Energy Transition Handbook - Flipbook - Page 27
Energy Transition Handbook 2021
27
Sea water air conditioning (SWAC)
SWAC is a renewable air conditioning system suitable for installations with high air
conditioning requirements that are located near a source of deep cold water.
The SWAC system collects cold water from appropriate sea depths where sea water
temperature is c.5-7 degrees Celsius, pumps it to the surface and uses it to cool fresh
water in the installation’s air conditioning system via a heat exchanger following which
the used water is returned to the sea at an appropriate temperature/depth.
A SWAC solution brings a number of
advantages, including:
•
logistics for onshore pipeline assembly,
launching and towing to the Project site
•
costs savings, including through reduced
electricity costs (up to 90% of electrical
consumption compared to a standard
cooling system)
•
offshore “S-lay” installation of large diameter
polyethylene pipelines to depths of 1,000
meters and greater
•
reducing the host installation’s reliance of
fossil fuels/other sources of cooling which
increases its security of supply and reduces its
carbon footprint
•
the broader risks associated with marine
construction/installation at significant sea
depths and exposure to corresponding adverse
weather and health and safety risks
•
eliminating conventional cooling solution
exposure to electricity price volatility
•
vessel availability risk (including as a result of
unforeseen delays to the works programme);
•
a long term solution that can provide cooling
for potentially 50 years or more
•
cavitation (rapid changes of pressure leading
to the formation of cavities) and pipe collapse
resulting from water suction with the pump
•
lower operation and maintenance cost
•
•
reduced noise and vibrations within the
installation compared to a conventional
cooling system
right sizing vs oversizing of the solution and
potential third party access opportunities (eg
to supply the terminal infrastructure at either
end of the tunnel and/or local district heating/
cooling schemes)
•
calibration of minimum acceptance criteria/
testing and availability and performance
guarantees and related delay and performance
liquidated damages and termination thresholds
if these levels are not met
•
impact of the solution on the marine
environment and habitats particularly at the
seawater outlet
•
decommissioning obligations and risk
Key issues/risks:
•
accuracy of seawater temperature depth
profiles and the impact of changes to those
profiles over the life of the project
•
tariff structure and tenor, including any take
or pay, fixed and variable components of the
tariff structure to reflect availability and usage
of the solution and any linkage to electricity
cost savings
•
off-taker credit risk and any implicit credit
exposure to demand
•
seafloor characteristics and offshore
pipe routing