Transcript Deep Ocean Water Application Facility (DOWAF) and Seawater

Honolulu Board of Water
Supply
Proposed Deep Ocean Water
Application Facility (DOWAF)
BWS Vision Statement
We will share our water management expertise and
provide services statewide and throughout the
Pacific to:
•
•
•
•
Benefit our global communities
Benefit our community by maintaining reasonable rates
Provide professional development opportunities for our staff
Support the growth of Hawaii’s economy
Overview
DOWAF will provide a multitude of renewable
resource products to the island of Oahu. The
Honolulu BWS is undertaking a study to assess
the most feasible site and mix of products to
develop a DOWAF
Oahu population is projected to grow from 876,000
to 1,030,000 by the year 2025. There currently is
a strain on developing more natural water
resources and dependence on imported oil for
fuel, while trying to achieve sustainability of
resources that will meet the needs of a growing
population
DOWAF conservation of groundwater and fossil
fuel supplies provides public benefits from the
deferral of rate increases for water and electricity
Potential products being assessed for DOWAF:
•Potable water from desalination – 5 mgd
•Electric power from OTEC – 2 MW
•Seawater air conditioning district cooling
systems – reduce electricity use
•Root zone irrigation for increased crop yields
and additional variety that can be grown
•Liquid Hydrogen for fuel cell production
•Aquaculture farming
The temperature of
Ocean Temperature Profile
tropical seawaters
changes with depth
0m
Warm Surface Water
(25 - 28 º C)
- 100 m
Thermocline
The deep water of
the ocean is cold
Everywhere in the
ocean
Cold Deep Water
(5 - 4 º C)
- 800 m
Water depth < 1000 m
Land mass
Regions marginally suitable
for OTEC:
T < 18 °C
18 °C<
T< 20 °C
Regions suitable for OTEC:
20 °C<
T< 22 °C
22 °C<
T< 24 °C
24 °C<
T
T = Temperature difference between surface and deep water in °C
Oahu 1
Bathymetry – Advanced 3D visualization
SW Pipe Systems:
3 Potential DOWAF Sites on Oahu
Coastline with good
access to deep cold
seawater
SITE A
SITE B
Figure 10
HONOLULU
Pipe route selection - Advanced 3D Expert System
SW Pipe Systems:
DEVELOPMENT PLAN
DISTRICTS
City General Plan
KOOLAULOA
NORTH SHORE
CENTRAL OAHU
WAIANAE
KOOLAUPOKO
EWA
PRIMARY URBAN CENTER
EAST HONOLULU
CENTRAL OAHU
DP AREA
PRIMA
URBAN CE
WAIANAE DP AREA
UH
o
ingt
Farr
Fa
gto
rrin
wy
nH
GC
y
n Hw
GC
Pearl
Harbor
West
Loch
PK
I
Fr
ee
wa
y
Makakilo
M
H1
PK
GC
Ewa Villages
GC
PK
olei
Kap
PK
P
y
wa
ark
I
WWTP
GC
GC
PK
I
Campbell
Industrial
Park
PK
M
City of
Kapolei
Kalaeloa
(BPNAS)
M
oad
PK
Ko Olina
PK
R
eaver
PK
GC
Fort W
GC
GC
GC
PK
M
GC
Ewa Marina
PK
PK
Project Location
Incorporates changes to the March 1996
recommended by the Honolulu Plan
Commission on July 24, 1
OTEC Off-shore Floating Barge
Examples of DOWAF Pipelines
Keahole, Hawaii
More examples of
DOWAF Pipelines
OTEC Open Cycle
water vapor as a working fluid
OPTION 1
OC-OTEC Process
In the Open Cycle the working fluid (water vapor) is vented after use. The
working fluid is NOT returned (therefore the term “open cycle”). The warm water is
evaporated in the low-pressure system containment and condensed by the cold water
Evaporator
Working fluid:
Water vapor
Condenser
Vacuum
Pump
Low pressure
differential
Turbine
INLET
EXHAUST
Warm ocean
surface water
INLET
Cold ocean
deep water
EXHAUST
OTEC Closed Cycle
ammonia as a working fluid
OPTION 2
CC-OTEC Process
In the Closed Cycle the working fluid (e.g. ammonia) is contained in an
enclosed flow systems (incl. Working fluid turbine, pumps, surface heat exchangers,
etc.) and is pumped back to the evaporator after condensation.
Working Fluid
Pump
Evaporator
IN
OUT
Warm ocean
surface water
Condenser
Working Fluid
Turbine
OUT
IN
Cold ocean
deep water
Deep Seawater Wells for District Cooling
5 – 7 deg C desired ~ 2,000 – 3,000 ft. depth
ALLUVIUM
SEALEVEL
UPPER CAPROCK
SCREENED
PART OF WELL
ARD
AQUIT
FRESHWATER
LOWER CAPROCK
BRACKISH WATER
CLAY AND
MARINE
SEDIMENTS
SALTWATER
BASALT
OPEN HOLE
NOT TO SCALE
Figure 7-5
Commercial Building
District Air Conditioning
System Use
Commercial Building Air
Conditioning System Use
For University of Hawaii
School of Medicine
Deep well to be used in lieu of deep water pipeline
Aquaculture Products
Kona Cold
Lobsters
cyanotec microalgae
Royal
Hawaiian
Sea
Farms edible
seaweed
and
Hawaiian
Sunfish
Major Feasibility Issues
• Seawater intake pipeline accessibility at an
adequate depth to obtain 4-5 deg C ~ 2 –3 miles
length, 2,500 – 3,000 ft depth
• The most viable mix of products - not necessarily
including OTEC requiring
T min 22 deg C,
deeper pipeline and expensive equipment
• Proximity to areas of demand
• Securing investment partners - Initial rough
estimate of a 5 mgd DOWAF ~ $60 M
Summary of Economic Benefits
• Reduce power cost and relieve future energy shortages
– Oahu uses ~ 1,700 MW
• Minimize our reliance on fossil fuel – Oahu uses ~ bil
barrels / yr
• Reduce electric and potable water costs for businesses
• Create aquaculture businesses for producing seafood
products
• Expand diversified agriculture industry
• Defer municipal water rate increases
• Establish partnerships with private businesses and
universities
Any Questions?