Estimates of global Ocean Thermal Energy Conversion (OTEC) resources using an ocean general circulation model

Global Ocean Thermal Energy Conversion (OTEC) resources are assessed for the first time with an ocean general circulation model (OGCM). Large-scale OTEC operations are represented with fluid sources and sinks of prescribed strength in global (4° × 4°) MITgcm simulations. Preliminary steady-state (time-asymptotic) results show similarities, but also significant differences with earlier one-dimensional (1-D) studies. It is confirmed that global OTEC resources are likely limited by OTEC flow effects on the stability of the vertical oceanic thermal structure. Such a limit is several times greater in a full three-dimensional context, however, with an estimated maximum annual OTEC net power production of about 30 TW. The significant OTEC flow rates corresponding to maximum net power output would result in a strong boost of the oceanic thermohaline circulation (THC). In contrast to simple 1-D analyses, the present simulations of large-scale OTEC operations also show a persistent cooling of the tropical oceanic mixed-layer. This would be balanced by a warming trend in the higher latitudes, which may practically limit OTEC deployment to smaller flow rates than at maximum net power output. An annual OTEC net power production of about 7 TW, for example, could be achieved with little effect on the oceanic temperature field.

► OTEC resources assessed for the first time with an ocean general circulation model.
► OTEC resources are limited by the stability of the oceanic thermal stratification.
► A maximum OTEC net power production of about 30 TW was estimated.
► With large OTEC operations, cooling of the tropical oceanic mixed-layer persists.
► At maximum OTEC power output, the Atlantic THC doubles from 15 Sv.