Scenario-based analyses of energy system development and its environmental implications in Thailand

Thailand is one of the fastest growing energy-intensive economies in Southeast Asia. To formulate sound energy policies in the country, it is important to understand the impact of energy use on the environment over the long-period. This study examines energy system development and its associated greenhouse gas and local air pollutant emissions under four scenarios in Thailand through the year 2050. The four scenarios involve different growth paths for economy, population, energy efficiency and penetration of renewable energy technologies. The paper assesses the changes in primary energy supply mix, sector-wise final energy demand, energy import dependency and CO₂, SO₂ and NO_x emissions under four scenarios using end-use based Asia-Pacific Integrated Assessment Model (AIM/Enduse) of Thailand.     

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.     

Identifying key factors and strategies for reducing industrial CO2 emissions from a non-Kyoto protocol member's (Taiwan) perspective

In this study we use Divisia index approach to identify key factors affecting CO₂ emission changes of industrial sectors in Taiwan. The changes of CO₂ emission are decomposed into emission coefficient, energy intensity, industrial structure and economic growth. Furthermore, comparisons with USA, Japan, Germany, the Netherlands and South Korea are made to have a better understanding of emission tendency in these countries and to help formulate our CO₂ reduction strategies for responding to the international calls for CO₂ cuts. The results show that economic growth and high energy intensity were two key factors for the rapid increase of industrial CO₂ emission in Taiwan, while adjustment of industrial structure was the main component for the decrease. Although economic development is important, Taiwan must keep pace with the international trends for CO₂ reduction. Among the most important strategies are continuous efforts to improve energy intensity, fuel mix toward lower carbon, setting targets for industrial CO₂ cuts, and advancing green technology through technology transfer. Also, the clean development mechanism (CDM) is expected to play an important role in the future.     

我国能源现状及某些重要战略对策

进入21世纪,中国能源面临着5大严峻挑战:能源供应紧张;液体燃料短缺;环境污染严重;温室气体排放;农村和城镇清洁能源供应等,严重制约了我国的可持续发展。我国以煤为主的能源格局仍将持续,控制能源生产和消费总量,节能减排,提高能源的综合利用效率,大力发展现代煤化工、可再生能源以及核能是我国能源发展的重要趋势。本文提出以煤气化为核心的多联产系统是我国能源发展的战略方向,各种能源(化石能源和可再生能源)都应在广义能源系统中找到"合适的位置"。     

Controllable proton and CO2 photoreduction over Cu2O with various morphologies

Simultaneous photocatalytic reduction of water to H₂ and CO₂ to CO was observed over Cu₂O photocatalyst under both full arc and visible light irradiation (>420 nm). It was found that the photocatalytic reduction preference shifts from H₂ (water splitting) to CO (CO₂ reduction) by controlling the exposed facets of Cu₂O. More interestingly, the low index facets of Cu₂O exhibit higher activity for CO₂ photoreduction than high index facets, which is different from the widely-reported in which the facets with high Miller indices would show higher photoactivity. Improved CO conversion yield could be further achieved by coupling the Cu₂O with RuO_x to form a heterojunction which slows down fast charge recombination and relatively stabilises the Cu₂O photocatalyst. The RuO_x amount was also optimised to maximise the junction's photoactivity.     

Electricity sector reforms in four Latin-American countries and their impact on carbon dioxide emissions and renewable energy

This paper analyzes carbon dioxide (CO₂) emissions related to energy consumption for electricity generation in four Latin-American countries in the context of the liberalization process. From 1990 to 2006, power plants based on renewable energy sources decreased its share in power installed capacity, and the carbon index defined as CO₂ emission by unit of energy for electricity production stayed almost constant for all countries with the exception of Colombia, where the index reduced due to increase in hydroelectricity generation in the last years. The paper also presents a new set of policies to promote renewable energy sources that have been developed in the four countries. The paper concludes that restructuring did not bring about environmental benefits related to a decrease in CO₂ emissions because this depend on the existence of committed policies, and dedicated institutional and regulatory frameworks.     

Integrated fossil fuel and solar thermal systems for hydrogen production and CO2 mitigation

In most current fossil-based hydrogen production methods, the thermal energy required by the endothermic processes of hydrogen production cycles is supplied by the combustion of a portion of the same fossil fuel feedstock. This increases the fossil fuel consumption and greenhouse gas emissions. This paper analyzes the thermodynamics of several typical fossil fuel-based hydrogen production methods such as steam methane reforming, coal gasification, methane dissociation, and off-gas reforming, to quantify the potential savings of fossil fuels and CO₂ emissions associated with the thermal energy requirement. Then matching the heat quality and quantity by solar thermal energy for different processes is examined. It is concluded that steam generation and superheating by solar energy for the supply of gaseous reactants to the hydrogen production cycles is particularly attractive due to the engineering maturity and simplicity. It is also concluded that steam-methane reforming may have fewer engineering challenges because of its single-phase reaction, if the endothermic reaction enthalpy of syngas production step (CO and H₂) of coal gasification and steam methane reforming is provided by solar thermal energy. Various solar thermal energy based reactors are discussed for different types of production cycles as well.     

The 2 °C scenario—A sustainable world energy perspective

A target-oriented scenario of future energy demand and supply is developed in a backcasting process. The main target is to reduce global CO₂ emissions to around 10 Gt/a in 2050, thus limiting global average temperature increase to 2 °C and preventing dangerous anthropogenic interference with the climate system. A 10-region energy system model is used for simulating global energy supply strategies. A review of sector and region-specific energy efficiency measures resulted in the specification of a global energy demand scenario incorporating strong energy efficiency measures. The corresponding supply scenario has been developed in an iterative process in close cooperation with stakeholders and regional counterparts from academia, NGOs and the renewable energy industry. The 2 °C scenario shows that renewable energy could provide as much as half of the world's energy needs by 2050. Developing countries can virtually stabilise their CO₂ emissions, while at the same time increasing energy consumption through economic growth. OECD countries will be able to reduce their emissions by up to 80%.     

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.     

The role of energy-service demand reduction in global climate change mitigation: Combining energy modelling and decomposition analysis

In order to reduce energy-related CO₂ emissions different options have been considered: energy efficiency improvements, structural changes to low carbon or zero carbon fuel/technologies, carbon sequestration, and reduction in energy-service demands (useful energy). While efficiency and technology options have been extensively studied within the context of climate change mitigation, this paper addresses the possible role of price-related energy-service demand reduction. For this analysis, the elastic demand version of the TIAM–UCL global energy system model is used in combination with decomposition analysis. The results of the CO₂ emission decomposition indicate that a reduction in energy-service demand can play a limited role, contributing around 5% to global emission reduction in the 21st century. A look at the sectoral level reveals that the demand reduction can play a greater role in selected sectors like transport contributing around 16% at a global level. The societal welfare loss is found to be high when the price elasticity of demand is low.     

CCS: A future CO2 mitigation option for Germany?—A bottom-up approach

The role that carbon capture and storage (CCS) technologies could play within the framework of an overall CO₂ mitigation strategy is examined in the form of scenarios up to 2030 with the example of Germany. As the calculations show, the use of CCS can represent an interesting mitigation option in view of stringent CO₂ reduction goals. The scenarios, performed with the aid of the IKARUS optimization model, however, also show that according to cost-efficiency criteria a large number of measures would have to be taken covering all energy sectors. CCS can at best represent one element in an overall strategy. The model results show that a mitigation goal for 2030 corresponding to a 35% reduction of CO₂ as compared to 1990 is necessary to trigger a significant contribution of CCS. As an alternative to a CO₂ restriction, we also calculated reduction scenarios based on CO₂ penalties. These scenarios showed that a penalty price of approximately 30 €/tCO₂ is necessary before CCS can be included in the model.     

The assessment of renewable energy planning on CO2 abatement in South Korea

Sources of renewable energies (for example landfill gas, wind, solar energy) are environmentally friendly and electric power generation in South Korea has concentrated on new and renewable energy technologies. The purpose of this paper is to study the economic and environmental influence of renewable energies on existing electricity generation market of South Korea with energy-economic model called ‘Long-range Energy Alternative Planning system’ and the associated ‘Technology and Environmental Database’. Business as usual scenario was based on energy supply planning with existing power plant. And then, the alternative scenarios were considered, namely the base case with existing electricity facilities, the installation plan of different renewable energy facilities, technological improvement and process dispatch rule according to merit order change. In each alternative scenario analysis, alternation trend of existing electricity generation facilities is analyzed and the cost of installed renewable energy plants and CO₂ reduction potential was assessed quantitatively.     

Energy consumption,CO2 emissions,and development in the UAE

This study investigated the impact of energy consumption and CO₂ emissions on the United Arab Emirates (UAE)’s economic and financial development. The vector autoregressive (VAR) model was applied. The results obtained in the study show that energy consumption and CO₂ emissions had a long-run relationship with the economic and financial development indicators in the UAE. It was also found that there was a significant causal relationship between energy consumption and CO₂ emissions on both economic and financial development indicator variables. The UAE is well known for its high economic and financial development owing to the fact that this country has achieved a fast economic growth in the last three decades. However, it is important that this country needs to increase its consumption of green energy to reduce CO₂ emissions.     

Role of energy efficiency standards in reducing CO2 emissions in Germany: An assessment with TIMES

Energy efficiency is widely viewed as an important element of energy and environmental policy. Applying the TIMES model, this paper examines the impacts of additional efficiency improvement measures (as prescribed by the ACROPOLIS project) over the baseline, at the level of individual sectors level as well as in a combined implementation, on the German energy system in terms of energy savings, technological development, emissions and costs. Implementing efficiency measures in all sectors together, CO₂ reduction is possible through substitution of conventional gas or oil boilers by condensing gas boilers especially in single family houses, shifting from petrol to diesel vehicles in private transport, increased use of electric vehicles, gas combined cycle power plants and CHP (combined heat and power production) etc. At a sectoral level, the residential sector offers double benefits of CO₂ reduction and cost savings. In the transport sector, on the other hand, CO₂ reduction is the most expensive, using bio-fuels and methanol to achieve the efficiency targets.     

CO2 emissions and reduction potential in China’s chemical industry

GHG (Increasing greenhouse gas) emissions in China imposes enormous pressure on China’s government and society. The increasing GHG trend is primarily driven by the fast expansion of high energy-intensive sectors including the chemical industry. This study investigates energy consumption and CO₂ emissions in the processes of chemical production in China through calculating the amounts of CO₂ emissions and estimating the reduction potential in the near future. The research is based on a two-level perspective which treats the entire industry as Level one and six key sub-sectors as Level two, including coal-based ammonia, calcium carbide, caustic soda, coal-based methanol, sodium carbonate, and yellow phosphorus. These two levels are used in order to address the complexity caused by the fact that there are more than 40 thousand chemical products in this industry and the performance levels of the technologies employed are extremely uneven. Three scenarios with different technological improvements are defined to estimate the emissions of the six sub-sectors and analyze the implied reduction potential in the near future. The results highlight the pivotal role that regulation and policy administration could play in controlling the CO₂ emissions by promoting average technology performances in this industry.     

Energy and environmental implications of carbon emission reduction targets: Case of Kathmandu Valley,Nepal

This paper analyzes the sectoral energy consumption pattern and emissions of CO₂ and local air pollutants in the Kathmandu Valley, Nepal. It also discusses the evolution of energy service demands, structure of energy supply system and emissions from various sectors under the base case scenario during 2005–2050. A long term energy system planning model of the Kathmandu Valley based on the MARKet ALlocation (MARKAL) framework is used for the analyses. Furthermore, the paper analyzes the least cost options to achieve CO₂ emission reduction targets of 10%, 20% and 30% below the cumulative emission level in the base case and also discusses their implications for total cost, technology-mix, energy-mix and local pollutant emissions. The paper shows that a major switch in energy use pattern from oil and gas to electricity would be needed in the Valley to achieve the cumulative CO₂ emission reduction target of 30% (ER30). Further, the share of electricity in the cumulative energy consumption of the transport sector would increase from 12% in the base case to 24% in the ER30 case.     

Experimental study on the performance of solar Rankine system using supercritical CO2

An experimental study is carried out to investigate the performance of a solar Rankine system using supercritical CO₂ as a working fluid. The testing machine of the solar Rankine system consists of an evacuated solar collector, a pressure relief valve, heat exchangers and CO₂ feed pump, etc. The solar energy powered system can provide electricity output as well as heat supply/refrigeration, etc. The system performance is evaluated based on daily, monthly and yearly experiment data. The results obtained show that heat collection efficiency for the CO₂-based solar collector is measured at 65.0–70.0%. The power generation efficiency is found at 8.78–9.45%, which is higher than the value 8.20% of a solar cell. The result presents a potential future for the solar powered CO₂ Rankine system to be used as distributed energy supply system for buildings or others.     

Ultrasonic spray pyrolysis synthesis of Ag/TiO2 nanocomposite photocatalysts for simultaneous H2 production and CO2 reduction

Simultaneous photocatalytic hydrogen production and CO₂ reduction (to form CO and CH₄) from water using methanol as a hole scavenger were investigated using silver-modified TiO₂ (Ag/TiO₂) nanocomposite catalysts. A simple ultrasonic spray pyrolysis (SP) method was used to prepare mesoporous Ag/TiO₂ composite particles using TiO₂ (P25) and AgNO₃ as the precursors. The material properties and photocatalytic activities were compared with those prepared by a conventional wet-impregnation (WI) method. It was found that the samples prepared by the SP method had a larger specific surface area and a better dispersion of Ag nanoparticles on TiO₂ than those prepared by the WI method, and as a result, the SP samples showed much higher photocatalytic activities toward H₂ production and CO₂ reduction. The optimal Ag concentration on TiO₂ was found to be 2 wt%. The H₂ production rate of the 2% Ag/TiO₂–SP sample exhibited a six-fold enhancement compared with the 2% Ag/TiO₂–WI sample and a sixty-fold enhancement compared with bare TiO₂. The molar ratio of H₂ and CO in the final products can be tuned in the range from 2 to 10 by varying the reaction gas composition, suggesting a viable way of producing syngas (a mixture of H₂ and CO) from CO₂ and water using the prepared Ag/TiO₂ catalysts with energy input from the sun.     

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.     

Development of a scalable infrastructure model for planning electricity generation and CO2 mitigation strategies under mandated reduction of GHG emission

In a power-generation system, power plants as major CO₂ sources may be widely separated, so they must be connected into a comprehensive network to manage both electricity and CO₂ simultaneously and efficiently. In this study, a scalable infrastructure model is developed for planning electricity generation and CO₂ mitigation (EGCM) strategies under the mandated reduction of GHG emission. The EGCM infrastructure model is applied to case studies of Korean energy and CO₂ scenarios in 2020; these cases consider combinations of prices of carbon credit and total electricity demand fulfilled by combustion power plants. The results highlight the importance of systematic planning for a scalable infrastructure by examining the sensitivity of the EGCM infrastructure. The results will be useful both to help decision makers establish a power-generation plan, and to identify appropriate strategies to respond to climate change.