Methane Hydrate as Alternative Energy Resource

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Methane HydrateasAlternative Energy Resource

• Speakers
• Yu, Jia Yuan
• Nguyen, Thai-Son

Burning synthetic (manmade) methane
hydrate (Courtesy of the U.S. Department of
Energy)
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Introduction

• Unawareness about methane hydrate in the past
• Growing interest today
• Speculation of great promise for the future

Physical appearance of hydrate crystal (Source
Nature)
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Outline

• This presentation will answer questions such as
• What is methane hydrate?
• How and where does it come from?
• What is its significance to humanity and the
  planet?
• How can it be exploited?

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Definition

• Simple chemical compound
• Water clathrate of methane
• Crystalline structure much denser in methane
  content
• Methane to water ratio of 1 to 5.75

Chemical structure of methane hydrate (Source
Scientific American)
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Formation

• Decomposition of organic detritus by anaerobic
  bacteria under seafloor sediments
• Methane gas evolves and dissolves in ocean water
• High pressure and low temperature allow hydrate
  formation

Phase chart for a mixture of methane and
water (source Nature)
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Occurrence

• Depths of at least 300 meters
• Outer continental margins
• High-latitude continental permafrost

Map of known and inferred methane hydrate
occurrences (Source US Geological Survey)
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Energy Potential

• Highly optimistic estimate
• Over half of organic carbon contained in hydrate
• How much of this amount is susceptible to cost
  efficient, environmentally friendly and
  geologically safe consumption?

Distribution of organic carbon in various
forms (Source US Geological Survey)
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Pros Cons

• Huge reserves at reasonable depths
• Even distribution of this resource around the
  world

• Abundance of natural gas supplies hence less
  economic incentives
• Lack of efficient technologies to recover the
  methane from the hydrate, in contrast to the
  mature technology and infrastructure for natural
  gas processing
• Absence of a field example of successful methane
  hydrate exploitation

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Extraction

• Challenges
• Rapid decomposition of hydrate due to temperature
  and pressure change
• Low hydrate concentration in sediments mostly
  mud and rocks
• Low productivity due to low pressure in hydrate
  reservoirs

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Depressurisation Technique

• Easy to implement for hydrate reservoir over the
  natural gas layer

Thermocrossection of Messoyakha field (modified
from Makogon, 1995)
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Five-spot technique

• 4 wells to form a square where steam or water is
  pumped in
• Gas is pushed out through the 5th well in the
  middle of the square

Five-spot technique
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Transportation

• Challenges
• Most of hydrate deposits are found under ocean
  floors
• Under-sea pipelines are extremely expensive and
  vulnerable

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Harvesting Sequence

• Methane transportation chain system

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Transportation Solution

• I- Methane solidification
• A mushy ice cream like hydrate is formed by
  swirling together gas and cold water in a high
  pressure environment

solidification
Foam-like structure
Pellets structure
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Transportation Solution

• II- Methane liquefaction steps
• A gaseous mixture of hydrogen and carbon is
  produced by partially combustion of the methane
• Iron or cobalt added to convert the mixture into
  a liquid
• The liquid can be readily transported by ship

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Methane use fuel

• Advantages over fossil fuels
• Heating
• Electricity production
• Easy distribution through existing natural gas
  pipelines
• Low carbon dioxide emission
• Fuel Cells
• No combustion, less carbon dioxide emission

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Contribution to global climate change

• Concern is justified because hydrate deposits
  contain over a thousand times more methane than
  in the atmosphere
• Slow venting from submarine faults results mainly
  in
• Oxidation to carbon dioxide by marine organisms
• Combination with calcium ions to form a crust of
  limestone
• Dissolution in ocean water

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Geologic hazard

• Risk of explosion during oil-drilling operations
• Over a longer period
• Accumulation of sediments
• Sinking of hydrate layers
• Melting under higher temperatures
• Under-consolidation
• Submarine landslide
• Tsunami

Effect of decreasing sea level on submarine
methane hydrate layer (Adapted from McIver)
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Summary
(Source New Scientist)
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Discussion

• Every source of non-renewable energy must be used
  with great wisdom weighting carefully the
  effects on human safety and the environment.
• There exist sources of energy that few people
  have ever heard of. We hope that our presentation
  will motivate everyone to open their mind to the
  unlimited number of alternative energy resource.