Offshore floating wind turbine-driven deep sea water pumping for combined electrical power and district cooling

Abstract

A new concept utilising floating wind turbines to exploit the low temperatures of

deep sea water for space cooling in buildings is presented. The approach is based on offshore

hydraulic wind turbines pumping pressurised deep sea water to a centralised plant consisting of

a hydro-electric power system coupled to a large-scale sea water-cooled air conditioning (AC)

unit of an urban district cooling network. In order to investigate the potential advantages of

this new concept over conventional technologies, a simplified model for performance

simulation of a vapour compression AC unit was applied independently to three different

systems, with the AC unit operating with (1) a constant flow of sea surface water, (2) a

constant flow of sea water consisting of a mixture of surface sea water and deep sea water

delivered by a single offshore hydraulic wind turbine and (3) an intermittent flow of deep sea

water pumped by a single offshore hydraulic wind turbine. The analysis was based on one year

of wind and ambient temperature data for the Central Mediterranean that is known for its deep

waters, warm climate and relatively low wind speeds. The study confirmed that while the

present concept is less efficient than conventional turbines utilising grid-connected electrical

generators, a significant portion of the losses associated with the hydraulic transmission

through the pipeline are offset by the extraction of cool deep sea water which reduces the

electricity consumption of urban air-conditioning units.