Tidal and Wave Energy Questions and Answers

Answer: B

Ocean thermal energy conversion is most suitable in the tropical region.

OTEC runs a heat engine between warm surface water and cold deep water. It needs a temperature difference of at least about 20 °C between the surface and a depth of about 1000 m, and that difference is found year-round only in tropical seas, where the surface stays at 25-28 °C. India's coasts and island territories, such as Lakshadweep, are suitable for this reason.

In sub-tropical, moderate and cold regions the surface water is cooler and the difference too small or too seasonal for an OTEC plant to run economically.

Answer: A

The maximum tidal energy potential in India is in the Gulf of Khambhat, option A. The Gulf has a large tidal range, of several metres, because of its funnel shape, and it has the highest tidal power potential of the Indian sites, with the Gulf of Kutch next.

The Gangetic delta in the Sundarbans (option B) has a much smaller potential. The coast of Odisha (option C) and the coast of Chennai (option D) have small tidal ranges and are not sites for tidal power. The range of the tide is what decides the potential.

Answer: A

The keyed answer is that both statements are true and (R) explains (A).

Ocean thermal energy conversion runs a heat engine between warm surface water and cold deep water, so it needs a large temperature difference between the two. Tropical and subtropical seas have the warmest surface water, so they are the most suitable, which is the assertion. The reason states the need for a minimum temperature gradient with depth before OTEC becomes feasible, and that is why only such seas qualify. The codes calling (A) or (R) false are not supported.

Answer: A

The minimum temperature difference between warm surface water and cold deep water needed for ocean thermal energy conversion is about 20 °C. This is the figure for the gradient given in the key, and the question asks for the least value required.

The values 10, 40 and 60 are not the accepted minimum: 10 is too small for a practical cycle, while 40 and 60 are far above what tropical oceans offer.

Testing each of the remaining options against the same fact shows that every one of them fails on the point the question is asking about, which confirms the keyed answer.