Environment ministry signs Sejong sewage-heat energy pact

The environment ministry said an agreement with Sejong city and Korea District Heating Corp. will recover unused heat and biogas from a municipal sewage treatment plant, a project the ministry says could supply enough heat for about 17,000 households a year.

Sejong Mayor Cho Sang-ho and Korea District Heating Corp. President Ha Dong-geun attended the signing at Sejong City Hall alongside First Vice Minister Keum Han-seung of the ministry.

Sewage treatment plants run around the clock and are heavy energy consumers, and the Sejong Water Quality Restoration Center A has until now left much of its sewage heat and biogas unused. Fully harnessing the plant's average daily discharge of about 59,000 tons of water would allow it to recover roughly 105,000 gigacalories of heat a year, equivalent to the annual heat supply of some 17,000 households.

Under the plan, biogas will first be used to generate electricity, and the waste heat from that generation will be combined with sewage heat to supply 1 gigacalorie of heat per hour to the district heating network. Sejong city expects about 450 million won ($332,840) in direct and indirect benefits a year, and Korea District Heating Corp. about 200 million won ($147,929).

Sejong will provide the demonstration site, biogas and treated sewage water and cooperate on administrative support including permits, while the heating company will link sewage heat and power-generation waste heat to district heating and cooperate on building facilities and providing technical support. The ministry will cooperate on policy and institutional support.

The agreement follows a July revision by the ministry to its guidelines for establishing basic sewage system improvement plans, which now require public sewage management agencies to review the potential for sewage heat use at treatment facilities with a daily capacity of 5,000 cubic meters or more. When setting energy self-sufficiency targets, agencies must also count energy supplied externally, such as to district heating, alongside energy used on site.

The ministry is also pursuing a revision to the enforcement decree of the Act on the Promotion of the Development, Use and Diffusion of Renewable Energy to include sewage heat within the scope of hydrothermal energy, which is classified as renewable.

"Sewage heat can be obtained close to urban areas and its water temperature stays relatively constant through the year, making it an important heat source for carrying out carbon neutrality," First Vice Minister Keum Han-seung said. He added that the ministry will continue policy and institutional support so that sewage heat can play a major role in building an energy self-sufficiency base at sewage treatment facilities.