That's not entierly true. They get very good efficiency, except because they need 800psi to function you cant reach very deep into a tank, so that's about 800psi a tank that you can't use...
An temporary alliance formed between the ocean and the sky with the goal of killing people. The ocean's ability to attack the land is limited, so it lends the sky some of its water and energy so it can assault people farther inland then it normally could. Hurricanes are far more powerful then the storms the sky creates on its own. They are just another reason the ocean must be destroyed