Current Economic Opportunities at the Strait of Gibraltar

The combination of weather driven, climate driven and oceanic dynamics has caused a continually flowing water current at the Strait of Gibraltar. It has been revealed in data pertaining to rainfall and evaporation in the region and offers future ocean-based economic development opportunity in the region. 

Introduction

A televised nature documentary has revealed that evaporation across the Mediterranean Sea removes three times the volume of water as the combined volume of rainfall over the sea and rivers flowing into the sea. The revelation is the result of weather related measurements having been taken over a timespan of several years in regions that surround the Mediterranean Sea and over the sea. Without water channels connecting the Mediterranean Sea to the world ocean, water levels would steadily decline over a period of several decades, as has occurred in the Aral Sea.

Stabilizing water levels in the Caspian Sea would require construction of a navigation canal and water channel to either the Black Sea or the Sea of Azov. Such a channel would increase the removal of water from the Mediterranean as prevailing summer winds blow across the region from north to south. A warmer future summer climate promises to raise surface water temperatures and increase future summer time evaporation across all of the Mediterranean, Black and Caspian Seas along with Sea of Azov. The cumulative effect would be to require massive replacement of seawater sourced from the world’s ocean.

Replacing Lost Seawater

Evaporation from the Mediterranean Sea sustains a flow of seawater from the Atlantic Ocean and through the Strait of Gibraltar. During high tide on the Atlantic Ocean, higher seawater level on the Atlantic side produce an observable slope in the seawater leading to the Mediterranean Sea side of the strait. As a result, seawater flows continually through the strait with highest flow velocity occurring at high tide. There are future prospects for that velocity to increase as warming climate increases future evaporation in the Mediterranean and Black Seas with future replenishment water also flowing into the Caspian Sea.

Due to continual evaporation, salinity is higher in the Mediterranean Sea than in the Atlantic Ocean. As of 2012, seawater flowed at two to three knots (1.544 m/s) eastward through the Strait of Gibraltar. A channel built between Sea of Azov and Caspian Sea would indirectly remove water from both Black Sea and Mediterranean Sea and together with increased future evaporation across both seas, increase water flow velocity through Strait of Gibraltar and possibly as high as 2.0 m/s. That is the minimum water velocity to sustain viable operation of kinetic turbines that could either drive water pumps or electrical generators.

Economic Opportunities

A continual flow of water through a channel offers numerous business related opportunities. The installation of submerged heat exchangers in the channel could sustain the condenser cooling requirements of a large, high-output steam-based thermal power station located along the coast of the strait. Such a power station could operate on concentrated solar thermal energy or nuclear power. A continually flowing current of seawater could allow for development of sea farms in the channel to raise various species of filter-feeder shell fish such as oysters and abalone, with the additional possibility of cultivating edible varieties of ocean vegetation.

The use of corrosion resistant cables connected to ballast on the seafloor and submerged flotation devices at depths below the sailing drafts of ships are able to suspend arrays of oyster farms, abalone farms and provide anchor points for downward growing commercial varieties of oceanic vegetation. Some varieties of oceanic vegetation are edible while other varieties have been processed into fertilizer for houseplants, gardens and small farms. The continually flowing current carries nutrients that sustain filter-feeder shellfish and various species of ocean vegetation.

Hydrokinetic Turbines

There may be future potential to install submerged hydrokinetic turbines under the narrowest and shallowest sections of the Strait of Gibraltar, to generate electric power for several hours every day when the Atlantic Ocean is at high tide and water current flows at 2 m/s. This history of the technology dates back over centuries and operation of waterwheel s that sustained the operation of numerous industries. Some modern submerged waterwheels are based on the design of three-bladed wind turbines. Modern versions of the traditional waterwheel are able to operate submerged in vertical-axis or transverse-axis mode.

There is the option of reducing costs by installing multiple transverse/vertical axis turbines in groups with drive shafts coupled and without requiring gearboxes. Each coupled group of turbines would drive a single water pump connected to the coast via flexible piping, with pumped water from multiple groups of turbines driving a single large shore-based electrical generator. The use of drive shafts with flexible drive-couplings based on corrosion-resistant ceramic bearings would allow groups of multiple three-bladed horizontal axis turbines to each drive a single submerged water pump linked to a shore-based electrical generator.

Conclusions

Evaporation across the Mediterranean Sea removes more water than all rainfall rivers flowing into the sea, in turn sustaining a continual flow of seawater through the Strait of Gibraltar.

The water current allows for installation of submerged heat exchangers under the strait that could provide the condenser requirements for the operation of steam-based thermal power stations, either solar of nuclear.

The continually flowing current of seawater offers future economic potential to develop fish farms and sea farms that cultivate commercially viable oceanic vegetation.

Warmer summer air temperatures across the Mediterranean Sea could increase future evaporation and along with the need to supply water lost from the Caspian Sea, increase seawater flow velocity through the Strait of Gibraltar to 2 m/s.

In the future should seawater flow at 2 m/s through the Strait of Gibraltar, the channel would be able to sustain the viable operation of hydrokinetic turbines that generate electric power.