Could damming straits be a way to generate power?

Question

There are different places on Earth like the Strait of Hormuz for the Persian Gulf or Bab-al-Mandab Strait for the Red Sea where because of the geography it becomes possible to create a dam. Such macro engineering projects would produce massive amounts of value such as being bridges to cross the sea/ continents and generate massive amounts of power.

Geo politics and the environmental impact these projects would have make them risky or unviable such as the two above. They never make it past some research paper. But what about more out of the way places? Can they be economically feasible? Why or why not would pursuing these be a good idea? Thanks!

Example 1 - Gulf of Aqaba

Is it possible to create a dam towards the end where it meets the Red Sea? Will it produce enough power to make a profit? It's out of the way and with its small area the environmental impact would be minimal relative to damming the entire Red Sea.

Example 2 - The White Sea

Barely anyone lives up there, the area is wholly under one country (Russia) so no one will be complaining about geopolitics. However its cold so the water freezes making the dam unusable and with little meaningful evaporation to change the sea level on either side of the dam, electricity production would be minimal. but global warming could help?

Example 3 - Lake Maracaibo

Follows the same logic as the above examples.

Example 4 - Gulf of California.

And many more.

All follow the same logic. Build a wall, water evaporates from one side to create a difference of water level, and then run it through turbines at a rate where the evaporation matches input (or not and just drain the entire area and start filling it up for more power).

Can these projects be done? Thanks!

Answer 1

Evaporation is a poor source of head to use for energy. The entire Mediterranean, as an evaporation basin, doesn't produce enough flow through the Pillars of Hercules (aka Straits of Gibraltar) to make damming practical, because of the width and depth of the dam that would be required (never mind the shipping disruption, as noted in another answer. In addition, entrapping water to produce head by evaporation will result in progressive salination; over time, this will result in destruction of any fishery within, along with an entire ecology as what was an arm of the sea becomes progressively more like the Great Salt Lake, the Dead Sea, or even Mono Lake.

Many large bodies of water with narrow straits at their mouths already have significant inflow without damming, but this can be harnessed at much lower cost and without disrupting shipping by using moored current flow turbines -- essentially streamlined floats anchored in place, with contrarotating turbine blades around the circumference (contrarotating to minimize tendency to roll the turbine; power is fed out along one of the anchor cables).

Even gulfs and bays that don't generate a significant net current will have daily flow inward and outward due to tides; in some locations, this can produce a current fast enough to be a serious hazard for relatively small ships and boats. These, again, are candidates for moored turbines, allowing shipping to continue even as energy is generated.

Answer 2

Yes, damming straits can be used to generate power.

It is possible, to generate power via tidal power. There are existing functioning power plants that are include dams in ocean/salt water.

Power from flow due to evaporation? Not so much.

The damning of seas/gulfs to generate power via flow into evaporating basins. I would rate this as technically possible. Practically speaking? No.

The costs would drastically exceed the benefits.

Costs to dam 100+ Km would be into the tens of trillions of dollars. Three gorges dam of ~2Km on land ~180 m height cost ~25 Billion. Other costs:

• loss of fishing
• extra cost to handle transport
• lost of habitat
• damage via increased salinity

I would expect that this hasn't been seriously considered because the costs are not easy to calculate with very expensive first order costs, very high second order and who knows how much tertiary costs. This would also have dramatic local weather affects plus potentially global affects. So much risk for some energy production.

In my opinion full coal ahead would be less environmental damage and downright green in comparison(coal for energy).

Answer 3

Damming some bays is impracticable from a technological perspective. The Gulf of California and the Gulf of Aqaba can be in excess of 900 m deep. Constructing a dam wall that high is not practical technologically or economically.

Also doing anything like that in the White Sea of northern Russia is impractical for climatic reasons, particularly if you are relying on evaporation to remove the "unnecessary" water.

Then there are other engineering issues of keying in the dam to the sides and floor of the bay and providing a water tight seal and whether it would be possible in some locations.

As for locations such a Lake Maracaibo, in Venezuela, I also question whether there is enough difference in height to generate enough electricity.

Answer 4

Gulfs and straits are generally very desirable locations for navigation, because of the favorable conditions they ensure. We even go as far as creating artificial straits when needed, see Panama and Suez.

This is why none of the project you mention went past the "on paper" phase: the economy of sea trade and transportation massively out-weights the economy of the produced energy.

Moreover, producing energy could be done less invasively by using the tidally induced currents within the strait. Studies have been conducted on the Strait of Messina, in Italy, (linked page is in Italian), and currently produces 100 kW with current at 3 m/s, with a potential of producing 22000 kWh per year.