• Advances in Energy Research
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• v.4 no.2
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• pp.121-146
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• 2016

This study is concerned with the analysis of two renewable technologies for electric energy production: wind energy and photovoltaic energy. The two technologies were assessed and compared by economic point of view, by using selected indicators characterized by a clear calculation approach, requirement of information easy to be collected, clear, but even complete, interpretation of results. The used economic indicators are Levelized Cost of Energy, $CO_2$ abatement cost and fossil fuel saving specific cost; these last two specifically aimed at evaluating the different capabilities that renewable technologies have to cut down direct $CO_2$ emissions and to avoid fossil fuel extraction. The two technologies were compared also from the environmental point of view by applying Life Cycle Assessment approach and using the environmental impact categories from the Eco-indicator'95 method. The economic analysis was developed by taking into account different energy system sizes and different geographic areas in order to compare different European conditions (Italy, Germany and Denmark) in term of renewable resource availability and market trend. The environmental analysis was developed comparing two particular types of PV and wind plants, respectively residential and micro-wind turbine, located in Italy. According to the three calculated economic indicators, the wind energy emerged as more favorable than PV energy. From the environmental point of view, both the technologies are able to provide savings for almost all the considered environmental impact categories. The proposed approach, based on the use of economic and environmental indicators may be useful in supporting the policies and the decision making procedures concerned with the promotion and use of renewables, in reference to the specific geographic, economic and temporal conditions.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.1
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• pp.89-99
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• 2014

The cultivation of biomass crops is now global demand for decreasing emissions of carbon dioxide ($CO_2$) from fossil fuel. Miscanthus species have been studied as a suitable crop for biomass production, due to its characteristics of fast growth and high biomass. In Korea, Miscanthus species have gained wide attention as an option for biomass production alternative to fossil fuels, recently. New strain of giant Miscanthus has been developed and two large trial sites for the giant Miscanthus production were built in the lower reaches of the Geum River. To evaluate the ecological influence of the giant Miscanthus as an bioenergy crop for the future, we investigated the impact of the construction of the giant Miscanthus production fields on the biota and also compared it with biota in paddy fields near the study sites. The biota including plants, amphibians, reptiles, mammals, avifauna, insects, and bugs was investigated. The plant diversity of the giant Miscanthus production fields was poorer than the paddy fields because the high height of the giant Miscanthus might hinder the growth of other plants. However, the giant Miscanthus production fields serves habitat to animals, leading to rich diversity of animals including avifauna, insects, and bugs. The rich diversity of the animals in the giant Miscanthus production fields coincides with the fact that the giant Miscanthus was grown without any pesticide, herbicide, and fertilizer. This study showed that the giant Miscanthus can influence on biota and further long term study is needed to elucidate the interaction between the diversity of biota and the giant Miscanthus.

• Journal of the Korean Society of Systems Engineering
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• v.12 no.1
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• pp.59-71
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• 2016

The Nuclear and Fossil Steam Turbines record a considerable number of failures annually. Some of these failures reported are as result of blade failure. The failure of the L-0 blade in a Steam Turbine is one of the most reported blade failure in Nuclear and Fossil steam turbines. This paper seeks to identify the best Non Destructive Evaluation (NDE) method or methods to be used in the steam turbine L-0 blades inspection process. The development of systems engineering processes presents an opportunity to apply NDE inspection to the L-0 blades. This process apply computer modelling of the L-0 using ANSYS and by simulating the stresses experienced by the L-0 blade during operation it is possible to identify the most susceptible areas for crack formation and growth. The results from these models compared to industry data for validation. The analysis of these results used to predict the most probable failure location and failure modes. Therefore NDE inspection can be applied to these areas with greater degree of accuracy. This would be beneficial in the increasing the accuracy in the detection of cracks and hence save inspection time and the overall inspection cost. Furthermore, not only the location for crack formation and NDE inspection determined but also best the NDE inspection technique/techniques to be applied appropriately on the L-0 blade are prescribed.

• Journal of the Korean Professional Engineers Association
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• v.28 no.4
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• pp.14-20
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• 1995

Discourses on global environment are not only limited to the matter of simple environmen-tal protection but also going to an imperative that every country should take the environ-mental aspects into more consideration, and if necessary even proceed to modify its own strategies for economic growth. It is because scores of existing International conventions and agreements on environmental caused tend to combine the environmental issues with trade sanctions and financial assistances in order to ensure a mandatory power in pushing themselves through on a global dimension. Particularly noteworthy is the so -called Green Round(GR) which substantially associates the Issues of environmental protection with some sanctions in international trade, its rationale is quite simple. The differentiated production costs rising from the difference in environmental standards among different countries may affect national competitiveness in in-ternational trade, therefore a need does exist to countervail this difference. In reality, however, severe dissention seems to have been exposed between the developed and developing countries around this matter, because national interests and priorities in national goals considerably differ among respective countries. Greenhouse gases such as carbon dioxide which caused global warming are mostly released from the combustion of fossil fuels. The perfect removal of released $CO_{2}$ is impossible with existing technologies, and moreover, it's not payable in economical terms. Therefore it will be more effective and desirable to make more efforts to prevent the release of the $CO_{2}$ it- self through energy conservation involving the development and promotion of clean and high-efficient energy technologies and energy sources, and the development and promotion of new & renewable energy resources, and so on. One of important national tasks In our country is to establish an Energy Policy consider-ing environmental impacts since Korea depends most of its energy consumption on the fossil fuels such as oil and coal.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.102-108
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• 2009

Fossil power plants firing lower grade coals or equipped with modified system for NOx controls are challenged with maintaining good combustion conditions while maximizing generation and minimizing emissions. In many cases significant derate, availability losses and increase in unburned carbon levels can be attributed to poor combustion conditions as a result of poorly controlled local fuel and air distribution within the boiler furnace. In order to develop a on-line combustion tuning system, field test was conducted at operating power boiler. During the field test the exhaust gases' $O_2$, NOx and CO was monitored by using a spatially distributed monitoring grid located in the boiler's high temperature vestibule and upper convective back-pass region. At these locations, the flue gas flow is still significantly stratified, and air in-leakage is minimal which enables tracing of poor combustion zones to specific burners and over-fire air ports. using these monitored information we can improving combustion at every point within the furnace, therefore the boiler can operate at reduced excess $O_2$ and gas temperature deviation, reduced furnace exit gas temperature levels while also reducing localized hot spots, corrosive gas conditions, slag or clinker formation and UBC. Benefits include improving efficiency, reducing NOx emissions, increasing output and maximizing availability. Discussion concerning the reduction of greenhouse gases is prevalent in the world. When taking a practical approach to addressing this problem, the best way and short-term solution to reduce greenhouse gases on coal-fired power plants is to improve efficiency. From this point of view the real time optimized combustion tuning approach is the most effective and implemented with minimal cost.

• Journal of ILASS-Korea
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• v.6 no.1
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• pp.18-24
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• 2001

Liquid fossil fuel contaminated by water can cause trouble in the combustion processes and affect the endurance of a combustion system. Using an optical sensor to monitor the water content instantaneously in a fuel pipeline is an effective means of controlling the fuel quality in a combustion system. In two component liquid flows of oil and water, the flow pattern and characteristics of water droplets are changed with various flow conditions. Additionally, the light scattering of the optical sensor measuring the water content is also dependent on the flow patterns and droplet characteristics. Therefore, it is important to investigate the detailed behavior of water droplets in the pipeline of the fuel transportation system. In this study, the flow patterns and characteristics of water droplets in the turbulent pipe flow of two component liquids of gasoline and water were investigated using optical measurements. The dispersion of water droplets in the gasoline flow was visualized, and the size and velocity distributions of water droplets were simultaneously measured by the phase Doppler technique. The Reynolds number of the gasoline pipe flow varied in the range of $4{\times}10^{4}\;to\;1{\times}10^{3}$, and the water content varied in the range of 50 ppm to 300 ppm. The water droplets were spherical and dispersed homogeneously in all variables of this experiment. The velocity of water droplets was not dependent on the droplet size and the mean velocity of droplets was equal to that of the gasoline flow. The mean diameter of water droplets decreased and the number density increased with the Reynolds number of the gasoline flow.

• Journal of Hydrogen and New Energy
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• v.18 no.4
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• pp.452-457
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• 2007

Titanium foil and mesh(anodized tubular $TiO_2$ electrode, ATTE) were anodized in a bath at $5^{\circ}C$ with 20V external bias applied, then annealed at different temperatures($450^{\circ}C{\sim}850^{\circ}C$) to obtain tubular $TiO_2$ on the Ti substrate. The prepared sample was used to investigate rate of hydrogen production as well as Cr(VI) reduction. The ATTEs annealed at relatively lower temperatures showed higher activity than those at relatively higher temperatures. In particular, the Cr(VI) reduction was pH-dependent. To improve photocatalytic Cr(VI) reduction with the ATTEs, two configurations, fixing foil type and rotating mesh type, were also compared. As a result, the rotating mesh type was much more effective for Cr(VI) reaction than the former due to the more efficient use of the light. In the rotating type reactor, as the rotating speed increased, the rate of the Cr(VI) reduction was getting faster.

• Journal of Hydrogen and New Energy
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• v.18 no.3
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• pp.244-249
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• 2007

The present work considers the concept of enzymatic photoelectrochemical generation of hydrogen through water splitting using a Xe lamp as a source of light. A solar cell was applied to the system in order to shift the level of electrochemical energy of the system, resulting in the rate of hydrogen production at $43\;{\mu}mol/(cm^2{\times}hr)$ in cathodic compartment with an anodized tubular $TiO_2$ electrode(ATTE, $5^{\circ}C$/1hr in 0.5 wt% HF-$650^{\circ}C$/5hr). The trend of the rate of hydrogen production, for the ATTEs with different annealing temperature from $350^{\circ}C$ to $850^{\circ}C$, fairly well coincided with the photoelectrical properties measured by potentiostat. The actual chemical bias through imposition of two electrolytes of different pHs between anode(13.68) and cathode(7.5) was 0.24eV.

• Journal of Hydrogen and New Energy
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• v.23 no.1
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• pp.100-109
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• 2012

In this paper, some ideas are proposed to establish the infrastructure of all-electric houses which are able to reduce primary energy consumption and $CO_2$ emission by adopting heat pump systems and induction heating cookers excluding the use of fossil fuel energy. This electrification concept is based on the consumption of only one type of energy which means electricity as secondary energy and the conventional fossil fuel energy is just consumed to generate electricity as primary energy. All-electric house is laid on the extension of the hydrogen economy in a long-term viewpoint so that the effectiveness of this new conceptual house is estimated analyzing the reduction of $CO_2$ emission. In this analysis, the balance of electricity supply and demand is considered including the construction of new power plants by renewable energy such as nuclear, IGCC and fuel cell because decarbonization is an essential element of hydrogen technology and economy and this action is accomplished in both supply and demand side of electricity. The results are able to contribute to develop various useful hydrogen policies and strategies and some detail researches are required previously to make the best application of this new conceptual house.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.73-84
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• 2015

Electricity generation using fossil fuels has caused environmental pollution. To solve this problem, research on new renewable energy sources (solar, wind power, geothermal heat, etc.) to replace fossil fuels is ongoing. These devices are able to generate power consistently. However, they have many weaknesses, such as high installation costs and limits to possible setup environments. Therefore, an active study on piezoelectric harvesting technology that is able to surmount the limitations of existing energy technologies is underway. Piezoelectric harvesting technology uses the piezoelectric effect, which occurs in crystals that generate voltage when stress is applied. Therefore, it has advantages, such as a wider installation base and lower technological costs. In this study, a piezoelectric harvesting device imitating seaweed, which has a consistent motion caused by fluid, is used. Thus, it can regenerate electricity at sea or on a bridge pillar, which has a constant turbulent flow. The components of the device include circuitry, springs, an electric generator, and balancing and buoyancy elements. Additionally, multiphysics analysis coupled with fluid, structure, and piezoelectric elements is conducted using COMSOL Multiphysics to evaluate performance. Through this program, displacement and electric power were analyzed, and the actual performance was confirmed by the experiment.