• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.10
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• pp.555-561
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• 2013

The effects of applying the micro CHP system to the domestic sector in Korea were investigated using annual cooling and heating demand data. Four prime movers, micro gas turbine, PEMFC, gas engine and Stirling engine, were compared for three operational modes. Two way buy-back was assumed for both electricity and heat. The Stirling engine gave the lowest $CO_2$ emission per energy for 300kWh monthly electricity production. However, PEMFC became more effective when considering PURPA criteria. PEMFC generated the least greenhouse gas with higher electrical efficiency for cooling. The Stirling engine, however, became competitive for heating with higher total efficiency.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.251-258
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• 2016

This article reports current status of micro fuel cell-combined heat and power (${\mu}FC$-CHP) systems which utilize both power and heat generated by fuel cells. There are several options for constructing CHP systems and among them, fuel cells are the most useful and their total energy efficiency combining heat and power can reach up to about 90%. Fuel cells are classified as five types based on the electrolyte, but the most suitable fuel cell types for the ${\mu}FC$-CHP system are proton exchange membrane fuel cells (PEMFCs) and solid oxide fuel cells (SOFCs). ${\mu}FC$-CHP systems have several advantages such as decrease of the transmission-distribution loss, reduced costs of electricity due to distributed power generation, and environmental-friendliness owing to zero emission. The main drawback of the ${\mu}FC$-CHP systems is the high initial investment, however, it keeps decreasing as the technology development reduces production costs. Currently, Japan is the most leading country of the ${\mu}FC$-CHP market, however, Korea tries to expand the market by planning the deployment of 1 million units of ${\mu}FC$-CHP systems and governmental subsidiary supporting of half of the install price. In this report, integration technologies for connecting FC and CHP, and technology trends of leading countries are presented as well.

• Journal of Energy Engineering
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• v.24 no.3
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• pp.67-73
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• 2015

Almost base-loaded power plants such as flaming coal and nuclear energy require large-scale transmission facilities (LTFs) in order to send electricity to remote consumption areas. As well known, LTFs incur various social costs. However, a decentralized generation source such as integrated energy business (IEB)-based combined heat and power (CHP) plant is located in nearby electricity-consuming area, and thus it does not demand LTFs, providing the benefits from avoiding the damages caused by them. This study attempts to measure the benefits of avoiding the damages from the LTFs by the use of the contingent valuation (CV) method. To this end, a national survey of randomly chosen 1,000 households was implemented and the public's willingness to pay (WTP) for substituting consumption of electricity generated from flaming coal-fired power plant, currently a dominant generation source in Korea, with that produced from IEB-based CHP plant. The results show that the WTP for the substitution is estimated to be about 41.4 won per kWh. Considering that this value amounts to 33% of the average price of residential electricity in 2014, the external benefit of the IEB-based CHP as a decentralized generation appears to be large.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.361-364
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• 2009

KEPRI has studied planar type SOFC stacks using anode-supported single cells and kW class co-generation systems for residential power generation. A 1kW class SOFC system consisted of a hot box part, a cold BOP part and a water reservoir. A hot box part contains a SOFC stack made up of 48 cells with $10{\times}10cm^2$ area and ferritic stainless steel interconnectors, a fuel reformer, a catalytic combustor and heat exchangers. Thermal management and insulation system were especially designed for self-sustainable operation. A cold BOP part was composed of blowers, pumps, a water trap and system control units. When a 1kW class SOFC system was operated at $750^{\circ}C$ with hydrogen, the stack power was 1.2kW at 30 A and 1.6kW at 50A. Turning off an electric furnace, the SOFC system was operated using hydrogen and city gas without any external heat source. Under self-sustainable operation conditions, the stack power was about 1.3kW with hydrogen and 1.2kW with city gas respectively. The system also recuperated heat of about 1.1kW by making hot water. Recently KEPRI developed stacks using $15{\times}15cm^2$ cells and tested them. KEPRI will develop a 5 kW class CHP system using $15{\times}15cm^2$ stacks by 2010.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.1
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• pp.11-18
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• 2018

A high efficiency integrated reforming system for improving the efficiency of the 5 kW PEMFC system used as the back up power of building was studied. The separated reforming system consisted of three parts - A steam reformer with two stage concentric circular shape, a heat exchanger type steam generator and a CO shift reactor. Temperature and steam carbon ratio (SCR) were control variables during operation. The operating conditions were optimized based on the thermal efficiency of the steam reformer as reformate gas composition changes at different temperature. In experiments, water was fully vaporized in the steam generator up to SCR 3.5 and the maximum thermal efficiency was achieved at the operating temperature around $700^{\circ}C$ in the steam reforming reactor. With the results of the separated reforming system research, we improved the shape of high efficiency integrated reformer. The performance evaluation of the integrated reformer was based on optimized operating conditions in SCR 3.5. As a result, the developed integrated reforming system maintained an efficiency of 76% and constant performance over 3,000 hours.