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Gran Canaria
Integrating cooling and distillation with the redevelopment of
the harbour area of Las Palmas
A recent
architectural competition for the redevelopment of the harbour area of Las
Palmas de Gran Canaria has given us the opportunity to expand on the Seawater
Greenhouse concept, working in collaboration with the architects Nicholas Grimshaw & Partners.
The Seawater
Greenhouse process utilises renewable energy in various ways, using a
combination of the sun, the sea and the atmosphere to create cooling and fresh
water. Its primary purpose is to enable crops to be grown in conditions that
are otherwise difficult or impossible as a consequence of extreme temperatures,
lack of fresh water, or both.
However, the
principles are not limited to agriculture and may readily be adapted to the
built environment. Indeed many of the principles have been in use since
antiquity to moderate the climate in hot, arid regions. The range of
possibilities for cooling is considerably enhanced by using seawater. This is a
relatively new development, requiring the use of low cost plastics for pipes,
pumps and heat exchangers (metals that are adequately corrosion resistant to
seawater are generally considered too expensive for such applications).
Every location has
its own unique climate features and solutions that work in one place will not
necessarily work in another. A good starting point is to look at those
conditions and see how they can be best exploited. Gran Canaria for example,
has abundant sunshine year round yet with moderate temperatures for its latitude
(which is the same as Kuwait). The surface seawater is quite cool as a result
of the Canary Current and upwelling of arctic water off the coast of Morocco.
It also lies in close proximity to very deep, cold seawater. Within 4 km of the
harbour, the seabed falls rapidly to a depth of 1000 metres, where the water
temperature is 9ºC. The mean wind speed of 7m/s and NNE direction are
remarkably constant year round.
These conditions
may all be used to provide sustainable and low cost methods of cooling, and the
production of fresh water.
The proposed
development affects an area of about 400 000 m2. In the sunny climate
of the Canary Islands,
the amount of solar energy falling on this area is very large, reaching about
320 MW. If, for example, just 1/10th of that energy were used to
distil fresh water from seawater, around 300 m3 per day of freshwater
would be produced. That could be enough to irrigate some 50,000 m2 of
gardens. If additional shade is created, then even larger garden areas could be
irrigated with the same amount of water.
The concept is
similar to that used in the Seawater Greenhouse, where solar heat is collected
from the roof of the greenhouse and fed into a distillation process that
produces freshwater. See the diagram below.
The general
approach is to use the same hardware to both collect solar energy and
provide shade and cooling for buildings, patios, atria etc. The need for
power-hungry air conditioning equipment will therefore be eliminated.
The design of the garden is based on circles of vegetation, water and sand
The water theatre, doubles as an outdoor auditorium with a capacity for 1,500 people, distills fresh water from the prevailing trade winds
The Harbor Authority building, located at the front of the Wharf of the Light.
The footbridge unites the harbour with a circular walkway
The garden at a higher level provides for cafeterias and restaurants underneath and retains the existing municipal market
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