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Gas HydratesGas HydratesGas HydratesGas HydratesGas Hydrates
- 1. EXPLOITATION OF GAS HYDRATESAS AN ENERGY RESOURCE K. Muralidhar Department of Mechanical Engineering Indian Institute of Technology Kanpur Kanpur 208016 India
- 2. Organization of thetalk Energy scenario What are gas hydrates Resource availability Exploitation of gas hydrates Environmental aspect
- 3. Assessing energy sources 1.Demand 2. Availability 3. Technology 4. Efficiency 5. Environmental impact 6. Cost
- 4. The 21st centuryimbalance Annual population increases at 2%. Energy use per capita increases at 2% per year. As a result, energy consumption increases at 4% per year. Doubles every 36 years!
- 5. 0 500 1000 1500 2000 2500 3000 3500 4000 1 4 710 13 16 19 22 25 28 31 34 37 40 43 46 49 52 World fossil consumption (1950-2003) Source: World Watch Institute, 2003 Coal Oil Natural Gas
- 6. Projected world energysupply
- 7.
- 8.
- 9. 50-75 12 5 3 2 2 5 6 2 19 14 4 4 10 87 17 Solar-PV Nuclear Gas Coal Hydro Wind Biomass Geothermal Solar Thermal 0 5 10 15 20 25 30 35 Cost of Electricity (cents/kWh) Cost of electricity (global average, 1998)
- 10. Equipment cost inIRs/kWh for electricity generation Solar Thermal 6 - 8 Nuclear 5 - 9 Natural Gas 5 - 9 Hydro 5 - 18.5 Wind 4.5 - 7 Coal 3.5 - 7 Geothermal 4.25 - 7 Biomass 4.15 - 8
- 11. Operations and maintenancecosts IRs/kWh Wind 1.3 Coal 2 Nuclear 2.2 Geothermal 2.7 Gas 3.1 Wood 3.1 Oil 4.1 Waste 4.5
- 12.
- 13. Summary Using everyyardstick: availability, efficiency, environment, and cost, the 21st century will see an irrevocable shift towards gas-based energy generation
- 14. Large scale powerproduction from gas Energy production from gas relies on the following technologies: Gas turbines Fuel cells (futuristic) Gas hydrates are a source of methane and can be integrated with these technologies.
- 15. Indian scenario Withno major findings of gas reserves it is essential to look for other alternative resources such as gas hydrates. Vast continental margins with substantial sediment thickness and organic content, provide favorable conditions for occurrence of gas hydrates in the deep waters adjoining the Indian continent.
- 16. Indian scenario (continued) Caution: Gas hydrates hold the danger of natural hazards associated with sea floor stability, release of methane to ocean and atmosphere, and gas hydrates disturbed during drilling pose a safety problem. Research: Development of a field model is quite necessary before the installation of a full scale setup in the sea bed.
- 17. What are gashydrates A gas hydrate consists of a water lattice in which light hydrocarbon molecules are embedded resembling dirty ice.
- 18. What are gashydrates (continued) Naturally occurring gas hydrates are a form of water ice which contains a large amount of methane within its crystal structure. They are restricted to the shallow lithosphere (2000- 4000 m depth) With pressurization, they remain stable at temperatures up to 18°C.
- 19. What are gashydrates (continued) The average hydrate composition is 1 mole of methane for every 5.75 moles of water. The observed density is around 0.9 g/cm3. One liter of methane clathrate solid would contain 168 liters of methane gas (at STP).
- 20. It is presentin oceanic sediments along continental margins and in polar continental settings. Where are gas hydrates located?
- 21.
- 22. Various issues relatedto extraction of gas hydrates
- 23. Recovery of MethaneGas from Gas Hydrates Modifying the equilibrium conditions by 1. Depressurization 2. Inhibitor injection 3. Thermal stimulation
- 24.
- 25. Decomposition of hydratesby depressurization, thermal, and chemical techniques
- 26. Exploitation schemes 1. DEPRESSURISATION:At fixed temperature, operating at pressures below hydrate formation pressure. 2. INHIBITION: Inhibition of the hydrate formation conditions by using chemicals such as methanol and salts. 3. HEAT SUPPLY: At fixed pressure, operating at temperatures above the hydrate formation temperature. This can be achieved by insulation or heating of the equipment.
- 27. Schematic representation ofproduction from a hydrate reservoir with underlying free gas
- 28. Hydrate dissociation andformation Molecular structure Phase equilibrium diagram Flow, transport, and chemical reactions in a complex pore network Research aspects
- 29. Schematic drawing ofgas exchanges
- 30. Mass transfer atconstant pressure and temperature
- 31. Mathematical Model u u u u u K f K p dt d 2 u u u u . t dt d Fluid flow is the porosity and K, the permeability.
- 32. Mathematical Model s f f eff f p Q T k T t T C , . . u s f s eff s p Q T k t T C , . 1 Heat transfer Solid Fluid
- 33. Species transport equation MathematicalModel g j i n j g ij i i i M t g 1 . . J u
- 34. List of undeterminedparameters • Dispersion coefficient • Permeability tensor • Inter-phase transport coefficient
- 35. Unanswered questions Stabilityboundary Destabilization dynamics Flow and transport in a hierarchical pore network System development Disaster management Cost considerations
- 36. Environmental impact Carbon sequestration Carbon capture and storage Carbon trap technologies
- 37. Conclusions 1. Irreversible shifttowards gaseous fuels. 2. Gas hydrates are secondary gas sources (internationally) but are primary, in the national context. 3. Safe exploitation of methane from hydrate reservoirs calls for a massive research program.
- 38.