw higher oil output and lower water-cut after CO₂ treatment. This project proves CO₂ is effective for heavy oil recovery. Recommendations are also made for future CO₂ huff and puff projects. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.