Balancing the energy demand by a resource circulation project in Daejeon,Korea

Demand for sustainable renewable energy is on an increase worldwide, whereas the supply is limited. This paper analyses the feasibility of generating electricity and supplying the surplus steam to Daeduk Industrial Complex, by incinerating the combustible municipal waste generated in Daejeon Metropolitan City. The economic feasibility of surplus biogas generated from the anaerobic digestion of food waste and food waste leachate has been analysed. This study estimated resource circulation facility to supply 23,200 m³/day of biogas generated to Daejeon Combined Heat and Power plant. By 2023, it is expected to supply 25.7 tons of steam per hour all year round. The additional steam demand in Daeduk Industrial Complex is estimated as 101,537 tons/year. Surplus biogas will be supplied through an additional 960-m new installation. The cost of biogas is estimated at 30% of the unit biogas production cost. Daejeon Combined Heat and Power plant expects to make 60% additional profit, and Daeduk Industrial Complex and the communities nearby expect to achieve 10% cost savings. It also reduces the dependence of energy on fossil fuels, contributes to national environmental energy policy in reduction in greenhouse gases, creates competitiveness in local business and reduces corporate tax and generates revenue.     

Numerical study of heat transfer characteristics of char from waste tire pyrolysis

To investigate heat transfer of char from waste tire pyrolysis, the cooling of char was simulated by the computational fluid dynamics. To scrutinize the heat transfer characteristics, bed height, temperature of cooling wall, and mixing time were selected as calculation parameters. From the results, increasing the char bed height from 0.005 to 0.02 m, the total heat transfer is decreased as from 45.5 to 26.5 J. As the char bed height is further increased from 0.02 to 0.06 m, the total heat transfer is decreased from 26.5 to 9.1 J. The char bed height affects the total heat transfer significantly. The total heat transfer decreases from 15.9 to 14.0 J as the temperature of cooling wall increases from 273.15 to 323.15 K. The total heat transfer mildly depends on the temperature of cooling wall. The particle mixing time increases from 10 to 120 s and the total heat transfer decreases from 28.6 to 22.6 J. It is noted that the particle contact is enhanced between char particles as well as the particles and cooling wall as the particle mixing time decreases. Consequently, heat transfer is augmented.     

Quality control for coal combustion products in South Korea through assessed pozzolanic-activity index with long-term property tests

In South Korea, nine million tons of fly ash (FA) are annually produced and approximately 70 % is reutilized for industrial demand. For the prompt reuse and insufficient reclamation site, quality control of FA which is main productive construction material from coal ash is very important. Assessed Pozzolanic-activity Index (API) test which needs only 2 days for evaluation of pozzolanic reaction is currently considered as an alternative of activity index measurement. This paper aims for an applicability of API test for prompt quality control and investigation of domestic FA properties. For the work, FAs from two different power plant types are prepared, and quality tests are carried out based on Korean Standards (KS) methods and API method. Lots of test results are compared with those from API and K-value test for FA with age of 7 days–1 year. From the test results for FA aged 1 year, API results are evaluated to be closely related with those from activity index and K-value, and the correlations are improved with increasing ages regardless of plant types. The applicability of API test is verified and the reduced period of FA quality evaluation can accelerate prompt use and the related process of FA.     

A comparison of refrigerant management policies and suggestions for improvement in South Korea

HFCs (hydrofluorocarbons) emerged as alternative refrigerants after the production of chlorofluorocarbons was banned and hydrochlorofluorocarbons were phased out, under the Montreal Protocol on Substances that Deplete the Ozone Layer. However, because the Kyoto Protocol considered HFCs as greenhouse gases, and their impact on climate change has been increasing, major developed countries have been strengthening existing regulations on the use of HFCs as refrigerants. South Korea has also passed various legislations related to refrigerant management. However, reports indicate that implementation of these regulations has been ineffective, due to the absence of a specific system for managing the production, use, and disposal phases of refrigerants. To identify and resolve these issues, this study investigates the current state of refrigerant management in South Korea for those three phases. Refrigerant management policies are compared between different legislatures, using the examples of the European Union, United States, and Japan. Based on the findings, five types of measures are suggested to reduce the production and consumption of refrigerants, and to improve refrigerant management regulations in ways that are most appropriate to the South Korean context.     

Future year ozone source attribution modeling study using CMAQ-ISAM

ABSTRACT

To achieve the current United States National Ambient Air Quality Standards (NAAQS) attainment level for ozone or particulate matter, current photochemical air quality models include tools to determine source apportionment and/or source sensitivity. Previous studies by the authors have used the Ozone and Particulate Matter Source Apportionment Technology and Higher-order Decoupled Direct Method probing tools in CAMx to investigate these source-receptor relationships for ozone. The recently available source apportionment for CMAQ, referred to as the Integrated Source Apportionment Method (ISAM), was used in this study to conduct future year (2030) source attribution modeling. The CMAQ-ISAM ozone source attribution results for selected cities across the U.S. showed boundary conditions were the dominant contributor to the future year highest July maximum daily 8-hour average (MDA8) ozone concentrations. Point sources were generally larger contributors in the eastern U.S. than in the western U.S. The contributions of on-road mobile emissions were around 5 ppb at most of the cities selected for analysis. Off-road mobile source contributions were around 20 ppb or nearly 30%. Since boundary conditions play an important role in future year ozone levels, it is important to characterize future year boundary conditions accurately. The current implementation of ISAM in CMAQ 5.0.2 requires significant computing resources for ozone source attribution, making it difficult to conduct long-term simulations for large domains. The computing requirements for PM source attribution are even more onerous. CMAQ 5.2 was released after this study was completed, and does not include ISAM. If an efficient version of ISAM becomes available, it could be used in long-term ozone and PM2.5 studies. Implications: Ozone source attribution results provide useful information on important emission source contribution categories and provide some initial guidance on future emission reduction strategies. This study explains a new source apportionment technique, CMAQ-ISAM, and compares it to CAMx OSAT. The techniques have similar results: ozone’s highest source contributor is boundary conditions, followed by point sources, then off-road mobile sources. The current version of ISAM in CMAQ 5.0.2 requires significant computing resources for ozone source attribution, while the computing requirements for PM source attribution are even more onerous. CMAQ 5.2 was released after this study was completed, and does not include ISAM.     

Accelerating preliminary eco-innovation design for products that integrates case-based reasoning and TRIZ method

While the innovativeness and market potential of a new product is normally emphasized, its environmental impact is often neglected. Despite their ability to help designers reduce the environmental impact of products throughout their life cycle, many eco-design methods focus on the redesign of existing products, necessitating a more innovative design capacity. This work describes a novel model to accelerate the preliminary eco-innovation product design by integrating the advantages of case-based reasoning and the TRIZ method. Previous cases from a database support a novel design to satisfy functional performances under the CBR framework. The innovative principles and evolution patterns of the TRIZ method can enhance the design level of new products to achieve eco-innovation. Four eco-innovation concepts for a PC mouse demonstrate the effectiveness of the proposed model.     

Toxicity of atrazine and its bioaccumulation and biodegradation in a green microalga,Chlamydomonas mexicana

This study evaluated the toxicity of herbicide atrazine, along with its bioaccumulation and biodegradation in the green microalga Chlamydomonas mexicana. At low concentration (10 μg L^?1), atrazine had no profound effect on the microalga, while higher concentrations (25, 50, and 100 μg L^?1) imposed toxicity, leading to inhibition of cell growth and chlorophyll a accumulation by 22 %, 33 %, and 36 %, and 13 %, 24 %, and 27 %, respectively. Atrazine 96-h EC50 for C. mexicana was estimated to be 33 μg L^?1. Microalga showed a capability to accumulate atrazine in the cell and to biodegrade the cell-accumulated atrazine resulting in 14–36 % atrazine degradation at 10–100 μg L^?1. Increasing atrazine concentration decreased the total fatty acids (from 102 to 75 mg g^?1) and increased the unsaturated fatty acid content in the microalga. Carbohydrate content increased gradually with the increase in atrazine concentration up to 15 %. This study shows that C. mexicana has the capability to degrade atrazine and can be employed for the remediation of atrazine-contaminated streams.     

EPR characterization of the catalytic activity of clays for PCE removal by gamma-radiation induced by acid and thermal treatments

Clays from tidal flat sediments showed efficient catalytic activity in the decomposition of PCE by gamma-radiation. The highest PCE removal of 98.6% was obtained with clays heated to 700 degrees C after acid treatment. The improved catalytic activity was identified by electron paramagnetic resonance (EPR) spectroscopy. The EPR spectra of clays were significantly changed by the acid and thermal treatments. The intensity of a narrow signal at g=2 (signal III) was decreased with increasing thermal treatment temperature and this increased the PCE removal efficiency. The acid treatment completely removed a broad signal at g=2 (signal II), decreased the intensity of signal III, and improved the gamma-radiation treatment of PCE.     

Development of a Speciated,Hourly, and Gridded Air Pollutants Emission Modeling System—A Case Study on the Precursors of Photochemical Smog in the Seoul Metropolitan Area,Korea

ABSTRACT

A speciated, hourly, and gridded air pollutants emission modeling system (SHEMS) was developed and applied in predicting hourly nitrogen dioxide (NO₂) and ozone (O₃) levels in the Seoul Metropolitan Area (SMA). The primary goal of the SHEMS was to produce a systemized emission inventory for air pollutants including ozone precursors for modeling air quality in urban areas.

The SHEMS is principally composed of three parts: (1) a pre-processor to process emission factors, activity levels, and spatial and temporal information using a geographical information system; (2) an emission model for each source type; and (3) a post-processor to produce report and input data for air quality models through database modeling. The source categories in SHEMS are point, area, mobile, natural, and other sources such as fugitive emissions. The emission database produced by SHEMS contains 22 inventoried compounds: sulfur dioxide, NO₂, carbon monoxide, and 19 speciated volatile organic compounds. To validate SHEMS, the emission data were tested with the Urban Airshed Model to predict NO₂ and O₃ concentrations in the SMA during selected episode days in 1994. The results turned out to be reliable in describing temporal variation and spatial distribution of those pollutants.