Mo Chung

Development of a Combined Energy-Demands Calculator for Urban Building Communities in Korea

A decision-support tool based on relational database technology is developed to aid the planning of energy supply systems for urban communities. The building-load models derived from the data measured or surveyed in Korea over the last two decades are computerized using Microsoft Access® as an application platform. The tool calculates energy demands for arbitrary combinations of buildings in an urban community without requiring detailed technological information. Nonexpert urban planners can use the package by providing simple input parameters such as floor area, building type, and city where the site is located. The program calculates the time series based on the demands for electricity, heating, cooling, and hot water loads for the 8760 hours of a year. It also produces indicative characteristics of each load type such as the annual maximums, trends of the daily maximums and minimums, and the annual sums of energy. Urban planners can use these characteristics of the load profiles in their decision processes at the early stages of planning. The detailed time series can be further exploited for subsequent analysis, such as device operational simulation or cost estimation if more sophisticated analysis is necessary. A case study for an actual project is presented for demonstrational purposes.

Feasibility study for retrofitting biogas cogeneration systems to district heating in South Korea

A feasibility study was performed to assess the technical and economic merits of retrofitting biogas-based cogeneration systems to district heating networks. Three district heating plants were selected as candidates for accommodating heat recovery from nearby waste treatment stations, where a massive amount of biogas can be produced on a regular basis. The scenario involves constructing cogeneration systems in each waste treatment station and producing electricity and heat. The amounts of biogas production for each station are estimated based on the monthly treatment capacities surveyed over the most recent years. Heat produced by the cogeneration system is first consumed on site by the waste treatment system to keep the operating temperature at a proper level. If surplus heat is available, it will be transported to the nearest district heating plant. The year-round operation of the cogeneration system was simulated to estimate the electricity and heat production. We considered cost associated with the installation of the cogeneration system and piping as initial investments. Profits from selling electricity and recovering heat are counted as income, while costs associated with buying biogas are expenses. Simple payback periods of 2–10 years were projected under the current economic conditions of South Korea. We found that most of the proposed scenarios can contribute to both energy savings and environmental protection.