The future choice of technologies and co-benefits of CO2 emission reduction in Bangladesh power sector

This paper examines the impacts of CO₂ emission reduction on future technology selection and energy use in Bangladesh power sector up to 2035 considering the base year 2005. It also examines the implications of CO₂ emission reduction targets on energy security of the country. The analysis is based on a long-term energy system model of Bangladesh using the MARKAL framework. The results show that the introduction of the CO₂ emission reduction targets directly affect the shift of technologies from high carbon content fossil-based to low carbon content fossil-based as well as clean, renewable energy-based technologies compared to the base scenario. With the CO₂ emission reduction target of 10–30%, the cumulative net energy imports during 2005–2035 would be reduced in the range of over 1400 PJ to 4898 PJ compared to the base scenario emission level. The total primary energy requirement would be reduced in the range of 5.5–15.2% in the CO₂ emission reduction targets and the primary energy supply system would be diversified compared to the base scenario.     

Impacts of wind power generation and CO2 emission constraints on the future choice of fuels and technologies in the power sector of Vietnam

This paper examines the impacts of wind power generation on the future choice of fuels and technologies in the power sector of Vietnam. The study covers a time frame of 20 yr from 2005 to 2025 and the MARKAL model has been chosen to be adaptable to this specific task. The results of the study show that on a simple cost base, power generated from wind is not yet competitive with that of fossil fuel-based power plants. In order to make wind energy competitive, either carbon tax or an emission reduction target on the system must be imposed. The presence of wind power would affect not only the change in generation mix from coal-based power plants to wind turbines but also an increase in the capacity of other technologies which emit less carbon dioxide. It thus helps reduce fossil fuel requirement and consequently enhances energy security for the country. The study also shows that wind turbine in Vietnam could be a potential CDM project for annex I party countries.     

Long-term CO2 emissions reduction target and scenarios of power sector in Taiwan

This study analyses a series of carbon dioxide (CO₂) emissions abatement scenarios of the power sector in Taiwan according to the Sustainable Energy Policy Guidelines, which was released by Executive Yuan in June 2008. The MARKAL-MACRO energy model was adopted to evaluate economic impacts and optimal energy deployment for CO₂ emissions reduction scenarios. This study includes analyses of life extension of nuclear power plant, the construction of new nuclear power units, commercialized timing of fossil fuel power plants with CO₂ capture and storage (CCS) technology and two alternative flexible trajectories of CO₂ emissions constraints. The CO₂ emissions reduction target in reference reduction scenario is back to 70% of 2000 levels in 2050. The two alternative flexible scenarios, Rt4 and Rt5, are back to 70% of 2005 and 80% of 2005 levels in 2050. The results show that nuclear power plants and CCS technology will further lower the marginal cost of CO₂ emissions reduction. Gross domestic product (GDP) loss rate in reference reduction scenario is 16.9% in 2050, but 8.9% and 6.4% in Rt4 and Rt5, respectively. This study shows the economic impacts in achieving Taiwan's CO₂ emissions mitigation targets and reveals feasible CO₂ emissions reduction strategies for the power sector.     

Factors affecting CO2 emission from the power sector of selected countries in Asia and the Pacific

This study analyzes the key factors behind the CO₂ emissions from the power sector in fifteen selected countries in Asia and the Pacific using the Log-Mean Divisia Index method of decomposition. The roles of changes in economic output, electricity intensity of the economy, fuel intensity of power generation and generation structure are examined in the evolution of CO₂ emission from the power sector of the selected countries during 1980–2004. The study shows that the economic growth was the dominant factor behind the increase in CO₂ emission in ten of the selected countries (i.e., Australia, China, India, Japan, Malaysia, Pakistan, South Korea, Singapore, Thailand and Vietnam, while the increasing electricity intensity of the economy was the main factor in three countries (Bangladesh, Indonesia and Philippines). Structural changes in power generation were found to be the main contributor to changes in the CO₂ emission in the case of Sri Lanka and New Zealand.     

The public perspective of carbon capture and storage for CO2 emission reductions in China

To explore public awareness of carbon capture and storage (CCS), attitudes towards the use of CCS and the determinants of CCS acceptance in China, a study was conducted in July 2009 based on face-to-face interviews with participants across the country. The result showed that the awareness of CCS was low among the surveyed public in China, compared to other clean energy technologies. Respondents indicated a slightly supportive attitude towards the use of CCS as an alternative technology to CO₂ emission reductions. The regression model revealed that in addition to CCS knowledge, respondents’ understanding of the characteristics of CCS, such as the maturity of the technology, risks, capability of CO2 emission reductions, and CCS policy were all significant factors in predicting the acceptance of CCS. The findings suggest that integrating public education and communication into CCS development policy would be an effective strategy to overcome the barrier of low public acceptance.     

Accounting for energy-related CO2 emission in China, 1991–2006

As the country with the second largest emitter of energy-related CO₂ gas, China experienced a dramatic decline in CO₂ emission intensity from 1991 to 2000, but since then the rate of decline slowed and CO₂ emission intensity actually increased in 2003. In this paper, the complete decomposition method developed by Sun is used to analyze the nature of the factors that influence the changes in energy-related CO₂ emission and CO₂ emission intensity during the period 1991–2006. We find that: (1) energy intensity effect is confirmed as the dominant contributor to the decline in CO₂ emission and CO₂ emission intensity, (2) economic activity effect is the most important contributor to increased CO₂ emission, and (3) economic structure and CO₂ emission coefficient effects are found to contribute little to the changes in CO₂ emission and CO₂ emission intensity, which actually increased CO₂ emission and CO₂ emission intensity over the period 1991–2006 except for several years.     

Allocation of energy resources for power generation in India: Business as usual and energy efficiency

This paper deals with MARKAL allocations for various energy sources, in India, for Business As Usual (BAU) scenario and for the case of exploitation of energy saving potential in various sectors of economy. In the BAU scenario, the electrical energy requirement will raise up to 5000 bKwh units per year or 752 GW of installed capacity with major consumers being in the industry, domestic and service sectors. This demand can be met by a mix of coal, hydro, nuclear and wind technologies. Other reneawbles i.e. solar and biomass will start contributing from the year 2040 onwards. By full exploitation of energy saving potential, the annual electrical energy demand gets reduced to 3061 bKwh (or 458 GW), a reduction of 38.9%.The green house gas emissions reduce correspondingly. In this scenario, market allocations for coal, gas and large hydro become stagnant after the year 2015.     

China’s regional CO2 emissions: Characteristics,inter-regional transfer and emission reduction policies

This paper analyzes the characteristics of China’s regional CO₂ emissions and effects of economic growth and energy intensity using panel data from 1997 to 2009. The results show that there are remarkable regional disparities among eastern, central and western areas, regional elasticities of per capita GDP and energy intensity on CO₂ emissions, which reflect the regional differences in economic development, economy structure and restraining function of energy intensity decrease on the emission. Energy intensity reducing is more effective to emission abatement for provinces with higher elasticity of energy intensity, but may not be significant for provinces with lower elasticity. The inverse distribution of energy production and consumption, regional unfairness caused by institutional factors like energy price and tax system result in inter-regional CO₂ emission transfer embodied in the power transmission. The calculation indicates that the embodied emission transfer was gradually significant after 2003, from eastern area to the central and western areas, especially energy production provinces in central area, which leads to distortion on the emission and emission intensity. The regional emission reduction targets and supporting policies should be customized and consistent with the actual situations rather than setting the same target for all the provinces.     

Exergy analysis and CO2 emission evaluation for steam methane reforming

This paper investigates the industrial production of hydrogen through steam methane reforming (SMR) from both exergy efficiency and CO₂ emission aspects. An SMR model is constructed based on a practical flow diagram including desulfurizer, furnace, separation unit and heat exchangers. The influence of reformer temperature (Tr) and steam to carbon (S/C) ratio is analyzed to optimize exergy efficiency and CO₂ emission. A clear correlation is obtained between exergy efficiency and CO₂ emission. Results also show optimal S/C ratio decreases with Tr. An exergy load distribution analysis which evaluates interactions between the system and its subsystems with parameter variations is employed to find promising directions for efficiency improvement. Results show that the greatest improvement lies in increasing efficiency of furnace without increasing its relative exergy load. Integration of oxygen-enriched combustion (OEC) with SMR is also evaluated. The integration of OEC can increase the system efficiency greatly when the reformer operates above critical point, while in other cases the system efficiency may decrease.     

Role of CO2 in the CH4 oxidation and H2 formation during fuel-rich combustion in O2/CO2 environments

The effect of CO₂ reactivity on CH₄ oxidation and H₂ formation in fuel-rich O₂/CO₂ combustion where the concentrations of reactants were high was studied by a CH₄ flat flame experiment, detailed chemical analysis, and a pulverized coal combustion experiment. In the CH₄ flat flame experiment, the residual CH₄ and formed H₂ in fuel-rich O₂/CO₂ combustion were significantly lower than those formed in air combustion, whereas the amount of CO formed in fuel-rich O₂/CO₂ combustion was noticeably higher than that in air. In addition to this experiment, calculations were performed using CHEMKIN-PRO. They generally agreed with the experimental results and showed that CO₂ reactivity, mainly expressed by the reaction CO₂ + H → CO + OH (R1), caused the differences between air and O₂/CO₂ combustion under fuel-rich condition. R1 was able to advance without oxygen. And, OH radicals were more active than H radicals in the hydrocarbon oxidation in the specific temperature range. It was shown that the role of CO₂ was to advance CH₄ oxidation during fuel-rich O₂/CO₂ combustion. Under fuel-rich combustion, H₂ was mainly produced when the hydrocarbon reacted with H radicals. However, the hydrocarbon also reacted with the OH radicals, leading to H₂O production. In fact, these hydrocarbon reactions were competitive. With increasing H/OH ratio, H₂ formed more easily; however, CO₂ reactivity reduced the H/OH ratio by converting H to OH. Moreover, the OH radicals reacted with H₂, whereas the H radicals did not reduce H₂. It was shown that OH radicals formed by CO₂ reactivity were not suitable for H₂ formation. As for pulverized coal combustion, the tendencies of CH₄, CO, and H₂ formation in pulverized coal combustion were almost the same as those in the CH₄ flat flame.     

Decomposition analysis of CO2 emission in long-term climate stabilization scenarios

To achieve the stabilization of greenhouse gas (GHG) concentrations in the atmosphere, the international community will need to intensify its long-term efforts. Many EU countries have released national long-term scenarios toward 2050, and their ambitious targets for CO₂ emission reduction are aiming at a decrease of more than 50% of today's emission. In April 2004, Japan began a research project on its long-term climate policy. This paper discusses the long-term scenarios in other countries and the medium-term scenarios in Japan to support the development of a Japan's long-term climate stabilization scenario. In this study, CO₂ emission is decomposed with an extended Kaya identity (indexes: CO₂ capture and storage, carbon intensity, energy efficiency, energy intensity, economic activity) and a Reduction Balance Table is developed.     

Power and cogeneration technology environomic performance typification in the context of CO2 abatement part I: Power generation

In this series of two articles, the concepts and approaches of environomic (thermodynamic, economic and environmental) performance ‘Typification’ of power generation technologies (Part I) and of combined heat and power (CHP) cogeneration technologies (Part II) in the context of CO₂ abatement are introduced. A methodology is then proposed for a flexible and fast project based power or CHP cogeneration system design evaluation though post-optimization integration of the operating and capital costs. This allows to effectively deal with the uncertainty of the project specific design and operation conditions (fuel, electricity and heat selling prices, project financial conditions such as investment amortization periods, annual operating hours, etc). Furthermore, the uncertainties linked to the external cost such as the CO₂ tax level under a tax scheme or the CO₂ permit price in the emission trading market can be assessed.     

A projection for global CO2 emissions from the industrial sector through 2030 based on activity level and technology changes

In this study, we simulate global CO₂ emissions and their reduction potentials in the industrial sector up to the year 2030. Future industrial CO₂ emissions depend on changes in both technology and industrial activity. However, earlier bottom-up analyses mainly focused on technology change. In this study, we estimate changes in both technology and industrial activity. We developed a three-part simulation system. The first part is a macro economic model that simulates macro economic indicators, such as GDP and value added by sector. The second part consists of industrial production models that simulate future steel and cement production. The third part is a bottom-up type technology model that estimates future CO₂ emissions. Assuming no changes in technology since 2005, we estimate that global CO₂ emissions in 2030 increase by 15 GtCO₂ from 2005 level. This increase is due to growth in industrial production. Introducing technological reduction options within 100 US$/tCO₂ provides a reduction potential of 5.3 GtCO₂ compared to the case of no technology changes. As a result, even with large technological reduction potential, global industrial CO₂ emissions in 2030 are estimated to be higher as compared to 2005 level because of growth of industrial production.     

The forecast of motor vehicle,energy demand and CO2 emission from Taiwan's road transportation sector

The grey forecasting model, GM(1,1) was adopted in this study to capture the development trends of the number of motor vehicles, vehicular energy consumption and CO₂ emissions in Taiwan during 2007–2025. In addition, the simulation of different economic development scenarios were explored by modifying the value of the development coefficient, a, in the grey forecasting model to reflect the influence of economic growth and to be a helpful reference for realizing traffic CO₂ reduction potential and setting CO₂ mitigation strategies for Taiwan. Results showed that the vehicle fleet, energy demand and CO₂ emitted by the road transportation system continued to rise at the annual growth rates of 3.64%, 3.25% and 3.23% over the next 18 years. Besides, the simulation of different economic development scenarios revealed that the lower and upper bound values of allowable vehicles in 2025 are 30.2 and 36.3 million vehicles, respectively, with the traffic fuel consumption lies between 25.8 million kiloliters to 31.0 million kiloliters. The corresponding emission of CO₂ will be between 61.1 and 73.4 million metric tons in the low- and high-scenario profiles.     

Regional energy resource development and energy security under CO2 emission constraint in the greater Mekong sub-region countries (GMS)

The paper evaluates effects of energy resource development within the Greater Mekong Sub-region (GMS) on energy supply mix, energy system cost, energy security and environment during 2000–2035. A MARKAL-based integrated energy system model of the five GMS countries was developed to examine benefits of regional energy resource development for meeting the energy demand of these countries. The study found that an unrestricted energy resource development and trade within the region would reduce the total-regional energy systems cost by 18% and would abate the total CO₂ emission by 5% as compared to the base case. All the five countries except Myanmar would benefit from the expansion of regional energy resource integration in terms of lower energy systems costs and better environmental qualities. An imposition of CO₂ emission reduction constraint by 5% on each of the study countries from that of the corresponding emissions under the unrestricted energy resource development in the GMS is found to improve energy security, reduce energy import and fossil fuels dependences and increase volume of power trade within the region. The total energy system cost under the joint CO₂ emission reduction strategy would be less costly than that under the individual emission targets set for each country.     

Light vehicle energy efficiency programs and their impact on Brazilian CO2 emissions

This paper analyses the impact of an energy efficiency program for light vehicles in Brazil on emissions of carbon dioxide (CO₂), the main greenhouse gas in the atmosphere. Several energy efficiency programs for light vehicles around the world are reviewed. The cases of Japan and Europe were selected for presentation here given their status as current and future world leaders in the control of passenger vehicle fuel consumption. The launching of the National Climate Change Plan and the pressure on the Brazilian car industry due to the world financial crisis make it a good time for the Brazilian government to implement such a program, and its various benefits are highlighted in this study. Three scenarios are established for Brazil covering the 2000–2030 period: the first with no efficiency goals, the second with the Japanese goals applied with a 10 years delay, and the third, with the Japanese goals applied with no delay. The consequences of a vehicular efficiency program and its middle and long-term effects on the consumption of energy and the CO₂ emissions are quantified and discussed. The simulation results indicate that efficiency goals may make an important contribution to reducing vehicular emissions and fuel consumption in Brazil, compared to a baseline scenario.     

Conventional and advanced CO2 based district energy systems

District energy systems can potentially decrease the CO₂ emissions linked to energy services, thanks to the implementation of large polygeneration energy conversion technologies connected to buildings over a network. To transfer the energy from these large technologies to the users, conventional district energy systems use water with often two independent supply and return piping systems for heat and cold. However, sharing energy or interacting with decentralised heat pump units often results in relatively large heat transfer exergy losses due to the large temperature differences that are economically required from the water network. Besides, the implementation of two independent supply and return piping systems for heat and cold, results in large space requirements in underground technical galleries. Using refrigerants as a district heating or cooling fluid at an intermediate temperature could alleviate some of these drawbacks. A new system has been developed, that requires only two pipes, filled with refrigerant, to meet heating, hot water and cooling requirements. Because of the environmental concerns about conventional refrigerants, CO₂, a natural refrigerant, used under its critical point, is considered an interesting candidate. A comparative analysis shows that both in terms of exergy efficiency and costs the proposed CO₂ network is favourable.     

Methods for calculating CO2 intensity of power generation and consumption: A global perspective

This paper compares five methods to calculate CO₂ intensity (g/kWh) of power generation, based on different ways to take into account combined heat and power generation. It was found that the method chosen can have a large impact on the CO₂ intensity for countries with relatively large amounts of combined heat and power plants. Of the analysed countries, the difference in CO₂ intensities is found to be especially large for Russia, Germany and Italy (82%, 31% and 20% differences in 2007, respectively, for CO₂ intensity of total power generation).     

The empirical effects of a gasoline tax on CO2 emissions reductions from transportation sector in Korea

The introduction of carbon tax is expected to mitigate GHG emissions cost-effectively. With this expectation identifying the impacts of carbon tax on energy demand and GHG emission reductions is an interesting issue. One of the basic methods of estimating these impacts is using the price elasticity.     

Solar energy powered Rankine cycle using supercritical CO2

A solar energy powered Rankine cycle using supercritical CO₂ for combined production of electricity and thermal energy is proposed. The proposed system consists of evacuated solar collectors, power generating turbine, high-temperature heat recovery system, low-temperature heat recovery system, and feed pump. The system utilizes evacuated solar collectors to convert CO₂ into high-temperature supercritical state, used to drive a turbine and thereby produce mechanical energy and hence electricity. The system also recovers heat (high-temperature heat and low-temperature heat), which could be used for refrigeration, air conditioning, hot water supply, etc. in domestic or commercial buildings. An experimental prototype has been designed and constructed. The prototype system has been tested under typical summer conditions in Kyoto, Japan; It was found that CO₂ is efficiently converted into high-temperature supercritical state, of while electricity and hot water can be generated. The experimental results show that the solar energy powered Rankine cycle using CO₂ works stably in a trans-critical region. The estimated power generation efficiency is 0.25 and heat recovery efficiency is 0.65. This study shows the potential of the application of the solar-powered Rankine cycle using supercritical CO₂.