Direct Air Capture Technologies Research Articles

Dual-Tuning Azole-Based Ionic Liquids for Reversible CO2 Capture from Ambient Air.

A strategy of tuning azole-based ionic liquids for reversible CO2 capture from ambient air was reported. Through tuning the basicity of anion as well as the type of cation, an ideal azole-based ionic liquid with both high CO2 capacity and excellent stability was synthesized, which exhibited a highest single-component isotherm uptake of 2.17 mmol/g at the atmospheric CO2 concentration of 0.4 mbar at 30 °C, even in the presence of water. The bound CO2 can be released by relatively mild heating of the IL-CO2 at 80 °C, which makes it promising for energy-efficient CO2 desorption and sorbent regeneration, leading to excellent reversibility. To the best of our knowledge, these azole-based ionic liquids are superior to other adsorbent materials for direct air capture due to their dual-tunable properties and high CO2 capture efficiency, offering a new prospect for efficient and reversible direct air capture technologies.

The nexus between direct air capture technology and CO2 emissions in the transport sector

Deploying negative emission technologies has become crucial for limiting the global temperature rise to approximately 1.5 °C above preindustrial levels. DAC technologies are being explored as one of the prospective options. These technologies have been thoroughly investigated as a potential project to capture CO2 emissions and provide purified air, natural gas, or fuel oil. An applied approach, on the other hand, was not taken into consideration while evaluating the influence that this technology has on emissions. For this reason, British Columbia provides a substantial chance to examine emissions that were produced after the DAC actions were put into place in 2015. In this study, the difference-in-differences methodology is employed for the very first time to compare the emissions that are produced by the transport sectors in British Columbia with those emitted by other provinces in Canada. The role that GDP and population play in the release of emissions is also taken into consideration in this paper. Based on the research results, it can be observed that the implementation of DAC initiatives has yielded notable effects. Evidence shows that the DAC effort has led to an average reduction of 0.08 in logarithmic CO2 emissions in the transport sector. By accounting for GDP and population, the empirical results indicate that DAC technology reduced CO2 emissions in British Columbia compared to provinces without DAC facilities. DAC initiatives are expected to become increasingly prevalent between the mid-2030s and 2040s. Overall policy implications suggest that there is a need for DAC technologies to collaborate with alternative mitigation technologies, or alternative technologies should collaborate with DAC technologies that are more efficient to achieve the targeted goals in a short time.

Amine-Functionalized Meso-Macroporous Polymers for Efficient CO2 Capture from Ambient Air.

Over the past decade, direct air capture (DAC) of carbon dioxide (CO2) using solid nanoadsorbents has garnered attention as a negative emission technology with high energy efficiency. Although operational, the large-scale deployment of DAC technologies has been significantly delayed due to the low performance and high cost of solid DAC nanoadsorbents. Herein, we present a novel family of meso-macroporous melamine formaldehyde (MF) materials with a facile preparation methodology, low capital cost, and unique physicochemical characteristics for DAC. The fabricated MF materials exhibit an extra-large pore volume of 5.19 cm3/g with a 24.6 nm average pore diameter. We show that the synthesized MF materials can be used as substrates and impregnated with different amounts of tetraethylenepentamine (TEPA) to act as chemical nanoadsorbents for DAC. Owing to the ultrahigh pore volume of MF, a substantial amount of 71 wt % TEPA (i.e., MF-TEPA71%) can be loaded, resulting in 2.65 mmol/g of CO2 uptake under DAC conditions. In addition, the superior physicochemical properties of MF lead to a high CO2 loading of 2.07 mmol/g with low TEPA loading in MF-TEPA33%. The prepared MF-TEPA nanoadsorbents can be successfully employed in different shapes (i.e., droplets, pellets, and coatings) and maintain their superiority across different temperatures and CO2 concentrations. This study provides a promising approach for developing meso-macroporous substrates through a straightforward and scalable synthesis method, representing a new avenue for the next generation of DAC nanoadsorbents with superior performance for practical applications.

The Case for Carbon Capture and Storage Technologies

In this paper, we use the literature to help us better understand carbon capture costs and how these estimates fare against those of avoided costs, focusing on bioenergy carbon capture and storage (BECCS), carbon capture and storage (CCS), as well as direct air capture technologies. We approach these questions from a meta-analysis perspective. The analysis uses meta-analysis tools while applying them to numerical rather than statistical studies. Our analysis shows that avoided costs are, on average, 17.4% higher than capture costs and that the carbon intensity of the feedstock matters: the estimates for coal-based electricity generation capture costs are statistically smaller than those for natural gas or air. From a policy perspective, the literature suggests that the costs of CCS are like the 45Q subsidy of USD 50 per metric ton of carbon captured.

The amine-functionalized alumina captures CO2 directly from the ambient air in the rotating adsorption bed

Global warming presents formidable challenges, prompting the exploration of Direct Air Capture (DAC) as a promising solution. This study employed the ultrasonic impregnation method to load polyethyleneimine (PEI) onto cost-effective millimeter-sized spherical γ-Al2O3 microspheres, thereby preparing an efficient amine-modified adsorbent. Characterization reveals a uniform dispersion of PEI, resulting in an adsorbent with an effective pore structure, enhancing CO2 diffusion. The adsorption experiment combines DAC with high gravity technology, best conditions at a PEI load of 16.37%, high gravity factor of 2.67, and gas flow rate of 30 L/min. Under these conditions, an impressive adsorption capacity of 41.75 mg/g was achieved, marking an increase of 12.11 mg/g compared to the traditional fixed-bed method. The amine efficiency also reaches 0.25. The Freundlich model outperforms the Langmuir model in fitting isotherm curves, suggesting that the experimental data align with the characteristics of a heterogeneous surface and multilayer adsorption. The fitting results of kinetic models further show that RAB's adsorption rate constant has a significantly better fitting value compared to traditional fixed bed methods. The research provides valuable insights for the application and development of DAC technology, enabling new possibilities for future carbon capture and emission reduction efforts.

Potential of wind turbines on the alteration of carbon dioxide concentration

Anthropogenic carbondioxide (CO2) emissions are a major factor in global warming, requiring significant cuts to combat climate change. A crucial technology to reduce global CO2 concentration is direct air capture (DAC) of CO2. However, existing DAC techniques are expensive because of low CO2 concentrations, and they frequently rely on fossil fuel-based energy. In this article, we investigate how wind turbines can influence local CO2 levels and potentially collaborate with DAC and other technologies. To explore this idea, we performed large-eddy simulations using two 5 MW commercial-scale wind turbines. We incorporated realistic CO2 profiles collected from 13 different global locations across different seasons. The simulations were performed under neutral atmospheric boundary layer conditions. The results demonstrate that the wake recovery mechanism of a wind turbine promotes rapid mixing of CO2 both above and below the turbine blade tips in the wind turbine wake. In cases where the initial concentrations of CO2 were elevated above the turbine, downward entrainment of CO2 occurred. Conversely, when high concentrations of CO2 were present in the lower atmosphere, wind turbines facilitated a decrease in concentration at that layer by up to 138 kg/m within the intermediate wake (within 7 diameters) of the second turbine, T2. These discoveries inspire further investigation into the potential synergies between wind turbines and DAC devices or local CO2 pollutant diverters, depending on the prevailing CO2 profile. Consequently, this article marks the initial showcase of wind turbines' capability to influence CO2 levels by creating an entrainment and removal effect.

High Gravity-Enhanced Direct Air Capture: A Leap Forward in CO2 Adsorption Technology

Given the global pressure of climate change and ecological equilibrium, there is an urgent need to develop effective carbon dioxide (CO2) capture technology. Due to its comprehensiveness and flexibility, Direct Air Capture (DAC) technology has emerged as a vital supplement to traditional emission reduction methods. This study aims to innovate Direct Air Capture (DAC) technology by utilizing the ultrasonic impregnation method to load Tetraethylenepentamine (TEPA) onto alumina (Al2O3) as the adsorbent. Furthermore, high gravity adsorption technology is integrated to significantly enhance the efficiency of DAC. Characterization tests, including BET, FTIR, TG, XRD, and SEM-EDS, confirm the structural stability and high capture capacity of the adsorbent. Additionally, this study demonstrates the rapid and efficient capture of CO2 from the air using TEPA-Al2O3 adsorbent under high gravity conditions for the first time. Under optimal conditions with TEPA loading at 15.06%, a high gravity factor of 2.67, and a gas flow rate of 30 L/min, TEPA-Al2O3 achieves a CO2 adsorption capacity of 48.5 mg/g in RAB, which is an improvement of 15.56 mg/g compared to traditional fixed-bed technology. Moreover, it reaches adsorption saturation faster under high gravity conditions, exhibiting a significantly higher adsorption rate compared to traditional fixed-bed systems. Furthermore, the adsorption process better conforms to the Avrami model. Steam stripping regeneration is utilized to regenerate the adsorbent, demonstrating excellent regeneration performance and stable adsorption capacity, thereby proving its feasibility and economic benefits as a DAC technology.

Membrane Separation Technology in Direct Air Capture.

Direct air capture (DAC) is an emerging negative CO2 emission technology that aims to introduce a feasible method for CO2 capture from the atmosphere. Unlike carbon capture from point sources, which deals with flue gas at high CO2 concentrations, carbon capture directly from the atmosphere has proved difficult due to the low CO2 concentration in ambient air. Current DAC technologies mainly consider sorbent-based systems; however, membrane technology can be considered a promising DAC approach since it provides several advantages, e.g., lower energy and operational costs, less environmental footprint, and more potential for small-scale ubiquitous installations. Several recent advancements in validating the feasibility of highly permeable gas separation membrane fabrication and system design show that membrane-based direct air capture (m-DAC) could be a complementary approach to sorbent-based DAC, e.g., as part of a hybrid system design that incorporates other DAC technologies (e.g., solvent or sorbent-based DAC). In this article, the ongoing research and DAC application attempts via membrane separation have been reviewed. The reported membrane materials that could potentially be used for m-DAC are summarized. In addition, the future direction of m-DAC development is discussed, which could provide perspective and encourage new researchers' further work in the field of m-DAC.

Evaluation of potassium glycinate as a green solvent for direct air capture and modelling its performance in hollow fiber membrane contactors

Current direct air capture (DAC) technology is largely cost-prohibitive for large scale implementation due to the excessive energy required to operate a combined absorption–desorption cycle. As the desorption process consumes much of the supplied energy, there is a demand to find more sustainable sorbent materials that maintain high absorptive capacities yet can be regenerated at lower working temperatures. This work evaluates potassium glycinate (GlyK) as one such alternative absorbent. Through conducting vapor–liquid equilibria and wetted wall column kinetic studies, GlyK is found to have comparable working capacities and liquid mass transfer coefficients to those reported for the industrial standard, monoethanolamine (MEA), yet outperforms it with regards to its distinctly low regeneration temperature. To further understand how GlyK would perform in an industrial scale DAC system, an Aspen Custom Modeler® (ACM) model is developed that integrates the experimentally obtained equilibria and kinetic data with the performance characteristics of a gas-solvent hollow fiber membrane contactor (HFMC). Full-scale simulations show that via implementing a 20°–90 °C absorption–desorption cycle, GlyK can capture up to 83 % of the CO2 in atmospheric air and be 55 % regenerated within a single membrane contactor pass. As these low working temperatures vastly outperform the conventional ∼ 40°–140 °C temperature swing currently implemented in industrial CO2 processing, GlyK is concluded to be a viable and sustainable option for use within energy-efficient DAC technology whereby renewable heat sources can be used.

China's energy-water-land system co-evolution under carbon neutrality goal and climate impacts

China's 2060 carbon neutrality goal has significant implications for energy, water, and land systems. However, the multi-sector dynamics among China's energy-water-land system have rarely been examined explicitly. This study adopts an integrated assessment framework to simulate China's energy-water-land system co-evolution under alternative carbon neutrality scenarios and climate impacts. Results show that although the net zero emission target provides the incentive for the energy system to move away from fossil fuels, total water withdrawal will increase due to the deployment of nuclear, bioenergy, and coal power plants with carbon capture and storage. Diversifying the negative emission technologies, by leveraging direct air capture technology, can alleviate the potential water stress and land use conflicts, which would otherwise be exacerbated by large-scale deployment of afforestation and bioenergy with carbon capture and storage. Northwest and northeast regions of China are the hotspots experiencing water withdrawal increases, while Bohai Rim and coastal regions are identified to experience fierce land competition. This study demonstrates the potential for general applicability to carry out resource planning and policy evaluation from the multi-sector coordination perspective.

Modeling and Performance Projections of a Dual-Purpose CO2 Capture and Energy Storage Device from Oceanwater

Carbon dioxide (CO2) capture and removal technologies are critical to limit global warming to 2 °C in the next few decades. In addition to the atmosphere, the oceans are large carbon sinks and have to-date captured about 25% of all anthropogenically released carbon. Therefore, ocean water CO2 capture can complement Direct Air Capture (DAC) technologies. To harness this source of CO2, this talk proposes, models, and analyzes the performance implications of a reversible, aqueous electrochemical flow device, which uses hydrogen and redox salt looping to achieve pH shifting. The reversible nature of this device enables its use in both power production and consumption modes, enabling CO2 capture to be powered exclusively by variable sources of renewable electricity. To model the performance of the proposed energy storage and CO2 capture device, we developed an equivalent circuit model to predict the current-voltage performance of this device mediated by ferricyanide/ferrocyanide and H2. Performance predictions are modeled as a function of key transport and thermodynamic conditions, specifically, for different mass transport rates of gases and aqueous electrolytes and different extents of pH shift between acidification and basification steps. Estimations of device performance are developed at both laboratory-scale and industrially relevant current densities. Modeled electrochemical energy intensity values of the overall device operation are compared to current state-of-the-art electrochemical ocean CO2 capture technologies to show the approach’s potential. Overall energy intensities are compared to current state-of-the-art DAC technologies. Our results show the energy intensity for CO2 capture during the reversible process has the potential to be reduced compared to present day DAC systems, but is highly sensitive to parasitics, ohmic losses, and the extent of competing reactions. Additionally, projections of the device energy-time profile are demonstrated to show the diurnal energy storage potential, specifically with applications to solar energy. Energy storage capabilities in the proposed device provide additional benefits of powering this CO2 capture device with renewable electricity while providing flexibility to manage grid-scale electricity demand. Overall, a reversible, pH-shifting based oceanic CO2 capture device offers holistic benefits from designing CO2 capture to operate exclusively from renewable electricity.

Research on Current and Future Aspects of Direct Air Capture of CO2

Direct Air Capture (DAC) technology is a revolutionary method that employs sorbents and a capturing mechanism to extract carbon dioxide (CO2) from the atmospheric air. This approach presents a highly adaptable and scalable solution for mitigating greenhouse gas emissions. Once the CO2 is captured, its potential uses are virtually limitless, spanning from industrial applications to secure underground storage for long-term sustainability. This research paper delves into the current status and future prospects of DAC technology, which holds immense promise for directly reducing atmospheric CO2 levels. The exploration encompasses the core principles of DAC, its diverse applications, the advantages it offers, the evolving landscape of this transformative technology, and the keen interest of major corporations in expanding the utilization of DAC. With its potential to reshape the way this generation combats climate change, DAC technology emerges as a pivotal tool in our efforts to address the global carbon challenge.

Direct Air Capture Technology and Its Application

Direct air capture technology (DAC) is integral to achieving carbon emission targets. This paper briefly analyses the application of DAC technology in indoor CO2 removal and CO2 mineralisation. Thanks to the elevated concentration of CO2 in the air (1000ppm) and the integrated DAC unit and air conditioning unit, the indoor CO2 removal system significantly reduces energy consumption. CO2 mineralisation, combined with DAC technology, offers a safe solution for permanent carbon storage and the possibility of obtaining a valuable end product by selecting the right mineralised feedstock. Future research should continue to focus on the development of adsorbent materials and the integration of CO2 capture with subsequent applications to achieve sustainability.

Market-pull, technology-push, and regulatory stringency determinants: All in need in firms' decisions for large-scale demonstration of direct air capture technologies

Carbon dioxide removal approaches such as direct air carbon capture and storage (DACCS) technologies have come to the fore as essential mitigation options to limit the increase in global warming to 1.5 °C. Previous studies have touched upon the technical, economic, environmental, and social and political feasibilities of DACCS technologies. These studies have commonly found that these technologies are not yet suitable for widespread deployment. However, large-scale demonstration projects have recently been successful, and facility construction for deployment is ongoing. There is a lack of studies exploring firm-level behaviors in DACCS technologies. What behavioral determinants are responsible for firms undertaking large-scale demonstrations and deployment with innovative but uncertain DACCS technologies? Using an analytical framework that included market pull, technology push, and regulatory stringency determinants, a case study of the firm, Carbon Engineering, was conducted. The results reveal that the most important determinants are regulatory factors that are vital for mobilizing financial resources.

Highly efficient catalytic direct air capture of CO2 using amphoyeric amino acid sorbent with acid‐base bi‐functional 3D graphene catalyst

Direct air capture (DAC) of CO2 is vital for combating global climate change, but DAC technologies have a low absorption efficiency due to the low concentration (∼400 ppm) of atmospheric CO2. A novel DAC technology was developed to solve this issue using lysine (an amino acid) as a sorbent and N-doped 3D graphene as an absorption/desorption-enhanced bifunctional catalyst. Introducing only 500 ppm N-3DG catalyst increased the working time (≥90% CO2 absorption efficiency) by 233% and its absorption capacity by 197%. The catalyst also significantly accelerated the CO2 working desorption capacity and rate by ∼280% and ∼338% at 70 °C, enabling regeneration of the sorbent by utilizing low-temperature waste heats. Furthermore, the excellent stability of the system was confirmed by 50 cyclic tests. The chemical mechanism driving catalytic CO2 capture was postulated and confirmed by density functional theory computations. This study provides a new strategy for developing next-generation DAC technologies.

파리협정 제6.4조 메커니즘에 따른 ‘제거’ 활동에 대한 우리나라 협상 방향 연구: 직접대기탄소포집(DAC) 기술 관점에서

파리협정 제6.4조 메커니즘에 따른 ‘제거’ 활동에 대한 우리나라 협상 방향 연구: 직접대기탄소포집(DAC) 기술 관점에서

Techno-economic analysis of a combined power plant CO2 capture and direct air capture concept for flexible power plant operation

The electric power sector must be deeply decarbonized at a reasonable cost to achieve economy-wide decarbonization goals via sustainable electrification of other sectors. While variable renewable energy generation is expected to dominate grid decarbonization efforts, variability creates the need for supply- and demand-side technologies that can operate flexibly to balance the system. This paper proposes a new concept for power plant flue gas capture integrated with a novel lime-based direct air capture technology to enable flexible operation of the power plant and achieve negative emissions under all operating scenarios. Steady-state models are developed, and sensitivity analyses are conducted on key process variables to investigate system performance. The results, presented at three different power plant loading levels (100 %, 40 %, and 0 %), demonstrate negative emissions of -0.188 tCO2/MWh at 100 % loading and -2.087 tCO2/MWh at 40 % loading. Economic modeling suggests the need for carbon credits exceeding $170/tCO2 to achieve positive net present values.

Role of Biological Carbon Mitigation in Carbon Sequestration: A Review

The imperative to address climate change has ushered in a growing interest in carbon sequestration as a mitigation strategy. While current methods offer some promise, they also come with a host of challenges, including technological limitations, environmental impacts, and economic barriers. This review paper provides a comprehensive analysis of the future prospects and recommendations for advancing carbon sequestration methods. Technological innovations are highlighted, particularly the advent of Direct Air Capture technologies, bioengineering for enhanced biological mitigation, and material science for more efficient storage. The policy landscape is discussed, emphasizing the need for robust carbon pricing mechanisms and international collaboration. Additionally, the paper identifies pressing areas for further research, such as long-term impact studies, the exploration of social and economic implications, and advances in monitoring and verification technologies. By synthesizing the emerging trends and potential strategies for overcoming current limitations, this paper aims to provide a cohesive roadmap for making carbon sequestration a viable and effective tool in the global effort to combat climate change.

Developing integrated direct air capture and bioenergy with carbon capture and storage systems: progress towards 2 °C and 1.5 °C climate goals

Negative emissions technologies are gaining widespread acceptance as crucial tools in achieving climate goals, such as keeping global temperatures below 2 °C of pre-industrial levels by 2100. Two technologies central to carbon dioxide removal efforts are direct air capture and Bioenergy with carbon capture and storage. While both technologies have undergone extensive study, only a few studies have explored the potential of using biomass as an energy source for direct air capture technology. This is despite bioenergy with carbon capture having the ability to provide carbon-negative heat and power, as well as its potential impact on the climate mitigation goals of the century. This study aims to investigate the feasibility of meeting the energy requirements of a direct air capture unit using bioenergy. Combining these units will result in compounded negative emissions for the integrated system. The objective is to examine the thermal and electrical requirements of the two primary approaches used in direct air capture design: the liquid solvent and solid sorbent direct air capture units, and to calculate the compounded negative emissions achieved by integrating them with bioenergy. The results of this study demonstrate that for a direct air capture plant capturing 1 mega ton of carbon dioxide per year, approximately 1200 and 2400 tons of biomass per day would be sufficient to meet the energy needs of the solid sorbent and liquid solvent direct air capture systems, respectively. The combined capture efficiency of both types of direct air capture systems integrated with bioenergy stands at 91.19% to 93.9% with overall carbon captured up to 1.51 mega tons of carbon dioxide per year. Over the century, integrating bioenergy into direct air capture units can remove gigaton levels of carbon from the atmosphere without disrupting the demand–supply dynamics of existing and future energy systems.

A comparative exergy-based assessment of direct air capture technologies

The 6th Assessment of the IPCC underlined the need for urgent measures for carbon dioxide removal from the atmosphere, so as to meet the 1.5 °C goal by the end of this century. One option to achieve this is direct air capture (DAC) technologies. This work assesses the thermodynamic performances of different categories of DAC technologies, i.e., adsorption-based, absorption-based, ion exchange, and electrochemical. An exergy analysis is performed on the DAC processes in each category to identify hotspots for efficiency loss within the system. The results show that the consumption of materials is responsible for 5–40% of the exergy consumption of the most-developed DAC processes. Despite their greater use of materials compared to absorption-based processes, adsorption-based processes, together with ion exchange technologies, have the highest exergy efficiencies of the DAC technologies investigated. Moreover, the results highlight the importance of limiting material consumption and electrifying large-scale DAC plants, which cannot run exclusively on waste heat from industrial processes.