Advanced Coal Technologies for sustainable power sector in India

In India, more than two-thirds of the total electricity is generated from coal-based power plants. The country will be heavily dependent on coal for electricity generation at least for a few more decades. A low carbon scenario for 2030 is projected and the results show that coal-based power plant will contribute to 58 % of electricity generated. This paper reports the sustainability assessment of several Advanced Coal Technologies (ACT), with and without a CO₂ capture system, for application in Indian coal-based power plants. In order to assess sustainability quantitatively, an index called Sustainability Index is estimated using a sequential combination of the Analytic Hierarchy Process and a multi-criteria decision-making method. The results show that ACTs like supercritical and ultra supercritical power plants with a carbon capture system have higher sustainability indices. These ACTs will help in reducing the CO₂ emissions and combat climate change. This study helps academicians, industrialists, policymakers, and other stakeholders to develop a technology roadmap for sustainable development in India.     

Back where it belongs

Capturing the harmful carbon that is produced during generation of electricity and burying it underground is not a new idea but, since its appearance in the UK Energy Review, it has again come into the spotlight. Carbon capture and storage (CCS) offers technological solutions to the production of harmful emissions from power generation. The review accepts as inevitable a long-term future for coal, and, according to the government, this new technology could cut carbon emissions form fossil fuels by between 80-90%, leading to the saving of several million tonnes of carbon by 2020. Basically CCS involves capturing the carbon dioxide (CO₂) released by burning fossil fuels and injecting it underground     

计及P2G和CCS的园区级电-热-气综合能源系统多目标优化

碳捕集和可再生能源利用已经成为减少碳排放的重要措施。但捕集到的二氧化碳利用方式不明确,弃风弃光现象频发,限制了上述2种措施的减排效果。文章通过耦合电转气(power to gas, P2G)技术和碳捕集系统(carbon capture system,CCS),将其扩展到园区级电-热-气综合能源系统中,建立了一种高比例可再生能源渗透水平下的经济低碳多目标优化模型,在多情景下模拟分析了该综合能源系统在某工业园区的运行效果。结果表明,该耦合能源系统排放的大部分CO₂可以被有效捕获并送往P2G装置用于合成燃气,为利用CO₂提供了新的思路,同时显著提高了系统对可再生能源的消纳能力。对P2G设备容量的敏感性分析表明,单纯增加P2G容量虽然能减少弃能率,但会增加碳排放,因此对P2G的容量规划应当综合考虑可再生能源可用量与碳排放之间的关系。     

The Conceptual Process Arrangement of a Steam–Gas Power Plant with Fully Capturing Carbon Dioxide from Combustion Products

The article proposes a new concept for designing power plants operating on natural gas and involving means for fully removing carbon dioxide from the cycle in the liquid phase form in order to subsequently bind or bury it for reducing the emissions of greenhouse gases into the atmosphere. In contrast to means used in the conventional power plant process arrangements for capturing CO₂ from the combustion products, the proposed concept involves the need to develop fundamentally new power engineering technologies, in which the CO₂ utilization system is intrinsically built into the cycle structure already at the initial stage of power plant design and optimization of its parameters. As an example, the process flow diagram of a natural gas fired power plant generating electricity and heat is considered. The integral indicators characterizing the thermal efficiency of such a power plant are given and compared with the similar indicators of the operating or newly designed plants fitted with CO₂ capturing systems, the process arrangement of which implies direct emission of carbon dioxide into the atmosphere. The comparison is carried out for the average ratio between the generated electricity and heat that has historically been established in the climatic zone of central Russia. It is shown that the proposed cycle features high thermodynamic efficiency and competitiveness with respect to the same indicators of alternative systems for combined generation of electricity and heat. The article suggests versions of the CO₂ capturing system configuration that allows, with the modern technological level of equipment, the carbon dioxide emissions to be reduced down to 0.5–5.0% of the total amount produced in firing natural gas.     

Negative price spiral caused by renewables? Electricity price prediction on the German market for 2030

Logistic regression models were built and used to show the influence of energy sources, fuel, emission prices and time variables on low and negative price events. The models were tuned and validated with data from 2019 to 2021. The results show that volatile generation of wind and solar power raises the likelihood of low and negative electricity prices. Flexible power sources such as gas power plants, as well as high grid load and conventional generation, relate to higher, more stable market prices. Higher CO₂ allowance prices also reduce the likelihood of negative prices, as flexible gas power plants with lower CO₂ emissions compared to inflexible coal power plants are more flexible. The biggest influence of the Covid-19-pandemic was on the grid load in 2020 and 2021, which dropped heavily and lowered the electricity price on the market. The prediction analysis shows that in 2030 more low and negative price events will occur if the power supply does not become more flexible. Gas power plants, especially gas turbine peaker plants, help to reduce low prices in the future.     

Sector coupling: Supporting decarbonisation of the global energy system

Natural gas provides significant energy supply, but also important flexibility services, especially in markets where winter heating load is high, and gas also provides flexibility and system services in power generation. These services are likely to become increasingly important as energy systems transition to lower carbon. But natural gas production and combustion must be phased out in a low carbon economy in applications where carbon capture and storage is not deployed.Options exist for decarbonizing the gas grid, enabling flexibility to be delivered with existing infrastructure. These include biologically derived methane, synthetic methane, and low carbon hydrogen, all potentially in a global context and deployed in sectors where decarbonisation is more difficult.Electric and hydrogen powered vehicles offer crucial routes to addressing transport emissions. These also have significant potential to be flexible users of electricity, facilitating the integration of renewable generation. Future planning and policy options need to consider these options in an integrated, long-term approach.     

碳排放及燃煤约束下的电源规划及其效益评价

优化电源规划是应对电力系统"碳锁定"效应,促进电力系统减少碳排放的重要举措。考虑到国内以煤炭为主的能源结构,有必要分析碳排放及燃煤约束对电源规划的影响。在分析碳捕集电厂运行特性的基础上,建立了考虑碳排放及燃煤约束的低碳电源规划模型,并在模型中采用典型日的运行校验系统是否具备足够的调峰能力。基于国内典型地区电力系统,对不同碳排放总量约束、不同可再生能源发展场景及不同煤炭资源供应约束下的常规火电及碳捕集电厂的扩展规划进行了优化分析,分析结论表明碳捕集电厂可以充分适应电力系统的碳减排目标,满足新能源大规模发展的调峰需求。     

考虑碳捕集电厂综合灵活运行下的含P2G和光热电站虚拟电厂优化调度

为了实现电力系统能源低碳化,大力发展碳捕集与封存技术和风光等新能源是低碳化的重要举措。但碳捕集电厂的最小出力技术约束和风电的反调峰特性限制了风电消纳和碳减排,利用碳捕集灵活运行方式下储液罐进行“能量时移”和“碳转移”,间接消纳风电和减少碳排放。利用碳捕集设备捕集的CO₂作为电转气原料,降低碳封存成本和电转气成本,进一步消纳弃风电量并获得售气收益。由于负荷具有早晚高峰特性,因此利用含储热式光热电站的良好调峰性能将白天的部分热量转移至晚高峰发电,缓解系统调峰压力。为此,文章构建了碳捕集电厂综合灵活运行下含电转气和光热电站虚拟电厂优化调度模型。并运用Matlab软件中YALMIP工具包中的商用求解器Cplex对模型进行优化计算。仿真结果表明,所提模型能进一步减少弃风、减少碳排放和缓解调峰压力。     

基于煤炭洗选工艺的火电厂CO2减排潜力分析

考虑从煤炭购买、洗选到发电过程及后续污染物处理的火电生产流程,建立了以最小发电成本为目标的火电企业CO2排放控制模型.以某火力发电厂为例,依据该厂逐月生产运行数据,污染处理及CO2减排控制能耗,核算了火力发电全流程不同环节的CO2排放量.采用情景分析方法对不同碳捕集技术下的发电成本及CO2排放量进行对比分析,结果表明：该火电厂燃煤发电所排放的CO2占其全部CO2排放量的96.00％,洗煤排放的CO2仅占0.38％,污染物处理间接和直接排放的CO2占3.62％.当采用吸收分离法、膜分离法和物理吸附法进行CO2捕集时,分别可以减少71.60％、76.47％和86.06％的CO2排放,发电成本则依次增加31.16％、41.52％和79.44％.     

当前我国燃煤火电机组降低CO2排放的途径

从我国的能源结构和CO2排放及气候变化的现实出发,分析了我国燃煤火电技术的发展方向,即在不可能短期内改变我国能源和电源结构的情况下,我国火电应当怎样应对减排CO2的压力和挑战。虽然现在正在开发的碳捕获和封存技术（carbon capture and storage,CCS）有可能达到CO2接近零排放,但在CCS技术能够得到大规模推广应用之前的一个相当长的时期,目前最可行、经济、可靠的燃煤机组CO2减排的途径是坚持“上大压小”政策大力发展大容量高效率超临界/超超临界机组,通过技术创新提高现有火电厂效率,提高现有600 ℃超超临界机组的净效率,开发先进的37.5 MPa/700 ℃/720 ℃/720 ℃双再热机组,将1 000~1 500 MW超超临界机组净效率提高至53%以上。     

考虑碳减排的发电商电量上网机制设计

现行的发电商上网电量基本上是按发电容量等比例确定,而上网电价则实行统一的“标杆电价”。基于碳排放约束下总上网电量发电成本最小原则,设计寡头发电商的上网电量分配机制与上网电价机制,并与现行的电量上网机制进行数值分析比较,分析结果表明：（1）新机制可诱导发电商真实地报告自己的成本类型、以保证碳排放约束下总发电成本最小目标的实施;（2）相对于现行的等比例电量上网机制,新机制有利于减排CO₂,且在相同排放水平下可节省总的发电成本;（3）新机制下低排放发电商电量优先上网,且可促使高排放机组逐步退出市场。     

二氧化碳的捕获和封存技术进展

人类活动产生的CO_2长期积累有可能对全球气候造成严重影响,通过CO_2捕获和封存(CCS)技术进行电厂脱碳是减少CO_2进入大气的一个重要切入点。电厂CO_2捕获技术路线分为燃烧前脱碳技术、燃烧后脱碳技术、纯氧燃烧技术以及化学链燃烧技术;CO_2捕获技术则主要有吸收法、吸附法和膜分离法等,其中膜分离法是最有发展潜力的技术。油气田、煤层田以及盐水层具有长期安全封存CO_2的能力,且有巨大的封存容量。     

面向碳中和的工业尾气电厂技术综述及其典型案例经济性分析

实现碳达峰和碳中和的"双碳"目标是国家的重大战略.工业尾气排放是温室气体的主要来源,控制工业尾气碳排放是碳减排工作的关键,探究碳中和背景下利用工业尾气发电实现碳减排的问题,具有重大现实意义.首先概述了尾气电厂的基本原理,以3种典型工业尾气为例,介绍尾气的组成成分和经尾气发电后污染物的变化情况,并介绍了尾气发电技术的基本原理;其次综述了尾气电厂技术方案,分析尾气发电的改造技术和难点,进而对尾气电厂技术方案的优缺点、应用场景、改造技术进行分析和比较,并对尾气电厂技术发展和研究现状进行综述;然后介绍了尾气电厂的典型案例及其效益,从单位造价角度对其进行经济性分析;最后结合我国尾气电厂发展现状,对未来尾气电厂的发展进行了展望,从技术、参与新能源消纳、并网影响、运营模式和政策完善等方面进行了探讨.     

中国燃煤电厂超低排放和节能改造的实践与启示

与推行超低排放前的2013年相比,2019年中国火电装机容量、发电量分别增长36.7%和19.5%,但烟尘、SO₂、NO_x排放量却分别下降87.3%、88.6%、88.8%。同期,全国火力发电行业厂用电率维持在6.01%,供电煤耗从321 g/(kW·h)下降到306.4 g/(kW·h),相当于2019年减排CO₂约27015万t,是国内目前最大的15万t/年碳捕集工程的1 801倍。为总结中国燃煤电厂超低排放和节能改造取得的重大成就,指导其他行业的污染治理及碳达峰与碳中和目标的高效经济的实现,系统研究最严排放标准、企业需求、国家重视、技术创新、经济激励政策等对燃煤电厂超低排放和节能改造成功实践的重要作用。结果表明,燃煤电厂超低排放工程、碳捕集工程等烟气治理工程不仅投资高,而且运行费用可观。烟气治理工程的顶层设计与持续推进是关键,技术突破和规范应用是保障,环保电价与激励政策是重点。就超低排放而言,超低电价等经济激励政策不能因为超低排放全面完成而取消,而应进一步优化,激励超低排放工程的高效运行。其他工业行业在推行超低排放过程中,应借鉴电力行业的成功经验,制定可行技术路线、工程技术规范、运行管理技术规范等国家环保标准,同时出台相关的经济激励政策,以确保超低排放工程建设好、运行好,真正实现减排效果。节能改造工程完成后,其运行不仅具有一定的经济效益,而且减排CO₂的能力较大,在碳达峰与碳中和的约束条件下,燃煤电厂应优先实施节能改造工程。在碳捕集工程能耗、成本、风险不能大幅下降的前提下,碳捕集工程不宜盲目推广。     

探索我国火力发电技术进一步升级之路

我国火电厂的规模已居世界第1, 要进一步节能降耗和实现清洁煤发电, 建议从研究提高燃煤机组的进汽参数和扩大高参数机组的应用、采用更先进的大、中和小型燃气轮机、慎重积极地发展整体煤气化联合循环( IGCC) 电厂、优化烟气净化工艺和研发CO2 捕集和贮存(CCS) 技术等几个方面总结国内外的经验, 使我国火力发电的技术达到世界一流。     

碳循环利用的垃圾焚烧电厂-烟气处理-P2G协调优化运行

垃圾焚烧电厂中垃圾热值普遍偏低,常需天然气作为辅助燃料,由此产生了大量的碳排放。为解决此环保难题,本文构建了基于碳循环利用的垃圾焚烧电厂-烟气处理-P2G协调优化运行模型,在焚烧电厂烟气处理后加装CO₂收集装置,结合P2G技术将回收的CO₂合成CH₄,实现碳循环和再利用。模型以售电收益、碳排放成本、辅助燃料购买成本、烟气处理及P2G功率运行成本等组成的综合净收益最大为目标,以焚烧发电、烟气处理、烟气收集、烟气存储、和P2G合成等运行参数为约束条件。仿真结果表明,利用峰谷分时电价,可优化不同时段的烟气存储装置、发电、烟气处理及P2G的运行状态,有效减少辅助燃料购买及碳排放成本,增加售电收益。采用含碳收集、P2G和辅助燃料补充协调优化运行的垃圾焚烧电厂,可充分实现碳循环利用,极大限度地减少碳排放,具有显著的经济及社会效益。     

碳捕集燃气热电机组碳循环及其虚拟电厂优化运行

针对新型含碳捕集热电联产燃气机组的碳利用和经济运行问题,构建其与风电、电转气（power-to-gas,P2G）聚合的虚拟电厂。将所排放的CO₂捕集并输送至P2G,作为电转气的碳原料,产气为燃气机组提供燃料补充,从而在虚拟电厂中实现碳循环利用。以虚拟电厂收益最大为目标,以CO₂捕集率、热电比、热电厂电出力以及电转气功率为决策变量,建立虚拟电厂优化运行模型。仿真结果表明,这种聚合模式的虚拟电厂,可获得更高的经济效益、更好的风电消纳效果、更低的碳排放。这种虚拟电厂及其碳循环利用方式,是一种有效的减少弃风、降低排放、增强碳利用的能源运转途径,具有显著经济及社会效益。     

碳捕集燃气热电机组碳循环及其虚拟电厂优化运行

针对新型含碳捕集热电联产燃气机组的碳利用和经济运行问题,构建其与风电、电转气（power-to-gas,P2G）聚合的虚拟电厂。将所排放的CO₂捕集并输送至P2G,作为电转气的碳原料,产气为燃气机组提供燃料补充,从而在虚拟电厂中实现碳循环利用。以虚拟电厂收益最大为目标,以CO₂捕集率、热电比、热电厂电出力以及电转气功率为决策变量,建立虚拟电厂优化运行模型。仿真结果表明,这种聚合模式的虚拟电厂,可获得更高的经济效益、更好的风电消纳效果、更低的碳排放。这种虚拟电厂及其碳循环利用方式,是一种有效的减少弃风、降低排放、增强碳利用的能源运转途径,具有显著经济及社会效益。     

基于多阶段减排规划的发电厂碳捕集系统优化配置

根据二氧化碳减排规划的要求,并充分考虑目前二氧化碳捕集和封存（carbon capture and storage,CCS）技术发展的阶段性与不确定性,建立以阶段综合费用最小为目标函数的发电厂减排规划模型。引入技术成熟度因子,并考虑到发电厂运行参数未来的变化,将CCS技术的阶段性与不确定因素进行量化,依据技术进步率对碳捕集系统减排指标进行分解。采用离散细菌群体趋药性算法（discrete bacterial colony chemotaxis,DBCC）进行求解,通过对实际算例的方针分析,得到系统在不同减排场景下的碳捕集系统最优配置方案与碳捕集系统投资策略。最后通过灵敏度分析得到在不同减排场景下各因素对减排成本的影响。结果证明了所提模型以及优化算法的有效性和正确性。     

基于风电-碳捕集电力系统的灵活性调峰策略

高比例风电并网增大了电力系统调峰负担,因此亟需提高电力系统调峰灵活性,助力新型电力系统低碳-零碳化的发展。分析碳捕集电厂优良的调峰性能及其用于调峰辅助服务的必要性,并论证碳捕集电厂低碳特性在碳交易中发挥的积极作用,由此提出碳捕集电厂灵活性调峰的运行策略,并阐述所提策略的低碳性与经济性。构建以电力系统综合成本最优为目标的风电-碳捕集调度模型,并基于此模型对比不同灵活运行方式下碳捕集电厂的低碳性能与经济效益。最后,在改进的IEEE 39节点系统中进行仿真,结果验证了所提模型可有效协调调峰资源,在满足电力系统调峰需求的同时降低系统的碳排水平与运行成本。