Decoupling Effects and Decomposition Analysis of CO2 Emissions from Thailand’s Thermal Power Sector

Electricity is the basic need of most economic sectors within a national economy. Electricity generation not only directly affects the amount of CO2 emissions, but it also indirectly affects a country’s economic system. For Thailand, the electricity generation sector represents the largest source of CO2 emissions, so it is necessary to investigate the potential factors contributing to the changes in CO2 emissions from this power sector. Here, a decoupling method was used to evaluate the relationships between energy consumption and the CO2 emissions from Thailand’s thermal power generation that were caused by economic developments during 2000–2011. Key factors affecting the evolution of CO2 emissions from Thailand’s thermal power sector were analyzed by Divisia index decomposition. Changes in the emission coefficient, heat rate, fuel intensity, electricity intensity and economic growth were investigated. The results reveal that energy consumption and CO2 emissions were coupled during 2000–2005, whereas a relative decoupling appeared for 2006–2011. Moreover, the economic effect was the critical factor for increased CO2 emissions from Thailand’s thermal power generation, while electricity intensity played a dominant role in decreased CO2 emissions. Since the CO2 emissions released from Thailand’s electricity generation are rapidly increasing, the Thai government will be required to reduce CO2 emissions in the future by enhancing energy conservation, reconstructing the fuel mix in power generation, promoting a shift in the economic structure toward less energy-intensive services, and orienting Thailand’s power industry towards low carbon electricity generation.


INTRODUCTION
Electricity is vital to our globally expanding world.It is an essential source of energy for many activities and most industries.In addition, electricity consumption relates to the economic growth of the country because electricity is a basic necessity that fuels the daily consumption of economic sectors.Growth in electricity use is often associated with a rise in GDP and improvement in the quality of life.Todoc et al. (2005) mentioned the strong connection among electricity consumption, income and status of the value-added manufacturing activity in Thailand.However, the rapid growth in Thailand's electricity demand presents a major challenge for electric utilities trying to ensure an adequate supply.
Thailand's power sector is heavily dependent on fossil fuels.Electricity-installed capacity can be categorized as thermal power, combined cycle, hydro power, gas turbine, diesel power, co-generation, gas engine and other power plants (geothermal, solar cell and wind turbine).In 2011, natural gas contributed to over 71.1% of total electricity generation, whereas coal and lignite, hydropower, fuel oil and diesel oil contributed 21.4%, 5.9%, 1.4% and 0.19%, respectively, to the grid electricity generation (Department of Alternative Energy Development and Efficiency, 2011a).Due to the power sector's high dependency on natural gas, the national generation scheme might experience a high risk under instability and fluctuation of future natural gas prices (Nakawiro et al., 2008).For this reason, the Ministry of Energy recently revealed that Thailand plans to buy electricity from China to boost its energy security and economic stability (BangkokPost, 2013).In addition, Thailand's electricity supply industry consists of three main generation groups.The Electricity Generating Authority of Thailand (EGAT), which currently provides about 48% of power generation has exclusive control over transmission lines, thereby monopolizing the buying power of the country's electricity (Department of Alternative Energy Development and Efficiency, 2011b).The other generation groups are the Independent Power Producers (IPPs) and Small Power Producers (SPPs) who sell much of their electricity to EGAT.EGAT sells bulk power to two distributors: (1) the Metropolitan Electricity Authority (MEA), that is responsible for the sale of electricity within Bangkok and surrounding areas; and (2) the Provincial Electricity Authority (PEA), that is responsible for electricity sale in the remaining parts of the country (Sawangphol and Pharino, 2011).Nonetheless, according to Energy Statistics in 2010, 42%, 28% and 21% of CO 2 emissions in Thailand came from the power, transportation, and manufacturing sectors, respectively (Department of Alternative Energy Development and Efficiency, 2011b).This demonstrates that the electricity sector is the largest source of CO 2 emission in Thailand.Besides, due to the growing international pressure on the government to take environmental issues more seriously, there are also demands within Thailand's power development itself concerning matters of environmental concern that will influence future policy directions.
Energy researchers have recently paid attention to the connection between economic activity and energy-related CO 2 emissions.Lin et al. (2012) focused on the modeling of economic-based linkage effects of CO 2 emissions from the electricity industry in Taiwan by using input-output analysis.Liu et al. (2012) adopted Input-Output Life Cycle Assessment (I-O LCA) to evaluate the environmental impact of Taiwan's electricity sector from 2001 to 2006.Gao et al. (2012) analyzed the decoupling of transportation energy consumption from the transportation industry in China from 1985 to 2009.Wang et al. (2013) applied the Logarithmic Mean Divisia Index (LMDI) to the electricity generation in China during 1991-2009.They concluded that the economic activity effect is the most important contributor to increased CO 2 emissions.However, decoupling is understood as the disconnection of the environmental pressure variable from the economic performance variable, while decomposition analysis is applied as a tool for investigating the mechanisms influencing energy consumption and its environmental side-effects.Therefore, the combination of decoupling index and decomposition analysis is an appropriate approach to determine the linkage effect between economic growth and energy-related CO 2 emissions and to identify the key factors related to changes of CO 2 emissions.
The term "decoupling" was first applied to environmental studies at the beginning of the 2000's by Zhang (2000).The decoupling concept has achieved global recognition as a significant concept of successful economy-environment integration, since it was introduced by Ernst Ulrich von Weizsäcker (Enevoldsen et al., 2007).Organization for Economic Cooperation and Development (OECD) countries also have a great interest in "decoupling" theory and its application, dividing the decoupling concept into relative coupling and absolute decoupling (OECD, 2002).Relative decoupling refers to a decrease of emissions intensity per unit of economic output, while absolute decoupling represents an overall decrease of emissions as Gross Domestic Product (GDP) increases.The application of decoupling analysis has been widely used.For example, Tapio (2005) presented a theoretical framework for the degrees of decoupling in the case study of transport in European Union (EU) 15 countries.Because Tapio first divided the decoupling indicators into coupling, decoupling and negative decoupling, and further subdivided these into eight logical possibilities, so, the Tapio indicators reflect the advantages of OECD indicators.Climent and Pardo (2007) investigated the relationship between GDP and energy consumption with several decoupling factors in Spain (1984Spain ( -2003)).They suggested that primary energy consumption plays an important role in limiting economic growth in Spain in the short-run.De Freitas and Kaneko (2011) examined the decoupling between the growth rate in economic activity and CO 2 emissions from energy consumption in Brazil from 2004 to 2009.Results illustrated that the decoupling was magnified when economic activity and CO 2 emissions moved in opposite directions in 2009.Luken and Piras (2011) reviewed the published literature on the decoupling of energy use and industrial output for six developing Asian countries.They found that China and Thailand have been more successful in achieving relative decoupling in the long term (1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008) and in the short term (2006)(2007)(2008) than the four other countries in their study.Sorrell et al. (2012) examined the decoupling of road freight energy use from economic growth in the United Kingdom during 1989 to 2004.Their result suggested that the UK achieved relative but not absolute decoupling of road freight energy consumption from GDP.Up to now, eight measurement methods for decoupling exist, but there is no consensus about the best decoupling indicators (Zhao et al., 2010).
Decomposition analysis has been widely used to identify and assess the contributors to the changes in energy consumption and its emission trends.It was one of the earliest techniques used in the late1970's to study the impact of changes in product mix on industrial energy demand.The two commonly used decomposition methods are Index Decomposition Analysis (IDA) and Structural Decomposition Analysis (SDA).IDA uses sector level data, while SDA uses the input-output (I-O) model and data to decompose the changes (Li et al., 2014).However, IDA has been recognized by researchers and analysts as a useful analytical tool for studying the drivers of changes in CO 2 emission and the relative importance of energy-related CO 2 emissions.Furthermore, Xu and Ang (2013) surveyed a number of studies related to IDA that were applied to CO 2 emissions.The conclusion was that several of the decomposition cases from different time periods showed a greater focus on electricity generation, particularly during 2006-2012.Several studies have adopted the decomposition methodology to analyze energy-related CO 2 emissions in the industry, power, and transportation sectors.For example, Lin and Chang (1996) adopted the Divisia index approach to decompose emission of SO 2 , NO x and CO 2 from major economic sectors in Taiwan during 1980 to 1992.They reported that economic growth had the largest positive effect on emission changes.Nag and Parikh (2000) analyzed the trends and components of CO 2 emissions intensity of power consumption in India by Divisia index method.Lin et al. (2006) adopted the Divisia index approach to identify key factors and strategies for industrial-related CO 2 emission in Taiwan (1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001) by comparing the USA, Japan, Germany, Netherlands and South Korea.They concluded that economic growth was the key factor increasing CO 2 emission for all countries.In addition, some studies have focused on decomposition of the changes in CO 2 emission from the power sector.For example, Shrestha et al. (2009) explored the key factors responsible for changes in the CO 2 emissions from the power sector in fifteen selected countries in Asia during 1980-2004, using the LMDI approach.They found that the economic growth and electricity intensity effects contributed to the increase of CO 2 emissions.Liu and Lin (2011) identified the major factor attributes for CO 2 emissions in Taiwan's electricity sector during 1990-2009 using the Divisia index method.The conclusion revealed that economic growth is the most important driving force for the increase of CO 2 emissions.However, other studies combined the decoupling index with the decomposition methodology.Lu et al. (2007) combined the decoupling index with the Divisia index method to investigate CO 2 emissions from highway transportation in Taiwan, Germany, Japan and South Korea during 1990Korea during -2003. .Results demonstrated that economic activity and motor vehicle growth were the major factors for the rise of CO 2 emissions for the four countries.Wang et al. (2013) analyzed the factors which influenced energy-related CO 2 emissions in Jiangsu province (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009) by using decoupling index and the LMDI.
We hope to obtain a better understanding of Thailand's thermal power sector performance during the period of 2000-2011 and to provide an in-depth understanding of how energy consumption, CO 2 emissions and economic activity have interacted.The purposes of our study are to identify the linkage effect between energy-related CO 2 emissions and economic growth via the decoupling analysis and to analyze the significant factors behind the evolution of CO 2 emissions from the thermal's power sector by the Divisia index decomposition.The simplest method to obtain the trend of energy consumption and CO 2 emissions toward the change of economic activity in examining periods is the advantage using of the decoupling index.Also, the decoupling index can be used as a tool to test sustainability between environmental pressure and economic growth occur.Meanwhile, the decomposition analysis is very useful for not only for understanding the driving forces influencing the changes of CO 2 emissions, but also in providing the appropriate strategies to reduce energy use and to mitigate CO 2 emissions.

Decoupling Analysis
By breaking down the linkages between economic growth and resource use, the Decoupling method is presented to ensure that the consumption of resources and associated impacts do not exceed the carrying capacity of the environment.In this study, the decoupling indicator is determined by the following equation.(OECD, 2002): where EP = Environmental Pressure, DF = Driving Force, T = End of period, T 0 = Start of period.
If the decoupling index is less than one, decoupling has occurred during that period, but the index does not indicate whether decoupling was absolute or relative.However, if the decoupling factor value is zero or negative, a coupling has appeared in that period.Decoupling occurs when the economic growth rate rise is faster than the environmental pressure growth rate.

Divisia Index Decomposition
The most frequently used IDA methodologies are the Laspeyres index and Divisia index.In their original form, both indices have the drawback of leaving a residual factor of emissions unexplained (Ang, 1995;Ang and Zhang, 2000).The removal of the residual term is performed by using the "jointly created and equally distributed" principle (Ang et al., 1998).However, this study adopted the Divisia Index decomposition with a rolling base year to analyze key factors affecting the evolution of CO 2 emissions from the electricity sector because it gives a smaller residual in decomposition, ease of use and understanding, as well as a clear result for interpretation (Ang and Lee, 1994;Lin and Chang, 1996;Ang, 2004).
We consider five factors that contributed to the changes of CO 2 emissions: the emission coefficient, heat rate, fuel intensity, electricity intensity and economic growth.We further divided the changes in CO 2 emissions into three different time periods: 2000-2003, 2003-2007 and 2007-2011.The CO 2 emission from electricity generation (Q t ) can be illustrated as: where Q t : total CO 2 emission from electricity generation in Thailand in year t (thousand tons), F t : amount of fossil fuel used (energy consumption) in Thailand electricity generation in year t (10 7 kilocalories), EG f : fossil fuel power generation (thermal power generation) in Thailand in year t (GWh), EG t : electricity generation in Thailand in year t (GWh), G t : the economic growth, gross domestic product at 2000 prices (GDP) in Thailand in year t (million US dollars).
Eq. ( 3) can be simplified to the following form: where By integrating both sides of Eq. ( 5) from year 0 to year t yields: However, according to the concept of the simple average Divisia method, the integral of Eq. ( 6) can be measured by the mean of the beginning-points and the end-points over a short period of time because the data in this study is discrete: DCF, DH, DFI, DEI, DG and RD in Eq. ( 7) represent the Divisia indices for effects due to changes in emission coefficient heat rate, fuel intensity, electricity intensity and economic growth, respectively; RD is the residual term due to the discrete approximation.

DATA CONSOLIDATION
The research period in this paper is from 2000 to 2011.Data on energy consumption and CO 2 emission from the Electricity generation sector, thermal power generation and total electricity generation were obtained from The Energy Statistic Database, Annual reports of Thailand Energy Situation and Annual reports of Electric Power in Thailand (Department of Alternative Energy Development andEfficiency, 2005a, b, 2011a, b;Energy Policy and Planning Office, 2012).CO 2 emission from electricity generation was estimated according to the Revised 2006 International Panel on Climate Change: Guidelines for National Greenhouse Gas Inventories (IPCC, 2006).The GDP data was collected from the World Bank Data (World Bank Group, 2013).

Energy Consumption and CO 2 Emissions from Thailand's Thermal Power Sector
Because fossil fuels continue to dominate Thailand's electricity generation, energy consumption from the power sector has risen from 20.69 × 10 7 kilocalories to 30.39 × 10 7 kilocalories between 2000 and 2011 (Table 1), with an average annual growth rate of 3.65%.The rapid growth of electricity demand in Thailand also contributed to the expansion of energy consumption.The pattern of energy consumption increased from 2000-2010, then it dropped in 2011 because severe flooding in 2011 caused a decrease in energy consumption (Fig. 1).Several industrial sectors, as well as some residential and commercial public services suffered from flooding, so the electricity demand became less.The CO 2 emissions rose from 57,434 thousand tons to 86,544 thousand tons between 2000 and 2011, with an average annual growth rate of 3.86% (Table 1).The CO 2 emissions from electricity generation generally increased during the study period, except for 2009 and 2011 (Fig. 1).Besides, major flooding in 2011 caused a decrease in CO 2 emissions.The shift of fossil fuel structure in electricity generation from high carbon energy content to a low one by reducing the share of coal products and oil, while increasing natural gas was the major reason for diminished CO 2 emissions in 2009.

Decoupling Analysis in Thailand's Thermal Power Sector
The decoupling factor of energy consumption can be   divided into two periods (Fig. 2).During the first period, from 2000-2005, the decoupling factor was negative; it ranged from -0.18 to -0.05.This is because the energy consumption growth rate in the electricity sector grew at a higher rate than its economic activity.From 2006-2011, the decoupling factor became positive (0.07 and 0.30).The value of the decoupling index represents a relative decoupling effect, which occurred when the growth rate of energy consumption grew slower than its economic activity.On the other hand, relative decoupling occurred in 2006-2011 due to the fuel switching in the power sector.The consumption of oil and lignite in the Thailand electricity generation decreased during 2006 to 2011, while the share of natural gas and renewable energy increased in the same period.
Furthermore, the decoupling of CO 2 emissions from GDP showed a similar trend to that of the decoupling of energy consumption (Fig. 2).The coupling effect occurred during 2000-2005 because the decoupling factor was negative (-0.16 to -0.02).In other words, the growth rate of CO 2 emission from the electricity sector was higher than the growth rate of GDP.However, the relative decoupling effect appeared in the latter period of 2006-2011 as reflected in the decoupling factor that increased from 0.09 to 0.28.This implies that the CO 2 emissions from the power sector where significantly reduced because of the focus on fuel choice and the combustion technology option.For example, the major choice of fuel consumption for electricity generation rely on natural gas 71.1% and renewable fuel (agricultural waste) 6.1% of the total fuel consumption of national grid in 2011 (Department of Alternative Energy Development and Efficiency, 2011a), and the substitution of an Integrated Gasification Combined Cycle (IGCC) technology was applied to the coal lignite base power plant.Moreover, the Thai government should investigate the potential use of carbon capture and storage (CCS) including further investment in research and development of clean coal technologies in order to provide a wider range of options in CO 2 mitigation in the country.
Nonetheless, the main fuel type of thermal power generation is natural gas, which is responsible for more than 60% of CO 2 emissions (Fig. 3).Coal and its products represented about 20-30% of the CO 2 emissions from power sector.Besides, the rise of oil prices in the Thailand market during 2007-2011 led to a decrease of oil shares in the power sector.However, other energy sources (renewable energy) attributed CO 2 emission less than 1%.

Decomposition analysis of Thailand's Thermal Power Sector
The decomposition analysis was based upon CO 2 emissions, energy consumption, thermal power generation, total electricity generation, and GDP (Table 2).The CO 2 emission in Thailand's power sector increased 29,173 thousand tons during 2000-2011 (Table 3).Economic growth was found to be the major factor responsible for the total increase in CO 2 of 55,924 thousand tons.The decomposition of CO 2 emissions from electricity generation during 2000-2011 and the details of each effect are described below.

Emission Coefficient
Emission coefficient (CF) contributed to the rise in CO 2 emissions (Fig. 4).The cumulative effects of emission coefficient in this study period led to an increase of 2,555 thousand tons in CO 2 emissions (Table 3).The major reason for the CO 2 emission increase is due to the increased share of oil in the power sector from 4.81% in 2000-2003 to 5.96% in 2003-2007 and the increased share of coal products in electricity generation from 2.25% in 2000-2003 to 4.32% in 2003-2007.However, CO 2 emission in sub period of 2007-2011 (1,870 thousand tons) was lower than that of 2003-2007 (2,950 thousand tons) because the reduced share of oil in the power sector (from 4.81% to 1.04%) and lignite (from 15.56% to 12.03%) in 2003-2007 to 2007-2011, respectively.Moreover, during the sub period of 2000-2003, the emission coefficient was the dominant factor in decreasing CO 2 emissions (2,265 thousand tons of CO 2 emissions) compared to other factors in the same period (Table 3).This is because the quantity of energy consumption and electricity generation in 2000-2003 were not as high as the recent years (2007)(2008)(2009)(2010)(2011).Also, the fuel consumption and the electricity generation are related to CO 2 emissions.Both were less, and this led to reduce CO 2 emission in the previous period; therefore, the emission coefficient factor influenced the decreased CO 2 emissions during 2000-2003.

Heat Rate
The heat rate effect (H) acted against the growth of CO 2 emission.The aggregate heat rate change contributed 7,818 thousand tons of CO 2 emissions decrease from 2000 to 2011.The heat rate effect in this study comes from the ratio between fossil fuel consumption and thermal power generation, and it represents the efficiency of thermal power plants in Thailand.Result reveals that even though CO 2 emissions decreased due to the heat rate effect in every sub-period, the decrease of CO  2007-2011 (Table 3).This is because increased amounts of natural gas and lignite in 2001-2003 influenced the growth rate of fuel consumption causing it to grow faster than its thermal power generation.In other words, The decreased of CO 2 emissions 3,095 and 4,135 thousand tons in 2003-2007 and 2007-2011, respectively, is not only result from the growth rate of thermal power plants being higher than that of fuel consumption, but it also due to the enhance of thermal power plant efficiency such as reducing the losses in power plants and using the combustion power plant technology.Furthermore, power generation efficiency is steadily increasing with the development and continued deployment of advanced combustion and gasification technologies.On the other hand, the technology transfer where the new power plant technology, such as Integrated Gasification Combine Cycle (IGCC) and Combined Cycle Gas Turbine (CCGT), should be added to substitute the old sources such as coal and lignite in order to provide a higher efficiency.The Thai government has considered the technology transfer option.The North Bangkok Combined Cycle Gas-Fired Power Plant (CCGP) or so called CCGT will become one of the largest power plants in Thailand after block 2 is installed in January 2016.It could act as a model for future plants, operating with higher efficiencies, improving air quality, requiring less fuel and minimizing CO 2 emissions compared to the existing other power plants (Power -Technology.com, 2014).

Fuel Intensity
The growth rate of thermal power generation was higher than that of the total electricity generation growth rate for most years; so, the fuel intensity effect (FI) is another component related to increase of CO 2 emission (Table 3).It contributed 542 thousand tons of emission increase from 2000 to 2011.Our results are consistent with the result obtained by Shrestha et al. (2009): fuel intensity factor affected the rise of CO 2 emissions.Our study also reveals that fuel intensity had little effect on increased CO 2 emissions when compared to the GDP effect.Besides, fuel intensity effect influenced the increase of CO 2 emission in sub period of 2003-2007 and 2007-2011, while emission decreased during 2000-2003 (259 thousand tons).It should be noted that the share of fossil fuel varied during the entire study period (Fig. 3), and this had a significant effect on the thermal power generation growth rate.Hence, the percentage share of fossil fuel in the electricity generation was an important factor escalating CO 2 emission.Because Thailand's electricity generation is always accompanied by fossil fuel-related CO 2 emissions, the focus of lower-carbon options in the near future should include reconstruction of fossil fuel in power generation towards the low-carbon energy by increasing the installation of renewable energy power plants or boosting hydropower.In addition, the government may need to assess the actual renewable potential because each part of the country contains different types of supplying potential regarding biomass, hydropower, and wind.

Electricity Intensity
The electricity intensity effect (EI) played an important role in decreasing CO 2 emissions during the study period.The cumulative effect of electricity intensity resulted in a decrease of 22,030 thousand tons of CO 2 emissions.However, during 2000-2003, the electricity intensity affected the increase of CO 2 emissions, whereas in other sub-periods it decreased (Table 3 and Fig. 4).From 2000 to 2003, the increase of CO 2 emissions of 5,489 thousand tons in the electricity intensity factor represents the second cause of increased CO 2 emission compared to the economic growth effect in the same period.This is because the electricity generation growth rate was higher that the GDP growth rate at that time (2000)(2001)(2002)(2003).In contrast, because of a growing population, the economic growth grew faster than electricity generation growth after 2003; so, the electricity intensity effect was found to be a major factor in reducing CO 2 emissions from thermal power generation in Thailand.Additionally, our results also correspond to the result obtained from Shrestha et al. (2009), which is that the electricity intensity effect acted against an increase in CO 2 emissions from the power sector.

Economic Growth
Economic activity (G) is the critical factor responsible for the increase of CO 2 emissions from Thailand's thermal power sector (Fig. 4).The increased effect of economic growth was up to 55,924 thousand tons of CO 2 emissions, which was much higher than other factors (Table 3).CO 2 emissions from electricity generation are closely connected to economic growth, which depends on a large electricity supply.On the other hand, upon considerations of the details, we found that the economic growth attributed to the decline  2).This indicates that the economic activity in Thailand was strengthened from an expansion of several industries and sectors, e.g., the petrochemical industries, textile industries, food and beverage industries and electricity sectors (Department of Alternative Energy Development and Efficiency, 2011b).It is typical that all nations work hard for better economic development, and most of them do not concern the consequences of its emissions.Therefore, the Thai government should not only focus on pursuing economic efficiency, but should also emphasize the shift of economic structure towards less energy-intensive services or toward high value-added products.

CONCLUSIONS
This paper focused on Thailand's thermal power generation from 2000 to 2011.The decoupling method and the Divisia index decomposition were adopted to examine the correlation between economic growth and energy-related CO 2 emissions and to identify the major driving forces that influenced the changes in CO 2 emissions.The analysis of the decoupling results shows that energy consumption and CO 2 emission experienced a coupling effect during 2000-2005, whereas for 2006-2011, it was decoupled.In addition, among the five factors affecting the changes of CO 2 emissions, economic growth (GDP) is the dominant factor that contributed to the CO 2 emissions increase, followed by the emission coefficient and fossil fuel intensity.However, since the economic growth of the country depends on a large electricity supply, so the GDP was found to be the key factor contributed to the increase of CO 2 emissions from Thailand's thermal power plant.On the other hand, the electricity intensity and heat rate effect are the major factors causing decrease CO 2 emissions due to the shifting of fuel structure towards a lower-carbon content and the improvement of power plant technology.Furthermore, the linkage of environmental pressure and economic activity from Thailand's thermal power sector tended towards sustainability after 2006.Also, the economic growth influenced the decrease of CO 2 emissions during 2007-2011 compared to that of 2003-2007.Consequently, the occurrence of decoupling after 2006 shows a correspondence with the decomposition result from 2007 to 2011.
In order to cope with the impact of CO 2 emissions related to the power sector and to achieve sustainable development, it is suggested that the Thailand government should aim at improving the efficiency of electricity use.Fossil fuel in the power generation should be reconstructed towards lower carbon sources, for example, increase the non-fossil fuel such as renewable energy.The new power plant technology should be enhanced to replace the old power plants.Energy imports can be reduced by encouraging the use of domestic energy resources.Electricity consumption can be lowered by implementation of energy conservation strategies, for example, by the use or purchase of energy-saving products.Infact, the Thai government has demanded that the Ministry of Energy set up a 10-Year Alternative Energy Development Plan (AEDP) (Ministry of Energy, 2012) and a 20-Year Energy Efficiency Development Plan (EEDP) (Ministry of Energy, 2011), which are aimed at creating the direction for increasing renewable energy by 25% in 2021 and improving the country's energy efficiency by 25% in 2030.In conclusion, the Thai government is determined to promote the continual increase of renewable energy, to enhance energy conservation, and improve the country's environmental quality.We hope this study can be of value to policy-makers and relevant agencies in setting strategies to reduce CO 2 emissions from thermal power generation for achieving sustainable development.
Fig. 3. Fuel type share of CO 2 emission from electricity generation.
of CO 2 emissions during 2000-2001 and 2008-2009.It should be noted that the magnitude of economic growth was significantly smaller during the sub-periods of 2000-2003 and 2007-2011.The Asian financial crisis of 1997 and the global financial crisis of 2008 reflect the slower growth in GDP and the electricity requirements as consequences of the financial crisis.However, based on constant 2000 prices, the GDP increased from 122,725 million US dollars in 2000 to 257,501 million US dollars in 2011 (Table the emission coefficient of fossil fuel consumption in electricity generation in Thailand in year t, H t = F t /EG f is the heat rate of thermal power generation in Thailand in year t, FI t = EG f /EG t is the fossil fuel intensity of electricity generation in Thailand in year t, and EI t = EG t /G t is the electricity intensity in Thailand in year t.The decomposition of CO 2 emissions growth rate Eq.(4) can be further decomposed into the sum of the growth rates for each component.By differentiating both sides of Eq. (4) with respect to time t, we obtain:

Table 1 .
Energy consumption, CO 2 emission from Thailand's thermal power sector and Gross Domestic Product (GDP).