NATURAL GAS HYDRATE TRANSPORTATIONDavid MannelDavid Puckett

CONTENTS Hydrate Synthesis

Hydrate Transportation

Hydrate Dissociation

Production Summary

LNG Cost Estimation

Economic Comparison

HYDRATE SYNTHESIS

HYDRATE SYNTHESISWater 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.

PC

Fresh Water Supply

Recycled Water

Purified Gas Supply

Recycled Gas

Reactor

Decanter

Hydrate-Water Slurry

Freezing Basin

Hydrate-Ice Blocks

Flare Gas

AbsorptionRefrigerator

PropaneRefrigerator

ReducedWaterSlurry

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

HYDRATE SYNTHESIS CSTR For 1.5 mtpa methane

production: Vtotal=(3,130 mol

CH4/s)/(1.29 mol/m3 * s) Vtotal=2,430 m3

32 reactors usedVreactor = 76 m3

Perry, R., & Green, D. (1997). Perry's Chemical Engineers' Handbook (7th ed.). McGraw-Hill.

HYDRATE SYNTHESIS CSTR

Equipment Cost: $1,760,000

Perry, R., & Green, D. (1997). Perry's Chemical Engineers' Handbook (7th ed.). McGraw-Hill.

HYDRATE SYNTHESIS Compressor

s Compressors sized using

PRO II

Compressor Equipment Cost:

Recycle Compressor Cost: $2,200,000

Intake Compressor Cost: $870,000

Total Cost: $3,070,000Perry, R., & Green, D. (1997). Perry's Chemical Engineers' Handbook (7th ed.). McGraw-Hill.

HYDRATE SYNTHESIS 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.

HYDRATE SYNTHESIS Heat

Exchangers Heat exchangers sized using:

Q=UA∆T

Heat exchanger cost based on area

Initial Cooling Heat Exchanger Area: 35,000 ft2

Initial Cooling Heat Exchanger Cost: $235,000

Post Cooling Heat Exchanger Area: 16,000 ft2

Post Cooling Heat Exchanger Cost: $113,000

Perry, R., & Green, D. (1997). Perry's Chemical Engineers' Handbook (7th ed.). McGraw-Hill.

HYDRATE TRANSPORTATION Capacity 145,000 metric tons Capacity of 186,000 m3

Length 290m Beam 45m Draught 18m Base price $165,000,000

UNCTAD, S. (2007). Review of Maritime Transport. New York and Geneva: United Nations.

HYDRATE TRANSPORTATION - SLURRY

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.

HYDRATE TRANSPORTATION - SOLID

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.

HYDRATE TRANSPORTATIONDistance

Transit Time (18kts)

Total Trip Time (Slurry/Solid)

Total Time Savings With Slurry

1000 mi 4.6 days 7.8 days/9.1 days

14.3%

2000 mi 9.3 days 12.5 days/13.8 days

9.4%

3000 mi 13.9 days 17.1 days/18.4 days

7.1%

4000 mi 18.5 days 21.7 days/23 days

5.7%

5000 mi 23.1 days 26.3 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.

HYDRATE TRANSPORTATION 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.

HYDRATE TRANSPORTATION 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.

HYDRATE TRANSPORTATION

Ambient Temperature Tank Outer Diameter29.5 mTank Thickness0.31mSteel Weight (if full length of vessel)113000 tons

0.31m

29.5m

HYDRATE TRANSPORTATION

Atmospheric PressureTank Outer Diameter29.5 mTank Thickness3.65mmSteel Weight (if full length of vessel)1300 tons

3.65mm

29.5m

HYDRATE TRANSPORTATION 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

HYDRATE TRANSPORTATION

Ballast

Ballast

Inner Hull

Insulation

Inner Membrane

Outer Membrane

HYDRATE TRANSPORTATION

358540 ton ice-hydrate blocks required

HYDRATE TRANSPORTATION 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

HYDRATE DISSOCIATION

PC

FC

Low PressureSteam

Condensate

SolidIce-Hydrate

Natural Gas toWater Removal

PressureVessel

Heating Kettle Liquid Water

HYDRATE DISSOCIATION Pressure Vessel size based on required

production level of natural gas.

For 1.5 mtpa capacity.

44 pressure vessels: V = 294 m3

$5,400,000

776 storage vessels: V = 150 m3

$30,000,000Perry, R., & Green, D. (1997). Perry's Chemical Engineers' Handbook (7th ed.). McGraw-Hill.

HYDRATE DISSOCIATION 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.

PRODUCTION SUMMARY 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

PRODUCTION SUMMARY The blocks of hydrates are decomposed in a

pressurized vessel.

The hydrate leaves the vessel at pipeline pressure.

LNG COST ESTIMATION Cost data for LNG was obtained at plant

capacities of 1 mtpa, 2 mtpa, and 3.5 mtpa.

LNG COST ESTIMATION Costs are taken as the average costs for a

range of plant designs.

LNG COST ESTIMATIONOperating Cost

Capacity Liquification (2007$/ton) Regasification (2007$/ton)1000000 71.25 11.8752000000 61.75 7.1253500000 52.25 4.75

LNG COST ESTIMATION 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.

ECONOMIC COMPARISON The TAC per ton of methane produced is

plotted against capacity in tons.

ECONOMIC COMPARISON 0 miles shows the TAC per ton that comes

from the production and regasification plants.

ProductionRegasification

ECONOMIC COMPARISON Distance from Algeria to Cove Point,

Maryland is about 4000 miles. TAC per ton is shown for 1000 – 5000 miles.

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100

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0 200000 400000 600000 800000 1000000 1200000 1400000 1600000 1800000 2000000

$/to

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Capacity (tons)

NGH TAC vs Capacity

0 miles

1000 miles

2000 miles

3000 miles

4000 miles

5000 miles

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

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Capacity (tons)

LNG TAC per ton

0 miles

1000 miles

2000 miles

3000 miles

4000 miles

5000 miles

6000 miles

7000 miles

8000 miles

9000 miles

10000 miles

Increasing distance increases TAC/ton.

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Capacity (tons)

NGH and LNG TAC vs Capacity

NGH 0 miles

NGH 1000 miles

NGH 2000 miles

NGH 3000 miles

LNG 0 miles

LNG 1000 miles

LNG 2000 miles

LNG 3000 miles

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

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Capacity (tons)

NGH and LNG TAC vs Capacity

NGH 4000 miles

NGH 5000 miles

NGH 6000 miles

NGH 7000 miles

LNG 4000 miles

LNG 5000 miles

LNG 6000 miles

LNG 7000 miles

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

ECONOMIC COMPARISON 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.

ECONOMIC COMPARISON

64%7%

30%

Natural Gas Hydrates Cost

BreakdownShippingSynthesisRegasification

21%

68%

11%

LNG Cost Breakdown

ShippingSynthesisRegasification

For 1.5 mtpa transported 4000

miles

ECONOMIC COMPARISON 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.

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600

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1200

1400

0 200000 400000 600000 800000 1000000 1200000 1400000 1600000 1800000 2000000

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Capacity (tons)

NGH FCI vs Capacity

0 miles

1000 miles

2000 miles

3000 miles

4000 miles

5000 miles

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

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($/t

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Capacity (tons)

NGH and LNG FCI per ton

NGH 0 miles

LNG 0 miles

The FCI/ton is cheaper for NGH.

ECONOMIC COMPARISON 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

ECONOMIC COMPARISON 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.

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

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ROI (

%)

Capacity (tons)

LNG 0 miles

0

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200

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

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ROI (

%)

Capacity (tons)

NGH ROI 3000 miles

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

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ROI (

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Capacity (tons)

LNG 3000 miles

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

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ROI (

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Capacity (tons)

NGH ROI 4000 miles

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

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ROI (

%)

Capacity (tons)

LNG 4000 miles

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

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($/t

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Capacity (tons)

NGH vs LNG Peak-Shaving

NGH FCI/ton

LNG FCI/ton

NGH TAC/ton

LNG TAC/ton

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

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Capacity (tons)

NGH vs LNG Peak-Shaving

NGH ROI ($100/ton)

LNG ROI ($100/ton)

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

CONCLUSION 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.

QUESTIONS