Power system planning with emission constraints: Effects of CCS retrofitting

Today, the world's energy needs are still supplied mainly from fossil fuel based resources. This is true for electricity generation as well, thus making the power sector responsible for 45% of greenhouse gas emissions. The present climate crisis has made it necessary to minimise emissions in power generation, with low-carbon energy sources taking on greater significance in recent years. However, most low-carbon sources have inherent problems, like intermittency and high capital expenditure. A suitable alternative is carbon capture and storage (CCS) technology which allows continued fossil fuel-based electricity generation at much lower rates of emission. Two approaches are possible in the deployment of CCS technology. The first is to introduce new power plants equipped for carbon dioxide (CO₂) capture, while systematically shutting down existing coal power plants. Another is to retrofit existing power plants for CO₂ capture. These approaches are compared in this work. The study shows that allowing CCS retrofitting of existing power plants can reduce the overall cost requirement significantly. In addition, a sensitivity analysis is also done to study the effect of nuclear energy on the overall energy mix.     

Fuzzy optimization of multi-period carbon capture and storage systems with parametric uncertainties

Carbon capture and storage (CCS) is an important technology option for reducing industrial greenhouse gas emissions. In practice, CO₂ sources are easy to characterize, while the estimation of relevant properties of storage sites, such as capacity and injection rate limit (i.e., injectivity), is subject to considerable uncertainty. Such uncertainties need to be accounted for in planning CCS deployment on a large scale for effective use of available storage sites. In particular, the uncertainty introduces technical risks that may result from overestimating the limits of given storage sites. In this work, a fuzzy mixed integer linear program (FMILP) is developed for multi-period CCS systems, accounting for the technical risk arising from uncertainties in estimates of sink parameters, while still attaining satisfactory CO₂ emissions reduction. In the model, sources are assumed to have precisely known CO₂ flow rates and operating lives, while geological sinks are characterized with imprecise fuzzy capacity and injectivity data. Three case studies are then presented to illustrate the model. Results of these examples illustrate the tradeoff inherent in planning CCS systems under parametric uncertainty.     

Carbon capture and storage-desirability from a risk management point of view

Environmental and safety risks related to carbon capture and storage concern leakages and accidental releases during transport and geological storage. Based on principles widely accepted in the EU and beyond in the discussion about the where’s and why’s of nuclear waste repositories, this paper discusses the desirability of carbon capture and storage from a risk management point of view, focusing on environmental risks on the global level (climate change). On this basis it is concluded that, if the key energy issue of coming generations, not just in Europe but all around the world, is not the abundance of fossil resources but rather an unacceptably high probability of global warming due to greenhouse gas emissions, then the solution should not include any massive hiding of the emissions but entirely focus on the avoidance based on improved technology in power plants and other industrial installations.     

京津冀电力结构调整大气污染物及CO2减排效应研究

基于2014年京津冀地区电力统计数据,引入多情景分析方法设定了不同的燃煤发电、燃气发电和可再生能源装机比例情景,测算了相应情景下的SO_2、NO_x和CO_2排放量,分析了该地区电力行业装机比例与大气污染物和温室气体减排潜力的关系。结果表明,在发电总装机容量一定的情况下,对燃煤发电和燃气发电来说,随其装机比例增加,SO_2、NO_x和CO_2排放量呈现逐渐增加的趋势。但相对于燃煤发电机组,燃气发电机组在一定程度上减少了SO_2、NO_x和CO_2的排放量,减排效果显著。对可再生能源发电来说,随其装机比例增加,SO_2、NO_x和CO_2的排放量呈现逐渐下降的趋势。     

Experimental Study on the Potential Application of Cottonseed Oil–Diesel Blends as Fuels for Automotive Diesel Engines

This paper presents the results of an experimental study on the direct application of cottonseed oil–diesel blends as fuel for diesel engine vehicles without using additional retrofit mechanical systems. The use of biofuels is one of the main actions promoted by the European Union and member states in an effort to tackle global warming, enhance energy security and contribute to regional development. Here, the possibility to blend cottonseed oil directly with fossil diesel as a fuel for diesel engines is examined. This option has lower cost and larger well-to-wheel greenhouse gas benefits than fatty acid methylesters. The paper presents measurements of important fuel properties, density, viscosity, cetane number and cold flow characteristics. In addition, a common rail Euro 3 compliant diesel car is tested using 10% v/v cottonseed oil–diesel blends in order to examine the effects on performance and emissions of regulated pollutants and CO₂. Furthermore, particle emission characteristics are studied, including total and solid particle number concentrations and particle size distributions over driving cycles and steady state modes. The results indicate that the test fuel presents good operating characteristics and limited effects on regulated emissions and vehicle performance. These results would justify further research on the direct use of vegetable oils as automotive fuels.     

Environmental consequence analysis for resource depletion

Resource depletion is of concern to both present and future generations in terms of access to resources. It is a prominent impact category within life cycle assessment (LCA) and sustainability assessment. This paper examines existing resource depletion approaches and indicators in the context of natural gas depletion, and their limitations in modelling the wider environmental consequences of resource consumption. Some existing models assume substitution of scarce fossil fuels with an alternative fossil fuel or mix, but do not consider all of the subsequent change in impacts. An additional methodology is proposed to measure the impact changes when fossil fuel substitution occurs as a result of scarcity. The methodology will demonstrate the effect of resource scarcity for individual processes but also multiple processes which operate at different levels of resource consumption with varying degrees of impacts. The methodology is applied to a scarcity situation of natural gas in Australia, where black coal is substituted for gas. It is first applied to natural gas consumed for electricity generation only. In the second case, the methodology is applied to the substitution of natural gas for both electricity generation and hydrogen production. The varying impacts on emissions to air and water, together with solid waste generation and water depletion, as a result of the substitution are used to reflect the consequences of fossil fuel depletion. The indicators also provide information on the impacts of substitution in each product, thus enabling users to prioritise products based on the impacts produced during natural gas allocation.     

中国经济增长对碳排放的影响分析

通过相关分析探讨了中国国内生产总值(GDP)的增长与碳排放量的关系.结果表明,二者有明显的相关性(R2＝0.958 1).进一步研究认为,由于中国投资率在35%～40%以上,且工业增加值占GDP的比重超过50%,因此中国过分依赖投资的经济增长方式和以第二产业(工业)为主的经济结构在很大程度上是导致温室气体排放量增加的主要原因.未来在全球化背景下,经济增长可转变为更多地依靠科技创新、技术进步和制度的改进,因此,调整经济增长方式和产业结构,可以在保持发展经济的同时,使碳排放强度呈逐渐下降的趋势.     

Retrofit of Water Network with Regeneration Using Water Pinch Analysis

This paper presents the development of a new systematic technique for the retrofit of water network with regeneration based on water pinch analysis. The procedure consists of two parts: retrofit targeting and design for a water network with regeneration unit(s). In the targeting stage, retrofit targets (utility savings and capital investment) were determined for a range of process parameters (total flowrate and/or outlet concentration of the regeneration unit) to obtain a savings versus investment curve. Next, the existing water network was re-designed to meet the chosen targets. A case study on paper making process was used to demonstrate the new methodology.     

Health risk assessment of emissions from a coal-fired power plant using AERMOD modelling

Current electricity generation mix in Malaysia consists of 58% gas, 33% coal and 9% hydro. It is anticipated that by year 2019, the generation mix will be at 64% coal, 32% gas and 4% hydro. Due to the increase in coal consumption for power generation, there is a critical need to evaluate the health risks for the population living in the vicinity of a coal-fired power plant in Malaysia. To date, such study related to the plant in Malaysia has never been published. In this study, health risk assessment (HRA) for air emission from a coal-fired power plant in Malaysia was carried out. Two pollutants from the Proposed New Environmental Quality (Clean Air) Regulation 201X (Draft) (i.e. SO₂ and Hg) were assessed for non-carcinogenic health risk, and two trace elements (i.e. As and Cr) were assessed for carcinogenic health risk. Both short-term and long-term health effects were evaluated. Air dispersion modelling (AERMOD) was used to predict the ground level concentration (GLC) within 10 km radius of the emission source. Based on the HRA, different health risks were identified for short-term and long-term dispersion of the studied pollutants. The findings indicate that a detailed assessment on the short-term and long-term health effects of the emissions from coal-fired power plant in Malaysia with meteorological factor as one of the significant factors influencing the emissions level is needed.     

基于STEAM的靠港船舶大气污染物排放清单研究

随着我国船舶排放控制区的设立,船舶大气污染物排放成为社会广泛关注的热点。以对城市影响显著的内河靠港船舶为研究对象,采用本土化的船舶交通排放估算模型(STEAM),结合船舶自动识别系统(AIS)中的船舶轨迹信息、船舶档案数据库信息及调研信息,实现基于船舶活动的"自下而上"的排放清单编制。将上述研究成果应用于南京龙潭集装箱港区,得到2014年该港区船舶大气物排放量分别为PM103.452 9 t、PM2.52.762 3 t、NOx196.004 4 t、SOx2.896 6t、CO 20.624 5 t、HC 8.127 8 t以及CO212 554.289 5 t。与整个港区排放相比,靠港船舶是SOx和NOx排放的重要来源,占比分别达到70.76%和58.16%。基于排放特性分析提出靠港船舶减排路径。     

目前我国温室气体CO2的排放及对策

根据我国目前人口、资源、生态环境和发展趋势，针对我国温室气体CO2的排放现状，提出了改善和解决这一问题的对策和建议。     

安徽省工业化石能源消费碳排放研究

按不同化石能源品种的消费量估算安徽省2004—2014年CO2排放量,分析该省工业行业能源消费量及化石能源消费碳排放量的变化规律。在此基础上,采用等维灰数递补动态GM(1,1)预测模型预测3种发展情景下2030年安徽省工业化石能源消费碳排放量。结果表明:安徽省工业化石能源消费CO2排放量由2004年的1.64亿t上升到2014年的4.25亿t;到2030年,在基准情景、低碳情景和强化低碳情景下将分别达到7.51亿t、6.06亿t和4.91亿t。     

Reducing the risk level for pipelines transporting carbon dioxide and hydrogen by means of optimal safety valves spacing

In many countries where electricity generation is based on their natural resources of fossil fuels a need arises to implement new power engineering technologies that allow carbon dioxide capture. Simultaneously, efforts are made to find new energy carriers which, if fired, do not involve carbon dioxide emissions. Hydrogen is one of such fuels with this future potential which is now becoming increasingly popular. Obviously, this means that the two gases mentioned above – carbon dioxide and hydrogen – will be produced in large quantities in future, which in many cases will necessitate their transport over considerable distances. If a pipeline failure occurs, the transport of the gases may pose a serious hazard to people in the immediate vicinity of the leakage site. This paper presents an analysis of the possibility of reducing the level of risk related to pipelines transporting CO₂ and H₂ by means of safety valves. It is shown that for a 50 km long and a 0.4 m diameter pipeline transporting gas with the pressure of 15 MPa the individual risk level can be reduced from 1·10⁻⁴ to 6.5·10⁻⁷ for CO₂ and from 1·10⁻⁶ to 6·10⁻¹⁰ for H₂. The social risk can be diminished in similar proportions.     

Thermodynamic method for the prediction of solid CO2 formation from multicomponent mixtures

The increase in GHG concentration has a direct effect on global climate conditions. Among the possible technologies to mitigate GHG emissions, CCS is being accepted to gain emission reduction. Such technology also involves cryogenic CO₂ capture processes based on CO₂ freeze-out or where the formation of solid CO₂ must be avoided. Captured CO₂ is usually transported in pipelines for the reinjection.The risk associated to the release of CO₂ is due to the changing temperatures and pressures the system may experience, which can lead to the deposition of solid CO₂ where it must be avoided. Prolonged exposure to dry ice can cause severe skin damage and its resublimation could pose a danger of hypercapnia. It is, thus, necessary to build up a tool able to predict the conditions in which CO₂ can freeze-out.A thermodynamic methodology based on cubic EoSs has been developed which is able to predict solid–liquid–vapor equilibrium of CO₂ mixtures with n-alkanes or H₂S which are usually found in equipment for acidic gas, mainly natural gas, treatment.The focus is a detailed analysis of the method performances when more than two components are present since, for such a case, literature does not provide significant modeling results.     

The influence of impurities on the transportation safety of an anthropogenic CO2 pipeline

Transportation safety is a key aspect of carbon capture and storage (CCS), which is a major technology used to reduce greenhouse gas emissions. Supercritical CO₂ pipelines have been certified as an optimised choice for CO₂ transportation. The results of this study show that the Peng–Robinson (PR) equation of state is recommended for analysis of the properties of supercritical CO₂. The influence of nonpolar and polar impurities on the two-phase region and the location of the sharp discontinuity in the density are found by analysing the ternary phase equilibrium and physical parameters using the PR equation of state. A transitional area between the supercritical phase and the dense phase, where the density changes abruptly, is defined as the quasi-critical region. This study describes the functional relation between the temperature and the pressure that defines the quasi-critical line by calculating the partial derivative equations and then determines the effect of impurities on the quasi-critical region of transported CO₂. Operational recommendations for pipeline transportation of flue CO₂ are developed using a pipeline operated by Sinopec as an example, demonstrating the influence of impurities in flue CO₂ on saturation pressure for control and prevention of fractures in CO₂ pipelines.     

Thermodynamics,economics and systems thinking: What role for air capture of CO2?

Air capture has recently been advanced by several parties as a solution to the problem of constraining – and ultimately reducing – atmospheric CO₂ in response to climate change. However, there are significant barriers pertaining to scale, energy needs and cost, which will hugely challenge the effectiveness and practicality of air capture. This paper examines the thermodynamics, energetics and economics and politics of air capture. These compare unfavourably with alternative approaches to atmospheric greenhouse gas reduction. An analysis is made of the energy cost of the one favoured DAC technology for which experimental results are available in the open literature – temperature/vacuum swing adsorption, and of one point source capture technology – oxyfiring of refinery FCCUs. We also examine the engineering effort required to implement atmospheric capture on a scale at which it could significantly reduce atmospheric levels of CO₂; and questions are addressed regarding its practicability and appropriateness. The analysis demonstrates that air capture remains at best a peripheral activity, at worst a distraction, until point sources of greenhouse gas emissions such as power stations, industrial flue gases, shale gas wellheads, anaerobic digestion plants and landfill sites have been completely decarbonised. When these and so many other unaddressed factors are affecting our global climate, the pursuit air capture, the ultimate “end-of-pipe” solution, is inappropriate.     

Hazards from carbon dioxide capture, transport and storage

Carbon capture and storage (CCS) is a developing technology which raises a number of issues in terms of safety. CCS involves a chain of processes comprising capture of carbon dioxide, transport and injection into underground storage. In work carried out for the IEA Greenhouse Gas R&D Programme, a number of high-level hazard identification (HAZID) studies have been performed with the help of industry experts. The HAZIDs considered a carbon capture and storage chain involving capture, pipeline transport and injection. HAZID has been performed at a high-level for such a CCS chain with three types of capture technology and using pipeline transport. It is hoped that the results of the HAZID studies will be of use to those carrying out CCS projects, but should not be a substitute for them carrying out a full suite of integrated hazard management processes. A number of example hazards have been described to raise awareness of the range of hazards in a CCS process and to identify barriers which could prevent, minimise, control or mitigate CCS hazards. Bow-tie diagrams have been produced to record the information from this study and to organise it in a systematic way so that it is far less likely that contributors to and mitigators of hazards will be missed. The diagrams are available in Excel spreadsheet format so that they can be used as the starting point for development by specific CCS projects. CCS technology is still advancing and a number of knowledge gaps in terms of safety have been identified which require further development.     

Ocean fertilization for geoengineering: A review of effectiveness,environmental impacts and emerging governance

Dangerous climate change is best avoided by drastically and rapidly reducing greenhouse gas emissions. Nevertheless, geoengineering options are receiving attention on the basis that additional approaches may also be necessary. Here we review the state of knowledge on large-scale ocean fertilization by adding iron or other nutrients, either from external sources or via enhanced ocean mixing. On the basis of small-scale field experiments carried out to date and associated modelling, the maximum benefits of ocean fertilization as a negative emissions technique are likely to be modest in relation to anthropogenic climate forcing. Furthermore, it would be extremely challenging to quantify with acceptable accuracy the carbon removed from circulation on a long term basis, and to adequately monitor unintended impacts over large space and time-scales. These and other technical issues are particularly problematic for the region with greatest theoretical potential for the application of ocean fertilization, the Southern Ocean. Arrangements for the international governance of further field-based research on ocean fertilization are currently being developed, primarily under the London Convention/London Protocol.     

Can boreal afforestation help offset incompressible GHG emissions from Canadian industries?

To mitigate greenhouse gas and comply with cap-and-trade systems, the carbon capture and storage (CCS) is presently unviable for industrials dealing with low concentration of CO₂ emissions. Alternatively, a new offset opportunity is being analysed in Canada: the afforestation of open woodlands (OWs) in the boreal territory. The results obtained from model simulations (with CBM-CFS3) showed that afforestation of boreal OWs can be a low C-intensive mitigation activity, in particular when understory planting is the chosen silvicultural approach, so that only 8–12 years are needed to reach a net positive C balance with the afforestation of OWs. A large-scale afforestation of boreal OWs – scheduled at 20 kha per year during 20 years for a maximum of 400 kha – could provide capped industrials with a significant offset potential, for instance up to nearly 8% offset of all Québec industrial process emissions (2009 data) after 45 years. In spite of a certain number of issues that can contribute to the uncertainty of the real environmental and economical benefits from the afforestation of OWs as a mitigation activity – most of which issues are discussed in this paper – this study presented a first glimpse at the extent to which the afforestation of boreal OWs in Québec can provide large emitters with eventually substantial and efficient GHG offset potential, especially those emitters tied up with incompressible GHG emissions.     

A mathematical approach for retrofit and optimization of total site steam distribution networks

This paper presents a generic mathematical model for retrofitting the steam power plants in an industrial site. The industrial sector under review consists of one steel mill, one oil refinery, and several petrochemical plants, where only small-scale steam integration has been implemented before this study. The relevant unit models in a typical steam power plant are established, and the steam plant retrofit problem is formulated as a mixed-integer nonlinear program (MINLP). Feasible retrofit alternatives suggested by experienced field engineers are investigated in sequence to examine the revenue of those possible modifications. The first scenario examines operational optimization of existent plants; the second option allows installation of one new turbine and replacement of several boilers and turbines with lower efficiency; the third scenario considers using a steam ejector to upgrade the disqualified import steam in the oil refinery. The significant merits from these three retrofit alternatives show that the proposed MINLP formulation has been a great help to enhance the inter-plant steam integration in an industrial sector.