• International Journal of Naval Architecture and Ocean Engineering
• /
• v.5 no.4
• /
• pp.559-568
• /
• 2013

Increased worldwide concerns about fossil fuel costs and effects on the environment lead many governments and scientific societies to consider the hydrogen as the fuel of the future. Many researches have been made to assess the suitability of using the hydrogen gas as fuel for internal combustion engines and gas turbines; this suitability was assessed from several viewpoints including the combustion characteristics, the fuel production and storage and also the thermodynamic cycle changes with the application of hydrogen instead of ordinary fossil fuels. This paper introduces the basic environmental differences happening when changing the fuel of a marine gas turbine from marine diesel fuel to gaseous hydrogen for the same power output. Environmentally, the hydrogen is the best when the $CO_2$ emissions are considered, zero carbon dioxide emissions can be theoretically attained. But when the $NO_x$ emissions are considered, the hydrogen is not the best based on the unit heat input. The hydrogen produces 270% more $NO_x$ than the diesel case without any control measures. This is primarily due to the increased air flow rate bringing more nitrogen into the combustion chamber and the increased combustion temperature (10% more than the diesel case). Efficient and of course expensive $NO_x$ control measures are a must to control these emissions levels.

• Environmental and Resource Economics Review
• /
• v.19 no.3
• /
• pp.597-632
• /
• 2010

There is general agreement that global warming is occurring and that the main contributor to this probably is the buildup of green house gasses, GHG, in the atmosphere. Two main contributors are the utilization of fossil fuels and the deforestation of many regions of the world. The burning of fossil fuels increases atmospheric carbon while the burning of fuel-wood reducing fossil fuel consumption along with its forest source maintain an atmospheric carbon level. The standing timber in the forests is a carbon sink, as are wood buildings and structures, and fossil fuel in the ground. This paper is designed to examine a number of current issues related to mitigating the global warming problem through forestry. For this purpose, we develop a modeling approach by integrating timber market, fossil fuel market and carbon cycling model. We use discrete time optimal control theory to identify optimal time paths, the laws of motion, and stationary stats solutions of endogenous variables in the model. On the basis of these results, we identify the optimal amounts of subsidies to be provided or taxes to be imposed by the regulatory agency to mitigate atmospheric carbon accumulation. We also present a numerical example to help illustrate the characteristics of variables in the model when the social cost for atmospheric carbon incrementally shifts upward. A surprising result is that the social cost function for atmospheric carbon has a very smaller impact on the optimal rotation period than previous literature suggested.

• Journal of Energy Engineering
• /
• v.16 no.2
• /
• pp.73-82
• /
• 2007

World energy demand has been dramatically increasing because of using much energy of developing countries in Asia. The other side, conventional fossil fuels supply has been gradually decreasing due to the limitation of fossil fuel reserves and changing to the use of environmental-friendly energy for prevention the emission of carbon dioxide, NOx and SOx. Based on these times and status, we get the n necessity of the conversion of environmental-friendly energy and the high effective utilization of conventional and unconventional energy. Recently, promised DME fuel as environmental-friendly and substituted oils will be introduced the status of technology and market in domestic and foreign.

• Transactions of the Korean hydrogen and new energy society
• /
• v.24 no.2
• /
• pp.113-120
• /
• 2013

A steam reformer is a chemical reactor to produce high purity hydrogen from fossil fuel. In the steam reformer, since endothermic steam reforming is heated by exothermic combustion of fossil fuel, the heat transfer between two reaction zones dominates conversion of fossil fuel to hydrogen. Steam Reforming is complex chemical reaction, mass and heat transfer due to the exothermic methane/air combustion reaction and the endothermic steam reforming reaction. Typically, a steam reformer employs burner to supply appropriate heat for endothermic steam reforming reaction which reduces system efficiency. In this study, the heat of steam reforming reaction is provided by anode-off gas combustion of stationary fuel cell. This paper presents a optimization of heat transfer effect and average temperature of cross-section using two-dimensional models of a coaxial cylindrical reactor, and analysis three-dimensional models of a coaxial cylindrical steam reformer with chemical reaction. Numerical analysis needs to dominant chemical reaction that are assumed as a Steam Reforming (SR) reaction, a Water-Gas Shift (WGS) reaction, and a Direct Steam Reforming(DSR) reaction. The major parameters of analysis are temperature, fuel conversion and heat flux in the coaxial reactor.

• Applied Chemistry for Engineering
• /
• v.20 no.6
• /
• pp.675-680
• /
• 2009

This article describes NO emission characteristics in SM coal combustion. Combustion experiments was performed in the method of increasing temperature after feeding coal and feeding coal after increasing temperature. NOx emission is in inverse proportion to combustion temperature at the fuel rich condition and it was caused by conversion fuel N to $N_{2}$ at the strong reduction condition. In addition, feeding gas flow rate increased as total fuel NOx increase by conversion of fuel N to NO at the oxidation condition. It could be separated in total fuel-N, volatile-N, char-N to NO according to analysis of total fuel NO emission from char combustion at each temperature. In the result, almost total NOx emission was caused by volatile-N in SM-coal.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.4
• /
• pp.522-533
• /
• 2012

This paper presents an adaptive strategy of GENCOs for reducing the greenhouse gas by fuel mix change. Fuel mix stands for generation capacity portfolio composed of different fuel resources. Currently, the generation sector of power industry in Korea is heavily dependent on fossil fuels, therefore it is required to change the fuel mix gradually into more eco-friendly way based on renewable energies. The generation costs of renewable energies are still expensive compared to fossil fueled resources. This is why the adaptive change is more preferred at current stage and this paper proposes an optimal strategy for capacity planning based on multiple environmental scenarios on the time horizon. This study used the computer program tool named GATE-PRO (Generation And Transmission Expansion PROgram), which is a mixed-integer non-linear program developed by Hongik university and Korea Energy Economics Institute. The simulations have been carried out with the priority allocation method in the program to determine the optimal mix of NRE(New Renewable Energy). Through this process, the result proposes an economic fuel mix under emission constraints compatible with the greenhouse gas mitigation policy of the United Nations.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.12
• /
• pp.1792-1797
• /
• 2013

Recently, due to the excessive use of fossil fuels, many studies about the fossil fuels such as solar and fuel cell energy source are progressing. Fuel cell system has high energy conversion efficiency. Also, fuel cell system is environmentally friendly system because the carbon emission is almost not occur. Therefore, the fuel cell system is considered as the core technology of in the fields of the future energy and environmental. Fuel cell system has an effect on distribution power system because another power source of other than large power plants. So, fuel cell system can be reason of power quality in the power system. In this paper, we constructed the system for an assessment on Islanding. The system is composed with power source, Impedance coordination load and linear load, fuel cell system. we are performed assessment on voltage and power quality in customer and the distributed power system during the Islanding of residential fuel cell system. In addition, no change in the impedance of power system, we made a islanding condition only using the actual load, As a variation of generation and load current under islanding, an analysis results based on assessment system showed that the power qualities of distribution system became more aggravation as effect of voltage sag and voltage swell phenomena.

• Tribology and Lubricants
• /
• v.26 no.1
• /
• pp.78-87
• /
• 2010

Biodiesel have been studied as alternative fuel due to solution of air pollution and fossil fuel exhaustion. Biodiesel from animal fat and vegetable oil was known as eco-friendly fuel like low toxicity, biodegradable compare to petrodiesel. In particular, biodiesel have excellent lubricity due to involved ester functional group. This paper shows the biodiesel's lubricity based on worldwide biodiesel research.

• Special Issue of the Society of Naval Architects of Korea
• /
• 2008.09a
• /
• pp.126-132
• /
• 2008

Cutting procedures whose qualifies are determined by various variables largely influences shipbuilding productivity. Particularly, defects in cutting shapes and cutting surface results in delay of the post shipbuilding stages such as welding and assemblage process. Because cutting procedures are influenced by various numbers of requirements according to the plate thickness, cutting precision can be maintained when the cutting conditions are appropriate. Existing cutting procedures utilize fossil fuels such as propane or ethylene as the main fuel component. Especially, when fossil fuel is applied to thick plate cutting, this process gives relatively slow cutting speed and generates large quantities of harmful polluting fumes. Recently, hydrogen-oxygen mixed gas generated by electrically dissociating water into Hydrogen and oxygen components is welcomed as an alternative fuel source. Also recent results report that alternative cutting fuel improves the cutting Dualities and speed. This paper presents that cutting characteristics and optimum cutting condition of hydrogen-oxygen mixed gas.

• New & Renewable Energy
• /
• v.7 no.3
• /
• pp.17-28
• /
• 2011

Biogas production and utilization are an emerging alternative energy technology. Biogas is produced from the biological breakdown of organic matter through anaerobic digestion. Biogas can be utilized for various energy sectors such as space heating, electricity generation and vehicle fuel. Especially, to be utilized as vehicle fuel, raw biogas needs to be upgraded that is mainly the removal of carbon dioxide to increase the methane content up to more than 95 ~ 97 vol% in some cases, similar to the composition of fossil-based natural gas. Usage of Biogas as a fuel of vehicles have an effect of reducing $CO_2$ emission compared to fossil fuels. Biomethane which is produced by upgrading of biogas is regarded as a good alternative energy and usage of clean energy is encouraged to deal with air pollution and waste management as well as production of clean energy. Recently, biogas projects for vehicle fuel are newly being launched and Korea government have also announced a plan for investment to develop biogas as a transport fuel. In this study, it is aimed to examine the potential feasibility of biomethane as a transport fuel. As a results, the status of biomethane, quality standard, quality characteristics, and upgrading technology of biogas were investigated to evaluate of biogas as a vehicle fuel of transportation.