Abstract
Previous investigations of the large-scale deployment of Ocean Thermal Energy Conversions (OTEC) systems are extended by allowing some atmospheric feedback in an ocean general circulation model. A modified ocean-atmosphere thermal boundary condition is used where relaxation corresponds to atmospheric longwave radiation to space, and an additional term expresses horizontal atmospheric transport. This produces lower steady-state OTEC power maxima (8 to 10.2 TW instead of 14.1 TW for global OTEC scenarios, and 7.2 to 9.3 TW instead of 11.9 TW for OTEC implementation within 100 km of coastlines). When power production peaks, power intensity remains practically unchanged, at 0.2 TW per Sverdrup of OTEC deep cold seawater, suggesting a similar degradation of the OTEC thermal resource. Large-scale environmental effects include surface cooling in low latitudes and warming elsewhere, with a net heat intake within the water column. These changes develop rapidly from the propagation of Kelvin and Rossby waves, and ocean current advection. Two deep circulation cells are generated in the Atlantic and Indo-Pacific basins. The Atlantic Meridional Overturning Circulation (AMOC) is reinforced while an AMOC-like feature appears in the North Pacific, with deep convective winter events at high latitudes. Transport between the Indo-Pacific and the Southern Ocean is strengthened, with impacts on the Atlantic via the Antarctic Circumpolar Current (ACC).
Highlights
The concept of Ocean Thermal Energy Conversion (OTEC), formulated by d’Arsonval and first tested at sea by Claude [1,2], has fascinated generations of engineers
It is not clear that invoking solar power alone is even appropriate since all heat fluxes at the ocean surface tend to balance one another [10]. This approach fails to recognize that relatively large seawater flow rates are required to operate OTEC power plants, and that the availability of deep cold seawater in tropical areas depends on large-scale oceanic circulation
From a 30 Sv (1 Sv = 106 m3 s−1) estimate of the thermohaline circulation that ventilates ocean basins, and a typical 3 m3 s−1 requirement to generate 1 MW of OTEC electricity, Cousteau and Jacquier sized the global OTEC resource at 10 TW [11]. This extremely simple argument is attractive in principle, but it still assumes that the cold seawater intensity of OTEC power production does not change, i.e., that the thermal structure of the water column is unaffected
Summary
The concept of Ocean Thermal Energy Conversion (OTEC), formulated by d’Arsonval and first tested at sea by Claude [1,2], has fascinated generations of engineers. It is not clear that invoking solar power alone is even appropriate since all heat fluxes at the ocean surface tend to balance one another [10] This approach fails to recognize that relatively large seawater flow rates are required to operate OTEC power plants, and that the availability of deep cold seawater in tropical areas depends on large-scale oceanic circulation. From a 30 Sv (1 Sv = 106 m3 s−1) estimate of the thermohaline circulation that ventilates ocean basins, and a typical 3 m3 s−1 requirement to generate 1 MW of OTEC electricity, Cousteau and Jacquier sized the global OTEC resource at 10 TW [11] This extremely simple argument is attractive in principle, but it still assumes that the cold seawater intensity of OTEC power production does not change, i.e., that the thermal structure of the water column is unaffected
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