Multi-objective optimization of molten carbonate fuel cell system for reducing CO2 emission from exhaust gases

The aim of this paper is to investigate the implementation of a molten carbonate fuel cell (MCFC) as a CO₂ separator. By applying multi-objective optimization (MOO) using the genetic algorithm, the optimal values of operating load and the corresponding values of objective functions are obtained. Objective functions are minimization of the cost of electricity (COE) and minimization of CO₂ emission rate. CO₂ tax that is accounted as the pollution-related cost, transforming the environmental objective to the cost function. The results show that the MCFC stack which is fed by the syngas and gas turbine exhaust, not only reduces CO₂ emission rate, but also produces electricity and reduces environmental cost of the system.     

Energy and CO2 emissions in Korea: Long-term scenarios and related policies

Korea will require increasingly higher energy inputs in coming years to further its economic development process. While due to the inconvenience of coal use and its negative impacts on the environment, Korea's reliance on its most carbon-intensive energy source will drop over the next few decades, the overall growth of energy demand (and particularly the rising consumption of oil) will translate into substantially higher emissions of energy-related CO₂. This paper presents the results of two long-term scenarios for Korea for the year 2025 in order to investigate the possibilities of constraining the future growth of energy and emissions. The results indicate that by improving energy efficiency through technological progress, fuel switching and related policies, Korea can begin to make the necessary transition to a less carbon-intensive future.     

单位电量CO_2排放强度与单位产值CO_2排放强度关系初探

电力单位产值CO2排放强度是全国单位产值CO2排放强度的重要组成部分,其既与电力行业排放绩效即单位发电量CO2排放强度有关,也与全社会能源效率、电气化水平、资源与市场情况等因素相关。本文系统分析了有关指标的统计特征、国际对比、影响因素及趋势预测,指出"十二五"及"十三五"期间,不论是单位电量CO2排放强度,还是电力单位产值CO2排放强度,其下降幅度都是有限的,需要理性看待并科学设置规划指标。     

CO2 emissions reduction by price deregulation and fossil fuel taxation A case study of Indonesia

As environmental issues, and the issue of global warming in particular, rise to the top of the international agenda, developing nations are faced with a major question: how to confront these environmental problems and simultaneously address a number of more pressing developmental imperatives? This paper tries to answer that question on a limited scale using Indonesia as a case study. The study indicates that by deregulating energy prices and imposing different levels of taxation on fossil fuels, Indonesia could reduce its CO₂ emissions without considerably suppressing the growth of its economy. In the long run, however, these policies cannot cope with the inevitable rise in coal-use in Indonesia, due to constraints on domestic natural gas and oil resources. Limiting the growth of coal consumption in the future will require direct technological intervention in the supply and demand of energy and a shift in current energy export and import policies.     

Optimizing CO2 avoided cost by means of repowering

Repowering fossil fuel power plants by means of gas turbines has been traditionally considered to increase power output and reduce NOx and SO₂ emissions both at low cost and short outage periods. At present, reduction in CO₂ emissions represents an additional advantage of repowering due to partial fuel shift and overall efficiency increase. This is especially important in existing installations with a CO₂ reduction mandatory that should be carried out in a short time and in a cost-effective manner.     

The impact of CHP generation on CO2 emissions

The combined generation of heat and power (cogeneration) is praised by many as a technique for reducing the emissions of CO₂ in industrialized nations. This is generally true but not always. In this article we discuss the impact of some major variables on the CO₂ emission reduction capacity of cogeneration. Two sets of variables are predominant: the characteristics of the CHP process and the composition of the electricity generation sector. We highlight the interaction between the two sets of variables with the help of diagrams.     

Energy demand and CO2 emissions reduction options in Nigeria

This paper presents policy options for reducing CO₂ emissions in Nigeria. The policies were formulated based on a thorough analysis of Nigeria's current energy consumption patterns and the projected evolution of key parameters that drive Nigeria's energy demand — primarily the rate of industrialization, the demand for transportation services, and the expansion of Nigeria's population. The study shows that the most promising options for reducing CO₂ emissions in Nigeria are improving energy efficiency and increasing the use of natural gas and renewable energy sources.     

Multi-objective optimization of an advanced combined cycle power plant including CO2 separation options

This paper illustrates a methodology developed to facilitate the analysis of complex systems characterized by a large number of technical, economical and environmental parameters. Thermo-economic modeling of a natural gas combined cycle including CO₂ separation options has been coupled within a multi-objective evolutionary algorithm to characterize the economic and environmental performances of such complex systems within various contexts.

The method has been applied to a case of power generation in Germany. The optimum options for system integration under different boundary conditions are revealed by the Pareto Optimal Frontiers. Results show the influence of the configuration and technical parameters on the electrical efficiencies of the Pareto optimal plants and their sub-systems. The results provide information on the relationship between power generation cost and CO₂ emissions, and allow sensitivity analyses of important economical parameters like natural gas and electricity prices. Such a tool is of interest for power generation technology suppliers, for utility owners or for project investors, and for policy makers in the context of CO₂ mitigation schemes including emission trading.     

China’s pre-2020 CO2 emission reduction potential and its influence

China achieved the reduction of CO₂ intensity of GDP by 45% compared with 2005 at the end of 2017, realizing the commitment at 2009 Copenhagen Conference on emissions reduction 3 years ahead of time. In future implementation of the “13th Five-Year Plan (FYP),” with the decline of economic growth rate, decrease of energy consumption elasticity and optimization of energy structure, the CO₂ intensity of GDP will still have the potential for decreasing before 2020. By applying KAYA Formula decomposition, this paper makes the historical statistics of the GDP energy intensity decrease and CO₂ intensity of energy consumption since 2005, and simulates the decrease of CO₂ intensity of GDP in 2020 and its influences on achieving National Determined Contribution (NDC) target in 2030 with scenario analysis. The results show that China’s CO₂ intensity of GDP in 2020 is expected to fall by 52.9%–54.4% than the 2005 level, and will be 22.9%–25.4% lower than 2015. Therefore, it is likely to overfulfill the decrease of CO₂ intensity of GDP by 18% proposed in the 13th FYP period. Furthermore, the emission reduction potentiality before 2020 will be conducive to the earlier realization of NDC objectives in 2030. China’s CO₂ intensity of GDP in 2030 will fall by over 70% than that in 2005, and CO₂ emissions peak will appear before 2030 as early as possible. To accelerate the transition to a low-carbon economy, China needs to make better use of the carbon market, and guide the whole society with carbon price to reduce emissions effectively. At the same time, China should also study the synergy of policy package so as to achieve the target of emission reduction.     

CO2 sequestration in Ontario, Canada. Part II: cost estimation

As the Kyoto target set for Canada is to reduce GHG emission by 6% of the 1990 level by 2008–2012, several options are being considered to achieve this target. One of the possible options in Ontario is geological sequestration of captured CO₂ in saline aquifers, where CO₂ is expected to be stored for long geological periods, from 100 to several thousand years depending on the size, property and location of the reservoir. The preferred concept is to inject CO₂ into a porous and permeable reservoir covered with a cap rock located at least 800 m beneath the earth's surface where CO₂ can be stored under supercritical conditions. This paper evaluates the capital and operating cost for CO₂ sequestration in southwestern Ontario from a 500 MW coal fired power plant. The main focus is on the cost of sequestration (CO₂ transport and injection), and thus, the cost of capturing and pressurizing the CO₂ from the plant flue gas is not considered here.

A significant amount of capital investment is necessary to transfer CO₂ from a 500 MW fossil fuel power plant to the injection location and to store it underground. Major components of the cost include: cost of pipeline, cost of drilling injection wells and installing platforms, since the more plausible injection area is under Lake Erie. Many uncertainties are associated with cost estimation; several are identified and their impacts are considered in this paper. The estimated cost of sequestration of 14,000 ton/day of CO₂ at approximately 110 bar in southwestern Ontario is between 7.5 and 14 US$/ton of CO₂ stored.     

CO2 emissions embodied in international trade: evidence for Spain

The objective of this paper is to analyse the sectoral impacts that Spanish international trade relations have on present levels of atmospheric pollution using an input–output model. We try to evaluate the exports and imports of the Spanish economy in terms of the direct and indirect CO₂ emissions (CO₂ embodied) generated in Spain and abroad. The results show a slightly exporting behaviour in the Spanish economy which, nevertheless, hides important pollution interchanges. Moreover, the sectors transport material, mining and energy, non-metallic industries, chemical and metals are the most relevant CO₂ exporters and other services, construction, transport material and food the biggest CO₂ importers, and those whose final demands also embody more than 70% of the CO₂ emissions.     

Comparative study of energy consumption and CO2 emissions between Beijing and London

From the view of geographic location, climate and population status, this paper makes a comparative study of the economy structure, transport system, energy supply and carbon emissions among a few cities, especially between Beijing and London, two mega-cities in the world. The developed tertiary industry, consummate transport system and low-carbon energy supply system in London can be referenced to assist Beijing in establishing a low-carbon development pathway. The difference in the statistical coverage of population between these two cities also brings about the divergence of energy consumption per capita and CO? emissions per capita between them.     

CO2 utilization options, Part I: An emission assessment framework

The utilization of CO₂ in various products and services must be carefully assessed in order to achieve reduced CO₂ emissions and simultaneously to add to the net economic benefit of society. In this paper, a framework for the assessment of CO₂ utilization options in the chemical industry is outlined in which the total CO₂ emission is estimated in four steps. First, the processes under study are surveyed to establish the consumption of different raw materials (reactants). Second, the CO₂ emission due to the content of fossil carbon in the reactants is determined, i.e. the material-related emission. Third, the CO₂ emission related to energy consumption in the studied processes is estimated, i.e. the direct energy-related emission. Fourth, the CO₂ emission related to energy consumption in the reactant production processes is estimated, i.e. the indirect energy-related emission.     

沿海地区可再生能源开发利用结构优化研究

针对我国目前能源开发利用可持续性及环境友好性差的问题,首先系统地分析了能源开发利用优化影响因素,在此基础上以经济效益、二氧化碳排放量、能源开发比例的综合效益最大为目标函数,从能源属性、经济、技术、环境和安全等方面考虑建立约束条件,构建了沿海地区可再生能源开发利用结构优化的多目标规划模型。以大连为例,对其沿海可再生能源结构进行优化,得到该地区目标年内的最优能源开发利用量,对模型进行了参数敏感性分析。研究成果可为可再生能源开发利用结构规划与政策制定提供参考。     

Evaluation of potential cost reductions from improved amine-based CO2 capture systems

Technological innovations in CO₂ capture and storage technologies are being pursued worldwide under a variety of private and government-sponsored R&D programs. While much of this R&D is directed at novel concepts and potential breakthrough technologies, there are also substantial efforts to improve CO₂ capture technologies already in use. In this paper, we focus on amine-based CO₂ capture systems for power plants and other combustion-based applications. The current performance and cost of such systems have been documented in several recent studies. In this paper we examine the potential for future cost reductions that may result from continued process development. We used the formal methods of expert elicitation to understand what experts in this field believe about possible improvements in some of the key underlying parameters that govern the performance and cost of this technology. A dozen leading experts from North America, Europe and Asia participated in this study, providing their probabilistic judgments via a detailed questionnaire coupled with individual interviews. Judgments about detailed technical parameters were then used in an integrated power plant modeling framework (IECM-CS) developed for USDOE to evaluate the performance and costs of alternative carbon capture and sequestration technologies for fossil-fueled power plants. The experts’ responses have allowed us to build a picture of how the overall performance and cost of amine-based systems might improve over the next decade or two. Results show how much the cost of CO₂ capture could be reduced via targeted R&D in key areas.     

Energy consumption and CO2 emissions of the European glass industry

An in-depth analysis of the energy consumption and CO₂ emissions of the European glass industry is presented. The analysis is based on data of the EU ETS for the period 2005–2007 (Phase I). The scope of this study comprises the European glass industry as a whole and its seven subsectors. The analysis is based on an assignment of the glass installations (ca. 450) within the EU ETS to the corresponding subsectors and an adequate matching of the respective production volumes. A result is the assessment of the overall final energy consumption (fuel, electricity) as well as the overall CO₂ emissions (process, combustion and indirect emissions) of the glass industry and its subsectors in the EU25/27. Moreover, figures on fuel mix as well as fuel intensity and CO₂ emissions intensity (i.e. carbon intensity) are presented for each of the subsectors on aggregated levels and for selected EU Member States separately. The average intensity of fuel consumption and direct CO₂ emissions of the EU25 glass industry decreased from 2005 to 2007 by about 4% and amounted in 2007 to 7.8 GJ and 0.57 _tCO₂${\mathrm{t}}_{{\text{CO}}_{\mathrm{2}}}$ per tonne of saleable product, respectively. The economic energy intensity was evaluated with 0.46 toe/1000€ (EU27).     

Tracking the genealogy of CO2 emissions in the electricity sector: An intersectoral approach applied to the Spanish case

This paper analyses the factors leading to CO₂ emissions in the Spanish electricity generation sector in order to propose effective mitigation policies aimed at tackling those emissions. Traditionally, two broad categories of those factors have been considered in the literature: those related to the supply of electricity (technological features of the sector) and those related to the level of economic activity (demand factors). This paper focuses on an additional element, which has usually been neglected, the structural factor, which refers to the set of intersectoral transactions (related to the technologies used in other productive sectors) which connect, in either a direct or an indirect way, the general economic activity with the supply of electricity and, thus, with the emissions of the electricity generation sector. This analysis allows us to identify the so-called “sectors structurally responsible for emissions” (SSER), whose production functions involve transactions which connect the demand for goods and services with the emissions of the electricity generation sector. The methodology is based on an input–output approach and a sensitivity analysis. The paper shows that there are structural rigidities, deeply ingrained within the economic system, which lead to emissions from the electricity generation sector for which this sector cannot be held responsible. These rigidities limit the effectiveness of policies aimed at emissions mitigation in this sector.     

Variables affecting energy efficiency and CO2 emissions in the steel industry

Specific energy consumption (SEC) is an energy efficiency indicator widely used in industry for measuring the energy efficiency of different processes. In this paper, the development of energy efficiency and CO₂ emissions of steelmaking is studied by analysing the energy data from a case mill. First, the specific energy consumption figures were calculated using different system boundaries, such as the process level, mill level and mill site level. Then, an energy efficiency index was developed to evaluate the development of the energy efficiency at the mill site. The effects of different production conditions on specific energy consumption and specific CO₂ emissions were studied by PLS analysis. As theory expects, the production rate of crude steel and the utilisation of recycled steel were shown to affect the development of energy efficiency at the mill site. This study shows that clearly defined system boundaries help to clarify the role of on-site energy conversion and make a difference between the final energy consumption and primary energy consumption of an industrial plant with its own energy production.     

An experimental investigation of NO2 emission characteristics of a heavy-duty H2-diesel dual fuel engine

This paper investigated the nitrogen dioxide (NO₂) emissions of a heavy-duty diesel engine operated in hydrogen (H₂)-diesel dual fuel combustion mode with H₂ supplemented into the intake air. Preliminary measurements using the 13-mode European Stationary Cycle (ESC) demonstrated the significant effect of H₂ addition on the emissions of NO₂. The detailed effects of H₂ addition and engine load on NO₂ emissions were examined at 1200 RPM. The addition of a small amount of H₂ increased substantially the emissions of NO₂ and the NO₂/NO_x ratio, especially at low load. Increasing the engine load was found to inhibit the enhancing effect of H₂ on the conversion of NO to NO₂ with the maximum NO₂/NO_x ratio observed at lower H₂ concentration. The maximum NO₂ emissions of the H₂-diesel dual fuel operation were three (at 70% load) to five (at 10% load) times that of diesel operation. Further increasing the addition of H₂ beyond the point with maximum NO₂ emissions still produced more NO₂ than for diesel-only operation. Based on the experimental data obtained, the engine load and maximum averaged bulk mixture temperature were not the main factors dominating the formation of NO₂ in the H₂-diesel dual fuel engine. A preliminary analysis demonstrated the significant effect of the unburned H₂ on NO₂ emissions. When mixed with the hot combustion product, the unburned H₂ that survived the main combustion process might further oxidize to raise the HO₂ levels and enhance the conversion of NO to NO₂. In comparison, the changes in the combustion process including the start of combustion, combustion duration and maximum heat release rate may not contribute substantially to the increased NO₂ emissions observed.     

The implications of the historical decline in US energy intensity for long-run CO2 emission projections

This paper analyzes the influence of the long-run decline in US energy intensity on projections of energy use and carbon emissions to the year 2050. We build on our own recent work which decomposes changes in the aggregate US energy–GDP ratio into shifts in sectoral composition (structural change) and adjustments in the energy demand of individual industries (intensity change), and identifies the impact on the latter of price-induced substitution of variable inputs, shifts in the composition of capital and embodied and disembodied technical progress. We employ a recursive-dynamic computable general equilibrium (CGE) model of the US economy to analyze the implications of these findings for future energy use and carbon emissions. Comparison of the simulation results against projections of historical trends in GDP, energy use and emissions reveals that the range of values for the rate of autonomous energy efficiency improvement (AEEI) conventionally used in CGE models is consistent with the effects of structural changes at the sub-sector level, rather than disembodied technological change. Even so, our results suggest that US emissions may well grow faster in the future than in the recent past.