Due to industrial development, growth in population and the consequentially increased use of fossil fuels in the 1970s and 1980s, the air pollution in Seoul has fallen into a serious condition. In particular, SO2 pollution in Seoul reached the highest level, more than four times of the national environment standards in 1980, and even more than 2 times the standards in 1990.
 
The main energy source in the 1960s was cheap coal that made up around 40% of the total energy consumption at that time. After the 1970s, petroleum replaced coal and became the main energy source because the use of oil was increased dramatically as the heavy chemical industry was developed, and the standard of living was greatly improved.
 
The major emission sources of SO2 were fossil fuels such as coal and petroleum. The sulfur content of fossil fuels was relatively higher than city gas and LPG. The SO2 concentration was still very high, because around 70% of the households in Seoul used coal briquettes as heating fuel in the 1990s. Accordingly, the Seoul Metropolitan Government and the central government planned to expand the supply of clean fuels and to introduce various projects in order to reduce SO2 emission.

When confirming the development plan for the Mok-dong new town in 1983, the Seoul Metropolitan Government adopted the heating method for the first time in Korea in which a portion of electric energy is provided from the cogeneration plants and the residual heat is used as the source of district heating for the new town. In order to implement this heating method, Seoul installed the “Mok-dong District Development Office” exclusively for the development of Mok-dong new town and made a business consignment agreement for the entire construction project and operation with the Korean Energy Management Corporation which was able to provide professional and specialized technical manpower. Seoul also consigned the design, construction, supervision and facility operation for the Mass Energy supply project to the SH Corporation. Under the scheme, the cogeneration plants in Gangseo region and Nowon region were constructed.

 
In 1984, Seoul provided around 26,000 households with heat. The number of households using the group heat energy provided by Seoul exceeded 240,000 in 2013.
 

◦   May 1983: Confirmation of New Town Development Plan in Mok-dong (Adoption of District Heating Method)
◦   Oct. 1983: Submission of Mass Energy Supply Project Plan (Draft) for Mok-dong Area
◦   Dec. 1983: Public Announcement of the Ordinance on Implementation and Consignment of Mass Energy Supply Project
◦   Dec. 1983: Consignment Agreement for the Mass Energy Supply Project for Mok-dong (Consignee: Korea Energy Management Corporation)
◦   Mar. 1984: Commencement of Design Service Contract
◦   Aug. 1984: Acquisition of Permission for Heat Supply Project
-    Supply Target: 26,629 Households in the New Towns in Mok-dong and Sinjeong-dong
-    Facility Scale: Heat Transmission Pipe (20㎞), Cogeneration Boiler (1 Unit of 100 tons/h and Turbine/Generator 21㎿), Heating-only Boiler (2 Units of 140 tons/h, 2 Units of 80 tons/h and 3 Units of 10 tons/h)
-    Project Period: Dec. 1983 ～ Dec. 1987
-    Project Budget: KRW 36,199 million
◦   Nov. 1984: Commencement of Construction of Waste Incinerator (Completed on Dec. 31^st, 1986)
◦   Jan. 1985: Commencement of Construction of Cogeneration Plant (Completed on Dec. 31^st, 1987)
◦   Oct. 1985: Commencement of Construction of Heat Transmission Facilities (Completed Nov. 30^th, 1987)
◦   Nov. 1985: Start of the 1^st Phase Heat Supply (Mok-dong Apt. 1 District, 1,882 Households)
◦   Aug. 1990: Confirmation of Mass Energy Supply Project for Gayang and Banghwa․Apt. 1 District
-    Supply Target: 24,314 Households in Gayang and Banghwa Apt. 1 District
-    Facility Scale (Linked to the existing Mok-dong Cogeneration Plant): Heating-only Boiler (2 Units of 110 tons/h), Heat Transmission Pipe (31.6㎞), 1 Site of Booster Pump Site
-    Project Period: Aug. 1990 ～ 30 Nov. 1993
-    Project Budget: KRW 30,603 million
◦   Apr. 1993: Confirmation of Mass Energy Supply Project for Deungchon and Banghwa Apt. 2 District
-    Supply Target: 14,365 Households in Deungchong and Banghwa Apt. 2 District
-    Facility Scale (Linked to the existing Mok-dong Cogeneration Plant): Heating-only Boiler (1 Unit of 110 tons/h, Heat Transmission Pipe (11.4㎞)
-    Project Period: Apr. 1993 ～ 10 Jan. 1995
-    Project Budget: KRW 8,961 million

◦   Oct. 1991: Service Agreement for the Basic Plan for the Mass Energy Supply Project in Nowon Region
-    Use of Burning Heat from the Sanggye Resource Recovery Facility
◦   Jun. 1992: Confirmation of Mass Energy Supply Project for Nowon Region
-    Supply Target: 104,968 Households in Nowon-gu, Dobong-gu and Jungnang-gu
-    Facility Scale: Cogeneration Boiler (1 Unit of 150 tons/h and Turbine Generator 37,000㎾), Heating-only Boiler(4 Units of 150 tons/h), Heat Transmission Pipe (80㎞)
-    Project Budget: KRW 80,760 million
-    Project Period: Jun. 1992 ～ Dec. 1996
◦   Jul. 1993: Permission for Mass Energy Project
◦   Dec. 1993: Commencement of Construction of Nowon Cogeneration Plant
◦   Dec. 1993: Commencement of Construction of Heat Transmission Pipe Installation
◦   Dec. 1994: Start of Heat Supply (3,420 Households in Gongneung 1 Land Development District)
◦   Dec. 1996: Completion of Nowon Cogeneration Plant
◦   Oct. 2009: Completion of the Fuel Cell (2.8MW) Generation Plant in the Nowon Cogeneration Plant
 

◦   Large amount of energy reduction due to the enhanced energy use efficiency (20～30%)
◦   Reduction of SOx, NOx and fine dust emissions thanks to the air environment improvement because of the reduced fuel use and concentrated environmental management
◦   Contribution to solving the power plant site problems and to reducing the power transmission loss
-    Relaxation of the peak load power in the summer season by supplying the district heating
◦   Decrease petroleum dependency through fuel diversification and increased use of unused energy such as the waste heat from resource recovery facilities and landfill gas
 

Thanks to the various policies and projects facilitated by the Seoul Metropolitan Government and the central government to provide clean fuel that emits low air pollutants, the SO2 concentration in Seoul has been remarkably reduced. SO2 concentration has been lower than the national environmental standards since 1994 and has been maintained at a very low level of around 0.005ppm stably since 2000.

The SO2 pollutant which was one of the main causes of air contamination in Seoul until the early 1990s have been rapidly reduced thanks to Seoul’s policy to supply various kinds of clean fuels and to expand such supply actively, no longer being a cause for concern. However, the NO2, fine dusts, etc. that are generated by using the fossil fuels like gasoline, diesel, etc. still remain major air pollution problems in Seoul. In addition, LNG, which had been regarded as a clean fuel, is not free from climate change issues attracting global interests in the aspect of air quality, because it emits greenhouse gases such as carbon dioxide.
 
In order to address these limits, Seoul prepared and implemented plans to expand the use of new and renewable energy including geothermal heat, sunlight, solar heat, fuel cells, etc. Specifically, Seoul has focused on expansion of facilities related to sunlight, fuel cells and geothermal heat and on heat generation using wastes. As a result, the total production of new and renewable energy in Seoul has increased nearly three times from 78,000 TOE in 2003 to 233,000 TOE in 2012. Nonetheless, the production amount of new and renewable energy in Seoul is just 2.6% of the nationwide production amount of new and renewable energy and makes up only 1.5% of the entire energy consumption of Seoul. As Seoul facilitates the introduction of sunlight generation facilities as a part of policy for “Reduction of One Nuclear Plant,” the weight of solar generation is expected to increase significantly.