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Cold Utilization Subsystem - Cooling Technology
One application for DOW technology is cost-effective air conditioning and industrial cooling. In warm climates and seasonally hot regions, air conditioning and industrial cooling consume an enormous amount of energy. For large buildings and hotels in tropical and subtropical climates, air conditioning represents the major source of energy demand for an entire complex. A single hotel room requiring from 0.75 to 1.0 ton of air conditioning per day has an energy requirement of 0.9 kW of electricity. A hotel complex or resort with 1,000 rooms has a possible peak electrical demand of one megawatt just for air conditioning.
DOW air conditioning uses the pumped deep seawater directly or the residual cold water after it has been pumped up and run through an OTEC plant. The components that make up a centralized seawater air conditioning system include: an intake pipe to carry the deep ocean water, a pumping station to bring the water up, a cooling station (aluminum or titanium heat exchangers) to transfer the heat from the fresh water circulating internally through the buildings to the cold seawater, and a return line through which the deep seawater goes back to the ocean (Van Ryzin and Leraand, 1992).
The NELHA, which is located in a tropical coastal desert, has utilized DOW for cooling administration buildings since 1986 at substantial energy savings. A similar seawater air conditioning system exists at Purdy's Wharf in Halifax, Nova Scotia. Stockholm Energy has been cooling properties in central Stockholm with cold water from the Baltic Sea since 1995. Also, a nearby lake can be the source of the cold water resource. The first large-scale application of this cooling technology is at Ithaca, New York, where a 63-inch pipeline was installed to link Cornell University and nearby Lake Cayuga in 1999. The pipeline accesses 4℃ water at a depth of 250 feet. The system, which can provide 20,000 tons of cooling, is supplying air conditioning to the Cornell University Campus and the Ithaca City Schools. Makai Ocean Engineering of Hawaii was involved in the design and construction of that facility. The second major application of the use of cold lake water may be the city of Toronto, Canada. Toronto city planners have been developing plans to utilize cold water from Lake Ontario to air condition the downtown district of the city.
It is calculated that utilizing DOW for cooling can save as much as 80% of the energy cost compared to typical compressor type cooling systems. A simple heat exchanger coupled with solar powered air fans can air condition schools, government buildings, sporting complexes, commercial buildings and residences cheaply. Dow cooling is both inexpensive and environmentally sound, for it uses no chemical compressor fluids and is sustainable with no emissions; it is a thermal process which generates no heat. It can be inexpensively distributed long distances horizontally along the shoreline. Moreover, commercial and residential unit systems using this technology cool and dry the interior air, creating an environment ideal for electronic equipment and dry storage. Additionally, coastal resort communities with large air conditioning demands can become more competitive by reducing operation and energy costs. One thousand gallons of DOW, which cost US10¢to pump, can cool 2,500 ft3. Payback periods for initial capitalization costs are quite small for large systems (Davidson, 2001).
Cold Utilization Subsystem - Freshwater Technology
Innovative technologies are being developed to enhance and capture condensation from surfaces cooled by flows of DOW to provide lifesaving fresh water to many coastal desert communities. Indeed, a vast proportion of the world's coastline is desert, and the largest obstacle to sustaining life is the scarcity of fresh, usable water. Although evaporation takes place, it rarely rains in coastal regions. Moisture rising from the ocean is carried inland across coastal lowlands, seldom falling as rain until it encounters a mountain range. DOW technology has provided innovative methods for producing fresh, potable water on tropical coastal deserts. The DOW developments that provide this most precious desert commodity are: desalinated water as a bonus byproduct of OTEC systems; fresh water rain from the Hurricane Tower; and condensate from pipes supplied with cold ocean water.
One method for producing large quantities of desalinated water is an adjacent function of the open-cycle OTEC system. As described previously, the system involves passing warm surface seawater into an area where the ambient pressure is reduced so that the seawater turns to steam. The resultant condensate is pure, salt-free fresh water that can be used for drinking or irrigation. In fact, the desalinated water produced by open-cycle plants is less saline than the water provided by most municipal water systems and is free of atmospheric and ground contaminants. The closed-cycle OTEC system can indirectly produce fresh water. The same cold ocean water that is employed to run the system can be transferred to a separate heat exchanger, and fresh water which condenses from the humid tropical air can be collected and stored as a potable water supply. Alternatively, a second stage consisting of a vacuum evaporator and a surface condenser can be added to the closed system for desalinated water production.
The discovery that large quantities of pure condensate are produced as a byproduct of both OTEC systems inspired Dr. John Craven and other DOW researches to invent a new exciting patented technology, christened the "Hurricane TowerTM", which also uses temperature differences to produce pure condensate (Craven and Sullivan, 1998) . The Hurricane Tower is a micro-climate structure in which nature's hurricanes are simulated to generate rain.
The Hurricane Tower model was carefully designed and fitted with the components and ingredients necessary to simulate a real hurricane. Warm surface seawater, which has been further heated in a solar pond covered with plastic, is introduced into the bottom of a 20-foot high tower to simulate the surface of the sea. A lightweight rotor driven by a motor installed in the tower floor simulates the hurricane vortex by spinning with a peripheral velocity of 100 mph. A heat exchanger made of tubing spiraled around the inside top of the tower and supplied with cold seawater simulates the lenticular cloud of ice of the tropopause (the upper limit of the troposphere). It has been determined that a tower of this size will be able to produce 10,000 gallons of pure fresh water per day.
Another method for producing desalinated water is the collection of fresh water condensate. CHC has shown that, as deep ocean water is passed through a heat exchanger, the amount of pure water condensate produced from the humid atmosphere is equal to 5% of the total quantity of cold water flowing through the system. In other words, if the relative humidity is over 80%, up to 5 liters of pure potable water can be produced for every 1,000 liters of deep seawater flowing through heat exchangers in the atmosphere. This is equivalent to approximately 4 inches of rain per day or 1,200 inches per year. Water can be captured at an elevation of 25 feet by utilizing a siphon which transports cold up where it can produce condensate. So far, the collection of condensate from an inexpensive heat exchanger with DOW in this mariner is the most cost-effective method for producing fresh water. For example, freshwater condensation can drip from the heat exchanging coiled tubing supplied with DOW into a storage tank in the CHC's "Rasmussen Rainmaker". At a flow rate of 1.5 gallons per minute of DOW, this system produces from the atmospheric moisture 11.5 gallons of fresh water per day or some 4,200 gallons per year. The water is surprisingly cold, and the system requires no moving parts or additional energy to operate.
Cold Utilization Subsystem - ColdAgTM Technology
Of all the applications of DOW technologies to date, the unique CHC invention, cold water agriculture or ColdAg, is proving to be the most remarkable The name "Blue Green Revolution" was chosen to designate this new form of agriculture in order to express the possibility of a blue ocean creating life and greenery in a coastal desert.
By utilizing only the cold from deep ocean water, a year-round-spring-like microclimate for plant roots under tropical desert conditions is created which produces ideal conditions for growth of tropical, subtropical and temperate crops. Basically, DOW pumped to the surface is directed into plastic pipes embedded in the soil at a particular plant root depth for the purpose of cooling the ground, thereby creating a spring-like microclimate that extends from below the plant roots to the soil surface. Since the soil surface is below the dew point, which is in the 60 to 70°F range in tropical coastal regions, moisture in the warm tropical air is drawn down to the cool soil causing freshwater condensate to form and be carried onto the cold pipes and plant roots by gravity. The soil is therefore largely self-irrigating. Plants are able to capture thermal energy created by the temperature difference between the roots and the foliage. This added energy potential enables the plants to grow at an incredible rate seen elsewhere only in springtime - 365 days a year in a coastal desert.
CHC has grown more than one hundred varieties of fruits, vegetables and herbs, all showing surprisingly high sugar and aromatic content, with ColdAg. The salt water is confined to the pipes and does not touch the plants or the ground. ColdAg has been developed using organic gardening techniques and has enormous potential for developing countries with tropical coastal deserts adjacent to deep ocean.
This revolutionary new form of agriculture also allows gardener researchers to exploit and manipulate the biophysical applications of cold to force and break dormancy in seasonal and perennial plants by turning off the cold water for a period and then restoring it, thereby simulating the effect of a temporary climate change. With the restoration of the cool root environment, dormancy is broken and the plant reenters its production cycle. This allows for the possibility of three or four annual harvest cycles in one year. The most convincing example of manipulating dormancy is with wine grapes. Subjecting grape vines to a short period of drought at local tropical desert temperatures by turning off the cold water and then restoring the water to break dormancy has resulted in a remarkable crop of the very best temperate grapes per vine every 110 days or a total of three crops a year.
One positive feature of ColdAg is that it requires no drainage; there is a complete absence of wastewater that threatens the environment by contributing run-off pesticides, herbicides and fertilizers as often occurs with traditional irrigation methods.
A particularly interesting spin-off has been the development of CHC EcoturfTM Technology. This will grow and maintain high quality turf consisting of grasses from virtually any climatic zone under tropical desert conditions. As with other plants, these world-class turfs use ColdAg TM technology that produces fresh water condensate from deep ocean water, reducing watering by at least 80% compared to traditional irrigation methods. They consist of longer, deeper grass roots that make better playing surfaces; they are able to withstand impact and then come back for more by repairing themselves quickly. This technology makes possible the development of high quality low-cost landscaping and creates safer playing surfaces for sports, e.g., soccer, baseball, football, lawn tennis, golf and lawn bowling, in tropical coastal desert locations.
Nutrient Utilization Subsystem - Marine Aquaculture
In nature, an upwelling, usually caused by the wind, that transports pure, nutrient-rich DOW to the surface occurs regularly in the world's oceans and seas. Although DOW upwelling constitutes only 0.5% of all seawater, it supports nearly 50% of the ocean's food web, from phytoplankton and microscopic zooplankton to fish. DOW aquaculture imitates in warm coastal desert regions the upwelling phenomenon of the natural world by using the still-cold (about 11℃) seawater after it has run through other DOW subsystems. This seawater, which has elevated levels of inorganic nitrates, phosphates and silicates, can be used in its 'pathogen-free' state or combined with surface seawater in aquaculture farms to produce environments acceptable to many temperate and tropical species of marine life. Its high nutrient levels produce more rapid growth and higher protein content in microalgae and macroalgae. It also allows the growth of temperate shellfish (e.g., Maine lobster) and fin fish (e.g., flounder and salmon).