A comparative review of potential ammonia-based carbon capture systems

Life cycle assessment of post-combustion carbon capture and storage for the ultra-supercritical pulverized coal power plant

In this paper, different emerging post-combustion technologies, i.e., monoethanolamine (MEA), aqueous ammonia, pressure swing adsorption (PSA), temperature swing adsorption (TSA), membrane and calcium looping, were applied to an ultra-supercritical coal-fired power plant for carbon capture. A 'cradle-to-grave' life cycle assessment (LCA) was conducted to evaluate the technical performance and environmental impacts of the power plant with six emerging carbon capture technologies. Carbon capture significantly influences the impact categories directly associated with flue gas emission. The application of carbon capture reduced the GWP in the range of 49-75 %. TAP also reduced in the range of 18-51 %. However, the human toxicity potential, eutrophication potential, ecotoxicity potential and particulate matter formation potential increased due to energy and resource consumption in the upstream and downstream processes. For the life cycle water consumption potential, it decreased by 8 % with calcium looping, whereas it increased in the range of 36-75 % with other post-combustion technologies. The highest reduction in GWP and the least reduction in power efficiency was observed in calcium looping because of the high-temperature heat recovery from flue gas and elimination of complex solvent manufacturing. The plant with aqueous ammonia and membrane separation had the second and third highest reductions in GWP. In addition, the lowest values for TAP, FEP, and MEP were obtained in the membrane system. With MEA for CO2 capture, the total GWP value of the plant is slightly higher than these three technologies mentioned above, and the highest HTPc, FETP, and METP can be observed in this case. TSA and PSA have the most significant environmental impacts in most categories due to higher energy requirements.

A venturi reactor with an excellent mass transfer performance for carbon dioxide capture

Mass transfer in liquid phase is the rate-limiting step for carbon dioxide capture by ammonia water, which results in a low total mass transfer coefficient and thus a poor carbon dioxide removal efficiency. For this issue, this study established a venturi reactor with an excellent mass transfer performance to promote mass transfer rate during carbon dioxide capture, and investigated the effect of operating parameters of the venturi reactor on carbon dioxide removal efficiency and overall mass transfer coefficient. The results showed that with an increasing flow rate of the jet from 8.31 to 12.73 L/min, the carbon dioxide removal efficiency decreased due to the increase of flow rate of flue gas, and the changing trend of overall mass transfer coefficient gradually transited from increasing to decreasing with the extension of reaction time. The carbon dioxide removal efficiency and the overall mass fraction coefficient increased upon the increase of ammonia concentration from 0.1 wt% to 0.75 wt%. With the increase of inlet carbon dioxide concentration from 7% to 19%, the carbon dioxide removal efficiency and the overall mass transfer coefficient decreased. Venturi reactor was of a fast mass transfer rate during carbon dioxide capture, and the maximum CO2 removal efficiency was 96.4% at ammonia concentration of 0.75 wt%, CO2 volume concentration of 15%, flow rate of jet of 8.36 L/min. This study provided a theoretical value for the development of venturi reactor for carbon dioxide capture.

Biopolymeric Nanocomposites for CO2 Capture

Carbon dioxide (CO2) impacts the greenhouse effect significantly and results in global warming, prompting urgent attention to climate change concerns. In response, CO2 capture has emerged as a crucial process to capture carbon produced in industrial and power processes before its release into the atmosphere. The main aim of CO2 capture is to mitigate the emissions of greenhouse gas and reduce the anthropogenic impact on climate change. Biopolymer nanocomposites offer a promising avenue for CO2 capture due to their renewable nature. These composites consist of biopolymers derived from biological sources and nanofillers like nanoparticles and nanotubes, enhancing the properties of the composite. Various biopolymers like chitosan, cellulose, carrageenan, and others, possessing unique functional groups, can interact with CO2 molecules. Nanofillers are incorporated to improve mechanical, thermal, and sorption properties, with materials such as graphene, carbon nanotubes, and metallic nanoparticles enhancing surface area and porosity. The CO2 capture mechanism within biopolymer nanocomposites involves physical absorption, chemisorption, and physisorption, driven by functional groups like amino and hydroxyl groups in the biopolymer matrix. The integration of nanofillers further boosts CO2 adsorption capacity by increasing surface area and porosity. Numerous advanced materials, including biopolymeric derivatives like cellulose, alginate, and chitosan, are developed for CO2 capture technology, offering accessibility and cost-effectiveness. This semi-systematic literature review focuses on recent studies involving biopolymer-based materials for CO2 capture, providing an overview of composite materials enriched with nanomaterials, specifically based on cellulose, alginate, chitosan, and carrageenan; the choice of these biopolymers is dictated by the lack of a literature perspective focused on a currently relevant topic such as these biorenewable resources in the framework of carbon capture. The production and efficacy of biopolymer-based adsorbents and membranes are examined, shedding light on potential trends in global CO2 capture technology enhancement.

Achieving sustainable emissions in China: Techno-economic analysis of post-combustion carbon capture unit retrofitted to WTE plants

China's aims of achieving CO2 emissions peak by 2030 and carbon neutrality by 2060 are crucial in guiding international efforts to mitigate climate change. Amine-based solvent technologies for capturing CO2 on a large scale have been implemented as retrofits in various industrial facilities, with a particular focus on coal-fired power plants. Nonetheless, its implementation within the waste-to-energy (WTE) industry is considerably limited and non-existent in China. This work presents a technical and economic evaluation of retrofitting a generic WTE facility in China with a carbon capture system. A rate-based process simulation model of the capture plant was developed in Aspen Plus, and the effect of equipment installation factors on capital cost was evaluated via the enhanced detailed factor (EDF) method. A set of key performance indicators were evaluated. The findings indicate that the energy demand linked to the capture system caused a decrease in efficiency by 13.17%, 14.85%, and 16.56% at 85%, 90%, and 95% capture rates, respectively, and the overall exergy efficiency of the system was reduced by 5.5%, 8.27%, and 10.63%, respectively. The estimated CO2 captured costs range from €56.41/tCO2 to €58.95/tCO2, while CO2 avoided costs range from €153.33/tCO2 to €236.47/tCO2. Retrofitting a CO2 capture unit at WTE facilities has the potential to substantially contribute to achieving the country's emission reduction targets. However, the successful implementation requires a comprehensive policy structure. This work offers some insights into the prospective integration of CO2 capture technology in China's WTE industry.

Trends in Research and Development for CO2 Capture and Sequestration

Technological and medical advances over the past few decades epitomize human capabilities. However, the increased life expectancies and concomitant land-use changes have significantly contributed to the release of ∼830 gigatons of CO₂ into the atmosphere over the last three decades, an amount comparable to the prior two and a half centuries of CO₂ emissions. The United Nations has adopted a pledge to achieve "net zero", i.e., yearly removing as much CO₂ from the atmosphere as the amount emitted due to human activities, by the year 2050. Attaining this goal will require a concerted effort by scientists, policy makers, and industries all around the globe. The development of novel materials on industrial scales to selectively remove CO₂ from mixtures of gases makes it possible to mitigate CO₂ emissions using a multipronged approach. Broadly, the CO₂ present in the atmosphere can be captured using materials and processes for biological, chemical, and geological technologies that can sequester CO₂ while also reducing our dependence on fossil-fuel reserves. In this review, we used the curated literature available in the CAS Content Collection to present a systematic analysis of the various approaches taken by scientists and industrialists to restore carbon balance in the environment. Our analysis highlights the latest trends alongside the associated challenges.

Tool for optimization of energy consumption of membrane-based carbon capture

The reduction of CO₂ emissions is a very challenging issue. The capture of CO₂ from combustion processes is associated with high energy consumption and decreases the efficiency of power-producing facilities. This can affect the economy and in specific cases, such as waste-to-energy plants, also their classification according to legislation. To allow the minimization of energy consumption, an optimization tool for membrane-based post-combustion capture was developed. The approach allows finding optimal membrane properties, membrane areas, and pressures for individual separation stages from the point of view of energy consumption. The core of the approach is represented by a mathematical model of the separation system that is based on a network flow problem. The model utilizes external simulation modules for non-linear problems to enable finding globally optimal results. These external modules approximate non-linear dependencies with any desired precision and allow using different mathematical descriptions of individual membrane stages without making changes to the model. Moreover, it allows easy substitution of the external module by experimental data and the model can be easily modified for specific purposes such as decision making, designing the separation process, as well as for regulation of process parameters in the case of dynamic operation. The ability of the model to optimize the process was verified on a case study and the results show that the optimization can significantly reduce the energy consumption of the process. For separation of 90% of CO₂ at the purity of 95% from initial flue gas with 13% CO₂ with state-of-the-art membranes based on the Robeson upper bound and three-stage process, the minimum power consumption was 1.74 GJ/t_CO2 including final CO₂ compression.

A Review of the Latest Trends in the Use of Green Ammonia as an Energy Carrier in Maritime Industry

This review paper examines the key barriers to using green ammonia as an alternative fuel in maritime industry. A literature survey is performed based on research articles and grey literature, with the aim of discussing the technoeconomic problems with and benefits of ammonia and the relevant technologies. The limitations of ammonia as a maritime fuel and its supply chain, the expected percentage demand by 2030 and 2050, its economic performance compared to other shipping fuels such as hydrogen, and the current regulations that may impact ammonia as a maritime fuel are discussed. There are several key barriers to ammonia’s wide adoption: (1) High production costs, due to the high capital costs associated with ammonia’s supply chain; (2) availability, specifically the limited geographical locations available for ammonia bunkering; (3) the challenge of ramping up current ammonia production; and (4) the development of ammonia-specific regulations addressing issues such as toxicity, safety, and storage. The general challenges involved with blue ammonia are the large energy penalty and associated operational costs, and a lack of technical expertise on its use. Regardless of the origin, for ammonia to be truly zero-carbon its whole lifecycle must be considered—a key challenge that will aid in the debate about whether ammonia holds promise as a zero-carbon maritime fuel.