• 한국기후변화학회지
• /
• 제8권1호
• /
• pp.1-10
• /
• 2017

Over the past centuries, industrialization in developed and developing countries has had a negative impact on global warming, releasing $CO_2$ emissions into the Earth's atmosphere. In recent years, the transportation sector, which emits one-third of total $CO_2$ emissions in the United States, has adapted by implementing a climate change action plan to reduce $CO_2$ emissions. Having an environmental policy might be an essential factor in mitigating the man-made global warming threats to protect public health and the coexistent needs of current and future generations; however, to my best knowledge, no research has been conducted in such a context with appropriate statistical validation process to evaluate the effects of climate change policy on $CO_2$ emission reduction in recent years in the U.S. transportation. The empirical findings using an entity fixed-effects model with valid statistical tests show the positive effects of climate change policy on $CO_2$ emission reduction in a state. With all the 49 states joining the climate change action plans, the U.S. transportation sector is expected to reduce its $CO_2$ emissions by 20.2 MMT per year, and for the next 10 years, the cumulated $CO_2$ emission reduction is projected to reach 202.3 MMT, which is almost equivalent to the $CO_2$ emissions from the transportation sector produced in 2012 by California, the largest $CO_2$ emission state in the nation.

• 마이크로전자및패키징학회지
• /
• 제27권4호
• /
• pp.11-17
• /
• 2020

Copper has been proved to be the best catalyst for electrochemical CO2 reduction reaction, however, for optimal efficiency and selectivity, its performance requires improvements. Electrochemical CO2 reduction reaction (RR) using CuO nanowire electrode was performed with different concentrations of KHCO3 electrolyte (0.1 M, 0.5 M, and 1 M). Cu(OH)2 was formed on Cu foil, followed by thermal-treatment at 200℃ under the air atmosphere for 2 hrs to transform it to the crystalline phase of CuO. We evaluated the effects of different KHCO3 electrolyte concentrations on electrochemical CO2 reduction reaction (RR) using the CuO nanowire electrode. At a constant current (5mA), low concentrated bicarbonate exhibited a more negative potential -0.77 V vs. Reversible Hydrogen Electrode (RHE) (briefly abbreviated as VRHE), while the negative potential reduced to -0.33 VRHE in the high concentration of bicarbonate solution. Production of H2 and CH4 increased with an increased concentration of electrolyte (KHCO3). CH4 production efficiency was high at low negative potential whereas HCOOH was not influenced by bicarbonate concentration. Our study provides insights into efficient, economically viable, and sustainable methods of mitigating the harmful environmental effects of CO2 emission.

• 한국환경복원기술학회지
• /
• 제12권2호
• /
• pp.95-105
• /
• 2009

Land Use Changes (LUCs) have effects on greenhouse gas emissions and carbon stocks in soil and vegetation. Therefore, predictions for LUC are very important for achieving quantitative targets of $CO_2$ reduction rates. Some research exists on carbon fluxes and carbon cycles to estimate carbon stocks in terrestrial ecosystems in Korea. However, these researches have limitations in terms of helping us understand future potential reductions of $CO_2$ that reflect the influence of LUC. The aim of this study is to analyze the reduction levels of $CO_2$ emissions while considering LUC scenarios that effect carbon fluxes for LCS basic study in the year 2030. In this study, a common approach to model the effects of LUC on carbon stocks is the use of CA-Markov technical process with LUC patterns in the past. Potential reduction of $CO_2$ is calculated by change of land use that contains different soil organic carbon, each land use type, and biomass in vegetation. An IPCC analytical method of natural carbon sink and coefficient results from previous study in Korea is used as a calculation method for potential reduction of $CO_2$. As a result, 12,419 KtC will be reduced annually, which is 8.3% percent of 2005 $CO_2$ emissions in Korea. This will result in 3,226 hundred million won of economic efficiency. In conclusion, conservation of natural carbon sinks is necessary even if the amount of potential reduction change is little.

• 한국수소및신에너지학회논문집
• /
• 제23권2호
• /
• pp.173-182
• /
• 2012

Effects of temperature, pressure, and gas residence time on methane combustion characteristics of mass produced oxygen carrier particle (OCN706-1100) were investigated in a pressurized fluidized bed reactor using methane and air as reactants for reduction and oxidation, respectively. The oxygen carrier showed high fuel conversion, high $CO_2$ selectivity, and low CO concentration at reduction condition and very low NO emission at oxidation condition. Moreover OCN706-1100 particle showed good regeneration ability during successive reduction-oxidation cyclic tests up to the 10th cycle. Fuel conversion and $CO_2$ selectivity decreased and CO emission increased as temperature increased. These results can be explained by trend of calculated equilibrium CO concentration. However, $CO_2$ selectivity increased as pressure increased and fuel conversion increased as gas residence time increased.

• Spatial Information Research
• /
• 제20권1호
• /
• pp.19-26
• /
• 2012

기후변화의 원인 중 탄소배출이 가장 큰 비중을 차지하고 있어 탄소배출 감소의 필요성이 전 세계적으로 제기되고 탄소배출을 감소하기 위한 국제적 움직임이 가속화되고 있다. 선진국들은 녹색산업을 신성장동력 산업으로 활용하는 전략을 추진 중이며 탄소저감형도시(low carbon city)에 대한 관심이 높아지고 있다. 현재 우리나라에서 진행되고 있는 U-City 사업에 대하여 U-City 도입 이전 도시와 U-City 도입 도시의 탄소배출량 변화를 분석하여 이산화탄소 저감효과에 대한 분석이 필요하다. 본 연구에서는 U-City 도입 이전과 도입 이후의 이산화탄소 발생량을 비교, 분석하여 U-City 도입에 따른 탄소저감 효과를 정량화하고자 하였다. U-City 도입이전의 도시는 1기 신도시 중에 성남시 분당구와 고양시 일산구를 대상으로 하였으며, U-City 도입이후의 도시로는 화성동탄 U-City를 선정하여 비교한 결과 탄소배출량이 30%정도 줄어든 것으로 결과가 도출되었다.

• 대한기계학회논문집B
• /
• 제28권4호
• /
• pp.371-381
• /
• 2004

Numerical simulation of $CO_2$ addition effects to fuel and oxidizer streams on flame structure has been conducted with detailed chemistry in H$_2$-O$_2$ diffusion flames of a counterflow configuration. An artificial species, which displaces added $CO_2$ in the fuel- and oxidizer-sides and has the same thermochemical, transport, and radiation properties to that of added $CO_2$, is introduced to extract pure chemical effects in flame structure. Chemical effects due to thermal dissociation of added $CO_2$ causes the reduction flame temperature in addition to some thermal effects. The reason why flame temperature due to chemical effects is larger in cases of $CO_2$ addition to oxidizer stream is well explained though a defined characteristic strain rate. The produced CO is responsible for the reaction, $CO_2$＋H=CO＋OH and takes its origin from chemical effects due to thermal dissociation. It is also found that the behavior of produced CO mole fraction is closely related to added $CO_2$ mole fraction, maximum H mole fraction and its position, and maximum flame temperature and its position.

• 한국연소학회지
• /
• 제20권3호
• /
• pp.8-12
• /
• 2015

The CO reduction characteristics of hot air stream diluted with exhaust gas in a perfectly stirred reactor (PSR) were investigated numerically. The dilution ratio ($\Omega$), inlet temperature ($T_{in}$), and residence time ($\tau$) were considered as parameters to investigate the effects of those on the emission indices for CO and $CO_2$ (EICO and $EICO_2$). The roles of dominant reactions and the production rates of major species were analyzed. It was found from the EICO trend that the supplied CO in the air stream was consumed. The EICO increased negatively with $T_{in}$ at fixed $\tau$ regardless of $\Omega$. However, the magnitude of EICO and minimum inlet temperature for CO reduction showed complicated trend according to the variation of $\tau$. It was identified that the OH radical, generated from the reactions, $O_2+H{\leftrightarrow}O+OH$ and $2OH{\leftrightarrow}H+H_2O$, affected the CO reduction by the reaction, $CO+OH{\leftrightarrow}H+CO_2$. However, the CO emission ratio increased at sufficiently high inlet temperature range due to the thermal dissociation of $CO_2$.

• 한국전자거래학회지
• /
• 제15권3호
• /
• pp.163-181
• /
• 2010

최근 온난화 현상에 따른 범세계적 위기가 초래됨에 따라 선진국을 중심으로 교토의정서가 체결되었으며, 이를 계기로 온실가스 규제가 본격화되기 시작하였다. 또한 교토의정서의 교토유연성체계라는 시장메커니즘이 도입되어 온실가스 배출에 대한 소유권이 설정되고, 수급에 따라 배출권 가격이 형성되는 등 새로운 무형의 자원을 거래하는 탄소시장이 등장하게 되었다. 학계에서는 탄소배출효과를 측정하는 방법론과 이를 탄소배출권의 경제적 비용으로 전환하고자 하는 연구들이 태동하기 시작하였다. 본 연구에서는 전자정부 정보화사업 중 하나인 G2B 시스템을 통해 전통적인 조달업무 프로세스가 온라인화 됨에 따라 저감되는 탄소 배출저감효과 즉, e-transformation화에 따른 탄소저감효과를 측정하는 ECRE(Evaluation of $CO_2$ Reduction in E-transformation)모델과 절차를 제시하고자 한다. ECRE 모델은 세계 기후협의체(IPCC)의 방법론을 근간으로 하여 크게 '이동 수단에 따른 탄소저감효과', '종이 문서 절감에 따른 탄소저감효과' 2가지의 탄소배출량을 측정하고 이를 탄소배출권의 경제적 비용으로 환산한다. 또한 본 연구에서는 탄소저감효과를 효과적으로 측정하기 위하여 5단계와 10개의 세부절차로 구성된 절차를 제시하였다. 본 연구에서 제시한 ECRE 모델과 절차를 이용하여 정부기관은 물론 온실가스 규제를 받게 되는 에너지 환경기업 등에서 정보화사업을 통한 탄소감축 실적의 추정 및 추가적인 정보화사업 추진으로 기대되는 탄소저감효과를 사전에 시뮬레이션해 볼 수 있는 도구로서 활용이 기대된다.

• 한국수소및신에너지학회논문집
• /
• 제32권1호
• /
• pp.53-62
• /
• 2021

Batch type reduction-oxidation tests were performed to check effects of temperature, pressure, gas velocity, and capacity on reduction characteristics of mass produced particle in a 0.5 MWth chemical looping combustion system. The fuel conversion and the CO2 selectivity increased as the temperature increased and as the gas velocity decreased. However the CO2 selectivity showed the maximum and decreased as the capacity increased because the CO emission increased. The results show that high temperature, low gas velocity and low inert gas concentration are preferable to ensure high reactivity of oxygen carrier in the fuel reactor.

• Ocean and Polar Research
• /
• 제37권3호
• /
• pp.201-209
• /
• 2015

To examine the effects of increased $CO_2$ concentration and seawater temperature on the photosynthesis and growth of forest forming Ecklonia cava (Laminariales, Phaeophyta), sporophytic discs and gametophytes were cultured under three $pCO_2$ concentrations (380, 750, 1000 ppm), four temperatures (5, 10, 15, $20^{\circ}C$ for sporophytes; 10, 15, 20, $25^{\circ}C$ for gametophytes), and two irradiance levels (40, $80{\mu}mol$ photons $m^{-2}s^{-1}$) for 5 days. Photosynthetic parameter values ($ETR_{max}$, $E_k$, and ${\alpha}$) were generally higher as sporophytic discs were grown under low temperature and increased $CO_2$ concentration at 750 ppm. However, photosynthesis of Ecklonia sporophytes was severely inhibited under a combination of high temperature ($20^{\circ}C$) and 1000 ppm $CO_2$ concentration at the two photon irradiance levels. The growth of gametophytes was maximal at the combination of 380 ppm (present seawater $CO_2$ concentration) and $25^{\circ}C$. Minimal growth of gametophytes occurred at enriched $pCO_2$ concentration levels (750, 1000 ppm) and high temperature of $25^{\circ}C$. The present results imply that climate change which is increasing seawater temperature and $pCO_2$ concentration might diminish Ecklonia cava kelp beds because of a reduction in recruitments caused by the growth inhibition of gametophytes at high $pCO_2$ concentration. In addition, the effects of increased temperature and $pCO_2$ concentration were different between generations - revealing an enhancement in the photosynthesis of sporophytes and a reduction in the growth of gametophytes.