Download or read book Computational Optimization of Design and Variable Operation of CO2 capture enabled Coal natural Gas Power Plants written by Charles A. Kang and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Climate change mitigation will require large reductions in CO2 emissions from electricity production. Some of these cuts will come from increased use of renewable energy resources, but it is likely that thermal power plants will be used for an extended period of time to maintain grid stability and accommodate seasonal variability in renewable generation. Therefore, thermal power plants with CO2 capture and storage (CCS) capability may coexist with renewable generation to provide reliable low-carbon electricity. Moreover, CCS-enabled facilities designed for constant operations are not necessarily optimal under the conditions that are likely to occur with increased renewable penetration. There is therefore a need to devise optimal designs and operating plans for flexible thermal power stations equipped with CCS. In this work, computational optimization is used to determine the design and operating plan of a coal-natural gas power station with CO2 capture, under a CO2 emission performance standard. The facility consists of a coal power plant undergoing a retrofit with solvent-based post-combustion CO2 capture. The heat for CO2 capture solvent regeneration is provided by a combined cycle gas turbine (CCGT) designed for combined-heat-and-power service. Variable facility operations are represented by discrete operating modes dispatched using the electricity price-duration curve. Two problem formulations are considered. In the `simplified-capture' problem formulation, the CO2 capture system is represented using a single variable for capacity, while heat integration (including a detailed treatment of the heat recovery steam generator component of the CCGT) is optimized jointly with variable operations. In the `full-system' problem formulation, the detailed design of the CO2 capture system is optimized alongside a full treatment of heat integration and variable operations. To accomplish this, a computationally efficient proxy model of the CO2 capture system is developed that reproduces the behavior of a full-physics Aspen Plus model. Both problem formulations are incorporated in a bi-objective mixed-integer nonlinear program in which total capital requirement (TCR) is minimized and net present value (NPV) is maximized. Pareto frontiers are generated for six scenarios constructed from recent historical data from West Texas, the United Kingdom, and India. All six scenarios are considered using the simplified-capture problem formulation. The West Texas base scenario and the India scenario, which differ greatly from each other, are considered using the full-system problem formulation as well. Results between the two formulations are quite consistent and show that hourly electricity price variability and the choice of objective function can have a large effect on optimal design and planned operations. In the West Texas base scenario, which has high price variability, the maximum NPV facility in the full-system formulation (NPV of $201 million, TCR of $510 million) has a time-varying operating plan in which the CO2 capture system has a utilization factor of 66% (out of a maximum of 85%). In this scenario the minimum TCR facility (NPV of $101 million, TCR of $333 million) has a constant operating profile. In contrast, low price variability in the India scenario results in constant operations regardless of objective. Two advanced CO2 capture processes -- the mixed salt and piperazine processes -- are considered using the simplified-capture formulation for the West Texas base scenario. The advanced processes are shown to outperform the standard monoethanolamine (MEA) process, with the mixed salt process outperforming the MEA process by 16% for maximum NPV and 14% for minimum TCR. The full-system formulation using the MEA process provides generally similar results to those from the simplified-capture formulation in both the India and West Texas base scenarios. However, the inclusion of the detailed design of the CO2 capture process in the full-system problem formulation provides valuable design information, such as the effect of the integer nature of the number of CO2 capture trains. Taken in total, the results of this study highlight the value of applying computational optimization to consider integrated plant design and variable operations together.

Download or read book Carbon Capture Technologies for Gas Turbine Based Power Plants written by Hamidreza Gohari Darabkhani and published by Elsevier. This book was released on 2022-09-24 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon Capture Technologies for Gas-Turbine-Based Power Plants explores current progress in one of the most capable technologies for carbon capture in gas-turbine-based power plants. It identifies the primary benefits and shortcomings of oxy-fuel combustion CO2 capture technology compared to other capture technologies such as pre-combustion and post-combustion capture. This book examines over 20 different oxy-combustion turbine (oxyturbine) power cycles by providing their main operational parameters, thermodynamics and process modelling, energy and exergy analysis and performance evaluation. The conventional natural gas combined cycle (NGCC) power plant with post-combustion capture used as the base-case scenario. The design procedure and operational characteristics of a radial NOx-less oxy-fuel gas turbine combustor are presented with CFD simulation and performance analysis of the heat exchanger network and turbomachinery. Overview of oxygen production and air separation units (ASU) and CO2 compression and purification units (CPU) are also presented and discussed. The most advanced stages of development for the leading oxyturbine power cycles are assessed using techno-economic analysis, sensitivity, risk assessments and levelized cost of energy (LCOE) and analysing technology readiness level (TRL) and development stages. The book concludes with a road map for the development of future gas turbine-based power plants with full carbon capture capabilities using the experiences of the recently demonstrated cycles. - Analyzes more than 20 models of oxyturbine power cycles, identifying the main parameters regarding their operation, process and performance simulations and energy and exergy analysis - Provides techno-economic analysis, TRL, sensitivity and risk analysis, LCOE and stages of development for oxy-combustion turbine power plants - Presents the design procedure and CFD simulation of a radial NOx-less oxy-fuel gas turbine combustor exploring its influence on heat exchanger network and turbomachinery - Supports practitioners, policymakers and energy industry managers seeking pathways to convert coal-fired power plants to gas-fired plants with zero CO2 emission

Download or read book Process Systems and Materials for CO2 Capture written by Athanasios I. Papadopoulos and published by John Wiley & Sons. This book was released on 2017-05-01 with total page 686 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive volume brings together an extensive collection of systematic computer-aided tools and methods developed in recent years for CO2 capture applications, and presents a structured and organized account of works from internationally acknowledged scientists and engineers, through: Modeling of materials and processes based on chemical and physical principles Design of materials and processes based on systematic optimization methods Utilization of advanced control and integration methods in process and plant-wide operations The tools and methods described are illustrated through case studies on materials such as solvents, adsorbents, and membranes, and on processes such as absorption / desorption, pressure and vacuum swing adsorption, membranes, oxycombustion, solid looping, etc. Process Systems and Materials for CO2 Capture: Modelling, Design, Control and Integration should become the essential introductory resource for researchers and industrial practitioners in the field of CO2 capture technology who wish to explore developments in computer-aided tools and methods. In addition, it aims to introduce CO2 capture technologies to process systems engineers working in the development of general computational tools and methods by highlighting opportunities for new developments to address the needs and challenges in CO2 capture technologies.

Download or read book Advances in Carbon Capture written by Mohammad Reza Rahimpour and published by Woodhead Publishing. This book was released on 2020-08-04 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Carbon Capture reviews major implementations of CO2 capture, including absorption, adsorption, permeation and biological techniques. For each approach, key benefits and drawbacks of separation methods and technologies, perspectives on CO2 reuse and conversion, and pathways for future CO2 capture research are explored in depth. The work presents a comprehensive comparison of capture technologies. In addition, the alternatives for CO2 separation from various feeds are investigated based on process economics, flexibility, industrial aspects, purification level and environmental viewpoints. - Explores key CO2 separation and compare technologies in terms of provable advantages and limitations - Analyzes all critical CO2 capture methods in tandem with related technologies - Introduces a panorama of various applications of CO2 capture

Download or read book Design Integration Schemes and Optimization of Conventional and Pressurized Oxy coal Power Generation Processes written by Hussam Zebian and published by . This book was released on 2014 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Efficient and clean electricity generation is a major challenge for today's world. Multivariable optimization is shown to be essential in unveiling the true potential and the high efficiency of pressurized oxy-coal combustion with carbon capture and sequestration for a zero emissions power plant (Zebian and Mitsos 2011). Besides the increase in efficiency, optimization with realistic operating conditions and specifications also shows a decrease in the capital cost. Elaborating on the concept of increasing the performance of the process and the power generation efficiency, as part of this Ph.D. thesis, new criteria for the optimum operation of regenerative Rankine cycles, are presented; these criteria govern the operation of closed and open feedwater heaters, and are proven (partly analytically and partly numerically) to result in more efficient cycle than the conventional rules of thumb currently practiced in designing and operating Rankine cycles. Simply said, the pressure and mass-flowrate of the bleed streams must be selected in a way to have equal pinch temperatures in the feedwater heaters. The criteria are readily applicable to existing and new power plants, with no associated costs or retrofitting requirements, contributing in significant efficiency increase and major economical and environmental advantages. A case study shows an efficiency increase of 0.4 percentage points without capital cost increase compared to a standard design; such an efficiency increase corresponds to an order of $40 billion in annual savings if applied to all Rankine cycles worldwide. The developed criteria allow for more reliable and trustworthy optimization, thus, four additional aspects of clean power generation from coal are investigated. First, design and optimization of pressurized oxy-coal combustion at the systems-level is performed while utilizing a direct contact separation column (DCSC) instead of a surface heat exchanger for more reliable and durable thermal recovery. Despite the lower effectiveness compared to a surface heat exchanger, optimization employing newly developed optimal operating criteria that govern the DCSC allow for an efficient operation, 3.8 percentage points higher than the basecase operation; the efficiency of the process utilizing a DCSC is smaller than that utilizing a surface heat exchanger but only by 0.32 percentage points after optimization. Optimization also shows a reduction in capital costs by process intensification and by not requiring the first flue gas compressor in the carbon sequestration unit. Second, in order to eliminate performance and economical risks that arise due to uncertainties in the conditions that a power generation process may be subjected to, the designs and operations that allow maximum overall performance of the process while facing all possible changes in operating condition are investigated. Therefore, optimization under uncertainty in coal type, ranging from Venezuelan and Indonesian coals to a lower grade south African Douglas Premium and Kleinkopje coal, and in ambient conditions, up to 10°C difference in the temperature of the cooling water, of the pressurized oxy-coal combustion are performed. Using hierarchic optimization and stochastic programing, the latter shown to be unnecessary, an ideally flexible design is attained, whereby the maximum possible performance of the process with any set of input parameters is attained by a single design. While in general a process designed for a specific coal has a low performance when the utilized coal is changed, for the pressurized oxy-coal combustion process presented herein, it is demonstrated that designing (and optimizing) while taking into consideration the different coal types utilized, results for each coal in performance that is equal to the maximum performance obtained by a design dedicated to that coal. The third aspect considered is flexibility with respect to load variation. Particularly with the increase of the power generation from intermittent renewable energy sources, coal power plants should operate at loads far from nominal, down to 35%. In general this results in efficiency significantly lower than the optimum. Therefore, while keeping the turbine expansion line design fixed to that of the nominal load in order to allow for a full range of thermal load operations, an elaborate study of the variations in thermal load for pressurized oxy-coal combustion is performed. Here too optimization of design and operation taking into consideration that load is not fixed results in a process that is flexible to the thermal load; the range of thermal load considered is 30..100%. The fourth aspect considered is a novel design for heat recovery steam generator (HRSG), which is an essential part of coal power plants, particularly oxy-coal combustion. It is the site of high temperature thermal energy transfer, and is shown to have potential for significant improvements in its design and operation. A new design and operation of the HRSG that allow for simultaneous reduction in the area and the flow losses is proposed: the hot combustion gas is splitted prior to entering the HRSG and prior to dilution with the recycling flue gas to control its temperature as dictated by the HRSG maximum allowed temperature. The main combustion gas flow proceeds to the HRSG inlet and requires smaller amounts of dilution and recycling power requirements compared to the conventional no splitting operation. The splitted fraction is introduced downstream at an intermediate location in the HRSG; the introduction of the splitted gas results in increasing the temperature of the flue gas and the temperature difference between the hot and the cold streams of the HRSG, particularly avoiding small temperature differences which require the most heat transfer area. Results include area reduction by 37% without change in the compensation power requirements, or a decrease in the compensation power requirements by 18% (corresponding to 0.15 percent points of the cycle efficiency) while simultaneously reducing the area by 12%.

Download or read book Carbon Dioxide Removal from Coal Fired Power Plants written by C. Hendriks and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: 1. 1. Greenhouse gas emissions and climate change . . . . . . . . . . . . . . 3 1. 1. 1. Emissions and concentrations of greenhouse gases 3 1. 1. 2. Impact of increasing greenhouse gases concentration 4 1. 2. Options to reduce carbon dioxide emissions 5 1. 2. 1. Carbon dioxide removal 8 1. 3. Scope of the thesis 10 1. 4. Outline of the thesis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1. 4. 1. General evaluation method. . . . . . . . . . . . . . . . . . . . . . . 12 1. 4. 2. Some notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 II. Simulation and optimization of carbon dioxide recovery from the flue gases of a coal-fired power plant using amines 14 Abstract 19 2. 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2. 2. The chemical absorption process. . . . . . . . . . . . . . . . . . . . . . . . 22 2. 2. 1. General process description. . . . . . . . . . . . . . . . . . . . . . . 22 2. 2. 2. Types of absorbent 23 2. 2. 3. Effects of flue gas contaminants 24 2. 3. Simulation of the scrubber in ASPEN PLUS . . . . . . . . . . . . . . . . . 25 2. 3. 1. ASPEN PLUS for flow sheet simulation 26 2. 3. 2. Simulation of the performance for the base-case design . . 26 the scrubber . . . . . . . . . . . . . . . . . . . . . . 29 2. 3. 3. Optimization of 2. 3. 4. Design and results 32 2. 3. 5. Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 2. 4. Integration of the scrubber in the power plant 35 2. 4. 1. Power loss caused by steam extraction 36 2. 4. 2. Power saved by avoiding preheating boiler feed water . . . 38 2. 4. 3. Power consumption by the carbon dioxide scrubber . . . . . 38 2. 4. 4. Power consumption for carbon dioxide compression . . . . . 38 2. 4. 5. Calculation of plant efficiency losses " . . . . . . . . . . . . . . 39 2. 5.

Download or read book Robust Optimization of a Post combustion CO2 Capture Absorber Column Under Process Uncertainty written by Ilse Mariana Cerrillo Briones and published by . This book was released on 2019 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, greenhouse gas (GHG) emissions is a global concern due to high concentrations of these gases in the atmosphere. Carbon capture and storage (CCS) has been suggested as an attractive alternative to curb intensive CO2 emissions and reduce its impact to the environment. CCS technologies provide a direct alternative to reducing the emissions from coal and gas-fired power generation plants. However, in order to implement commercial-scale CO2 capture plants, further studies are needed to mitigate all possible costs of this technology such as high energy consumption. This work presents a study on a robust design optimization framework for a pilot-scale absorber column in post-combustion CO2 capture. A mechanistic model describing the behaviour of a post-combustion CO2 absorber column is explicitly considered. The proposed formulation takes into account uncertainty that will impact the absorber column due to seasonal or unexpected changes in the operating policies of a fossil-fired power plant, e.g., changes in the flue gas stream, as well as uncertainty associated with the physical thermodynamic properties of the species involved in the absorption process. Furthermore, in addition to the presence of model uncertainty, a multi-objective optimization in a multi-period scenario explicitly describing year-long seasonal changes in flue gas has been considered. Different scenarios were assessed in order to evaluate the impact of uncertainty and multi-period changes on the optimal multi-objective process design. Optimal design specifications between different number of uncertain realizations and periodical changes were studied. However, higher computational demands were observed under extensive evaluations of uncertainty. Results from this study suggest that larger dimensions in design are required when the optimization was evaluated under uncertainty and under multi-periods scenarios considering uncertainty. The results show that the optimal design considering uncertainty and seasonal changes will be able to comply with the CO2 capture policies. Thus, post-combustion CO2 capture systems must be designed under these conditions to ensure feasibility of these plants during operation.

Download or read book Advances in Carbon Management Technologies written by Subhas Sikdar and published by CRC Press. This book was released on 2020-03-19 with total page 471 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Carbon Management Technologies comprises 43 chapters contributed by experts from all over the world. Volume 1 of the book, containing 23 chapters, discusses the status of technologies capable of yielding substantial reduction of carbon dioxide emissions from major combustion sources. Such technologies include renewable energy sources that can replace fossil fuels and technologies to capture CO2 after fossil fuel combustion or directly from the atmosphere, with subsequent permanent long-term storage. The introductory chapter emphasizes the gravity of the issues related to greenhouse gas emissionglobal temperature correlation, the state of the art of key technologies and the necessary emission reductions needed to meet international warming targets. Section 1 deals with global challenges associated with key fossil fuel mitigation technologies, including removing CO2 from the atmosphere, and emission measurements. Section 2 presents technological choices for coal, petroleum, and natural gas for the purpose of reducing carbon footprints associated with the utilization of such fuels. Section 3 deals with promising contributions of alternatives to fossil fuels, such as hydropower, nuclear, solar photovoltaics, and wind. Chapter 19 of this book is freely available as a downloadable Open Access PDF at http://www.taylorfrancis.com under a Creative Commons Attribution-Non Commercial-No Derivatives (CC-BY-NC-ND) 4.0 license.

Download or read book Carbon Capture Storage and Utilization written by Malti Goel and published by CRC Press. This book was released on 2019-02-21 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon capture and storage (CCS) is among the advanced energy technologies suggested to make the conventional fossil fuel sources environmentally sustainable. It is of particular importance to coal-based economies. This book deals at length with the various aspects of carbon dioxide capture, its utilization and takes a closer look at the earth processes in carbon dioxide storage. It discusses potential of Carbon Capture, Storage, and Utilization as innovative energy technology towards a sustainable energy future. Various techniques of carbon dioxide recovery from power plants by physical, chemical, and biological means as well as challenges and prospects in biomimetic carbon sequestration are described. Carbon fixation potential in coal mines and in saline aquifers is also discussed. Please note: This volume is Co-published with The Energy and Resources Institute Press, New Delhi. Taylor & Francis does not sell or distribute the Hardback in India, Pakistan, Nepal, Bhutan, Bangladesh and Sri Lanka

Download or read book Handbook of CO2 in Power Systems written by Qipeng P. Zheng and published by Springer Science & Business Media. This book was released on 2012-06-05 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Handbook of CO2in Power Systems' objective is to include the state-of-the-art developments that occurred in power systems taking CO2emission into account. The book includes power systems operation modeling with CO2emissions considerations, CO2market mechanism modeling, CO2regulation policy modeling, carbon price forecasting, and carbon capture modeling. For each of the subjects, at least one article authored by a world specialist on the specific domain is included.

Download or read book Emerging Carbon Capture Technologies written by Mohammad Khalid and published by Elsevier. This book was released on 2022-04-22 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon dioxide (CO2) capture and conversion to value added products, such as chemicals, polymers, and carbon-based fuels represents a promising approach to transform a potential threat to the environment into a value-added product for long term sustainability. Emerging Carbon Capture Technologies: Towards a Sustainable Future provides a multidisciplinary view of the research that is being carried out in this field, covering materials and processes for CO2 capture and utilization and including a broad discussion of the impact of novel technologies in carbon capture on the energy landscape, society and climate. Of interest to students, researchers and professionals in industries related to greenhouse gas mitigation, post-combustion CO2 capture processes, coal-fired power plants, environmental sustainability, green solvents, green technologies, and the utilization of clean energy for environmental protection, this book covers both the experimental and theoretical aspects of novel materials and process development providing a holistic approach toward a sustainable energy future. Includes a wide range of processes and their applications Covers the experimental and theoretical aspects of novel materials and process development Includes techno-economics analysis, regulation, policies and future prospects

Download or read book Carbon Capture written by Jennifer Wilcox and published by Springer Science & Business Media. This book was released on 2012-03-27 with total page 337 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book approaches the energy science sub-field carbon capture with an interdisciplinary discussion based upon fundamental chemical concepts ranging from thermodynamics, combustion, kinetics, mass transfer, material properties, and the relationship between the chemistry and process of carbon capture technologies. Energy science itself is a broad field that spans many disciplines -- policy, mathematics, physical chemistry, chemical engineering, geology, materials science and mineralogy -- and the author has selected the material, as well as end-of-chapter problems and policy discussions, that provide the necessary tools to interested students.

Download or read book Carbon Capture and Storage Including Coal fired Power Plants written by Todd P. Carington and published by . This book was released on 2010 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nationally-recognised studies and our contacts with a diverse group of industry representatives, non-governmental organisations, and academic researchers show that key barriers to CCS deployment include (1) underdeveloped and costly CO2 capture technology and (2) regulatory and legal uncertainties over CO2 capture, injection, and storage. Among the key technological barriers are a lack of experience in capturing significant amounts of CO2 from power plants and the significant cost of capturing CO2, particularly from existing coal-fired power plants, which are the single largest source of CO2 emissions in the United States. Compounding these technological issues are regulatory and legal uncertainties, including uncertainty regarding liability for CO2 leakage and ownership of CO2 once injected. According to the IPCC, the National Academy of Sciences, and other knowledgeable authorities, another barrier is the absence of a national strategy to control CO2 emissions (emissions trading plan, CO2 emissions tax, or other mandatory control of CO2 emissions), without which the electric utility industry has little incentive to capture and store its CO2 emissions. Moreover, according to key agency officials, the absence of a national strategy has also deterred their agencies from addressing other important practical issues, such as resolving how stored CO2 would be treated in a future CO2 emissions trading plan.

Download or read book Developments and Innovation in Carbon Dioxide CO2 Capture and Storage Technology written by M. Mercedes Maroto-Valer and published by Elsevier. This book was released on 2010-06-21 with total page 561 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon dioxide (CO2) capture and storage (CCS) is the one advanced technology that conventional power generation cannot do without. CCS technology reduces the carbon footprint of power plants by capturing and storing the CO2 emissions from burning fossil-fuels and biomass. This volume provides a comprehensive reference on the state of the art research, development and demonstration of carbon capture technology in the power sector and in industry. It critically reviews the range of post- and pre-combustion capture and combustion-based capture processes and technology applicable to fossil-fuel power plants, as well as applications of CCS in other high carbon footprint industries. Foreword written by Lord Oxburgh, Climate Science Peer Reviews the economics, regulation and planning of carbon capture and storage for power plants and industry Explores developments in combustion processes and technologies for CO2 capture in power plants

Download or read book Carbon Capture written by Syed Abdul Rehman Khan and published by BoD – Books on Demand. This book was released on 2021-03-17 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book differs from others on the subject of pollution and carbon emissions by focusing on environmental issues at domestic levels. It presents important information on the far-ranging effects of greenhouse gases on the environment and examines potential solutions to controlling carbon emissions.

Download or read book CO2 Capture and Storage written by Kamel Bennaceur and published by OECD Publishing. This book was released on 2008 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: At head of title: International Energy Agency.

Download or read book Coal fired Power Plants and Carbon Dioxide Issues written by Matthew W. Shuester and published by Nova Science Publishers. This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Any comprehensive approach to substantially reduce greenhouse gases must address the world's dependency on coal for one-quarter of its energy demand, including almost half of its electricity demand. To maintain coal in the world's energy mix in a carbon-constrained future would require development of a technology to capture and store its carbon dioxide emissions. This situation suggests to some that any greenhouse gas reduction program be delayed until such carbon capture technology has been demonstrated. However, technological innovation and the demands of a carbon control regime are interlinked; a technology policy is no substitute for environmental policy and should be developed in concert with it. This book explores developing a means to control coal-derived greenhouse gas emissions which is an imperative if serious reductions in world-wide emissions are to occur in the foreseeable future.