atural Gas Hydrate Transportation * David Mannel ** , David Puckett ** , and Miguel Bagajewicz University of Oklahoma- Chemical Engineering Abstract We investigate the possible use of hydrates for natural gas transportation using shops. Natural gas hydrates were found to be economically less favorable than LNG for the transportation of natural gas. However, natural gas hydrates were found to be economically viable for small capacity peak- shaving plants and natural gas storage. The ships have small refrigeration units to keep the blocks of hydrate frozen, since they are shipped at atmospheric pressure. For a shipping distance of 4,000 miles and 1.5 million tons of hydrate per annum, the fixed capital investment for shipping the natural gas hydrates is $1,100,000,000. - The natural gas hydrates are produced in a stirred tank reactor, and then they are frozen into blocks and loaded onto ships. The required fixed capital investment is $23,000,000 with a production rate of 1.5 million tons per annum. All equipment prices are given for a production of 1.5 million tons per annum. 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. - LNG Natural Gas Hydrate Synthesis Peak-Shaving 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. References The blocks of hydrates are decomposed in a pressurized vessel, and then leaves the vessel at pipeline pressure. The fixed capital investment for the regasification facility is $140,000,000 for a production rate of 1.5 million tons per annum. Natural Gas Hydrate Transportation Natural Gas Hydrate Regasification Liquefied Natural Gas Natural Gas Hydrates PC FC Low Pressure Steam C ondensate Solid Ice-H ydrate N atural G as to W aterRem oval Pressure Vessel H eating Kettle Liquid W ater 50 100 150 200 250 300 0 200000 400000 600000 800000 1000000 1200000 1400000 1600000 1800000 2000000 $/ton Capacity (tons) NGH TAC vsCapacity 0m iles 1000m iles 2000m iles 3000m iles 4000m iles 5000m iles Increasing distance increases the TAC/ton. Adding ships causes a sharp increase in TAC/ton. 0 20 40 60 80 100 120 140 160 180 0 500000 1000000 1500000 2000000 2500000 3000000 3500000 4000000 ($/ton) Capacity (tons) LNG TAC perton 0miles 1000miles 2000miles 3000miles 4000miles 5000miles 6000miles 7000miles 8000miles 9000miles 10000 m iles Increasing distance increases TAC/ton. A positive ROI occurs with sales of $80/ton. -60 -40 -20 0 20 40 60 80 100 0 500000 1000000 1500000 2000000 2500000 3000000 3500000 4000000 ROI(% ) Capacity (tons) LNG 0 m iles 0 20 40 60 80 100 120 140 160 180 200 A positive ROI occurs with sales of $100/ton for low production capacities. -25 -20 -15 -10 -5 0 5 10 0 2000000 4000000 6000000 8000000 10000000 12000000 RO I (% ) Capacity (tons) NGH ROI 4000 m iles 0 20 40 60 80 100 120 140 160 180 200 As distance increases the sales increases to $180/ton to maintain a positive ROI. -60 -40 -20 0 20 40 60 80 0 500000 1000000 1500000 2000000 2500000 3000000 3500000 4000000 ROI(% ) Capacity (tons) LNG 4000 m iles 0 20 40 60 80 100 120 140 160 180 200 As distance increases the sales increases to slightly above $120/ton to maintain a positive ROI. 0 50 100 150 200 250 300 350 400 0 500000 1000000 1500000 2000000 2500000 3000000 3500000 ($/ton) Capacity (tons) NGH vsLNG 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. -10 -5 0 5 10 15 20 25 0 1000000 2000000 3000000 % Capacity (tons) NGH vsLNG Peak-Shaving NGH RO I($100/ton) LNG RO I ($100/ton) Natural gas hydrate peak- shaving has a higher ROI than LNG. CSTR cost $1,760,000 Compressor Equipment Cost: Recycle Compressor Cost: $2,200,000 Intake Compressor Cost: $870,000 Total Cost: $3,070,000 Pump cost: $690,000 Heat exchanger cost Initial Cooling Heat Exchanger Cost: $235,000 Post Cooling Heat Exchanger Cost: $113,000 44 pressure vessels: V = 294 m 3 $5,400,000 776 storage vessels: V = 150 m 3 $30,000,000 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 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. Capacity 145,000 metric tons Capacity of 186,000 m 3 Length 290m Beam 45m Draught 18m Base price $165,000,000 Atmospheric Pressure Tank Outer Diameter 29.5 m Tank Thickness 3.65mm Steel Weight 1300 tons Ambient Temperature Tank Outer Diameter 29.5 m Tank Thickness 0.31m Steel Weight 113000 tons 3585 40 ton ice- hydrate blocks required ) This work was done as part of the capstone Chemical Engineering class at the University of Oklahoma *) Capstone Undergraduate students Cost data for LNG was obtained at plant capacities of 1 mtpa, 2 mtpa, and 3.5 mtpa. Costs are taken as the average costs for a range of plant designs. Economic Comparison Ballard, A. L., & Sloan, E. D. (2001). Hydrate phase diagrams for methane + ethane + propane mixtures. Chemical Engineering Science (53), 6883-6895. Englezos, Kalogerakis, Dholabhai, & Bishnoi. (1987, November). Kinetics of formation of methane and ethane gas hydrates. Chemical Engineering Science , 2647-2666. Koh, C. A., & Sloan, E. D. (2007). 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