Development of Carbon Dioxide Capture Technologies in Coal-Fired Power Plants

With a particular reference to China Huaneng Group's practices in CO_2 capture, this article presents a brief ing on the current development of CO_2 capture technologies in coal-fired power plants both in China and abroad. Sooner or later, the integration of CO_2 capture and storage (CCS) facility with coal-fired power plant will be inevitably put on the agenda of developers.

Optimization of an Existing Coal-fired Power Plant with CO²Capture

Nowadays, the worsening environmental issue caused by CO2 emission is greatly aggravated by human activity. Many CO2 reduction technologies are under fast development. Among these, monoethanolamine (MEA) based CO2 capture technology has been paid great attention. However, when connecting the CO2 capture process with a coal-fired power plant, the huge energy and efficiency penalty caused by CO2 capture has become a serious problem for its application. Thus, it is of great significance to reduce the related energy consumption. Based on an existing coal-fired power plant, this paper proposes a new way for the decarburized retrofitting of the coal-fired power plant, which helps to improve the overall efficiency of the power plant with less energy and efficiency penalty. The decarburized retrofitting scheme proposed will provide a new route for the CO2 capture process in China.

Environmental life cycle assessment of Indian coal-fired power plants

Coal is the backbone of the Indian power sector. The coal-fired power plants remain the largest emitters of carbon dioxide, sulfur dioxide and substantial amounts of nitrogen oxides, which are associated with climate and health impacts. Various CO2 mitigation technologies （carbon capture and storage--CCS） and SO2/NOx mitigation technologies （flue gas desulfurization and selective catalytic reduction） have been employed to reduce the environmental impacts of the coal-fired power plants. Therefore, it is imperative to understand the feasibility of various mitigation technologies employed. This paper attempts to perform environmental life cycle assessment （LCA） of Indian coal-fired power plant with and without CO2, SO2 and NOx mitigation controls. The study develops new normalization factors for India in various damage categories, using the Indian emissions and energy consumption data, coupled with the emissions and particulate emission to come up with a final environmental impact of coal-fired electricity. The results show a large degree of dependence on the perspective of assessment used. The impact of sensitivities of individual substances and the effect of plant efficiency on the final LCA results is also studied.

Optimal Bidding and Operation of a Power Plant with Solvent-BasedCarbon Capture under a CO2 Allowance Market： A Solution with aReinforcement Learning-Based Sarsa Temporal-Difference Algorithm

In this paper, a reinforcement learning （RL）-based Sarsa temporal-difference （TD） algorithm is applied tosearch for a unified bidding and operation strategy for a coal-fired power plant with monoethanolamine（MEA）-based post-combustion carbon capture under different carbon dioxide （CO2） allowance market con-ditions. The objective of the decision maker for the power plant is to maximize the discounted cumulativeprofit during the power plant lifetime. Two constraints are considered for the objective formulation. Firstly,the tradeoff between the energy-intensive carbon capture and the electricity generation should be made un-der presumed fixed fuel consumption. Secondly, the CO2 allowances purchased from the CO2 allowance mar-ket should be approximately equal to the quantity of COs emission from power generation. Three case stud-ies are demonstrated thereafter. In the first case, we show the convergence of the Sarsa TD algorithm andfind a deterministic optimal bidding and operation strategy. In the second case, compared with the inde-pendently designed operation and bidding strategies discussed in most of the relevant literature, the SarsaTD-based unified bidding and operation strategy with time-varying flexible market-oriented CO2 capturelevels is demonstrated to help the power plant decision maker gain a higher discounted cumulative profit.In the third case, a competitor operating another power plant identical to the preceding plant is consideredunder the same CO2 allowance market. The competitor also has carbon capture facilities but applies a differ-ent strategy to earn profits. The discounted cumulative profits of the two power plants are then compared,thus exhibiting the competitiveness of the power plant that is using the unified bidding and operation strat-egy explored by the Sarsa TD algorithm.

Improving Prediction Accuracy of a Rate-Based Model of an MEA-BasedCarbon Capture Process for Large-Scale Commercial Deployment

Carbon capture and storage （CCS） technology will play a critical role in reducing anthropogenic carbondioxide （CO2） emission from fossil-fired power plants and other energy-intensive processes. However, theincrement of energy cost caused by equipping a carbon capture process is the main barrier to its commer-cial deployment. To reduce the capital and operating costs of carbon capture, great efforts have been madeto achieve optimal design and operation through process modeling, simulation, and optimization. Accuratemodels form an essential foundation for this purpose. This paper presents a study on developing a moreaccurate rate-based model in Aspen Plus for the monoethanolamine （MEA）-based carbon capture processby multistage model validations. The modeling framework for this process was established first. The steady-state process model was then developed and validated at three stages, which included a thermodynamicmodel, physical properties calculations, and a process model at the pilot plant scale, covering a wide rangeof pressures, temperatures, and CO2 loadings. The calculation correlations of liquid density and interfacialarea were updated by coding Fortran subroutines in Aspen Plus. The validation results show that the cor-relation combination for the thermodynamic model used in this study has higher accuracy than those ofthree other key publications and the model prediction of the process model has a good agreement with thepilot plant experimental data. A case study was carried out for carbon capture from a 250 MWe combinedcycle gas turbine （CCGT） power plant. Shorter packing height and lower specific duty were achieved usingthis accurate model.

A coal-fired power plant integrated with biomass co-firing and CO_(2) capture for zero carbon emission

A promising scheme for coal-fired power plants in which biomass co-firing and carbon dioxide capture technologies are adopted and the low-temperature waste heat from the CO_(2) capture process is recycled to heat the condensed water to achieve zero carbon emission is proposed in this paper.Based on a 660 MW supercritical coal-fired power plant,the thermal performance,emission performance,and economic performance of the proposed scheme are evaluated.In addition,a sensitivity analysis is conducted to show the effects of several key parameters on the performance of the proposed system.The results show that when the biomass mass mixing ratio is 15.40%and the CO_(2) capture rate is 90%,the CO_(2) emission of the coal-fired power plant can reach zero,indicating that the technical route proposed in this paper can indeed achieve zero carbon emission in coal-fired power plants.The net thermal efficiency decreases by 10.31%,due to the huge energy consumption of the CO_(2) capture unit.Besides,the cost of electricity(COE)and the cost of CO_(2) avoided(COA)of the proposed system are 80.37/MWhand41.63/tCO_(2),respectively.The sensitivity analysis demonstrates that with the energy consumption of the reboiler decreasing from 3.22 GJ/tCO_(2) to 2.40 GJ/tCO_(2),the efficiency penalty is reduced to 8.67%.This paper may provide reference for promoting the early realization of carbon neutrality in the power generation industry.

Prediction of cost and emission from Indian coal-fired power plants with C02 capture and storage using artificial intelligence techniques

Coal-fired power plants are one of the most important targets with respect to reduction of CO2 emissions.The reasons for this are that coal-fired power plants offer localized large point sources(LPS)of CO2 and that the Indian power sector con tributes to roughly half of all-India CO2emissions.CO2capture and storage(CCS)can be implemented in these power plants for long-temi decarbonisation of the Indian economy.In this paper,two artificial intelligence(Al)techniques—adaptive network based fuzzy inference system(ANFIS)and multi gene genetic programming(MGGP)are used to model Indian coal-fired power plants with CO2 capture.The data set of 75 power plants take the plant size,the capture type,the load and the CO2 emission as the input and the COE and annual CO2 emissions as the output.It is found that MGGP is more suited to these applications with an R2 value of more than 99%between the predicted and actual values,as against the^96%correlation for the ANFIS approach.MGGP also gives the traditionally expected results in sensitivity analysis,which ANFIS fails to give.Several other parameters in the base plant and CO2 capture unit may be included in similar studies to give a more accurate result.This is because MGGP gives a better perspective toward qualitative data,such as capture type,as compared to ANFIS.

Review on current advances,future challenges and consideration issues for post-combustion CO_2 capture using amine-based absorbents

Among the current technologies for post-combustion CO2 capture,amine-based chemical absorption appears to be the most technologically mature and commercially viable method.This review highlights the opportunities and challenges in post-combustion CO2 capture using amine-based chemical absorption technologies.In addition,this review provides current types and emerging trends for chemical solvents.The issues and performance of amine solvents are reviewed and addressed in terms of thermodynamics,kinetics,mass transfer,regeneration and solvent management.This review also looks at emerging and future trends in post-combustion CO2 capture using chemical solvents in the near to mid-term.

Low-carbon Operation of Combined Heat and Power Integrated Plants Based on Solar-assisted Carbon Capture

Accelerating the development of renewable energy and reducing CO_(2)emissions have become a general consensus and concerted action of all countries in the world. The electric power industry, especially thermal power industry, is the main source for fossil energy consumption and CO_(2)emissions. Since solvent-based post-combustion carbon capture technology would bring massive extra energy consumption, the application of solar-assisted carbon capture technology has attracted extensive attention. Due to the important role of coal-fired combined heat and power plants for serving residential and industrial heating districts, in this paper, the low-carbon operation benefits of combined heat and power integrated plants based on solar-assisted carbon capture(CHPIP-SACC) are fully evaluated in heat and power integrated energy system with a high proportion of wind power. Based on the selected integration scheme, a linear operation model of CHPIP-SACC is developed considering energy flow characteristics and thermal coupling interaction of its internal modules. From the perspective of system-level operation optimization, the day-ahead economic dispatch problem based on a mix-integer linear programming model is presented to evaluate the low-carbon benefits of CHPIP-SACC during annual operation simulation. The numerical simulations on a modified IEEE 39-bus system demonstrate the effectiveness of CHPIP-SACC for reducing CO_(2)emissions as well as increasing the downward flexibility. The impact of different solar field areas and unit prices of coal on the low-carbon operation benefits of CHPIP-SACC is studied in the section of sensitivity analysis.

Pilot testing of CO_(2) capture from a coal-fired power plant-Part 2:Results from 1-MWe pilot tests

Using a 1-MWe slipstream pilot plant,solid-sorbent-based post-combustion CO_(2) capture was tested at a coal-fired power plant.Results from pilot testing were used to develop a preliminary full-scale commercial design.The sorbent selected for pilot-scale evaluation during this project consisted of an ion-exchange resin that incorporated amines covalently bonded to the substrate.A unique temperature-swing-absorption(TSA)process was developed that incorporated a three-stage fluidized-bed adsorber integrated with a single-stage fluidized-bed regenerator.Overall,following start-up and commissioning challenges that are often associated with first-of-a-kind pilots,the pilot plant operated as designed and expected,with a few key exceptions.The two primary exceptions were associated with:(i)handling characteristics of the sorbent,which were sufficiently different at operating temperature than at ambient temperature when design specifications were established with lab-scale testing;and(ii)CO_(2) adsorption in the transport line between the regenerator and adsorber that preloaded the sorbent with CO_(2) prior to entering the adsorber.Results from the pilot programme demonstrate that solid-sorbent-based post-combustion capture can be utilized to achieve 90%CO_(2) capture from coal-fired power plants.

Pilot testing of CO_(2) capture from a coal-fired power plant-Part 1:Sorbent characterization

Post-combustion CO_(2)capture followed by sequestration is one of the only feasible means to significantly reduce CO_(2)emissions from existing fossil-fuel-fired power plants.This paper is Part 1 of a two-part paper highlighting key results from a project sponsored by the US Department of Energy and supported by industrial groups with the objective of demonstrating the viability of solid sorbents for CO_(2)capture.The overall objective of the effort was to validate solid sorbent-based post-combustion CO_(2)capture through slipstream pilot testing at a coal-fired power plant using a temperature-swing adsorption process.In Part 1 of this work,the results from laboratory characterization of the sorbent selected for the pilot-scale demonstration are presented.A great deal of research related to sorbent development and evaluation has occurred to date but,for the most part,these promising materials have yet to be paired with a feasible process and demonstrated at the pilot scale.The sorbent selected for pilot-scale evaluation under this project consisted of an ion-exchange resin that incorporated amines that were covalently bonded to the substrate.During the sorbent characterization portion of this work,the sorbent was characterized by a range of methods intended to provide information to support the design and operation of the pilot-scale CO_(2)-capture process,including equilibrium adsorption isotherms,adsorption and regeneration kinetics,impact of moisture and oxygen on CO_(2)working capacity,sorbent thermal properties,sorbent strength and attrition,and optimum particle-size distribution.This paper reports results from sorbent characterization testing and how these characteristics influenced the type and size of the CO_(2)-capture process equipment.In Part 2 of this work,results from tests of 1-MWe pilot-scale process equipment loaded with the sorbent described in Part 1 will be presented and analysed.

Collaborative robust dispatch of electricity and carbon under carbon allowance trading market

The launch of the carbon-allowance trading market has changed the cost structure of the power industry.There is an asynchronous coupling mechanism between the carbon-allowance-trading market and the day-ahead power-system dispatch.In this study,a data-driven model of the uncertainty in the annual carbon price was created.Subsequently,a collaborative,robust dispatch model was constructed considering the annual uncertainty of the carbon price and the daily uncertainty of renewable-energy generation.The model is solved using the column-and-constraint generation algorithm.An operation and cost model of a carbon-capture power plant(CCPP)that couples the carbon market and the economic operation of the power system is also established.The critical,profitable conditions for the economic operation of the CCPP were derived.Case studies demonstrated that the proposed low-carbon,robust dispatch model reduced carbon emissions by 2.67%compared with the traditional,economic,dispatch method.The total fuel cost of generation decreases with decreasing,conservative,carbon-price-uncertainty levels,while total carbon emissions continue to increase.When the carbon-quota coefficient decreases,the system dispatch tends to increase low-carbon unit output.This study can provide important guidance for carbon-market design and the low-carbon-dispatch selection strategies.

Low-Carbon Dispatch of an Integrated Energy System Considering Confidence Intervals for Renewable Energy Generation

Addressing the insufficiency in down-regulation leeway within integrated energy systems stemming from the erratic and volatile nature of wind and solar renewable energy generation,this study focuses on formulating a coordinated strategy involving the carbon capture unit of the integrated energy system and the resources on the load storage side.A scheduling model is devised that takes into account the confidence interval associated with renewable energy generation,with the overarching goal of optimizing the system for low-carbon operation.To begin with,an in-depth analysis is conducted on the temporal energy-shifting attributes and the low-carbon modulation mechanisms exhibited by the source-side carbon capture power plant within the context of integrated and adaptable operational paradigms.Drawing from this analysis,a model is devised to represent the adjustable resources on the charge-storage side,predicated on the principles of electro-thermal coupling within the energy system.Subsequently,the dissimilarities in the confidence intervals of renewable energy generation are considered,leading to the proposition of a flexible upper threshold for the confidence interval.Building on this,a low-carbon dispatch model is established for the integrated energy system,factoring in the margin allowed by the adjustable resources.In the final phase,a simulation is performed on a regional electric heating integrated energy system.This simulation seeks to assess the impact of source-load-storage coordination on the system’s low-carbon operation across various scenarios of reduction margin reserves.The findings underscore that the proactive scheduling model incorporating confidence interval considerations for reduction margin reserves effectively mitigates the uncertainties tied to renewable energy generation.Through harmonized orchestration of source,load,and storage elements,it expands the utilization scope for renewable energy,safeguards the economic efficiency of system operations under low-carbon emission conditions,and empirically validates the soundness and efficacy of the proposed approach.

考虑碳-绿证市场耦合的多虚拟电厂电-碳P2P交易模型

为了探索多市场交易下虚拟电厂(VPP)之间的点对点(P2P)交易模式,提出一种考虑碳-绿证市场耦合的多VPP电-碳P2P交易模型。建立包含光伏、储能、中央空调、碳捕集机组和用户负荷的多VPP聚合模型,建立绿证-碳配额耦合的VPP交易模型;在此基础上,基于合作博弈理论,建立多VPP社会效益最大化模型,采用交替方向乘子法对模型进行分布式求解,并建立非对称纳什议价模型对合作剩余利润进行分配;通过算例分析验证所提模型能在提升经济效益的同时,减少VPP的CO_(2)排放量。

Economic analysis of atmospheric mercury emission control for coal-fired power plants in China

Coal combustion and mercury pollution are closely linked, and this relationship is particularly relevant in China, the world＇s largest coal consumer. This paper begins with a summary of recent China-specific studies on mercury removal by air pollution control technologies and then provides an economic analysis of mercury abatement from these emission control technologies at coal-fired power plants in China. This includes a cost-effectiveness analysis at the enterprise and sector level in China using 2010 as a baseline and projecting out to 2020 and2030. Of the control technologies evaluated, the most cost-effective is a fabric filter installed upstream of the wet flue gas desulfurization system（FF ＋ WFGD）. Halogen injection（HI） is also a cost-effective mercury-specific control strategy, although it has not yet reached commercial maturity. The sector-level analysis shows that 193 tons of mercury was removed in 2010 in China＇s coal-fired power sector, with annualized mercury emission control costs of 2.7 billion Chinese Yuan. Under a projected 2030 Emission Control（EC） scenario with stringent mercury limits compared to Business As Usual（BAU） scenario, the increase of selective catalytic reduction systems（SCR） and the use of HI could contribute to 39 tons of mercury removal at a cost of 3.8 billion CNY. The economic analysis presented in this paper offers insights on air pollution control technologies and practices for enhancing atmospheric mercury control that can aid decision-making in policy design and private-sector investments.

Post-combustion slipstream CO_(2)-capture test facility at Jiangyou Power Plant,Sichuan,China:facility design and validation using 30% wt monoethanolamine(MEA)testing

Given the dominant share of coal in China’s energy-generation mix and the fact that>50% of the power plants in the country are currently<15 years old,efforts to significantly reduce China’s CO_(2) footprint will require the deployment of CO_(2) capture across at least part of its fleet of coal-fired power plants.CO_(2)-capture technology is reaching commercial maturity,but it is still necessary to adapt the technology to regional conditions,such as power-plant design and flexible operation in the China context.Slipstream facilities provide valuable field data to support the commercialization of CO_(2) capture.We have built a slipstream facility at Jiangyou power plant in Sichuan that will allow us to explore China-relevant issues,especially flexible operation,over the next few years.We plan to share our results with the broader CO_(2)-capture and CO_(2)-storage(CCS)community to accelerate the deployment of CCS in China.This paper describes the design of the slipstream facility and presents results from our steady-state qualification tests using a well-studied benchmark solvent:30% wt monoethanolamine(MEA).The results from our MEA tests compare favorably to results reported from other slipstream-test facilities around the world,allowing us to commission our system and establish a reference baseline for future studies.

含碳捕集电厂与氢能多元利用的综合能源系统低碳经济调度

随着中国“碳达峰·碳中和”战略的不断推进,综合能源系统的绿色低碳转型迫在眉睫。针对传统碳捕集电厂灵活性较差、风电并网难以消纳等问题,提出一种含碳捕集电厂与氢能多元利用的综合能源系统低碳经济调度模型。首先,引入储液罐对传统碳捕集电厂进行改造,提高电厂应对风电波动的运行灵活性;其次,构建含两段式电转气、氢燃料电池、储氢罐和掺氢热电联产在内的氢能多元利用结构,以充分挖掘氢能利用与碳捕集电厂的协同运行潜力。在此基础上,引入阶梯碳交易机制,建立以碳交易、碳封存、燃煤及购气成本之和最小为优化目标的低碳经济调度模型。算例结果表明,文中模型能够有效提高系统的风电消纳水平和能源利用效率,具有显著的低碳经济效益。此外,碳交易基准价格的合理设定能够引导系统提高碳捕集水平。

考虑风电爬坡灵活调节的碳捕集电厂低碳经济调度

为实现“双碳”目标,风电等可再生能源的使用是减少碳排放的根本途径,而碳捕集电厂是降低碳排放的直接手段。但风电具有与生俱来的波动性,风电的骤升骤降会影响碳捕集电厂“电碳耦合”特性,从而对碳捕集效果带来不利影响。而储液罐通过增减自身溶液量可近似地存储释放能量,为解决上述问题提供了可能。该文首先搭建碳捕集电厂数学模型,分析储液罐通过增减溶液量带来的储放能量与碳捕集设备能耗之间的关联,研究储液罐的双向调节能力;然后,提出上爬坡碳超前补偿和下爬坡碳滞后补偿调度策略,双向调节储液罐使碳捕集电厂电碳解耦;接着,构建跟随风电爬坡进行调节的低碳经济调度模型;最后,对含碳捕集电厂、高碳电厂和风电场的电力系统进行仿真,证明所提方法的有效性。

考虑超碳需求响应的综合能源系统低碳优化调度

西北地区新能源发展迅速,充分利用当地独有的光热资源优势,同时结合火电低碳化改造与新能源协同运行,有利于推动当地能源系统绿色低碳转型。为尽最大限度地提升系统的减碳能力,提出一种基于源荷协同降碳的超碳需求响应模型,将动态碳排放因子作为分时电价的惩罚因子,从而将源侧碳信号传递至荷侧,驱使用户侧进行低碳性状态转移。首先,在日前调度阶段,构建预调度-再调度两阶段调度运行机制,再调度根据预调度的系统状态信息进行超碳需求响应,来深度降低系统碳排量。其次,将光热电站引入综合能源系统,与风电场、碳捕集电厂协同运行,从而构建高比例新能源场景,来验证超碳需求响应在此场景下的减碳效益。最后,建立了基于超碳需求响应的预调度-再调度两阶段低碳调度模型。经算例仿真分析表明,所提源荷协同降碳的新思路能有效提高系统的减碳能力,深入挖掘系统的降碳空间,提升系统的经济效益。

含整体煤气化燃料电池-碳捕集电厂的风火储系统分布鲁棒调度方法

整体煤气化燃料电池(integrated gasification fuel cell,IGFC)是与碳捕集技术高度适配的清洁、高效、稳定的绿色煤电技术,有望克服传统碳捕集技术在低浓度CO_(2)环境下产生的高成本、高能耗问题。该文构建含IGFC碳捕集电厂的风火储发电系统。研究IGFC碳捕集电厂的运行机理,对IGFC内部各环节建立数学模型,提出工况匹配时燃烧利用率和阴极空气利用率需要满足的运行条件,并针对该型碳捕集电厂的电碳特性进行分析。为计及风电出力的不确定性,构建风火储系统的两阶段分布鲁棒经济调度模型,引入k阶适应性理论,提出基于正交支撑子集策略的求解方法来获得鲁棒对等式。最后,在改进IEEE-30节点系统中进行算例分析,结果表明,该型碳捕集电厂可利用阳极碳富集的优势,实现系统低碳经济调度的目标,并验证所提优化方法能为可行解提供可解释性。