The Emission Level Change of Air Pollutants Since the Implementation of the Total Air Pollutant Emission-Cap Management System

2. 1 Investigation for the Reinforcement of the Standard Concentration of BACT

Among air pollutant reduction technologies, the standards for BACT, which can be currently applied or mean the level of technologically feasible and cost-effective prevention facilities (KMOE, 2020), are periodically strengthened in accordance with the development of prevention facility technology, and this is specified in Annex 1 of the Enforcement Rules of the Air Management Area Act (formerly Special Act on Atmospheric Improvement in the Metropolitan Area). The history of strengthening the standard concentration of the BACT applied to power generation facilities was investigated by examining the history of amendments to laws and regulations.

2. 2 Emission Trend of Power Plants Subject to TAPEMS

The emission concentration trend of power generation facilities was investigated by classifying them according to fuel properties and facility types, and analyzing data for a total of 11 years from 2008, when TAPEMS was introduced, to 2019. Fuel properties were classified into solid, liquid, gaseous fuels, and facility types were mainly divided into thermoelectric power plant and combined heat & power plant. Thermoelectric power plant drives a turbine with the power of steam, and combined heat & power plant generates primary power by rotating a gas turbine, and produces steam using high-temperature and high-pressure exhaust gas to drive the steam turbine for secondary power generation (KMOE, 2014). The concentration and emission data used in the study were extracted from the ‘Workplace Air Pollutant Management System (www.stacknsky.or.kr)’. Concentration data was selected for large outlets equipped with Stack Tele-Monitoring System (STMS), and data on emissions and fuel consumption included small outlets calculated by emission coefficient and self-measurement in addition to outlets with STMS. The target analyte materials were nitrogen oxides and sulfur oxides, and TSP was excluded.

2. 3 The Effect Analysis of the Implementation of TAPEMS

In addition to TAPEMS, workplaces that emit air pollutants are subject to various regulations, such as emission concentration standards (Air Act), environmental impact assessment consultation standards, local government ordinances, and integrated environmental management (from 2017). However, the most differentiated atmospheric policy between the metropolitan area and non-metropolitan areas was TAPEMS. The net effect of TAPEMS was calculated by comparing the emission concentrations of the metropolitan and non-metropolitan workplaces. The emission concentration was compared with the data for 9 years, from 2010 to 2018, and facilities where it is difficult to clearly know the concentration depending on the fuel using two fuels were excluded from the analysis target.

3. 1 Reinforcement of Standard Concentration of BACT

The standard concentration of BACT used in calculating the allowance has been strengthened twice (in 2013 and 2018) after the TAPEMS was implemented in 2008. However, in 2020, when the TAPEMS is expanded to the whole country, some of the BACT standards have been relaxed so that new workplaces can settle into the TAPEMS stably.

Tables 2 and 3 summarize the reinforcement details of the BACT standards. From 2008 to 2018, the BACT standard for nitrogen hydroxide in power generation facilities was strengthened from 33% (solid fuel-fired power generation) to 80% (solid-liquid-gas combined power generation, etc.). However, facilities installed before the implementation of the TAPEMS applied relaxed BACT standards.

Table 2.

BACT standards of NOx. (ppm)

Table 3.

BACT standards of SOx. (ppm)

The BACT standard for sulfur oxides has been strengthened from 29% (liquid fuel-fired power generation) to 67% (gaseous fuel power generation, etc.).

3. 2 Emissions Trend of Power Generation Facilities and Effect of Introduced TAPEMS

Even though the number of target workplace has steadily increased due to target grade (class 1 → class 1~3) and regional (including 4 cities in Gyeonggi-do) expansion since the implementation of the TAPEMS in 2008, emissions in 2019 was decreased down to 39% for nitrogen oxides and 47% for sulfur oxides of maximum amounts (NO_x in 2010, SO_x in 2013), respectively (Fig. 1).

Fig. 1.

Annual emissions and number of facilities of power plant.

The emission concentration of all power generation facilities in 2019 decreased by 58% (53.1 → 22.5 ppm) for nitrogen oxides and 51% (62.3 → 30.8 ppm) of sulfur oxides compared to 2008 (Table 4). This indicates that the emission decrease is made by the decrease of emission concentration.

Table 4.

NOx & SOx concentration of power generation facilities. (ppm)

3. 3 Power Generation Facility using Solid Fuel

In 2019, most of the power generation facilities using solid fuel subject to TAPEMS used bituminous coal as fuel (99.7%) and some of them used wood (0.3%).

Table 5 shows the nitrogen oxide concentration by year of power generation facilities. After the introduction of TAPEMS, the average concentration of nitrogen oxides in solid fuel-using facilities decreased by 65% (82.6 → 28.8 ppm). By facility, Thermoelectric power plants decreased by 63% (40.9 → 15.3 ppm) and combined heat and power plants decreased by 64% (116.0 → 42.2 ppm).

Table 5.

NOx concentration of solid fuel-using power generation facilities. (ppm)

The BACT standard for thermal power generation facilities using solid fuel was strengthened to 15 ppm by 2017 and 10 ppm after 2018. Compared with the BACT standard applied until 2017, the emission concentration was lowered from 273% (2008) to 107% (2017) of the BACT (Fig. 2). The BACT concentration of cogeneration facilities was strengthened from 50 ppm by 2017 to 10 ppm after 2018, and the emission concentration was lowered from 232% in 2008 to 125% in 2017 (Fig. 3).

Fig. 2.

NOx concentration of solid fuel-using thermoelectric power plant.

Fig. 3.

NOx concentration of solid fuel-using combined Heat & power plant.

Sulfur oxides from power generation facilities using solid fuel decreased by 65% (48.8 → 17.3 ppm) in 2018 compared to 2008. Those of thermal power generation facilities and cogeneration facilities decreased by 57% (33.7 → 14.5 ppm) and 67% (60.8 → 20.2 ppm), respectively (Table 6).

Table 6.

SOx concentration of solid fuel-using power generation facilities. (ppm)

The sulfur oxide BACT standard for thermal power plants was strengthened to 25 ppm by 2012 and 20 ppm by 2017. In 2008, the level was 167% compared to the reinforced BACT, but in 2017, the level was 77%, meeting the BACT standard (Fig. 4). The BACT standard for cogeneration facilities was strengthened to 50 ppm by 2012 and 25 ppm by 2017. It was decreased to 243% in 2008 and 130% in 2017 compared to 2017 BACT (Fig. 5).

Fig. 4.

SOx concentration of solid fuel-using thermoelectric power plant.

Fig. 5.

SOx concentration of solid fuel-using combined Heat & power plant.

In order to calculate the net effect of the TAPEMS, the emission concentration was compared with the solid fuel power generation facility located in the non-metropolitan area. As shown in Figs. 6 and 7, it was found that nitrogen oxides and sulfur oxides were lower by about 32% and sulfur oxides by about 30% at the target workplaces. Although the difference in concentration between workplaces subject to and not subject to the TAPEMS system is gradually decreasing due to the strengthening of concentration standards and the upward leveling of emission reduction technology, the performance indicates that the emission concentration in facilities subject to the TAPEMS is consistently low.

Fig. 6.

NOx comparison between regulated and unregulated areas (solid fuel power plant).

Fig. 7.

SOx comparison between regulated and unregulated areas (solid fuel power plant).

If the above concentration difference is converted into emission amounts, 25,146 tons of nitrogen oxides and 29,571 tons of sulfur oxides were reduced for 9 years (2010~2018) due to the introduction of the TAPEMS (Tables 7, 8).

Table 7.

NOx Emission reduction (ton) due to the implementation of the TAPEMS (solid fuel).

Table 8.

SOx Emission reduction (ton) due to the implementation of the TAPEMS (solid fuel).

3. 4 Power Generation Facility using Liquid Fuel

Liquid fuels used in power generation facilities subject to TAPEMS are bunker C (BC) oil, low Sulfur Waxy Residue (LSWR) mainly and their portions were 89% for BC oil and 11% for LSWR, respectively. After the introduction of the TAPEMS, the average concentration of nitrogen oxides decreased by 32% (87.6 → 59.9 ppm) in liquid fuel-using facilities, by 15% (67.0 → 56.7 ppm) in thermal power generation facilities, and by 28% (101.3 → 72.5 ppm) in cogeneration facilities (Table 9).

Table 9.

NOx concentration of liquid fuel-using power generation facilities. (ppm)

Thermal power generation facilities using liquid fuel have 4 outlets at one business site, and they were installed before the implementation of the TAPEMS and are subject to the relaxed BACT standards. As shown in Fig. 8, the emission concentration gradually decreases as the BACT standard is strengthened.

Fig. 8.

NOx concentration of liquid fuel-using thermoelectric power plant.

Although it seems that the emission concentration of cogeneration facilities has not decreased since 2010, in terms of the number of facilities, 3 of 6 liquid fuel-using facilities in 2008 were converted to LNG, and 2 facilities were closed (Fig. 9). Therefore, the overall pollution level was decreased. The fuel consumption of power generation facilities after the introduction of the TAPEMS, the consumption of liquid fuel in power generation facilities decreased and the consumption of gaseous fuel, which emits relatively little pollutants, increased (Table 10).

Fig. 9.

NOx concentration of liquid fuel-using combined Heat & Power plant.

Table 10.

Annual fuel usage for power generation facilities.

One facility, which has been operating continuously since 2008, is emitting the higher concentration pollutants than the BACT standard (Fig. 9). The operation rate of this plant shows a decreasing trend every year, and it was over-allocated by the pre-improvement allocation method (~2017), which allocates based on the maximum operation rate during the past period. Since 2018, this has been improved and allocation is made based on the average operation rate instead of the maximum operation rate.

As shown in Table 11, after the introduction of the TAPEMS, the average concentration of sulfur oxides using liquid fuel decreased by 14% (73.6 → 63.2 ppm) in power generation facilities and by 35% (64.2 → 41.7 ppm) in thermal power generation facilities decreased. However, that was increased by 87% (79.8 → 149.0 ppm) in cogeneration facilities.

Table 11.

SOx concentration of liquid fuel-using power generation facilities. (ppm)

Thermal power plants subject to the relaxed BACT standards for existing installations gradually decreased in concentration as the BACT standards were strengthened (Fig. 10). In cogeneration facilities as with nitrogen oxides, the number of facilities decreased from 6 to 1, but the emission concentration of one facility currently in operation did not decrease (Fig. 11), and a allowance reducing the emission more than 50% of 2017 until 2022 was allocated to that facility by improving the allocation method.

Fig. 10.

SOx concentration of liquid fuel-using thermoelectric power plant.

Fig. 11.

SOx concentration of liquid fuel-using combined Heat & Power plant.

Comparing the concentration with liquid fuel-using thermal power generation facilities in non-metropolitan areas, plants subject to the TAPEMS emit 15% less nitrogen oxides and 6% lower sulfur oxides than non-targeted plants on average (Figs. 12, 13).

Fig. 12.

NOx comparison between regulated and unregulated areas (liquid fuel power plant).

Fig. 13.

SOx comparison between regulated and unregulated areas (liquid fuel power plant).

As shown in Table 12, if the effect of the introduction of the TAPEMS is converted into emissions, 2,063 tons of nitrogen oxides and 1,961 tons of sulfur oxides were reduced for 9 years (2010~2018).

Table 12.

NOx Emission reduction (ton) due to the implementation of the TAPEMS (liquid fuel).

Table 13.

SOx Emission reduction (ton) due to the implementation of the TAPEMS (liquid fuel).

In the case of liquid fuel power plants, the effect of introducing the TAPEMS was smaller than that of solid fuel facilities. The low effect can be explained by the relaxed BACT standards applied to liquid fuel power plant. Another factor is that sufficient incentives for facility investment have not occurred by allocating facilities whose utilization rates are on a declining trend based on the past maximum utilization rates.

In the Air Management Area Act, which was newly established due to the nationwide expansion of the TAPEMS, the relaxed BACT standard is applied to facilities installed before 2015. For active investment in facility improvement of existing facilities, it seems desirable to apply the same BACT standard to all facilities after 2025.

3. 5 Power Generation Facility using Gas Fuel

Types of gaseous fuel include LNG, LFG (Land Fill Gas), LPG, biogas, and by-product gas. LNG accounts for 98.8% of the total, so the concentration analysis targeted LNG-using facilities with a high proportion of use and did not analyze sulfur oxides with insignificant occurrence. Also, concentration analysis was conducted without classifying facilities because most of the facilities using LNG are internal combustion engines for power generation. Only one facility used thermal power generation.

The nitrogen oxide concentration of gas-fueled power plants decreased by 55% (41.6 → 18.8 ppm) in 2018 compared to 2008 (Table 14). BACT standards are classified according to the amount of power generation but compared with the most strengthened BACT standard for cogeneration (10 MW or more, 10 ppm), in 2008, it was lowered from 416% to 188% in 2019 (Fig. 14).

Table 14.

NOx concentration of gas fuel-using power generation facilities.

Fig. 14.

NOx concentration of gas fuel-using power plant.

Compared to the concentration with LNG power generation facilities in non-metropolitan areas, those in the facilities subject to the TAPEMS emitted 7% lower nitrogen oxide (Fig. 15). According to major policy pillars such as the Master Plan for Energy and the Master Plan for Power Supply and Demand, the pro-portion of LNG power generation is increasing, and the emission standards applied to LNG power generation have recently been greatly strengthened. In addition, non-metropolitan areas where the TAPEMS was not implemented are judged to have low emission levels because various prevention facilities such as low-temperature catalysts can be applied due to the nature of gaseous fuels that do not emit sulfur oxides and particulate matter (Kim et al., 2020).

Fig. 15.

NOx comparison between regulated and unregulated areas (gas fuel power plant).

If the difference in concentration between workplaces subject to and not subject to the TAPEMS is considered as the effect of introducing the TAPEMS and converted into emissions, the amount of nitrogen oxides reduced between 2010 and 2018 is 9,453 tons (Table 15).

Table 15.

NOx Emission reduction (ton) due to the implementation of the TAPEMS (gas fuel).

The proportion of LNG power generation is expected to increase further under the national energy policy, which sets the reduction of nuclear and coal power plants and the expansion of renewable energy (MOTIE, 2019). Currently, LNG power plants are mainly responsible for peak load of power demand, but in the near future, they will play a major role in supporting base generation and stabilization of renewable energy. It is necessary to pay attention to the wide range of NO_x concentration in LNG power plants ranging from 3.3 to 56.6 ppm, and to review the system improvement so that LNG power plants with low pollution levels are operated first through the TAPEMS. In the power generation market, power supply is ranked in descending order of unit price. In general, nuclear power plants have the lowest fuel cost, followed by coal, gas, and oil power plants (Kim and Shin, 2018). The unit price of power generation is mainly determined by the fuel cost, and the cost of greenhouse gas emission is also included (KPX, 2021). If the electricity market operation rules are amended to include the cost of NO_x & SO_x emission in the electricity generation cost, the TAPEMS will be able to contribute to the realization of environmental power supply in which eco-friendly facilities are operated first. However, it is necessary to increase the cost of purchasing emission to the extent that the priority order can be reversed, and for this, it is necessary to consider methods such as the introduction of allowance auctioning for the power generation industry and the strengthening of BACT standards (e.g., the top 10% level).

3. 6 Social Benefits of TAPEMS

Air pollution can have damaging impacts on human health, productivity, and the health of the environment. These detrimental impacts have an associated economic or social cost (Ricardo E&E, 2019). The amount of air pollutants reduced by the implementation of TAPEMS was converted into social costs using the coefficient suggested by Ricardo E&E (2019).

As shown in Table 16, a total of 36,663 tons of NO_x reduction for 9 years (2010-2018) due to the TAPEMS resulted in social benefits of KRW 308,231 million. The social benefits of solid fuel-using facilities accounted for the largest share at KRW 211,408 million.

Table 16.

Benefits of Air Pollutant Emission-Cap Management System (power plant).

A total of 31,532 tons of sulfur oxides were further reduced, resulting in social benefits of KRW 268,253 million. As with nitrogen oxides, the greatest benefit occurred in solid fuel-using facilities.