Towards a practical resource assessment of the extractable energy in the Agulhas ocean current

Abstract

In a found region of energetic flow in the Agulhas Current, two locations are analysed. It is found that the current core borders on the mid-shelf (91 m depth) location and off-shore (255 m depth) location lies within its predominant path, with mean velocities of 1.34 m/s and 1.59 m/s respectively at a 30 m depth. In the period analysed only one large meander is noted at a depth of 30 m. The percentage current reversals are 4.1% and 3.1% at the mid-self and off-shore locations, respectively.

The most suited developed technology found to potentially deploy in this current is Minesto Deep Green turbine. The found capacity factor and specific yield for one Minesto (DG-12) 500 kW turbine at 30 m depth is estimated to be 62% with (4886 kWh/year)/kW for the mid-shelf location and 76% with 5416 (kWh/year)/kW for the off-shore location. Through a simplified analysis, the capacity credit of a possible 2000 MW array is analysed. It is found that an ocean current power plant can add to the load carrying capacity of the country and outperforms onshore wind power plants in this respect. The largest barriers at present are the cost and mooring challenges which presents a need for a detailed economic assessment to determine if associated costs of working in deeper waters (off-shore site) are justified.