This project was designed to investigate the economic and commercial feasibility of using cold deep ocean water (DOW) in an integrated system that would provide fresh water through atmospheric condensation and increased or new crop production through application of cold water agriculture techniques. Such an integrated system would likely be constructed in tandem with other DOW technologies, such as Sea Water Air Conditioning (SWAC), Ocean Thermal Energy Conversion (OTEC) and use of the deep ocean water for aquaculture.
The primary site for this study is the island of Saipan in the Commonwealth of the Northern Marianas Islands (CNMI). Saipan was chosen because of its dire fresh water and energy situation and the need to prove DOW concepts in tropical or semi-tropical environments. The CNMI Government had indicated its ready interest in helping to implement this project. A secondary site, as a control for the cold water agriculture experiments, was the Waimanalo Research Station of the University of Hawaii’s College of Tropical Agriculture & Human Resources (CTAHR).
The first task was to establish the feasibility of accessing deep ocean water on Saipan. As a general statement, this requires installation of a piping system that can bring sufficient quantities of cold DOW to the surface for the applications envisaged, which could potentially include not only the cold agriculture and potable water production technologies under investigation, but also Sea Water Air Conditioning, Ocean Thermal Energy Conversion, aquaculture or other technologies. In fact, using the same piping system for several of these applications in series or in tandem is probably necessary to justify the cost of the deep ocean pipes. So, the first question to be answered was whether or not the pipes themselves are feasible in the chosen location. Makai Ocean Engineering, arguably the world’s leading designer and builder of deep ocean pipes, took the lead in this part of our investigation. The answer is clear: the placement of pipes off Marpi Point on Saipan's northern coast is feasible, but at a cost of between $15 and $25 million depending on design, capacity, and precise location.
Once the feasibility of the deep pipes was established, the project focused on the twin technologies of cold agriculture and fresh water condensation. Cold agriculture (ColdAg™) was pioneered in the 1990s by Common Heritage Corporation in demonstration plots at the Natural Energy Laboratory of Hawaii. Our objective for ColdAg™ under this grant was to establish a scientific baseline for production of needed temperate zone crops in an arid tropical area using cold DOW to create the necessary growing conditions for the crops. Actual deep ocean water, of course, was not used since no deep ocean pipe yet exists off Saipan or at Waimanalo, but the cold DOW was simulated using fresh water cooled to the desired temperatures. The basic concept was to run chilled water through a closed piping system a few inches deep in the soil, chilling the soil and the plant roots to create “Spring-like” conditions for the temperate zone crops being tested. Our thesis was that such conditions chill the roots, produce fresh water condensation in the soil near the roots and may, through resultant water flow, prompt transport of natural nutrients from surrounding soil to the root systems. Results from the tests on Saipan were excellent, achieving high quality temperate zone crops in an area where they could ordinarily not be grown. Results from the control plots in Waimanalo were problematic, owing to an infestation of nematodes and failure of a generator, which made Waimanalo’s results inconsistent. The Saipan results, however, indicate that ColdAg™ was proven as a viable means of producing temperate zone crops in an arid, tropical area where such growth was otherwise not possible. The results appear to confirm the beneficial effects of creating the “Springtime” environment for the crops, though we have not yet confirmed the impact of condensation or nutrient flow. More trials are needed. The general outline of an integrated ColdAg™ system, using sample products, is shown below:
The primary site for this study is the island of Saipan in the Commonwealth of the Northern Marianas Islands (CNMI). Saipan was chosen because of its dire fresh water and energy situation and the need to prove DOW concepts in tropical or semi-tropical environments. The CNMI Government had indicated its ready interest in helping to implement this project. A secondary site, as a control for the cold water agriculture experiments, was the Waimanalo Research Station of the University of Hawaii’s College of Tropical Agriculture & Human Resources (CTAHR).
The first task was to establish the feasibility of accessing deep ocean water on Saipan. As a general statement, this requires installation of a piping system that can bring sufficient quantities of cold DOW to the surface for the applications envisaged, which could potentially include not only the cold agriculture and potable water production technologies under investigation, but also Sea Water Air Conditioning, Ocean Thermal Energy Conversion, aquaculture or other technologies. In fact, using the same piping system for several of these applications in series or in tandem is probably necessary to justify the cost of the deep ocean pipes. So, the first question to be answered was whether or not the pipes themselves are feasible in the chosen location. Makai Ocean Engineering, arguably the world’s leading designer and builder of deep ocean pipes, took the lead in this part of our investigation. The answer is clear: the placement of pipes off Marpi Point on Saipan's northern coast is feasible, but at a cost of between $15 and $25 million depending on design, capacity, and precise location.
Once the feasibility of the deep pipes was established, the project focused on the twin technologies of cold agriculture and fresh water condensation. Cold agriculture (ColdAg™) was pioneered in the 1990s by Common Heritage Corporation in demonstration plots at the Natural Energy Laboratory of Hawaii. Our objective for ColdAg™ under this grant was to establish a scientific baseline for production of needed temperate zone crops in an arid tropical area using cold DOW to create the necessary growing conditions for the crops. Actual deep ocean water, of course, was not used since no deep ocean pipe yet exists off Saipan or at Waimanalo, but the cold DOW was simulated using fresh water cooled to the desired temperatures. The basic concept was to run chilled water through a closed piping system a few inches deep in the soil, chilling the soil and the plant roots to create “Spring-like” conditions for the temperate zone crops being tested. Our thesis was that such conditions chill the roots, produce fresh water condensation in the soil near the roots and may, through resultant water flow, prompt transport of natural nutrients from surrounding soil to the root systems. Results from the tests on Saipan were excellent, achieving high quality temperate zone crops in an area where they could ordinarily not be grown. Results from the control plots in Waimanalo were problematic, owing to an infestation of nematodes and failure of a generator, which made Waimanalo’s results inconsistent. The Saipan results, however, indicate that ColdAg™ was proven as a viable means of producing temperate zone crops in an arid, tropical area where such growth was otherwise not possible. The results appear to confirm the beneficial effects of creating the “Springtime” environment for the crops, though we have not yet confirmed the impact of condensation or nutrient flow. More trials are needed. The general outline of an integrated ColdAg™ system, using sample products, is shown below:
This project was not intended to produce a working prototype of a fresh water condensation system, but to further the research and design work needed to get us to that point. The concept is known to anyone who has taken a cold glass filled with ice outside in the summer. Our design work drew on an early prototype built by Common Heritage Corporation (CHC) at the Natural Energy Laboratory of Hawaii (NELHA). That prototype, which we called SkyWater, successfully produced fresh water from the atmosphere using condensation brought about be piping cold DOW through the system. Efficiencies were improved by also using available trade winds to enhance the cooling effect of the deep ocean water. Still, efficiencies were not good enough to justify fullscale applications and many questions remained concerning the design of water collectors, condensation surfaces and the materials that could increase efficiencies.
Early SkyWater Design
Nisymco Inc. had done independent research and was brought into the project to take the lead on improving our designs. New designs were produced that combine the approaches of the two companies, and considerable progress was made on identifying appropriate materials to enhance efficiency. Building actual prototypes was beyond the scope of the project and will require additional funding.
The bottom line is that (1) deep ocean pipes are a feasible option for installation off Saipan; (2) temperate zone crops were successfully grown where they otherwise could not be grown; and (3) a vastly updated and, we believe, more efficient design was produced for condensing fresh drinking water from the atmosphere.
Economic feasibility remains a question. The "killer applications" for Deep Ocean Water have been Sea Water Air-Conditioning (SWAC) and, to a lesser extent, Ocean Thermal Energy Conversion (OTEC), neither of which were investigated in this project. SWAC is in use commercially in several projects around the world, notably in Halifax, Nova Scotia, at Cornell University (using cold lake water), at the University of Hawaii Medical School in Honolulu, and at an InterContinental Bora Bora Resort & Thalasso Spa in French Polynesia. The latter claims that SWAC has cut their electricity bill by more than 90%, thoroughly and quickly justifying the costs of putting down a deep pipe. OTEC is less proven, but we understand that efficiencies are showing dramatic improvements and that commercial operations are on the horizon. Our conclusion is that either SWAC or OTEC can justify the installation of the DOW piping system. When used as part of a system which includes SWAC and/or OTEC, ColdAg™ and SkyWater can dramatically enhance the economic viability of an integrated project by adding on new products and revenues at little or no additional initial cost. Our detailed economic analysis, included in the Technical Discussion below, concludes that the annual savings from a DOW system using SWAC, SkyWater and ColdAg™ would likely be about 11% of its capital cost.
The project was carried out by Saipan DOW Project LLC, a wholly-owned subsidiary of Common Heritage Corporation (CHC). Partners and contractors include Makai Ocean Engineering, Nisymco Inc., Nauticos LLC, Kekepana International Services, Shimokawa Architects, Inc., SSFM International Inc., Air Masters Inc. and FMS Consulting Services. Faculty and personnel of the University of Hawaii’s College of Tropical Agriculture & Human Resources were among our investigators.
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