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Caribbean Environmental Health Institute (CEHI)Tel.: 1 758 452 2501; Email: [email protected]
Desalinization Plants in Selected Caribbean Countries
Presented at
International Seminar On Techniques To Increase Water Availability In Areas Where A Shortage Occurs
Santiago, Chile: 17 – 18 December, 2005
By
Herold Gopaul
Outline of Presentation
Introduction Why Desalinization Desalinization Plants in Selected Countries
(Antigua and Barbuda, The Bahamas, Barbados, British Virgin Islands, Grenada, St. Lucia and Trinidad and Tobago)
Summary of Issues Recommendations
Map of the Caribbean
Introduction
The desired future for the Caribbean is a sustainable future where water resources management will be integrated, effective and efficient (Vision on Water, Life and the
Environment for the 21st Century for the Caribbean). Sustainability of the region's water
resources dictates that land and water management should be interdependent and indivisible.
Introduction - Water Resources Management Issues in the Caribbean Viewed globally, the region is well
endowed with water resources however, problems with accessibility and distribution – some are water scarce(Barbados ranked 15th most water scarce in the world)
Per capita water availability will shrink to half by the year 2025.(Rapid population growth and trends in urbanization, tourism, rural development, and agricultural and industrial development)
Introduction – Water Resources Management Issues in the Caribbean
Human activities influence both the availability and quality of the water resources
Land-based pollution and contamination of freshwater resources
Integrated Water Resources Management Issues in the Caribbean
Seasonal influx of Tourists
Tourism is dependent on the quality of the coastal areas and has a potentially significant negative impacts on the water resources (consumption is 7 – 9 times that of local consumers)
Over-extraction of groundwater has led to depletion of water resources leading to reliance on desalination with consequential economic impact
Introduction - Water Resources Management Issues in the Caribbean
Highly dependent on rainfall to feed surface intakes and replenish groundwater. (problems with rainfall patterns and geology)
Potential impacts of CV/CC and sea level rise
Poor land use planning and soil management in watersheds reduce freshwater capturing capacity, affect coastal water quality and aquatic bio-diversity.
Rio Grande River, Jamaica
Why Desalinization?
Countries resort to desalination either:
To address historical water scarcity situation: Barbados, BVI
To augment conventional sources: Trinidad, Grenada, St. Lucia
To augment supplies where other augmentation methods are not in wide spread use: barging in the Bahamas, RWH in Grenada and Antigua
To ensure some level of sustainability and reliability
To address issues of remoteness from central suppliers: the Bahamas, Barbuda
Desalinization Plants in Antigua & BarbudaSituation:
No significant surface water
Prone to drought (40.98 inches)
Limited land space for surface catchments; reservoir-dependent
Insufficient groundwater
Stipulated Rooftop RW catchments and storage
Government agreed to Desalinization for supply augmentation
Easy access to feed stock
Cheap electricity (at the time; late 1980s)
Desalinization Plants in Antigua & Barbuda
Comparative Costs of Water Production
Ground Water : US $2.50/cubic metre
Surface Water : US $3.00/cubic metre
Desalinated Water: US $4.70/cubic metre
Government subsidies Desalinated water by US$2.50/1,000 gals.
Desalinization Plants in Antigua & Barbuda Technology
Reverse Osmosis – using sea water
Multi-Stage Flash Distillation dual electricity generation facility – using sea water (18.2 MW and 2mgd of water)
Daily Water Production by Type (Gallons/day)
Ground Water : 450,000 (non-drought conditions)
Surface Water : 700,000 (non-drought conditions)
Reverse Osmosis: 2,000,000
Multi-Stage Flash Distillation: 2,000,000
Desalinization Plants in Antigua & Barbuda
Ownership 2 MSFD – private (sells water & electricity to the State)
1 RO – Government
5 ROs – Private – 2000,000 mgd each (Build, Operate, own and transfer – sells water to the State)
1 RO 27,000g/d on Barbuda - Private – (Build, Operate, own and transfer – sells water to the State)
A number of small ROs privately owned and operated (do not sell water to the State)
Desalinization Plants in the Bahamas
Situation:
700 islands and cays
Only 3 islands has significant water resources
Where groundwater is found in natural aquifers – concerns of sea level rise on quality
Supply Augmentation includes barging; groundwater abstraction and rainwater harvesting
RWH is not very popular as a result of seasonal variability, making supplies unreliable
Groundwater can be costly: land acquisition and cost of pre-treatment
Cost of desalinated water in New Providence is comparable to barging from islands; it has superior quality, reliable and sustainable
Desalinization Plants in The Bahamas
Technology
Reverse Osmosis – using sea water; borehole water
Multi-Stage Flash Distillation – using sea water; borehole water
Vapour Compression Distillation - using sea water
Desalinization Plants in the Bahamas
Ownership
1 RO – Government (444,000 gpd)
2 MSFD – Government (672,000 and 1,200,000 gpd)
1 VCD – Government 12,000 gpd average)
A number of ROs - Build, own, operate and transfer – private (sells water to the State)
A number of ROs privately owned and operated (do not sell water to the State)
Over 200 ROs plants in operations in the Bahamas
Desalinization Plants in the Bahamas
Issues
ROs Plants have been customized to use diesel fuel
Increase consumption of desalinated water
Desalinated water has replaced groundwater an the main source
Challenges include vulnerability of the system to natural disasters; disruption of electricity and quality of the feed stock
Desalinization Plants in the Barbados
Situation:
Limestone cap below surface catchments allows for natural aquifer
Groundwater accounts for 80% of fresh water and 98% of potable water prior to desalinization
Concerns over the contamination of the groundwater
Ranked 15th in the world in water scarce countries
Heavily dependent on rainfall
Increase in per capita of water (agriculture, manufacturing and tourism)
Measures to protect water resources; zoning, incentives, building requirements for RWH
Desalinization Plants in Barbados
Technology
Reverse Osmosis – using brackish water from wells and seawater
Ownership
1 RO – Private (build, own, operate, transfer; sells water to the State) using brackish water
1 RO – Private (build, own, operate, transfer; sells water to the State; no longer in operation) using brackish water
I RO – Private; does not sell water to the State; use for landscaping and golf course; uses seawater
Desalinization Plants in Barbados
Issues
Desalinated water is mixed with chlorinated groundwater
The is now a greater acceptance to using desalinated water through PA/PE
The cost of desalinated water is slightly higher than that of groundwater (brackish water is of high quality – low salinity)
The brine can be reintroduced into deep borehole near the coast with affecting the receiving waters
Challenges include vulnerability of the system to natural disasters; disruption of electricity, cost of energy and quality of the feed stock if TDS rises
Desalinization Plants in the British Virgin IslandsSituation:
Made up 23 of islands and cays
Limited freshwater
Heavily dependent on tourism
Water sources – seasonal streams and springs, wells and rainwater harvesting
RWH not suitable for large scale application such as the tourism industry
95% of the water is provided by the State
90% of water consumed is by domestic users
2 mgd is the estimated requirement of water in the BVI
Desalinization Plants in British Virgin Islands
Technology
7 Reverse Osmosis – using sea water; privately owned, sell water to the State
1 Multi-Stage Flash Distillation – using sea water; generates electricity and produces water and sells to the State
Desalinization Plants in British Virgin Islands
Issues
Plants are established under the build, own, operate, transfer arrangement
Government may allocate State-own land for the establishment of the plants
Desalinated water is purchased by government at an average cost of US$18.60/1000gallons
Cost of production of desalinated water ranges from US49.00 - $20.00 per 1000 gallons
Plant operators and all but one manager are locals,
Desalinization Plants in Granada
Situation:
Tri-island state; Grenada, Carriacou and Petite Martinique
Significant surface and spring water in Grenada
Carriacou and Petite Martinique rely on RWH and to a lesser extent on groundwater
Desalinization Plants in Grenada
Technology
3 Reverse Osmosis – using sea water; owned and managed by the State
Some hotels have small ROs plants using seawater
Grenada – 400,000 US g/d Petite Martinique – 30,000 g/d Carriacou – 100,000 US g/d
Cost of production EC $18 – $20/1000 gallons Cost to consumer – EC $0.02/gallon
Desalinization Plants in Grenada
Issues
Plants are plagued by operational and maintenance problems
No service contract with manufacturer – full cost for any assistance
Storage capacities in Petite Martinique and Carriacou is insufficient – production is a function of immediate demand
Plants are therefore unused for long period
Damage to suction pipe from recent severe weather conditions
Low public acceptance of desalinated water in Petite Martinique and Carriacou
Desalinization Plants in St. Lucia
Situation:
Rainfall varies across the island ranging between 1,200 mm – 3,500 mm
Most of the rainfall drains to the sea
Government does not utilize desalinization as a supply augmentation option; groundwater exploration is preferred
Desalinization Plants in St. Lucia
Technology
2 Reverse Osmosis – I using sea water and the other brackish water; owned and managed by private hotels to augment the water authority supply
A number of RO plants are coming on stream with the construction of tourism facilities on the Island
Desalinization Plants in Trinidad & Tobago
Situation:
Surface (65%) and groundwater (25%)
Desalination (10%)
Unaccounted for and illegal access (51%)
Increase in water production for the period 1997 – 2002 (276.8 346.7 m/gallon)
Country heavily industrialized
Need for a reliable supply to the industrial estate
Desalinization Plants in Trinidad & TobagoTechnology
1RO Plant – using sea water owned and managed by private joint venture (local and foreign partners); 22mgd
Build, own, operate and sell after 20 years arrangement
Half the production is sold to the industrial estate through the water authority
Summary of Issues
The main technologies currently in use: Thermal technologies
Multi-stage flash distillation Multiple effect distillation Vapour compression distillation
Membrane technologies Brackish water reverse osmosis Seawater reverse osmosis
Summary of Issues
Reverse osmosis appears to be replacing the thermal technologies
Thermal technologies persist where this is coupled with electricity generation
Summary of Issues
Tendency towards design-build-own-operate contracts with manufacturers resulting in:
Contractual agreements to sell water exclusively to contracting agency/industry
Reduced need for resident expertise
Summary of Issues
National Policy
Generally addressed water resource management but not specifically desalination
Water scarce countries more likely to have policies
Not all were formal or even written
Summary of Issues
Desalination likely to increase
More expensive than processing surface and groundwater
Poor public reaction can be linked to poor public education where water scarcity is an emergent problem and consumers are used to other traditional sources.
Summary of Issues
Pricing structures in some countries:
Reflects production costs
Are subsidized by government and varied by user category
Appears to elicit less sensitivity in geographically water scarce countries
Recommendations
Governments should adopt a structured approach to the implementation of desalination:
•Establish national policies within the framework of national water resource management plans
• Involve stakeholders especially those with a regulatory role
• Establish clear procedures and guidelines for specifications, applications, implementation and monitoring of desalination plants
• Where rainfall is reliable; encourage other less costly augmentation options such as RWH
THANK YOU FOR YOURATTENTION
