In the tropics, the deep sea is cold and the sea surface is very warm.
That temperature difference can be harnessed and turned into electricity.
For more than a century, researchers have explored the idea of ocean thermal energy conversion.
Theres nothing fundamentally new to the idea of extracting power from temperature differences.
The challenge is finding the right spot, where the temperature differences make it worthwhile.
At present, pilot plants are only able to generate a fraction of what a large wind turbine can.
But on the positive side, ocean thermal plants can generate power 24 hours a day.
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To get this cold water, these plants have pipes stretching down 600 meters into the deep sea.
The downside is at present, the technology isnt ready for prime time.
Apilot plantin Hawaii installed by Makai Ocean Engineering in 2015 has a capacity of 100 kilowatts.
The main technical challenge to overcome is getting access to the large volumes of cold seawater required.
Makais pilot uses a pipe one meter in diameter which plunges 670 meters into the ocean depths.
This kind of infrastructure is expensive and must be built to withstand corrosion and cyclones.
If the plants are built offshore, the cost of transmission lines adds to the overall expense.
Makai estimates 12 commercial-scale offshore plants could cover Hawaiis total electricity needs.
If OTEC plants can be built large enough, the cost will come down.
But theres another challenge too.
Why is such a huge volume of water required?
In short, a thermodynamic bottleneck.
Could OTEC find a use despite the cost and technical challenges?
Still, OTEC could play a useful role in tackling several challenges at once.
It may even be possible to use OTEC plants toproduce hydrogenas an export commodity in small island states.
To meet our urgent emission reduction goals, it is worth exploring all renewable energy options.
We shouldnt write off OTEC just yet.
File this under has potential, but needs more work.
