Usually you would use the water's potential energy - the fact that the water is at a certain height, and can provide energy by falling down. It need not be water - it just so happens that (1) in some places there are large amounts of water available that has potential energy (as in a lake in the mountains); and (2) it is relatively easy to convert that potential energy to other types of energy.
The sun
Sun supplies energy. It initiates the first step of water cycle.
Best for what? Not powering cars. The advantages of "water energy" is that nature supplies it "free" (as a result of sunlight and the hydrological cycle) and that its "renewable". As long as the sun shines.
Yes oceans drive water cycle supply. Water is evaporated from oceans.
Glucose supplies energy to the body. Wind, Solar, Water. Nuclear, and coal/petroleum products provide energy to homes and businesses. Electric and gasoline provide energy for vehicles.
Energy from the sun
From geothermal energy supplies or from the sun
Fresh water supplies can be cleaned up by the water cycle
The sun supplies light energy to a leaf through the process of photosynthesis. This energy is used by the leaf to convert carbon dioxide and water into glucose, which provides the plant with food and energy for growth.
Fresh water supplies can be cleaned up by the water cycle
The sun. The sun's energy comes in the form of heat. This begins the cycle with evaporation.
Carbohydrates, fats and proteins yield the energy the body needs to fuel its various activities. Vitamins, minerals and water do NOT yield energy, but perform other tasks such as maintenance and repair.