Transitioning from Thermal Desalination to Reverse Osmosis The Benefits and Process Hurdles

Transcription

1 CaribDA 2012 Conference & Exposition 80 Years of Desalination Makes For One Happy Island in conjunction with W.E.B. Aruba N.V. s 80 th Anniversary Celebration June 2012 in Aruba Transitioning from Thermal Desalination to Reverse Osmosis The Benefits and Process Hurdles Miles B. Beamguard, Ph.D. Seven Seas Water Corporation 1

2 Existing Desalination US Virgin Islands Water and Power Authority (VIWAPA) Low-Temperature Horizontal Tube ME (LT-HT ME) Desalination Multi-Effect Distillation (MED) needs: high-pressure (150 psi) steam low-pressure (23 psi) steam St. Thomas 4.35 MGD Installed St. Croix 3.65 MGD Installed 2

3 Cost of Desalination Rising Cost of Water from VIWAPA has risen significantly over the past 10 years due to: Aging Equipment Cost of Oil $16.87 in 1999 to peak of $ in 2008 Currently VIWAPA pays $128 per barrel 3

4 Preliminary Economic Study In 2007 VIWAPA contracted R.W. Beck to look at current and future costs R. W. Beck identified the change from Thermal to Reverse Osmosis (RO) desalination as a significant cost savings VIWAPA issued RFP for 3 year,1.5 MGD RO plant for St. Croix For maintenance of existing MED units To evaluate RO costs RFP won by Seven Seas Water (7Seas) 1.5 MGD Plant constructed and operational in 92 days on April 30,

5 Preliminary Economic Study RFP won by Seven Seas Water (7Seas) 1.5 MGD Plant constructed and operational in 92 days on April 30,

6 Theoretical Comparison of RO to MED In 2003 US Bureau of Reclamation issued the Desalting Handbook for Planners, Third Edition Based on 1999 capital and operational prices Relative Water Costs were 79.5% more for MED than SWRO for a 10 MGD facility 6

7 Theoretical Adjustment for Oil and CPI Price per 1000 gallons was computed MED - $4.27, SWRO - $2.38 Steam and Electrical costs in 1999 were removed from the total cost to get to 1999 base cost MED - $2.43, SWRO - $2.02 Base Costs escalated with 3% CPI to get to 2011 Base Costs MED - $3.47, SWRO - $2.88 Steam and Electrical costs were calculated using 759% increase in oil costs from 1999 to 2011 ($16.87-$128.00) MED - $13.92, SWRO - $2.70 Total 2011 Cost (discounting thermal steam and power by 50% for other beneficial uses) was found as: MED - $10.43, SWRO - $5.58 7

8 Final Theoretical Pricing Technology Low-Temp MSF (oncethrough) High-Temp MSF (oncethrough) Low-Temp MSF (recirculation ) High-Temp MSF (recirculation ) Low-Temp Horizontal Tube ME High-Temp Vertical Tube ME Mechanical Vapor Compressio n Sea Water Reverse Osmosis % Cost $/kgal $ 6.43 $ 5.40 $ 6.43 $ 5.40 $ 4.27 $ 4.27 $ 4.37 $ 2.38 % of SWRO 270% 227% 270% 227% 180% 180% 184% 100% Steam and Electrical % Cost of Oil $ 1.61 $ 1.35 $ 1.61 $ 1.35 $ 1.83 $ 1.83 $ 2.23 $ Cost of Oil $ $ $ $ $ $ $ $ $/kgal Without Oil $ 4.82 $ 4.05 $ 4.82 $ 4.05 $ 2.43 $ 2.43 $ 2.14 $ $/kgal Without Oil (Assume 3% CPI) $ 6.87 $ 5.77 $ 6.87 $ 5.77 $ 3.47 $ 3.47 $ 3.06 $ $/kgal With Oil (Assume 3% CPI) $ $ $ $ $ $ $ $ 5.58 % of SWRO without Oil 341% 287% 341% 287% 311% 311% 358% 100% 2011 $/kgal With Oil (Assume 3% CPI) - Discounted $ $ $ $ $ $ $ $ 5.58 % of SWRO without Oil 232% 195% 232% 195% 187% 187% 206% 100% 1999 Oil $ Current Oil $ Oil Price Ratio

9 Actual Plant Production Costs Basis MED operational costs based on operational numbers from Harley and Richmond Production Facilities MED capital costs based on Desalting Handbook SWRO electrical price based on guaranteed energy consumption of new 2011 contract SWRO total water price based on negotiated base water rate of new 2011 contract 9

10 MED Operational Conditions St. Croix Total Capacity of 3.65 MGD (Demand 2.3 MGD) # MGD #4 and # MGD each # MGD St. Thomas - Total Capacity of 4.35 MGD (Demand (2.7MGD) #1 and # MGD each # MGD # MGD Recovery Desalination recovery (Product to Desal Feed) between 36% and 47% with an average of 41%. Total recovery (Product to Total Feed) between 11% and 16% with an average of 15%. 10

11 SWRO Operational Conditions St. Croix Initial Build Capacity of 3.7 MGD Existing 1.5 MGD SWRO #1 and #2 1.1 MGD each SWRO #3 1.1 MGD (Future) Ultra-Pure Water 200 kgal/day nominal St. Thomas - Initial Build Capacity of 3.3 MGD SWRO #1, #2, #3 1.1 MGD each SWRO #4 1.1 MGD (Future) Ultra-Pure Water 225 kgal/day nominal Recovery Desalination recovery (Product to Desal Feed) 40% Ultra-Pure Water Facility (Product to Total Feed) between 81% and 85% 11

12 MED Steam Requirements Low Pressure (23 psi) Total need is about 275,000 lbs per hour $ a barrel for No. 2 fuel Allocation of $13.09/ton of steam to the MED units Average low pressure steam cost is $5.53 per kgal of water High Pressure (150 psi) Total need is about 6,500 lbs per hour $96.98 a barrel for No. 6 fuel Allocation of $36.33/ton of steam to the MED units Average low pressure steam cost is $0.37 per kgal of water Total Steam Cost - approximately $5.90 per kgal of water production. Range of $ $6.44 per kgal 12

13 MED Electrical Requirements Total power consumption includes seawater pumping, desalination, and a 10% adder for ancillary equipment Average total power consumption was 9.41 kwhr/kgal of production Using a marginal power rate of $0.18/kWhr Total Electrical Power Cost which averages $1.69 per kgal of water production with a range of $ $2.01 per kgal. 13

14 Consumables MED Consumables which included antiscalants and anti-corrosives averaged $0.16 per kgal of water production with a range of $ $0.18 per kgal. SWRO Consumables Included in BOO Contract 14

15 Operations MED On St. Croix the Operations water cost was $0.81 per kgal of water production On St. Thomas the Operations water cost was $0.73 per kgal of water production SWRO Operations Included in BOO Contract 15

16 MED Total Costs Breakdown Total Water Costs without Steam & Depreciation - $2.05 / kgal Total Water Costs with Steam but no Depreciation - $7.94 / kgal Capital Cost MED Based on Desalting - $9 / GPD of water Between a cost of capital of 10-12% this ranges between $ $3.30 / kgal 16

17 Total Costs Comparison All Inclusive MED total water cost is estimated at a low of $10.58 and a high of $12.74 per kgal of water production with an average of $ SWRO total water cost is estimated between $ $6.20 per kgal of water production depending on final BOO Contract and electrical costs. Theoretical and Actual Numbers are Comparable 17

18 MED Footprint MED average area per unit of capacity is 7.31 ft 2 /kgal/day St.Thomas St. Croix 18

19 SWRO Footprint SWRO average area per unit of capacity is 3.99 ft 2 /kgal/day St. Croix St.Thomas 19

20 MED to SWRO Conversion Hurdles Negotiating a new contract with BOO Provider Finding adequate space for new plant since old plant must continue to run Modification of existing permits Extraction and Discharge are reduced due to higher recovery Thermal load goes down TDS goes up due to higher recovery Rebalancing Power Plant Reduced or Reallocation of Steam Production Larger Electrical Load Good for Load Shedding Redistributing Operational Manpower 20

21 Conclusions VIWAPA in an effort to reduce costs performed both a paper and pilot study to evaluate alternative water production methods Based on operation of pilot and negotiated BOO contract with Seven Seas Water, VIWAPA has a guaranteed minimum water production capacity and maximum water production price Based on both theoretical and operational data, VIWAPA expects to save over 50% compared to their current operations. While there are some hurdles along the way, the benefits of switching far outweigh the costs and only get exacerbated as energy prices continue to rise 21

22 References and Acknowledgements References R.W. Beck, Power Supply Evaluation. Virgin Islands Water and Power Authority US. Bureau of Reclamation. Desalting Handbook for Planners, 3 rd Edition, Acknowledgement The authors would like to thank Chris Ferreras, VIWAPA and Dwight Nicholson, VIWAPA for their help in pulling together all of the existing MED and Steam data. 22

23 Questions? Miles B. Beamguard, Ph.D. Senior Design Engineer, Seven Seas Water Corporation Hugo V. Hodge, Jr., CPQ Executive Director, Virgin Islands Water and Power Authority 23