Air Pollutant Emission Abatement of the Fossil-Fuel Power Plants by Multiple Control Strategies in Taiwan

: This study is an investigation of air pollutant emission abatement in the electricity generation sector from fossil-fuel power plants in Taiwan in 2014 and 2018. PM concentrations are determined by the results of regular tests, while SOx and NOx are determined by continuous emission monitoring systems (CEMS) of ﬂue gas from power plants. The results indicate that electricity generation from fossil-fuel power plants increased by 13.8% from 2014 to 2018. However, emissions of air pollutants from fossil-fuel power plants declined during this period. The results indicate that the annual emissions of SOx, NOx, and PM were 40,826, 59,196, and 5363 tons per year (TPY), respectively, in 2014. The emissions decreased to 30,097 TPY (28% reduction) for SOx, 48,530 TPY (18% reduction) for NOx, and 4496 TPY (16% reduction) for PM in 2018. The ensemble mean values of each air pollutant emission factor also decreased signiﬁcantly. SOx emissions decreased from 0.2443 to 0.1583 mg/kWh (35% reduction). NOx emissions decreased from 0.3542 to 0.2552 g/kWh (28% reduction). PM emissions decreased from 0.0321 to 0.0236 mg/kWh (26.5% reduction). The results indicated that phasing out of high-pollutant generating units and switching the fuel from coal to natural gas could abate the emissions of SOx and PM, and NOx emissions could be abated by introducing control devices. In addition, new power generation sectors will be constructed and equipped with ultra-low emission control systems to reduce air pollution and create a cleaner and healthier electricity generation system in Taiwan.


Introduction
Electricity has been a critical element in modern countries around the world for centuries. There are multiple ways to generate electricity from various power sources. Fossil-fuel power generation has been the most popular process by which to generate electricity in most countries in the last few centuries. However, there are many environmental impacts accompanying generation of power from fossil fuels. Air pollution is the most critical issue due to adverse health effects caused by particulate matter, SOx, NOx, heavy metals, PAHs, etc. Air pollutant emissions from fossil fuels used for power generation processes also cause photochemical smog, loss of visibility, acid rain, and greenhouse gases, which also have significant environmental impacts. In 2019, global energy consumption totaled 584 × 10 18 joules with fractions of 33% from oil, 24% from gas, 27% from coal, 5.3% from renewable sources, 6.4% from hydropower, and 4.3% from nuclear plants [1]. These data indicate that fossil fuels accounted for 84% of the total energy consumption in 2019. In the electricity power generation sector, fossil fuels contributed approximate 64% (17,604 terawatt) in 2018 (BP, 2020). There were 80 million tons (Mt) of SO 2 , 107 Mt of NOx, and In Taiwan, the government adopted energy policies related to the power supply that changed the fraction to 50% from natural gas, 27% from coal, 20% from renewable energy, and about 3% from others [3]. Natural gas is a well known, cleaner fossil fuel, but it also causes emissions of air pollutants, especially NOx emissions. However, the air pollution problem has become a public concern, which has pushed the government to adopt several strategies to continuously reduce air pollutant emissions from the power generation sector in the last decade. These strategies include retirement of aged, polluting power generation units fueled by coal and oil, construction of new LNG power generators, construction of new coal power generators with ultra-low emission technology, and improvements in the air pollution control efficiency of existing units. These programs have reduced emissions of PM, SOx, and NOx from power generation sectors and obviously improved air quality in Taiwan during the last ten years.
Fossil fuels can be depleted in the future. Renewable energy (bioenergy, solar energy, wind energy, geothermal energy, ocean, hydropower, etc.) [24,25] and cleaner energy (hydrogen energy, fuel cells, etc.) [26,27] could be alternative fuels for fossil-fuel energy, which can also eliminate the risk of energy depletion and global warming.
In addition, CO 2 and climate change are important issues for power plants. Some new concepts have been introduced: selective configuration of exhaust gas recirculation systems to reduce CO 2 emission in the natural gas combined-cycle power plants [28], and CO 2 capture and reduction via different methods [29,30].
In Taiwan, the renewable energy will contribute 20% of the nation's energy requirement by 2025 [3]. A solar radiation power plant is set to provide 2802 to 20,000 MW (20 GW) during 2018 to 2025, and wind power generation may increase to 5 GW by 2025 [3]. Cleaner electricity production is an important issue for government, which needs to reduce excessive air pollution and fossil-fuel effects on climate change.
In the present study, emission abatement of SOx, NOx, and PM from fossil-fuel-based electricity power generation plants in Taiwan was investigated. Data from 2014 and 2018 were used to evaluate the effectiveness of various control strategies in terms of achieving the goal of cleaner electricity generation in Taiwan. In addition, the potential abatement of air pollutant emissions by 2025 due to switching from coal-fired power generation units to natural gas for the purpose of electricity generation was also investigated.

Power Plant Operating Data
In Taiwan, most power plants are managed by the Taipower Company, which is a government-owned organization. In 2018, the Taipower Co. produced approximately 78% of the electricity in Taiwan. There are nine private power companies that contribute approximately 22% of the electricity generated. Taipower Co. operated 59 fossil-fuel units in 2014 (21 coal-fired units, 6 oil-fired units, and 32 LNG-fired units) and 59 units in 2018 (24 coal-fired units, 4 oil-fired units, and 31 LNG-fired units), as shown in Table 1. The power generation profile changed during this period due to implementation of various programs.
This study investigates the characteristics of air pollutant emissions, carried out by analyzing the public database for specific power plants in Taiwan. In Taiwan, each power generation unit is required by law to periodically submit its operational records to the Environmental Protection Administration. These data include emissions, operation hours, and loading. More detailed data are released from various management offices of the power plants.
In 2014, there were 6 oil-fueled generator units, 21 coal-fired units, and 32 LNG-fueled units in operation. All oil-fueled units are to be shut down and dismantled by 2025, and the number of LNG-fueled units will increase based on the energy policies. The data from 59 generation units in 13 power plants represented approximately 75% of the total power generation and 95% of the coal-fired generation capacity in 2018. Figure 1 shows the trend of the electricity generation profiles in Taiwan. This study investigates the characteristics of air pollutant emissions, carried ou analyzing the public database for specific power plants in Taiwan. In Taiwan, each po generation unit is required by law to periodically submit its operational records to Environmental Protection Administration. These data include emissions, operation ho and loading. More detailed data are released from various management offices of power plants.
In 2014, there were 6 oil-fueled generator units, 21 coal-fired units, and 32 LN fueled units in operation. All oil-fueled units are to be shut down and dismantled by 2 and the number of LNG-fueled units will increase based on the energy policies.
The data from 59 generation units in 13 power plants represented approximately 7 of the total power generation and 95% of the coal-fired generation capacity in 2018.

Air Pollutant Emission Data
Air pollutant emission data for NOx and SOx emissions for each power plant w derived from the emissions reporting system managed by the Taiwan EPA [33]. All c fired units are required by law to be equipped with CEMS and to submit reports. M emission data were calculated from CEMS records and air pollution fee records. CEMS system follows the criteria established by the United States Environmental Pro tion Agency (USEPA) and United Kingdom in Europe [34,35]. The oil-based and LN based units are not required to have CEMS; therefore, their emission data were estima

Air Pollutant Emission Data
Air pollutant emission data for NOx and SOx emissions for each power plant were derived from the emissions reporting system managed by the Taiwan EPA [33]. All coalfired units are required by law to be equipped with CEMS and to submit reports. Most emission data were calculated from CEMS records and air pollution fee records. The CEMS system follows the criteria established by the United States Environmental Protection Agency (USEPA) and United Kingdom in Europe [34,35]. The oil-based and LNG-based units are not required to have CEMS; therefore, their emission data were estimated using periodic source testing records. The CEMS database was developed by the Taiwan EPA in 2003. CEMS data comprise dependable hourly averages.
However, there is not a CEM system providing mass PM emissions data in Taiwan. The mass PM emissions data from each unit under consideration were therefore derived from regular source test data. Thus, the data quality was not as good as that for SOx and NOx.

Emissions Factor for Each Power Plant
The emissions factor for power plants is typically expressed as the weight of pollutants divided by a unit of electricity generated, as follows: where W i is the pollutant emissions per year (g/year) (i is for PM, SOx, and NOx); EP j is the electricity generated (kWh/year), where j represents oil, LNG, and coal combustion. Based on the CEMS criteria, the uncertainty of emission factors were less than 20%.

Air Pollutant Emissions from Different Fuel-Based Power Generation Units
In Taiwan Table 2. SOx and NOx were determined using a CEMS, and PM was determined by a regular test of emission sources.
The annual electricity generated from various fuel-based units in the last ten years grew by 13.4% in Taiwan, as shown in Figure 1. In 2014, the total electricity generated was approximately 219.2 × 10 9 kWh (2.9% from oil, 37.5% from coal, 32.3% from LNG, and 28.3% from others). In 2018, the total electricity generated was approximately 233.3 × 10 9 kWh (2.8% from oil, 38.8% from coal, 38.6% from LNG, and 19.8% from others). The growing demand for electricity has placed much pressure on power generation management, especially as it relates to air pollution abatement.
In 2014, the annual electricity generated from various fuel-based units was 47.5% (coal), 3.1% (oil), and 28.1% (LNG), respectively. Coal was the dominant source of electricity in Taiwan before the energy transformation policy was enacted.
In 2018, the fraction of electricity generated comprised 47.6% (coal), 3.0% (oil), and 33.5% (LNG), respectively. However, the fraction of the annual electricity generated from coal and LNG increased. During these years, the energy transformation program authorized the demolition of two aged oil-fueled units, two aged coal-fired units, and three aged LNG-fueled units. At the same time, four coal-fired units and one LNG-fueled unit were retrofitted, and the performance of air pollution control devices was evaluated and improved. One LNG-fueled unit was introduced into the fossil-fuel power generation system. The fraction of various fuels applied for generating electricity changed, which also altered the air pollution emissions accordingly. The output of electricity fueled by LNG increased by 27% from 2014 to 2018. The output of coal-based electricity generated also gradually increased during this period.
Annual emissions of PM, SOx, and NOx in 2014 and 2018 from various fuel-based units are shown in Table 2. Annual emissions of SOx, NOx, and PM were reduced by 26%, 18%, and 16% from 2014 to 2018, respectively. In terms of the SOx emissions, major abatement of emissions was contributed by coal-based units with 7361 TPY (ton per year) and oilfueled units with 3406 TPY. However, the emissions from LNG-fueled units increased slightly with 38 TPY due to incremental increases in natural gas consumption. In terms of NOx emissions, a major reduction in emissions was also contributed by coal-fired units The results indicate that the emissions of these three air pollutants were contributed mostly by coal-fired units, which were the dominant sources in the fossil-fuel power generation category in Taiwan. However, the NOx emissions were increased by oil-fueled and LNG-fueled units. This means that reductions by improving the efficiency of NOx emissions from coal-based units were offset by incremental increases in emissions from LNG-fueled and oil-fueled units. Resulting from its high air pollution emission and older electric generation system, the oil power plant will be phased out after 2025.

Coal-Fired Generation Units
The air pollutant emission factors for the coal-fired generation units are shown in Figure 2.
18%, and 16% from 2014 to 2018, respectively. In terms of the SOx emissions, major abatement of emissions was contributed by coal-based units with 7361 TPY (ton per year) and oil-fueled units with 3406 TPY. However, the emissions from LNG-fueled units increased slightly with 38 TPY due to incremental increases in natural gas consumption. In terms of NOx emissions, a major reduction in emissions was also contributed by coal-fired units with 13,254 TPY. The emissions from oil-fueled units and LNG-fueled units increased, with 592 and 1997 TPY, respectively. In terms of PM emissions, a major reduction in emissions was contributed by coal-fired units, with 868 TPY, and a minor reduction in emissions contributed by LNG-fueled units, with 28 TPY. The emissions from oil-based units increased slightly, with 30TPY.
The results indicate that the emissions of these three air pollutants were contributed mostly by coal-fired units, which were the dominant sources in the fossil-fuel power generation category in Taiwan. However, the NOx emissions were increased by oil-fueled and LNG-fueled units. This means that reductions by improving the efficiency of NOx emissions from coal-based units were offset by incremental increases in emissions from LNG-fueled and oil-fueled units. Resulting from its high air pollution emission and older electric generation system, the oil power plant will be phased out after 2025.

Coal-Fired Generation Units
The air pollutant emission factors for the coal-fired generation units are shown in Figure 2. In 2014, the SO2 emission factor from each generation unit ranged between 0.105 and 0.742 g/kWh, with an average of 0.362 g/kWh, reflecting a 7.07-fold difference. The emission factor for NOx from each generation unit ranged between 0.235 and 0.566 g/kWh, with an average of 0.428 g/kWh, reflecting a 2.41-fold difference. The PM emission factor In 2014, the SO 2 emission factor from each generation unit ranged between 0.105 and 0.742 g/kWh, with an average of 0.362 g/kWh, reflecting a 7.07-fold difference. The emission factor for NOx from each generation unit ranged between 0.235 and 0.566 g/kWh, with an average of 0.428 g/kWh, reflecting a 2.41-fold difference. The PM emission factor from each generation unit ranged between 0.023 and 0.049 g/kWh, with an average of 0.044 g/kWh, reflecting a 2.13-fold difference.
In 2018, the SO 2 emission factor from each generation unit ranged between 0.080 and 0.412 g/kWh, with an average of 0.251 g/kWh, reflecting a 5.15-fold difference. The NOx emission factor from each generation unit ranged between 0.093 and 0.408 g/kWh, with an average of 0.273 g/kWh, reflecting a 4.39-fold difference. The PM emission factor from each generation unit ranged between 0.002 and 0.043 g/kWh, with an average of 0.032 g/kWh, reflecting a 21.5-fold difference.
The maximum SOx, NOx, and PM emission factor decreased by approximately 44.5, 27.8, and 12.0% from 2014 to 2018, respectively. The ensemble mean values for the SOx, NOx, and PM emission factors were 30.5, 36.0, and 28.0%, in descending order, respectively. The NOx emissions improved significantly. These results indicate that retirement of the old However, significant variations in the pollutant control efficiency among the various units were observed.

LNG-Fueled Generation Units
The air LNG-fuel pollutant emission factors are shown in Figure 3. In 2014, the SO 2 emission factor from each generation unit ranged between N.D. (not detected) and 0.021 g/kWh, with an average of 0.0015 g/kWh. The NOx emission factor from each generation unit ranged between 0.047 and 1.122 g/kWh, with an average of 0.272 g/kWh, reflecting a 23.71-fold difference. The PM emission factor from each generation unit ranged between N.D. and 0.046 g/kWh, with an average of 0.018 g/kWh. However, the SOx emission factor from the LNG-fuel generation units was very low compared to those of coal-fired units. It was surprising that the PM in the LNG-fuel emissions was unexpectedly high. The maximum value of LNG-fired generation units was approximately equal to the level of the coal-fired unit in 2014. g/kWh, reflecting a 21.5-fold difference.
The maximum SOx, NOx, and PM emission factor decreased by approximately 44.5, 27.8, and 12.0% from 2014 to 2018, respectively. The ensemble mean values for the SOx, NOx, and PM emission factors were 30.5, 36.0, and 28.0%, in descending order, respectively. The NOx emissions improved significantly. These results indicate that retirement of the old polluting units and introduction of new coal-fired generation units with high performance air pollutant control devices could clearly reduce the emissions of SOx and NOx.
However, significant variations in the pollutant control efficiency among the various units were observed.

LNG-Fueled Generation Units
The air LNG-fuel pollutant emission factors are shown in Figure 3. In 2014, the SO2 emission factor from each generation unit ranged between N.D. (not detected) and 0.021 g/kWh, with an average of 0.0015 g/kWh. The NOx emission factor from each generation unit ranged between 0.047 and 1.122 g/kWh, with an average of 0.272 g/kWh, reflecting a 23.71-fold difference. The PM emission factor from each generation unit ranged between N.D. and 0.046 g/kWh, with an average of 0.018 g/kWh. However, the SOx emission factor from the LNG-fuel generation units was very low compared to those of coal-fired units. It was surprising that the PM in the LNG-fuel emissions was unexpectedly high. The maximum value of LNG-fired generation units was approximately equal to the level of the coal-fired unit in 2014.  In 2018, the SOx emission factor from each LNG-fuel generation unit ranged between N.D. and 0.019 g/kWh, with an average of 0.0016 g/kWh. The NOx emission factor from each generation unit ranged between 0.072 and 0.403 g/kWh, with an average of 0.200 g/kWh, reflecting a 5.60-fold difference. The PM emission factor from each generation unit ranged between 0.003-0.038 g/kWh, with an average of 0.014 g/kWh, reflecting a 12.67-fold difference.
The average SOx and NOx emission factor did not appear to change between 2014 and 2018. The average value of the PM emission factor dropped by 26.1%. The maximum NOx and PM emission factors decreased by approximately 64.1% and 16.9% from 2014 to 2018, respectively. The NOx and PM emissions improved significantly due to the retirement of old, highly polluting LNG-fired generation units. Figure 4 shows the pollutant emissions per kWh for the different fossil fuels. In 2014, the SO 2 electric generation emissions were 1.635 g/kWh; NOx emissions were 0.658 g/kWh, and PM emissions were 0.054 g/kWh for the oil power plants. In 2018, the SO 2 emissions were 1.157 g/kWh; NOx emissions were 0.805 g/kWh, and PM emissions were 0.056 g/kWh for oil-powered plants. Based on the pollution emissions in 2014, the ment of old, highly polluting LNG-fired generation units. Figure 4 shows the pollutant emissions per kWh for the different fossil fuels. In 2014, the SO2 electric generation emissions were 1.635 g/kWh; NOx emissions were 0.658 g/kWh, and PM emissions were 0.054 g/kWh for the oil power plants. In 2018, the SO2 emissions were 1.157 g/kWh; NOx emissions were 0.805 g/kWh, and PM emissions were 0.056 g/kWh for oil-powered plants. Based on the pollution emissions in 2014, the emission factors decreased by 29.2%, increased by 22.3% for NOx, and exhibited a slight increase of 3.7% for PM compared with those in 2018. These data indicate that air pollutant emission abatement was significant. Implementation of abatement programs could lead to clean electricity generation and improve air quality in Taiwan. However, significant variations in pollutant control efficiency among the various generation units were observed.

Emission Characteristics of Different Power Plants
Emissions of air pollutants from fossil-fueled electricity generation units depend on many parameters. The type of fuel, the capacity of the generation unit, the combustion technology, air pollution control devices, and operation management strongly influence emissions [21]. These data indicate that air pollutant emission abatement was significant. Implementation of abatement programs could lead to clean electricity generation and improve air quality in Taiwan. However, significant variations in pollutant control efficiency among the various generation units were observed.

Emission Characteristics of Different Power Plants
Emissions of air pollutants from fossil-fueled electricity generation units depend on many parameters. The type of fuel, the capacity of the generation unit, the combustion technology, air pollution control devices, and operation management strongly influence emissions [21].
In this study, the relationship between the PM-SOx-NOx emission factors were examined to evaluate the overall potential co-benefiting effects of these control strategies on air pollution abatement.
The capacities of the coal-fired and LNG-fueled power generation units were classified into three categories: category-I (C-I < 400 MW), category-II (C-II: 400-600 MW), and category-III (C-III > 600 MW). There were no data for the C-I group in Taiwan. The electricity generation of the coal power plant for groups C-II and C-III was 64,028.9 and 22,475.6 kWh, respectively, in 2014. The electricity generation of the coal power plant for groups C-II and C-III was 53,828.4 and 42,119.6 kWh, respectively, in 2018. In Taiwan, the generation units corresponding to groups C-II and C-III accounted for around 74.0% and 26.0% of total fossil-fueled electricity generation in 2014, and 56.1% and 43.9% in 2018, respectively.
The emission factors for the various air pollutants are shown in Figure 5. The PM emission factors for the C-II and C-III coal-fired power generation units were 0.0460 and 0.0311 g/kWh in 2014, and 0.0415 and 0.0162 g/kWh in 2018, respectively. The SOx emission factor of for the C-II and C-III coal-fired power generation units were 0.4055 and 0.2095 g/kWh in 2014 and 0.3203 and 0.1442 g/kWh in 2018. For the coal-fired generation units, the NOx emission factors for C-II and C-III were 0.5634 and 0.2595 g/kWh in 2014, respectively, and were 0.3329 and 0.1810 g/kWh in 2018. The NOx emission factors for groups C-II and C-III both decreased significantly. The maximum SOx and NOx values for the coal-fired generation units decreased significantly, which means the local impacts on air quality were improved. 22,475.6 kWh, respectively, in 2014. The electricity generation of the coal power plant for groups C-II and C-III was 53,828.4 and 42,119.6 kWh, respectively, in 2018. In Taiwan, the generation units corresponding to groups C-II and C-III accounted for around 74.0% and 26.0% of total fossil-fueled electricity generation in 2014, and 56.1% and 43.9% in 2018, respectively.
The emission factors for the various air pollutants are shown in Figure 5.  For the LNG-fueled units, groups C-I, C-II, and C-III were 15,123.1, 24,608.2, and 32,594.9 kWh, respectively, in 2014. In 2018, the electricity generation from LNG-fueled plants was 14,136.0, 28,674.0, and 45,543.3 kWh, corresponding to C-I, C-II and C-III, respectively, in 2018. Most of the LNG-fueled units emitted less PM (< 0.04 g-PM /kWh) and SOx (<0.005 g-SOx /kWh). The NOx emission factors ranged from 0.072 to 0.403 g-NOx/kWh. Some LNG-fueled generation units emitted large amounts of NOx due to a lack of a NOx control system.
The PM emission factor for the LNG-fueled power generation units from groups C-I, C-II, and C-III were 0.0345, 0.0083, and 0.0141 g/kWh, respectively, in 2014 and were 0.0202, 0.0085 and 0.0146 g/kWh in 2018, respectively. The PM emission factor decreased slightly only in group C-I.
For the LNG-fueled generation units, the NOx emission factors for C-I, C-II, and C-III were 0.4775, 0.1545, and 0.2061 g/kWh in 2014 and were 0.1971, 0.1783, and 0.2231 g/kWh in 2018, respectively. The NOx emission factor in group C-I decreased significantly, but it slightly increased in C-II and C-III.
In the LNG-fueled power generation units, the SOx emission factors for groups C-I, C-II, and C-III were 0.00041, 0.00310, and 0.00054 g/kWh, respectively, in 2014 and were 0.00197, 0.00206, and 0.00086 g/kWh, respectively, in 2018. The SOx emission factor did not change significantly.
The results indicate that large capacity units had a higher PM and NOx emissions for LNG power plants. In the early stage, the LNG power plants were not equipped with the air pollution control system. After 2014, the stringent emission standards were conducted, and then the older LNG power plants were equipped with the NOx emission control system and reduced NOx, but they did not have control systems for PM and SOx emission. Larger capacity LNG systems were constructed and permitted before 2014, and air pollution control devices will be retrofitted in the next future year.
In the case of the coal-fired power plants, the large capacity units had low air pollution emissions due to higher combustion efficiency and better air pollution control systems [36]. The new source emission standards for coal-fired power plants in the US are 0.0408 g/kWh for PM, 0.1814 mg/kWh for SO 2 , and 0.4899 mg/kWh for NOx [37]. In 2018, the average PM emissions for US coal-fired power plants was 0.0236 g/kWh; SO 2 was 0.1583 g/kWh, and NOx was 0.2552 g/kWh (EIA, 2021) [14]. Compared with the US, the coal-fired units in Taiwan in 2018 had higher emissions than those in the US by 1.34-fold for PM, 1.59-fold for SO 2 , and 1.07-fold for NOx, respectively. The results indicate that the air pollution control efficiency for coal-fired power plants in Taiwan should be further improved to reduce the emissions of PM and SOx even though the improvements between 2014 and 2018 were obvious. Figure 6 compares the PM emission factor with the SOx and NOx emission factors for the coal-fired power plants. The results indicate that the PM emission factor had a correlation with SOx (r = 0.70) emissions and a slight correlation with NOx (r = 0.41) emissions.  Figure 7 compares the PM emission factor with the SOx and NOx emission factors for the LNG-fueled generation units. There was no clear correlation between the PM and SOx emission factors (r = −0.11) and only a slight correlation with NOx (r = 0.54). PM emissions may be correlated with SOx or NOx emissions due to fuel effects, control technology, or other parameters [38][39][40]. However, no clear trends were observed among these data.  emission factors (r = −0.11) and only a slight correlation with NOx (r = 0.54). PM emissions may be correlated with SOx or NOx emissions due to fuel effects, control technology, or other parameters [38][39][40]. However, no clear trends were observed among these data.

Air Pollution Emissions and Control Equipment
The emission factors were grouped into various categories by air pollution control devices, as shown in Table 3. In oil-fueled generation units, a low NOx burner and over-fire air are usually applied for combustion modifications, and an electrostatic precipitator with an efficiency in the range of 89.5-91.9% is used for PM control. The average emission factors for SOx and PM are higher than those of the coal-fired and LNG-fueled generation units.
Most LNG-fueled units are equipped with low NOx burners (LNBs) to reduce NOx emissions. Since 2014, many LNG-fueled units have been retrofitted and equipped with selected catalytic reduction (six sets) or dry low NOx combustion systems (DLN) associated with the SCR process (five units). Some units have added steam/water injection processes (three units) or are equipped with LNB and steam and water injection (SWI) (three PM Emission Factor (g/kWh)

Air Pollution Emissions and Control Equipment
The emission factors were grouped into various categories by air pollution control devices, as shown in Table 3. Table 3. Air pollutant emission factors (g/kWh) for the fossil-fuel power generation sector in Taiwan. In oil-fueled generation units, a low NOx burner and over-fire air are usually applied for combustion modifications, and an electrostatic precipitator with an efficiency in the range of 89.5-91.9% is used for PM control. The average emission factors for SOx and PM are higher than those of the coal-fired and LNG-fueled generation units.
Most LNG-fueled units are equipped with low NOx burners (LNBs) to reduce NOx emissions. Since 2014, many LNG-fueled units have been retrofitted and equipped with selected catalytic reduction (six sets) or dry low NOx combustion systems (DLN) associated with the SCR process (five units). Some units have added steam/water injection processes