• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.13-14
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• 2011

Methane Hydrates or Natural Gas Hydrates (hereinafter NGH) are solid-state energy source formed by the clathration of methane gas in water molecules at low temperature and high pressure. NGH is also known as "burning ice" because of its burning property and appearance similar to that of dry ice. Today, concerns about the NGH are rising as an environment-friendly energy source that can replace fossil fuels. In this paper, to keep pace with the research and development of the NGH, the properties of the NGH and the general features of NGH carriers are introduced.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.10
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• pp.1002-1010
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• 2015

Natural gas hydrates are newly emerging as an environment-friendly source of energy to substitute for fossil fuels in the 21stcentury.NGHs are reported to holds much amounts of natural gas (up to 182 standard volumes of gas per volume of hydrate); they are easy to store and safe to carry at about minus 20 degree Celsius under atmospheric pressure because of the self-preservation phenomenon of gas hydrates. The transporting method by gas-ice-hydrate ship carriers has been introduced and developed by a variety of industry and research institutions. Our team has been conducted to develop NGH total systems, including a breakthrough NGH carrier for sea transportation, since 2011. The NGH pellet carrier does not require a separate cooling system for cargo, and the initial temperature is maintained through insulation of the cargo tanks throughout the transport to the final destination. The heat conducted from the exterior and passing through the insulation material of the hull should be cut off as much as possible, but heat inflow inside the cargo tank from an external source is inevitable during transport. In this study, the heat transfer in a cargo tank of a 115K NGH carrier was analyzed through simulation with a commercial CFD code to estimate the boil-off gas/boil-off rate on the developed carrier and understand major hazards that could significantly impact the safety of the vessel.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.5
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• pp.589-601
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• 2014

Natural gas hydrate (NGH) is emerging as a new eco-friendly source of energy to replace fossil fuels in the 21st century. It is well known that the Natural Gas Hydrate contains large amount of natural gas about 170 times as much as its volume and it is easy to be stored and transported safely at about $-20^{\circ}C$ under atmospheric pressure due to so called "self-preservation effect". The option of gas transport by gas hydrate pellets carrier has been investigated and developed in various industry and academy. The natural gas hydrate pellet carrier is on major link in a potential gas hydrate process chain, starting with the extraction of natural gas from the reservoir, followed by the production of hydrate pellets and the transportation to an onshore terminal for further processing or marketing. In recent years, Korean project team supported by Korean Government has been working on the development of NGH total systems including novel NGH carrier since 2011. In order to increase the knowledge on the NGH pellet carrier developed and to understand the major hazards that could have significant impact on the safety of the vessel, this paper presents and evaluates the pros and cons of cargo holds, loading and unloading systems through the analysis of current patent technology. Based on the proven and well-known technologies as well as potential measures to mitigate sintering and minimize mechanical stress on the hydrate pellet in the self-preservation state, this study presents the conceptual and basic design for NGH carrier.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.686-686
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• 2009

가스하이드레이트는 수소결합을 하는 물분자의 고체상 격자(Lattice)내에 포집되어 들어가는 기체분자로 구성된 결정화합물로서 외형적인 형태는 얼음과 거의 유사하다. 천연가스 하이드레이트 기술의 최대장점으로는 액화천연가스(LNG)는 초저온인 $-162^{\circ}C$의 저장조건이 필요하지만 천연가스하이드레이트(NGH)기술은 비교적 온화한 조건인 $-15^{\circ}C$에서 천연가스를 고체상태로 저장/이용할 수 있다는 것이다. 천연가스를 $-162^{\circ}C$에서 액화시킨 LNG상태로 생산, 수송, 저장하는 경우보다 고체상태인 NGH(Natural Gas Hydrate)로 만들어서 생산, 수송, 저장할 경우 천연가스의 생산, 수송, 저장, 재가스화 등의 일련의 공정과 비교해볼 때 LNG방법보다 약 24%이상의 경비를 절감을 할 수 있다고 보고되어지고 있다. 따라서, 천연가스의 수송 및 저장기술에서의 탁월한 경제성으로 인해 선진국에서는 가스하이드레이트에 대한 활발한 연구가 진행되고 있다. 특히 일본은 5Ton/Day용량의 NGH 생산플랜트를 건설하여 시운전 중에 있다. NGH기술의 주요 활용분야는 대용량의 가스매장량을 요구하여 LNG공정기술을 적용할 수 없는 중소형가스전 또는 한계가스전에 경제적으로 적용하는 해양수송분야와 천연가스 공급망이 갖춰져 있지 못한 지역에 NGH Pellet형태로 수송/재기화하여 활용하는 내륙운송이 분야가 있다. 국내에서는 지식경제부 국책과제인 ETI(Energy Technology Innovation)사업을 시작으로 국가경쟁력 제고 차원에서 이러한 기술의 기반구촉 및 실증화 사업이 진행되고 있다. 주요 내용으로는 NGH Process Flow, Overall NGH Process concept diagram, NGH Carrier outline, NGH Land Transportation chain 등이 포함되어 있다.