Energy lost...???
How is energy lost? The salt water and waste water are ultimately going to mix any way you slice it, so why waste that? We can use it. It's no different in principle from sunlight falling on solar cells instead of the ground below. Even if it were true that energy were somehow lost from the ocean (although the water got there via rivers after solar evaporation from the ocean, so it's really solar energy), how much greater the loss when we burn fossil fuels representing limited stores of solar energy garnered over millions of years.
For whatever reason, some of the comments here fail to recognize that almost any form if not all forms of energy we use are ultimately solar energy. It's just that using forms of solar that are short cycles instead of millions of years and that are inherently balanced in terms of our current global conditions don't unleash carbon dioxide from the past to upset our current balance, such as it may be. (See the second paragraph of my comment in reply to the worry that CO(2) gets generated when in fact it is net zero for the whole process.)
