THE COLD UTILIZATION SUBSYSTEM
COLD UTILIZATION
The second subsystem - cold utilization is depicted in th illustration
Here the most economically valuable use of deep ocean water appears
in the form of air conditioning and industrial cooling. Conventional
means of cooling are in fact forms of reverse OTEC. As a consequence
they pay a heavy Carnot efficiency penalty. On the average these
systems generate ten times as much heat as they remove in terms
of cold.. The Natural Energy Laboratory makes extensive use of
this efficiency in all of its cooling processes. A simple double
pipe heat exchanger which substitutes for the refrigeration equipment
was employed for our main laboratory building. The cost of the
double pipe replacement is several hundred dollars and required
no engineering of any sophistication. The monthly savings in cost
for this building are approximately $3000.00 from a previous total
bill of about $3,500.00. Large areas of the industrial world such
as the West Coast of the United States could realize huge savings
in energy costs, in CO2 generation and in restoration of the microclimate
of major cities. In small villages where air conditioning is considered
a luxury, the major energy use appears in the cooling facilities
for fisheries and other perishable food items. As will be shown
the need for such cooling and cold storage facilities will be
greatly increased as the deep ocean water is employed for aquaculture
and agriculture.
Another major cold utilization for deep ocean water is in the
generation of fresh water and other distillation and fermentation
processes. Classical approaches to this generation focus on evaporation
of surface waters utilizing high vacuum Figure 16 and condensation
with deep ocean water. This techniques energy efficient but requires
moderately sophisticated and expensive technology. Less efficient
but simpler are the use of elemental condensation plates. In its
simplest form condensation is removed from heat exchanger modules
manufactured by roll bonding techniques. Thus low cost units whose
cost are order of magnitude $100.00 can produce from fifteen to
thirty gallons of distilled water per day. In places like Christmas
Island or Cape Verde where potable water is at a premium this
simple technique can easily provide self sufficiency. Most recently
there has been designed and patented a tower that simulates a
hurricane The Hurricane Tower which produces water as a hurricane produces water.
But condensation techniques coupled with biophysical applications
of cold have produced a surprising result in terms of agriculture
in coastal desert areas. Quite simply black plastic irrigation
pipe is embedded in agricultural soil at a depth which corresponds
to the root depth of the species to be cultivated. Deep ocean
water is passed through these pipes and heavy condensation is
induced. An inadvertent happening in the early development of
this process demonstrated the potential for organic gardening
with minimum attention for a wide variety of valuable agricultural
crops. In this instances a field of strawberry plants were prepared
in accordance with the coldwater (Coldag) technique. For unexpected
personal reasons the individual who was assigned the task of tending
the beds was absent for a period of four months. With minimum
tending by volunteers the strawberry plants proliferated in a
healthy ground cover as shown in this historic picture. Of particular
significance was the growth of the strawberry plants beyond the
prepared beds along the exposed coldwater pipes. This demonstrates
beyond any doubt that the growth mechanism relates to the cold
and the condensate produced by the process. When this environmentally
sustainable organic form of garden was recognized a cooperative
farm was formed with volunteer who agreed to develop a wide variety
of crops. Surprisingly almost every species produce crops of high
quality unusual sweetness and rapid growth. It is now recognized
that the thermodynamic processes in plant growth play a major
role in the transport of phosphates and nitrates to the fruiting
and vegetation areas and that the production of high energy products
such as sugar is highly dependent upon temperature differences
along the transport path of these nutrients. Thus the application
of cold in the root area of spring crops produces unusually sweet
fruit while it is known that the application of cold to the ripening
of fall fruits has a similar result. As a consequence tests are
being conducted with modifications of the air temperature as well
as root temperature. More than seventy five crops with varying
locations of cold application have now produced in a span of only
five months. The section on Cold Water Agriculture depicts a number of these successful products.
After the deep ocean water has been employed in one or more cold
utilization applications it can be utilized again for the residual
cold (about 13 degrees C) and the nutrients.