Carbon Capture And Storage Processes Research Articles

Options for net zero emissions hydrogen from Victorian lignite. Part 2: Ammonia production

This the second of a two-part study investigating the feasibility of producing export quantities (770 t/d) of blue hydrogen meeting international emissions standards, by gasification of Victorian lignite plus carbon capture and storage (CCS). Part 1 focussed on the resources, energy requirements, and greenhouse gas emissions associated with the production of gaseous and liquefied hydrogen, while Part 2 focusses on the production of ammonia as an alternative hydrogen carrier for export.In this study, an Aspen Plus simulation of a conventional 1500 t d−1 iron-based catalyst Haber-Bosch ammonia synthesis process is developed and incorporated into the earlier lignite-to-hydrogen process model. Development of the simulation involves (i) estimation of the instantaneous rate kinetics, (ii) calibration against test data for a reactor of known dimensions, (iii) scaling up the bed dimensions to achieve a target production capacity, (iv) selecting an appropriate feed gas composition to optimise performance, (v) adjusting purge gas flowrates to achieve stable operation, and (v) incorporation into the previous lignite-to-hydrogen simulation.This study finds that 178.2 t h−1 liquid ammonia and all electricity required to support the process can be produced from 1050 t h−1 Victorian lignite. Surprisingly, the simulation results show that the electrical power requirement for ammonia synthesis (176.4 MW) is essentially the same as that needed for liquefaction of an equivalent output of hydrogen (175.5 MW). On this basis both options are equally attractive, although ammonia synthesis is at a higher level of technological maturity than large-scale hydrogen liquefaction.This is the first study to quantify the greenhouse gas emissions intensity of ammonia production from lignite, accounting for the full production chain from lignite mining to CO2 sequestration. It is found that ammonia can be produced from Victorian lignite with very low CO2 emission intensity (0.49 kgCO2-e kgNH3−1) equivalent to that of next-generation natural gas reforming with CCS processes. If required, the emission intensity can be reduced to 0.05kgCO2-e kgNH3−1 with a post-combustion CO2 capture system, and then made carbon neutral by co-gasification with ≤1.4% biomass.For comparison, this study also examines the implications of producing the same quantity of green ammonia using renewable energy alone. It is estimated that production of 178.2 t h−1 green ammonia would require 1946 MW renewable energy and associated transmission infrastructure. In Victoria, this could be supplied by a wind farm with a 5.4 GW rated capacity, occupying an area of over 72,000 ha. This is highly unlikely to be a viable option.This analysis indicates that clean hydrogen in the form of ammonia, produced in Victoria by lignite gasification with CCS, can be consistent with global emissions reductions targets over the next few decades. The unique combination of low-cost lignite and high-quality CO2 storage geology means that Victoria is well placed to become a significant exporter of low-emissions ammonia to the world market. Further research is recommended on recovery of energy from the low grade waste heat streams and opportunities for additional electricity generation using the organic Rankine cycle.

Technical performance and environmental assessment of an ionic liquid-based CCS process for hydrogen production

Hydrogen (H2) production combined with carbon capture and storage (CCS) is anticipated to be an important technology contributing to reduce the carbon footprint of current fossil-based H2 production systems. This work addresses for the first time the techno-environmental assessment of a CCS process based on the ionic liquid [Bmim][Acetate] for H2 production by steam methane reforming (SMR) and the comparison to conventional amine-based systems. Two different SMR plants using MDEA or [Bmim][Acetate] for CO2 capture were rigorously modelled using Aspen Plus to compute material and energy needs and emissions. Literature and simulation results were then used to perform a life cycle impact assessment (LCIA) of these processes based on the ReCiPe model. Solvent synthesis, CCS process and hydrogen production stages were considered for the cradle-to-gate analysis. Results showed that although [Bmim][Acetate] is a priori more harmful to the environment than amines (in a kg-to-kg comparison), LCIAs carried out for both CCS processes showed from 5 to 17 % lower environmental impacts values for all estimated categories when using [Bmim][Acetate] due to a 9.4 % more energy-efficient performance than MDEA, which also reduced a 17.4 % the total utility cost. Indeed, if a typical amine loss rate of 1.6 kg/tCO2 is assumed, the values of the environmental impacts increase up to 14 % for the IL-based CCS plant, but still maintaining its favorable results over MDEA. As consequence, the SMR plant with the IL-based CCS system exhibited 3–20 % lower values for most of the studied impact categories. These results contribute to shed some light on evaluating the sustainability of ILs with respect to conventional solvents for CO2 capture and to guide the synthesis of new more sustainable ILs but also, they would be used to compare the environmental burdens from the synthesis and process performance of other promising ILs for CO2 capture that are not environmentally assed yet.

Accurate experimental (p, ρ, T) data of the (CO2 + O2) binary system for the development of models for CCS processes

The limited availability of accurate experimental data in wide ranges of pressure, temperature, and composition is the main constraining factor for the proper development and assessment of thermodynamic models and equations of state. In the particular case of carbon capture and storage (CCS) processes, there is a clear need for data sets related to the (carbon dioxide + oxygen) mixtures that this work aims to address. This work provides new experimental (p, ρ, T) data for three binary (CO2 + O2) mixtures with mole fractions of oxygen x(O2) = (0.05, 0.10, and 0.20) mol·mol−1, in the temperature range T = (250 to 375) K and pressure range p = (0.5 to 13) MPa. The measurements were performed with a high-precision single-sinker densimeter with magnetic suspension coupling. The density data were obtained with estimated expanded relative uncertainties of 0.02% for the highest densities and up to 0.3% for the lowest ones.The results were compared to the corresponding results calculated by the current reference equations of state for this kind of mixtures, namely the EOS-CG (combustion gases) and the GERG-2008 equation of state, respectively. The EOS-CG yields better estimations in density than the GERG-2008 equation of state. The results from the EOS-GC model show no systematic temperature dependence. For the GERG-2008 model, however, this criterion is significantly less fulfilled.

Techno-economic assessment of alternative fuels in second-generation carbon capture and storage processes

Several technical methods are currently discussed to meet the objectives of the United Nations Framework Convention on Climate Change 21st Conference of the Parties, Paris, France (Paris Agreement) in terms of carbon dioxide (CO2) concentration in the Earth’s atmosphere. In addition to efficiency improvements, reduction of energy consumption, and the utilization of renewable energy sources, the application of carbon capture and storage (CCS) technologies seems to be unavoidable. Whereas all these measures aim on the reduction of CO2 that is being newly released, there is the approach to remove CO2 from the atmosphere that has already been emitted. This can be achieved by the utilization of bioenergy in CCS processes. Within this paper, the utilization of alternative fuels in two second-generation CCS processes is assessed. In this regard, chemical looping combustion (CLC) and calcium looping (CaL) are two promising technologies. Both processes have proven their feasibility already in semi-industrial scale. The assessment includes three different types of fuel namely coal, biomass, and solid recovered fuel (SRF). The analysis is twofold: first, a heat and mass balance calculation reveals the specific CO2 emissions of each power system; second, a cost analysis points out the feasibility from an economic point of view. The highest CO2 removal can be achieved by a biomass-fired CLC unit (− 696 gCO2/kWhe). Furthermore, it was found that the co-combustion of SRF even at moderate co-firing rates allows for noteworthy improved economics of the CCS system. Therefore, the utilization of waste-derived fuels in the context of CCS processes should be put more into focus in future research activities.

Thermophysical Properties and Phase Behavior of Fluids for Application in Carbon Capture and Storage Processes.

Phase behavior and thermophysical properties of mixtures of carbon dioxide with various other substances are very important for the design and operation of carbon capture and storage (CCS) processes. The available empirical data are reviewed, together with some models for the calculation of these properties. The systems considered in detail are, first, mixtures of carbon dioxide, water, and salts; second, carbon dioxide-rich nonelectrolyte mixtures; and third, mixtures of carbon dioxide with water and amines. The empirical data and the plethora of available models permit the estimation of key fluid properties required in the design and operation of CCS processes. The engineering community would benefit from the further development, and delivery in convenient form, of a small number of these models sufficient to encompass the component slate and operating conditions of CCS processes.

Application potential of solar-assisted post-combustion carbon capture and storage (CCS) in China: A life cycle approach

Although post-combustion carbon capture (PCC) has been regarded as a near-commercial technology, the scale-up development of PCC the technology remains hindered by its severe thermodynamic and economic penalties. As a consequence, the solar-assisted carbon capture and storage (CCS) technology is emerging recently, which poses a promising possibility to offset the power generation loss caused by the intensive energy consumption from PCC process. Nevertheless, the application potential of the solar-assisted CCS technology would highly depend on its realistic greenhouse gas (GHG) mitigation benefit as well as its cost relative to alternative low carbon technologies. Thus, it is required to apply an improved assessment practice to recognize solutions for such sustainable power supply chains, considering an increasing threatening from climate change.In this study, solar-assisted post-combustion CCS processes are analyzed trough a life cycle approach, combing life cycle GHG assessment and life cycle cost analysis. A typical 300MWe coal-fired power plant in China is taken as the case study. Three scenarios are further analyzed: (1) base case integrated with CCS process; (2) base case integrated with CCS and solar-assisted reboiler heating process; (3) base case extended to CCS and solar-assisted repowering process. Results show that the solar-assisted repowering case has considerable advantage in both GHG mitigation potential and cost aspect with superior life cycle GHG reduction rate and life cycle cost of energy removed (LCOR) at 73.7% and 37.2$/tco2−eq respectively. While the solar-assisted reboiler heating case does not have evident competition superiority. It is further highlighted that the GHG emissions from the upstream and transportation stages are also critical for Chinese CCS chains.

The Potential of CO2 Capture and Storage Technology in South Africa’s Coal-Fired Thermal Power Plants

The global atmospheric concentration of anthropogenic gases, such as carbon dioxide, has increased substantially over the past few decades due to the high level of industrialization and urbanization that is occurring in developing countries, like South Africa. This has escalated the challenges of global warming. In South Africa, carbon capture and storage (CCS) from coal-fired power plants is attracting increasing attention as an alternative approach towards the mitigation of carbon dioxide emission. Therefore, innovative strategies and process optimization of CCS systems is essential in order to improve the process efficiency of this technology in South Africa. This review assesses the potential of CCS as an alternative approach to reducing the amount CO2 emitted from the South African coal-fired power plants. It examines the various CCS processes that could be used for capturing the emitted CO2. Finally, it proposes the use of new adsorbents that could be incorporated towards the improvement of CCS technology.

Carbon Capture and Storage: concluding remarks

This paper aims to pull together the main points, messages and underlying themes to emerge from the Discussion. It sets these remarks in the context of where Carbon Capture and Storage (CCS) fits into the spectrum of carbon mitigation solutions required to meet the challenging greenhouse gas (GHG) emissions reduction targets set by the COP21 climate change conference. The Discussion focused almost entirely on carbon capture (21 out of 23 papers) and covered all the main technology contenders for this except biological processes. It included (chemical) scientists and engineers in equal measure and the Discussion was enriched by the broad content and perspectives this brought. The major underlying theme to emerge was the essential need for closer integration of materials and process design - the use of isolated materials performance criteria in the absence of holistic process modelling for design and optimisation can be misleading. Indeed, combining process and materials simulation for reverse materials molecular engineering to achieve the required process performance and cost constraints is now within reach and is beginning to make a significant impact on optimising CCS and CCU (CO2 utilisation) processes in particular, as it is on materials science and engineering generally. Examples from the Discussion papers are used to illustrate this potential. The take-home messages from a range of other underpinning research themes key to CCUS are also summarised: new capture materials, materials characterisation and screening, process innovation, membranes, industrial processes, net negative emissions processes, the effect of GHG impurities, data requirements, environment sustainability and resource management, and policy. Some key points to emerge concerning carbon transport, utilisation and storage are also included, together with some overarching conclusions on how to develop more energy- and cost-effective CCS processes through improved integration of approach across the science-engineering spectrum. The discussion was first-rate in the best traditions of Faraday Discussions and hopefully will foster and stimulate further cross-disciplinary interactions and holistic approaches.

Co-firing coal with biomass in oxygen- and carbon dioxide-enriched atmospheres for CCS applications

Biomass combustion and carbon capture and storage (CCS) individually represent significant options for decarbonising the power generation sector and when combined may permit a carbon–neutral or even carbon-negative process. Despite this potential, little research has been published that examines the combustion of biomass in atmospheres with application in CCS processes. This work reports on bench- and laboratory-scale testing of biomass and coal combustion in atmospheres enriched in O2 and CO2 which are relevant for retrofitting power stations for oxyfuel combustion. At bench-scale, thermogravimetric analysis shows substituting N2 as the combustion diluent with CO2 has little impact on the combustion properties of the fuels but that increasing the O2 concentration accelerates combustion of coal and biomass chars. Results from cofiring three biomasses with coal at 20kW scale suggest substitution of N2 with CO2 significantly reduces temperatures, carbon burnout and emissions of NO while combustion in O2-enriched conditions has the opposite effects. Emissions of NO and SO2 were found to reduce compared to air in combustion atmospheres enriched with O2 and CO2 while combustion temperatures and carbon burnout slightly increased.

Modelling CO2 –Water Thermodynamics Using SPUNG Equation of State (EoS) Concept with Various Reference Fluids

Due to the continuous increase of CO2 emission to environment, the Carbon Capture and Storage (CCS) processes gained a very high importance in the last decades. One common CO2 impurity during various CCS processes is water. Therefore, the calculation of CO–water thermodynamic properties is a vital issue. This work preliminary investigates the accuracy of the extended corresponding states equation of state SPUNG using various reference fluids for the density and vapour liquid equilibrium (VLE) calculations of the CO2 - water system. The evaluation is done by comparing the numerical prediction with experimental data. The study is conducted at different mixture concentrations, and covering a broad range of conditions. The study is conducted using N2, O2, C1, C2, C3, and C4 as reference fluids. The results show an impact on density prediction. On the other hand, the VLE calculations exhibited very low sensitivity to varying reference fluids.

Adsorption kinetics for CO2 on highly selective zeolites NaKA and nano-NaKA

Carbon dioxide removal from flue gas via swing adsorption processes requires adsorbents with a high CO2 selectivity and capacity. These properties are particularly valuable to reduce the cost of carbon capture and storage (CCS). Zeolite NaKA was studied for its ability to selectively adsorb CO2 from flue gas, as we previously observed that zeolite NaKA, with a K+/(K++Na+) ratio of 17atomic%, was highly selective towards CO2 over N2 adsorption by tuning the size of the pore window apertures [1]. The reduced pore apertures may, however, retard the adsorption rate of CO2. Here, we studied the kinetics of CO2 adsorption on regularly sized zeolite NaKA and on nano-sized zeolite NaKA. We used in situ infrared (IR) spectroscopy and observed that CO2 physisorbed relatively rapidly. Density functional theory (DFT) was used for quantum chemical calculations, and the results indicated that CO2 molecules bridged across two or three Na+ ions in the samples with no or very small amount of K+. When more K+ ions are present the CO2 molecules no longer bridged across multiple metal ions and adopted an end-on configuration. The calculation showed a shift in the stretching vibration frequency of physisorbed CO2 as observed by IR spectroscopy. Nano-sized zeolite NaKA were synthesised and studied to improve the rate of CO2 adsorption, as the diffusion rate typically increases quadratically with decreasing particle size. Still, the CO2 adsorption rate on nano-sized zeolites NaA and NaKA did not increase significantly. For nano-sized zeolite NaA, we speculate that the absence of such an increased rate is an effect from a skin layer that had formed on the nano-sized zeolite NaA, a layer that was possibly related to intergrowths with extremely small crystals on the surface. The apparently slow adsorption kinetics of CO2 on nano-sized zeolite NaKA was more difficult to explain because it could relate to imperfections within the small crystals, remaining water, or other effects. Overall, the CO2 adsorption rates on zeolite NaKA crystals of different sizes were fast and relevant for the time scales required for adsorption based CCS processes, such as vacuum and temperature swing adsorption (VSA/TSA).

Densities of the carbon dioxide + hydrogen, a system of relevance to carbon capture and storage

The densities of the carbon dioxide (CO2) and hydrogen (H2) mixtures (xH2=0.020,0.075 and 0.100) have been determined at six temperatures from 288.15 to 333.15K and pressures up to 23.0MPa using a high-pressure vibrating-tube densitometer. The experimental temperatures and pressures cover a range of sub- and supercritical conditions, providing essential information for the optimum design and operation of compressors and pipeline networks in carbon capture and storage (CCS). It was found that a concentration of H2 as low as 2% could lower the density by as much as 25% compared to pure CO2. The data were used to calculate the excess molar volumes, showing highly non-ideal mixing behaviour of the binary system of CO2+H2. The new density data were also compared to those predicted using the GERG-2004 equation of state (Kunz, O. et al., 2007. The GERG-2004. Wide-range equation of state for natural gases and other mixtures, Düsseldorf). The deviations between the calculated and experimental data are 0.6%, 1.7% and 1.8%, respectively, for the mixtures with xH2=0.020,0.075 and 0.100. These results suggest that the GERG-2004 equation of state has the potential for accurate prediction of the volumetric property of CO2 mixtures containing H2 in the CCS processes, and further parameterisation of GERG-2004 or development of new equations of state specifically tailored for CCS mixtures is required.

Carbon capture and storage: The way ahead

Abstract The paper gives a general introduction and overview of Carbon Capture and Storage (CCS) with an emphasis on the capture of CO 2 and other greenhouse gases from the waste gas streams of power plants and industrial processes. This stage accounts for about 80% of the overall cost of the CCS process so is the area where efficiency and cost improvements will have the greatest future impact. The major drivers for continuing to use fossil fuels for most of this century are first considered and the need to implement CCS as one of many measures to mitigate carbon emissions. Current targets will require a commercial CCS capacity to remove about 10Gte CO 2 pa by 2050. The overall features of CCS processes are described – capture, compression and transport, sub-surface storage – covering the main capture options and the three main types of storage site (deep saline aquifers, depleted oil and gas reservoirs and unmineable coal seams). The current status of large-scale CCS demonstration projects is reviewed....

Greener Solvent Selection and Solvent Recycling for Carbon Dioxide Capture

Carbon capture and storage (CCS) constitutes an extremely important technology that is constantly being improved to minimize the amounts of carbon dioxide (CO2) entering the atmosphere. According to the Global CCS Institute, there are more than 320 worldwide CCS projects at different phases of progress. However, current CCS processes are accompanied with a large energy and efficiency penalty. This paper models and simulates a post-combustion carbon capture system, that uses absorption as a method of separation, in Aspen Plus V7.2. Moreover, the CAPE-OPEN Simulated Annealing (SA) Capability is implemented to minimize the energy consumed by this system, and allow coal-fired power plants to use similar carbon capture systems without losing 20 to 40 % of the plant's output.

Valuation of consequences arising from CO2 migration at candidate CCS sites in the US

Abstract Carbon Capture and Storage (CCS) represents a potentially effective means of addressing climate change. However, CCS processes create a suite of risks, including possibly injury to private and public sector interests, which will continue beyond the operational life of the project. Concerns regarding potential damages and attendant financial liability remain a barrier to commercial-scale deployment of CCS. The public dialogue on ‘liability’ as it relates to CCS has been clouded by a failure to clearly define what is at risk, and whether the consequences of such risks are material from a financial perspective. Focus on anecdotal references has contributed to unreasonable expectations and misunderstanding with respect to the amount and timing of funds necessary for the responsible deployment of CCS. Analytic evaluation of the range of potential impacts and calculation of financial consequences can illuminate: (1) the dollar amounts that need to be managed; (2) the set of circumstances under which amounts will present; and (3) the time frame over which these dollars will be needed. This paper applies an analytic framework drawn from damages estimation methodologies used in comparable contexts and incorporates risk-based probabilistic modeling to assist stakeholders in evaluating the potential consequences of CO 2 migration at three candidate CCS sites. Specifically, it presents preliminary, order-of-magnitude estimates for potential public human health impacts associated with the operational phase of CCS activities at three proposed, non-selected USDOE FutureGen sites: (1) Tuscola, Illinois; (2) Jewett, Texas; and (3) Odessa, Texas. Attendant analyses applying the same methodology currently are underway to value damages associated with environmental resources, e.g., ground water, and atmospheric releases of CO 2 , as well as damages associated with the post-operational period.