Ocean Thermal Energy Conversion Energy and Aquaculture

It is interesting to see how aquaculture is being promoted as a secondary outcome or byproduct if you like for a renewable energy system called Ocean Thermal Energy Conversion (OTEC). Without going into detail of what this system is, it basically involves harnessing solar energy stored in the sea. In certain tropical regions, deep ocean water can be pumped to the surface and the temperature difference is enough to generate electricity. 

As with all promising technologies, there is a big catch with OTEC energy. It requires massive investment. By itself, the cost per kilowatt of energy makes OTEC energy much less attractive than many of its alternatives.

However, as the stakeholders in OTEC energy technologies are keen to point out, there appear to be a number of very valuable benefits of the OTEC scheme. When these benefits are taken into account, the economics of OTEC energy would become significantly more attractive.

Byproducts and other benefits of OTEC include, production of fresh water, also the cold seawater byproduct can be used for air conditioning and also for cooling soil to enable certain types of agriculture not usually suited to the tropics. A further side benefit is the potential applications to aquaculture. The main benefits are stated as follows:

The cold, deep seawater required for OTEC has three principal advantages for aquacultural systems:

• Cold – The consistent low temperature of the deep water not only allows the culture of valuable cold water organisms in the tropics, it also provides (when mixed with the surface water or allowed to warm in the tropical sun) a means of precise, reliable and cost effective temperature control over the full temperature range from 6^oC to 25^oC.
• Nutrient-rich – The deep water is enriched with dissolved Nitrogen, Phosphorus, Carbon, and other chemicals which are essential to plant growth in the ocean.
• Pure – Since there is very little life at the depths from which it is pumped, the deep water has very few pathogens or viable plant cells. This permits the disease-free culture of sensitive organisms and the production of pure plant cultures without interference from competing species.

The above was taken from one of the companies are trying to implement the technology (see http://www.ocees.com/mainpages/Aquaculture.html). It is also stated in the above web page that the benefits above are even more advantageous when combined with the benefits of tropical aquaculture (e.g., fast growth in tropical sun etc.). 

It seems that this is an idea that is worth giving more consideration, not just for its primary benefit (energy), but also for its secondary benefits.

As has been pointed out in other posts, there is expected to be a dramatic increase in demand for aquaculture in the next 20 or so years.

One would also expect that an aquaculture system with access to this type of cold sea water should be able to develop some significant competitive advantages over their competitors.

It goes without saying that society can and will continue invest into renewable energy in the future. It is a necessity and governments as well as private institutions are already pumping millions upon millions of dollars into new renewable energy technologies such as wind, solar and hydro.

I wonder whether in 20 years time, if we wont be looking back and saying - if only we spend that little extra money on that OTEC plant integrated with fresh water, agriculture and aquaculture byproducts instead of those other technologies that were more attractive based on only the cost per kilowatt?

Tags: Deep Seawater, Ocean Thermal Energy Conversion, Renewable Energy, Tropical Aquaculture
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