Transcript Desalinization in the Caribbean

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
Caribbean Environmental Health Institute (CEHI)
Tel.: 1 758 452 2501; Email: [email protected]
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 &
Barbuda
Situation:

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 pretreatment

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
Islands
Situation:

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 &
Tobago
Technology

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
THANK YOU FOR YOUR
ATTENTION