Artificial upwelling using offshore wind energy for mariculture applications
Offshore wind is proposed as an energy source to upwell nutrient-rich deep water to the ocean photic layers. A spar-buoy wind turbine with a rigid tube about 300 m long is proposed as a pipe to drive deep water up to the surface. The minimum energy required to uplift the water is the potential energ...
| Authors: | , , |
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| Format: | article |
| Publication Date: | 2016 |
| Country: | España |
| Institution: | Universitat Politècnica de Catalunya (UPC) |
| Repository: | UPCommons. Portal del coneixement obert de la UPC |
| Language: | English |
| OAI Identifier: | oai:upcommons.upc.edu:2117/186114 |
| Online Access: | https://hdl.handle.net/2117/186114 https://dx.doi.org/10.3989/scimar.04297.06B |
| Access Level: | Open access |
| Keyword: | Mariculture Artificial upwelling Mariculture applications Ocean fertilization Offshore wind energy Spar-buoy wind turbine Aqüicultura marina Àrees temàtiques de la UPC::Enginyeria agroalimentària::Pesca::Aqüicultura |
| Summary: | Offshore wind is proposed as an energy source to upwell nutrient-rich deep water to the ocean photic layers. A spar-buoy wind turbine with a rigid tube about 300 m long is proposed as a pipe to drive deep water up to the surface. The minimum energy required to uplift the water is the potential energy difference between surface waters inside and outside the pipe, which depends on the background density profile. The corresponding surface jump or hydraulic head, h, calculated for several analytical and experimental density profiles, is of the order of 10 cm. If the complete turbine power (of the order of several MW) is used for raising the water (assuming a 100% pump efficiency), in a frictionless flow, very large water volumes, of the order of thousands of m 3 s -1 , will be transported to the photic layers. In a more realistic case, taking into account pipe friction in wide pipes, of the order of 10 m radius, and a power delivered to the fluid of 1 MW, the volume transport is still very large, about 500 m 3 s -1 . However, such a large amount of dense water could sink fast to aphotic layers due to vertical static instability (the fountain effect), ruining the enhancement of primary production. Hence, some ways to increase the turbulent entrainment and avoid the fountain effect are proposed. From the energetic viewpoint, artificial upwelling using offshore wind energy is a promising way to fertilize large open sea regions. This mariculture application is, however, severely subjected to atmosphere and ocean climatology, as well as to ecological dynamics. The general problem is multidisciplinary, and some important physical, engineering and ecological questions need to be seriously addressed to improve our confidence in the ap-proach presented here. |
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