• Clean Technology
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• v.26 no.4
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• pp.329-335
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• 2020

Methanol synthesized from renewable hydrogen and captured CO2 has recently attracted great interest as a sustainable energy carrier for large-scale renewable energy storage. In this study, molten carbonate fuel cell's performance was investigated with the direct conversion of methanol into syngas inside the anode chamber of the cell. The internal reforming of methanol may significantly improve system efficiency since the heat generated from the electrochemical reaction can be used directly for the endothermic reforming reaction. The porous Ni-10 wt%Cr anode was sufficient for the methanol steam reforming reaction under the fuel cell operating condition. The direct supply of methanol into the anode chamber resulted in somewhat lower cell performance, especially at high current density. Recycling of the product gas into the anode gas inlet significantly improved the cell performance. The analysis based on material balance revealed that, with increasing current density and gas recycling ratio, the methanol steam reforming reaction rate likewise increased. A methanol conversion more significant than 90% was achieved with gas recycling. The results showed the feasibility of electricity and syngas co-production using the molten carbonate fuel cell. Further research is needed to optimize the fuel cell operating conditions for simultaneous production of electricity and syngas, considering both material and energy balances in the fuel cell.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.1
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• pp.48-53
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• 2006

The purpose of this paper is to investigate the optimal condition of the SynGas production by reforming of propane using plasmatron. Plasma was generated by air and arc discharge. The effects of applied steam, $CO_2$ or Ni-catalyst on propane conversion, yield of hydrogen and $H_2/CO$ ratio as well as correlation of syngas were studied. When the variations of $O_2/C_3H_8$ flow ratio, $H_2O/C_3H_8$ flow ratio and $CO_2/C_3H_8$ flow ratio were $0.94{\sim}1.48,\;4.3{\sim}10\;and\;0.8{\sim}3.05$ respectively, Under the condition mentioned above, result of $H_2O/C_3H_8$ flow ratio was maximum $H_2$ concentration, or $28.2{\sim}31.6%$, and result of $H_2O/C_3H_8$ flow ratio with catalyst was minimum CO concentration or $6.6{\sim}7.1%$ and the ratio of hydrogen to carbon monoxide($H_2/CO$) were $3.89{\sim}4.86$.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.5
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• pp.653-659
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• 2017

Objective: This trial was performed to examine the effects of ruminally degradable starch (RDS) levels in total mixed ration (TMR) with low corn-based starch on the milk production, whole-tract nutrient digestibility and nitrogen balance in dairy cows. Methods: Eight multiparous Holstein cows (body weight [BW]: $717{\pm}63kg$; days in milk [DIM]: $169{\pm}29$) were assigned to a crossover design with two dietary treatments: a diet containing 62.3% ruminally degradable starch (% of total starch, low RDS) or 72.1% ruminally degradable starch (% of total starch, high RDS). Changes to the ruminally degradable levels were conducted by using either finely ground corn or steam-flaked corn as the starch component. Results: The results showed that dry matter intake, milk yield and composition in dairy cows were not affected by dietary treatments. The concentration of milk urea nitrogen was lower for cows fed high RDS TMR than low RDS TMR. The whole-tract apparent digestibility of neutral detergent fiber, acid detergent fiber and crude protein decreased, and that of starch increased for cows fed high RDS TMR over those fed low RDS TMR, with no dietary effect on the whole-tract apparent digestibility of dry matter and organic matter. The proportion of urinary N excretion in N intake was lower and that of fecal N excretion in N intake was higher for cows fed high RDS TMR than those fed low RDS TMR. The N secretion in milk and the retention of N were not influenced by the dietary treatments. Total purine derivative was similar in cows fed high RDS TMR and low RDS TMR. Consequently, estimated microbial N flow to the duodenum was similar in cows fed high RDS TMR and low RDS TMR. Conclusion: Results of this study show that ruminally degradable starch levels can influence whole-tract nutrient digestibility and nitrogen balance in dairy cows fed low corn-based starch diets, with no influence on performance.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.12
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• pp.1690-1698
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• 2011

Feedlot and in vitro ruminal experiments were conducted to assess the effects of saponin-containing surfactant applied during tempering of barley grain on cattle growth performance and on ruminal fermentation. In the feedlot experiment, treatments with three barley grain/barley silage based diets were prepared using barley grain at 7.7% moisture (dry, D), after tempering to 18% moisture (M), or after tempering with a saponin-based surfactant included at 60 ml/t (MS). Each treatment was rolled at settings determined previously to yield optimally processed barley. A total of 180 newly weaned British${\times}$Charolais steers were fed three diets in 18 pens for a 63-d backgrounding period and 91-d finishing period to determine feed intake, growth rate and feed efficiency. Cattle were slaughtered at the end of the experiment to measure the carcass characteristics. Tempering reduced (p<0.001) volume weight and processing index, but processing characteristics were similar between MS and M. Tempering increased (p<0.05) growth during backgrounding only, compared with D, but did not affect feed intake in either phase. During backgrounding, feed efficiency was improved with tempering, but during finishing and overall this response was only observed with the surfactant. Tempering did not affect carcass weight, fat content or meat yield. Surfactant doubled the proportion of carcasses grading AAA. In the in vitro experiment, barley (500 mg; ground to <1.0 mm or steam-rolled) was incubated in buffered ruminal fluid (40 ml) without or with surfactant up to 20 ${\mu}l/g$ DM substrate for 24 h. Surfactant increased (p<0.05) apparent DM disappearance and starch digestibility but reduced productions of gas and the volatile fatty acid and acetate:propionate ratio, irrespective of barley particle size. Compared with feeding diets prepared with non-tempered barley, tempering with surfactant increased the feed efficiency of feedlot steers. This may have arisen from alteration in processing characteristics of barley grain by surfactant rather than its direct effect on rumen microbial fermentation.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.2
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• pp.156-165
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• 2017

This study quantitatively assessed the environmental impacts of fuel cell (FC) systems by performing life cycle assessment (LCA) and analyzed their energy efficiencies based on energy return on investment (EROI) and electrical energy stored on investment (ESOI). Molten carbonate fuel cell (MCFC) system and polymer electrolyte membrane fuel cell (PEMFC) system were selected as the fuel cell systems. Five different paths to produce hydrogen ($H_2$) as fuel such as natural gas steam reforming (NGSR), centralized naptha SR (NSR(C)), NSR station (NSR(S)), liquified petroleum gas SR (LPGSR), water electrolysis (WE) were each applied to the FCs. The environmental impacts and the energy efficiencies of the FCs were compared with rechargeable batteries such as $LiFePO_4$ (LFP) and Nickel-metal hydride (Ni-MH). The LCA results show that MCFC_NSR(C) and PEMFC_NSR(C) have the lowest global warming potential (GWP) with 6.23E-02 kg $CO_2$ eq./MJ electricity and 6.84E-02 kg $CO_2$ eq./MJ electricity, respectively. For the impact category of abiotic resource depletion potential (ADP), MCFC_NGSR(S) and PEMFC_NGSR(S) show the lowest impacts of 7.42E-01 g Sb eq./MJ electricity and 7.19E-01 g Sb eq./MJ electricity, respectively. And, the energy efficiencies of the FCs are higher than those of the rechargeable batteries except for the case of hydrogen produced by WE.

• Journal of Energy Engineering
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• v.21 no.1
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• pp.47-54
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• 2012

Korean government has initiated integrated-energy business (IEB) in Mokdong for energy conservation in 1983. Since then, IEB has been steadily expanding. This paper attempts to apply input-output(I-O) analysis to examine the economic effects of IEB. A static I-O framework is employed, focusing on three topics in its application: the impact of the investment of IEB on the production of other sectors and the inter-industry linkage effect; supply shortage effects of the IEB ; and the impact of the rise in IEB rate on prices of other products. The paper pays closer attention to IEB sector by taking the sector as exogenous and then investigating its economic impacts. The results can be widely utilized in decision-making about IEB policy.

• Journal of Environmental Science International
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• v.23 no.5
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• pp.943-962
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• 2014

Industrial gas drying, dilute gas mixtures purification, air fractionation, hydrogen production from steam reformers and petroleum refinery off-gases, etc are conducted by using adsorptive separation technology. The pressure swing adsorption (PSA) has certain advantages over the other methods, such as absorption and membrane, that are a low energy requirement and cost-effectiveness. A key component of PSA systems is adsorbents that should be highly selective to a gas being separated from its mixture streams and have isotherms suitable for the operation principle. The six standard types of isotherms have been examined in this review, and among them the best behavior in the adsorption of $CO_2$ as a function of pressure was proposed in aspects of maximizing a working capacity upon excursion between adsorption and desorption cycles. Zeolites and molecular sieves are historically typical adsorbents for such PSA applications in gas and related industries, and their physicochemical features, e.g., framework, channel structure, pore size, Si-to-Al ratio (SAR), and specific surface area, are strongly associated with the extent of $CO_2$ adsorption at given conditions and those points have been extensively described with literature data. A great body of data of $CO_2$ adsorption on the nanoporous zeolitic materials have been collected according to pressure ranges adsorbed, and these isotherms have been discussed to get an insight into a better $CO_2$ adsorbent for PSA processes.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.829-831
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• 2009

폐기물, 석탄 등 다양한 시료의 가스화 반응을 통해서 발생되는 합성가스는 CO, $H_2$, $CO_2$가 주성분으로 가스엔진, 가스터빈 등의 연료로 사용하여 발전하거나 합성반응을 통해 다양한 화학원료로의 전환이 가능하다. 또한 폐기물, 석탄 등의 다양한 원료의 가스화 반응에 의해 발생한 합성가스로부터 F-T(Fischer-Tropsch) 합성을 통한 인조합성석유, Non F-T 합성을 통한 메탄올, DME(Dimethyl Ether) 등을 제조할 수 있으며, 메탄화 반응을 통해 대체천연가스(SNG, Substitute Natural Gas)로 제조하여 활용하는 방안도 가능하다. 또한 현재 상업용 규모의 수소 제조 방법 중에서 가장 경제적인 방법으로 천연가스를 개질하여 CO, $H_2$가 주성분인 합성가스를 만든 다음 수성가스 전환, PSA(Pressure Swing Adsorption)통해 $CO_2$와 $H_2$를 분리하여 생산하고 있으나, 천연가스 가격의 상승 및 다양한 시료로부터 향후 경제성 확보가 가능한 수소 제조 방법에 대한 연구가 진행되고 있으며, 석탄 가스화 및 폐기물 가스화를 통해 얻어진 합성가스로부터의 수소 제조 공정이 개발 및 상업화 추진되고 있다. 본 연구에서는 폐기물 가스화를 통해 발생한 합성가스에 대하여 수성가스 전환 반응을 통한 수소 생산 특성 및 수성가스 전환 반응의 공간속도 변화 및 스팀주입량 변화에 따른 반응 특성을 고찰하였다.

• Journal of the Korean Applied Science and Technology
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• v.21 no.3
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• pp.225-230
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• 2004

Synthesis gas is a high valued compound as a basic chemicals at various chemical processes. Synthesis gas is mainly produced commercially by a steam reforming process. However, the process is highly endothermic so that the process is very energy-consuming process. Thus, this study was carried out to produce synthesis gas by the partial oxidation of methane to decrease the energy cost. The effects of reaction temperature and flow rate of reactants on the methane conversion, product selectivity, product ratio, and carbon deposition were investigated with 13wt% Ni/MgO catalyst in a fluidized bed reactor. With the fluidized bed reactor, $CH_4$ conversion was 91%, and Hz and CO selectivities were both 98% at 850$^{\circ}C$ and total flow rate of 100 mL/min. These values were higher than those of fixed bed reactor. From this result, we found that with the use of the fluidized bed reactor it was possible to avoid the disadvantage of fixed bed reactor (explosion) and increase the productivity of synthesis gas.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.4
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• pp.265-270
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• 2014

Protease producing microorganisms were isolated from many kinds of food waste and fermented foods, which contains high amount and variable kinds of degraded substances. Several microorganisms were identified by 16S rRNA full sequencing analysis methods. The activity of protease was analyzed and identified in variable conditions for the application. For industrial use for biowaste treatment some proteases were isolated, identified and selected from microbial cells. And the tests were carried for the further use. The protein degrading activity at low temperature is useful for the treatment of organic waste, which contains much proteins. By the protein degradation process the organic waste can be utilized in variable fields, for example from feedstuff supplement to fertilizer for agriculture. Bacterial cells with protease activity at low temperature were isolated and identified. The optimal conditions for microbial cultivation and protease production were studied.