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US-12622371-B2 - Open aquatic algae cultivation system with semipermeable liner sections for improved environmental uptake of carbon dioxide

US12622371B2US 12622371 B2US12622371 B2US 12622371B2US-12622371-B2

Abstract

An open aquatic algae cultivation system (OAACS) with an algae impermeable liner that includes semipermeable liner sections for improved environmental uptake of carbon dioxide is disclosed. OAACS comprises a buoyant framework, an algae impermeable liner with a structure largely impermeable to the cultivated algae culture but with semipermeable liner sections permeable to dissolved inorganic carbon, a culture, and a mooring system. Practical semipermeable liner sections are also disclosed.

Inventors

  • Stuart Bussell

Assignees

  • Stuart Bussell

Dates

Publication Date
20260512
Application Date
20221121

Claims (20)

  1. 1 . A floating generally rectangular algae cultivation system with a length, a width, and ends designed for flotation and positioning on the surface of a body of water and wherein the positioning is for creation of a unidirectional longitudinal wind driven surface current of an algae culture within the system comprising: a) a buoyant framework arranged into longitudinal members along the entire length and transverse members along the entire width with a set of two longitudinal and two transverse members forming all four of the ends and at least one interior transverse member, wherein the longitudinal and transverse members comprise pipes that are conduits for a plurality of process fluids selected from the group comprising nutrient feeds, culture, and surrounding water; b) an algae impermeable liner comprising at least three sections, wherein each section is attached to the longitudinal members and adjacent sections are attached either to each other or to an interior transverse member, wherein the buoyant framework and the algae impermeable liner create a containment structure and the at least three sections comprise; i. at least two semipermeable liner sections having two planar surfaces, an interior, and pores through the interior, wherein the semipermeable liner sections are permeable to dissolved inorganic carbon; and ii. at least one nutrient impermeable liner section that is impermeable to nutrients added to the system; wherein the at least three sections are arranged consecutively from upstream to downstream such that one semipermeable liner section starts upstream of the at least one interior transverse member and continues downstream to it; one nutrient impermeable liner section starts at the at least one interior member and continues downstream from it, and one semipermeable liner section starts at the downstream end of the one nutrient impermeable liner section and continues downstream from it; c) a mooring system; and d) at least one of culture harvesting and nutrient replenishment systems positioned at each of the two transverse members forming two of the ends and the at least one interior transverse member.
  2. 2 . The algae cultivation system according to claim 1 wherein the mooring system comprises a mooring line.
  3. 3 . The algae cultivation system according to claim 1 wherein the mooring system comprises a buoy system.
  4. 4 . The algae cultivation system according to claim 1 wherein the buoyant framework comprises at least one bundle of at least two tubes.
  5. 5 . The algae cultivation system according to claim 1 wherein at least one of the longitudinal members connects to at least one of a ship, platform, buoy, tank, or a piping network.
  6. 6 . The algae cultivation system according to claim 1 wherein the nutrient feeds include at least one selected from the group consisting of nitrogen, iron, and phosphorous.
  7. 7 . The algae cultivation system according to claim 1 wherein the interior transverse member further comprises at least one platform.
  8. 8 . The algae cultivation system according to claim 7 wherein the at least one platform comprises at least one platform support that floats in the culture and is arranged to form lengthwise channels together with the algae impermeable liner.
  9. 9 . The algae cultivation system according to claim 1 wherein the system is more than 1 kilometer long and more than 100 meters wide.
  10. 10 . The algae cultivation system according to claim 1 which further comprises a submersion system for lowering the cultivation system below the surface of the body of water.
  11. 11 . The algae cultivation system according to claim 10 wherein the longitudinal members comprise at least one bundle of at least two pipes and at least one of the pipes is a ballast tube.
  12. 12 . The algae cultivation system according to claim 11 wherein the submersion system comprises systems to change the buoyancy of the ballast tube.
  13. 13 . The algae cultivation system according to claim 10 which further comprises a depth pressure sensor for controlling the depth of submersion of the algae cultivation system.
  14. 14 . The algae cultivation system according to claim 10 wherein the submersion system comprises a winch system.
  15. 15 . The algae cultivation system according to claim 14 wherein the winch system comprises a free hanging submerging line that extends to a subsurface.
  16. 16 . The algae cultivation system according to claim 1 wherein there are at least two algae cultivation systems.
  17. 17 . The algae cultivation system according to claim 1 wherein the cultivation system further comprises the process fluids.
  18. 18 . The algae cultivation system according to claim 17 wherein the process fluids comprise a culture in the containment structure.
  19. 19 . The algae cultivation system according to claim 1 wherein the semipermeable liner section comprises fibers.
  20. 20 . The algae cultivation system according to claim 19 wherein the fibers comprise at least one hydrophobic polymer.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. provisional application number U.S. 63/281,941, filed Nov. 22, 2021, naming Stuart Bussell as inventor. FIELD OF THE DISCLOSURE This disclosure relates most generally to a cultivation system, which is an algae cultivation system floating on the surface of a body of water. The disclosure also relates to the cultivation of algae using the algae cultivation system of the disclosure to grow an algae culture in a containment system, by exposing it to sunlight, wind, and waves. BACKGROUND OF THE DISCLOSURE Photosynthetic algae have long been recognized as a potential source of large amounts of biomass (Richmond and Hu 2013). Algae grow significantly faster than plants, offering the promise of more rapid conversion of CO2 into useable organic materials. However, to date, algae have been unable to compete on a large scale with traditional plant-based agriculture for a number of reasons, including: 1) they normally require large amounts of costly water to cultivate, 2) the costs of installing and maintaining an algae pond can be cost prohibitive, 3) operational costs, including supplemental CO2 supplies and energy for mixing to operate high productivity ponds, can be cost prohibitive, and 4) harvesting the algae from the ponds can be costly. Traditional large-scale algae cultivation also competes with traditional agriculture and other land uses for high insolation level land. Once the algae are harvested, the costs of converting them to useable products are comparable to conventional crops and will depend upon the final desired products and the quality of the starting materials relative to them. If improvements to algae cultivation techniques are able to make the cultivation of algae more cost effective than conventional plant-based agricultural crops, large-scale generation of algal biomass can be used as a supplement or replacement for conventional products like food, agricultural feeds, and fuels. Traditional systems to grow algae have been limited in scale and characterized by high installation and operating costs. They are categorized into three distinct groups, open systems, closed systems, and hybrid systems. The categorization is based on whether cultures are exposed to the surrounding environment. Open systems are exposed, closed systems are not, and hybrid systems attempt to combine the best qualities of the other two systems. A typical open system is the raceway pond. It derives its name from its resemblance to a horse racetrack. Large raceway ponds generally encompass no more than 2-3 acres of growth area, because larger ponds are unable to effectively establish recirculation in the direction opposed to any prevailing winds. The pond depth is typically several feet deep, and the culture is usually circulated around the track by using a powered paddle wheel. The paddle wheel provides mixing to the pond. Expenses for nutrients, including CO2 gas, water, and power are some of the major operating costs of an open system. Substantial fixed costs, like the installation of the pond and the cost of the land on which it sits, also contribute to making the costs of operating open systems prohibitive compared to conventional crop farms. Referring to the list of cost factors above, open systems are prone to all four and represent the base case for the following comparisons. There are many types of closed systems that have been developed for the cultivation of algae in an attempt in improve the yields from these cultures and thus reduce costs. The logic behind these attempts is that by using a well-controlled system that is isolated from environmental contamination, high yielding species of algae can be cultivated without interference from others, and conditions for the culture can be optimized for highest yields. Comparing the cost factors of closed systems to racetrack type open systems, they suffer from the same ones, but the balance between them is shifted. Closed systems have the potential to save water because they suffer from less evaporation during cultivation. However, the evaporation in open systems provides a mechanism to cool the culture, and cost savings from using less water can easily be surpassed by more energy needed to cool the culture. Because closed systems are more highly engineered, installation and maintenance costs of closed systems tend to be much higher than those for racetrack type open systems. Finally, while yields tend to be higher for closed systems, the operational costs tend to be higher, mitigating, or even overwhelming, any potential benefits from the higher yields. Scale of operation for closed systems tend be smaller than open systems because of high associated infrastructure costs. Hybrid systems attempt to mix the best qualities of open and closed systems in order to achieve economic competitiveness. Usually, small closed systems grow a preferred algae species which then seed a large open system. Th