The environmental impact of ocean thermal energy conversion

The main environmental impact of an OTEC plant results from the pumping of water from below 1000 m and then returning it at a much lower depth. The surface water for an OTEC plant is taken at around 20 m depth, so the mixed hot and cold water must be returned at around 60 m depth to prevent it returning directly to the hot water input.

The volumes of water involved are enormous and the movement of water from lower to upper regions of the seas and oceans could have a significant impact on the local marine environment. There is little evidence available today to indicate what the effect would be, but the danger of this impact is likely to limit the exploitation of OTEC, at least until extensive environmental studies have been carried out.

The warm water heat exchanger in an closed cycle OTEC plant is likely to be subject to biofouling. This must be prevented to maintain efficiency. The only way to prevent biofouling is by chemical treatment, probably with chlorine, leading to some release into the sea. Such releases would need to be closely monitored and would have to fall within legal limits.

Construction of an OTEC plant will lead to some seabed disruption but this is likely to be short term and relatively minor. There will also be the danger of small releases of oil and, in the case of a closed cycle OTEC plant of thermodynamic fluid. The impact of such releases should be of a similar to those from existing offshore facilities.

Solar Stirling Engine Basics Explained

Solar Stirling Engine Basics Explained

The solar Stirling engine is progressively becoming a viable alternative to solar panels for its higher efficiency. Stirling engines might be the best way to harvest the power provided by the sun. This is an easy-to-understand explanation of how Stirling engines work, the different types, and why they are more efficient than steam engines.

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