1. N ATURAL G AS H YDRATE T RANSPORTATION David Mannel David Puckett

2. C ONTENTS Hydrate Synthesis Hydrate Transportation Hydrate Dissociation Production Summary LNG Cost Estimation Economic Comparison

3. H YDRATE S YNTHESIS

4. Water content in hydrate slurry is frozen to form hydrate-ice blocks at 241 K. Blocks are then depressurized to 1 atm and handled in solid form. 1 mtpa, 750 psia, 388 K 6.47 mtpa, 750 psia, 298K 19.41 mtpa, 750 psia, 273K 7.47 mtpa, 14.7 psia, 241K 750 psia, 273K

5. H YDRATE S YNTHESIS CSTR For 1.5 mtpa methane production: V total =(3,130 mol CH 4 /s)/(1.29 mol/m 3 * s) V total =2,430 m 3 32 reactors used V reactor = 76 m 3 Perry, R., & Green, D. (1997). Perry's Chemical Engineers' Handbook (7th ed.). McGraw-Hill.

6. H YDRATE S YNTHESIS CSTR Equipment Cost: $1,760,000 Perry, R., & Green, D. (1997). Perry's Chemical Engineers' Handbook (7th ed.). McGraw-Hill.

7. H YDRATE S YNTHESIS Compressors Compressors sized using PRO II Compressor Equipment Cost: Recycle Compressor Cost: $2,200,000 Intake Compressor Cost: $870,000 Total Cost: $3,070,000 Perry, R., & Green, D. (1997). Perry's Chemical Engineers' Handbook (7th ed.). McGraw-Hill.

8. H YDRATE S YNTHESIS Pumps Pumps sized using P = HQη/3960 H = 150ft n = 74% Q = 3,800 lb/s Pump cost: $690,000 Perry, R., & Green, D. (1997). Perry's Chemical Engineers' Handbook (7th ed.). McGraw-Hill.

9. H YDRATE S YNTHESIS Heat Exchangers Heat exchangers sized using: Q=UAT Heat exchanger cost based on area Initial Cooling Heat Exchanger Area: 35,000 ft 2 Initial Cooling Heat Exchanger Cost: $235,000 Post Cooling Heat Exchanger Area: 16,000 ft 2 Post Cooling Heat Exchanger Cost: $113,000 Perry, R., & Green, D. (1997). Perry's Chemical Engineers' Handbook (7th ed.). McGraw-Hill.

10. H YDRATE T RANSPORTATION Capacity 145,000 metric tons Capacity of 186,000 m 3 Length 290m Beam 45m Draught 18m Base price $165,000,000 UNCTAD, S. (2007). Review of Maritime Transport. New York and Geneva: United Nations.

11. H YDRATE T RANSPORTATION - S LURRY Slurry Transport Advantages Faster loading and unloading (8400 – 14000 tons per hour). Ease of handling hydrate as fluid. Slurry Transport Disadvantages Loss of ship capacity to anti- freezing agents (4% - 5% of cargo weight). Additional equipment required to remove anti-freezing agents from gas.

12. H YDRATE T RANSPORTATION - S OLID Solid Transport Advantages Simplified regasification facility. Slightly more capacity per ship than with slurry (4% - 5%). Solid Transport Disadvantages Slower loading and unloading (2000 – 4000 tons per hour). Additional solid handling equipment required.

13. H YDRATE T RANSPORTATION DistanceTransit Time (18kts) Total Trip Time (Slurry/Solid) Total Time Savings With Slurry 1000 mi4.6 days7.8 days/9.1 days14.3% 2000 mi9.3 days12.5 days/13.8 days 9.4% 3000 mi13.9 days17.1 days/18.4 days 7.1% 4000 mi18.5 days21.7 days/23 days5.7% 5000 mi23.1 days26.3 days/27.6 days 4.7% Slurry handling is the best option for shipping distances of 2500 miles or less. Solid handling is the best option for shipping distances of 3500 miles or more.

14. H YDRATE T RANSPORTATION Hydrate is stored in ship at equilibrium with either temperature or pressure. The two limiting conditions are 1 atm of pressure at 241 K or 85 atm of pressure at 285 K. Determinants of optimum pressure and temperature are cost and weight of steel required in hydrate storage vessel.

15. H YDRATE T RANSPORTATION Faupel formula used to determine minimum steel thickness necessary for hydrate storage vessel. Minimum Bursting Pressure = (2/3)*Yield Tensile Strength*ln(Ratio of Inner and Outer Diameters) 1020 carbon steel used. Yield tensile strength of 1020 carbon steel is 350 Mpa.

16. H YDRATE T RANSPORTATION Ambient Temperature Tank Outer Diameter 29.5 m Tank Thickness 0.31m Steel Weight (if full length of vessel) 113000 tons 0.31m 29.5m

17. H YDRATE T RANSPORTATION Atmospheric Pressure Tank Outer Diameter 29.5 m Tank Thickness 3.65mm Steel Weight (if full length of vessel) 1300 tons 3.65mm 29.5m

18. H YDRATE T RANSPORTATION Shipping cost for 1.5 mtpa and distance of 4000 miles. Shipping at ambient temperature (FCI): $2,050,000,000 Shipping at atmospheric pressure (FCI): $1,100,000,000

19. H YDRATE T RANSPORTATION Ballast Inner Hull Insulation Inner Membrane Outer Membrane

20. H YDRATE T RANSPORTATION 3585 40 ton ice-hydrate blocks required

21. H YDRATE T RANSPORTATION Refrigeration can be used to prevent hydrate dissociation. With 4 of polyurethane insulation and a well- sealed cargo hold, 1.5 tons of refrigeration are required. Cost of refrigeration $6,300

22. H YDRATE D ISSOCIATION

23. Pressure Vessel size based on required production level of natural gas. For 1.5 mtpa capacity. 44 pressure vessels: V = 294 m 3 $5,400,000 776 storage vessels: V = 150 m 3 $30,000,000 Perry, R., & Green, D. (1997). Perry's Chemical Engineers' Handbook (7th ed.). McGraw-Hill.

24. H YDRATE D ISSOCIATION Heating Costs for the kettle Found using the heat of dissociation of methane hydrates, the specific heats of hydrate and water, and the required gas flow rate. Cost of 1 MM BTU assumed to be $7.33 Total heating cost $40,000,000 Rueff, R. M., Sloan, E. D., & Yesavage, V. F. (1988). Heat Capacity and Heat of Dissociation of Methane Hydrates. AIChE Journal, 1468-1476.

25. P RODUCTION S UMMARY The natural gas hydrates are produced in a stirred tank reactor. The hydrates are frozen into blocks and loaded onto ships. The ships have small refrigeration units to keep the blocks frozen. The ships are at atmospheric pressure

26. P RODUCTION S UMMARY The blocks of hydrates are decomposed in a pressurized vessel. The hydrate leaves the vessel at pipeline pressure.

27. LNG C OST E STIMATION Cost data for LNG was obtained at plant capacities of 1 mtpa, 2 mtpa, and 3.5 mtpa.

28. LNG C OST E STIMATION Costs are taken as the average costs for a range of plant designs.

29. LNG C OST E STIMATION Operating Cost CapacityLiquification (2007$/ton)Regasification (2007$/ton) 100000071.2511.875 200000061.757.125 350000052.254.75

30. LNG C OST E STIMATION Shipping costs are contracted out at $65,000/day for 57,000 tons LNG. The total annualized cost for a LNG tanker is less than $23,000,000/year, or $63,000/day. Contracting out the shipping is the worse case scenario for LNG. UNCTAD, S. (2007). Review of Maritime Transport. New York and Geneva: United Nations.

31. E CONOMIC C OMPARISON The TAC per ton of methane produced is plotted against capacity in tons.

32. E CONOMIC C OMPARISON 0 miles shows the TAC per ton that comes from the production and regasification plants. Production Regasification

33. E CONOMIC C OMPARISON Distance from Algeria to Cove Point, Maryland is about 4000 miles. TAC per ton is shown for 1000 – 5000 miles.

34. Increasing distance increases the TAC/ton. Adding ships causes a sharp increase in TAC/ton.

35. Increasing distance increases TAC/ton.

36. LNG has a lower TAC/ton for transportation distances greater than 0 miles.

37. Increasing transportation distance increases the difference in the TAC/ton for LNG and NGH.

38. E CONOMIC C OMPARISON The cost of shipping LNG is less than the shipping cost for NGH. LNG has a higher energy density than NGH. 1 ton LNG = 1 ton natural gas 1 ton hydrate = 0.134 tons natural gas and 0.866 tons water. NGH requires 7 times the shipping weight of LNG.

39. E CONOMIC C OMPARISON For 1.5 mtpa transported 4000 miles

40. E CONOMIC C OMPARISON The FCI per ton of natural gas is plotted against the capacity in tons. 0 miles shows the FCI for the production and regasification plants.

41. FCI/ton increases with transportation distance. Adding ships produces a large increase in FCI/ton.

42. The FCI/ton is cheaper for NGH.

43. E CONOMIC C OMPARISON The ROI is found by dividing the profit by the TCI. The TCI is found by assuming that TCI=FCI+WC=FCI/0.85 The profit is taken as sales-cost-depreciation, or sales-TAC. Sales is varied between $0 and $200 per ton of methane

44. E CONOMIC C OMPARISON ROI is found by: ROI=((Sales-TAC)/TCI)*(ton/ton) ROI=(Sales/ton-TAC/ton)/(TCI/ton) ROI=((Sales/ton)/(TCI/ton))-((TAC/ton)/(TCI/ton)) (TCI/ton) and (TAC/ton) have already been calculated, therefore (Sales/ton) is only thing to vary.

45. A positive ROI occurs with sales of $80/ton.

46. A positive ROI occurs with sales of $100/ton for low production capacities.

47. A positive ROI occurs with sales of $160/ton.

48. A positive ROI occurs with sales of $120/ton.

49. As distance increases the sales increases to $180/ton to maintain a positive ROI.

50. As distance increases the sales increases to slightly above $120/ton to maintain a positive ROI.

51. Natural gas hydrate peak-shaving has a lower TAC/ton and FCI/ton than LNG.

52. Natural gas hydrate peak-shaving has a higher ROI than LNG.

53. C ONCLUSION LNG has a lower TAC and a higher ROI. LNG is a proven and well developed technology. LNG is a better option than NGH for the transport of natural gas. The TAC/ton, FCI/ton, and ROI is better for NGH with transportation distances of 0 miles. NGH is a better option for peak-shaving the cost of natural gas.

54. Q UESTIONS