There's not a lot of talking about hydroelectric energy these days, even though it generates the majority of electric power from renewable energies worldwide.
In its typical form, hydroelectricity requires a dam to collect and compress a huge quantity of water, which is then channelled underground towards turbines.
If we don't take the initial costs into account, production of hydroelectric power has the advantage of being relatively low cost and not generating any CO₂.
On the other hand, the main disadvantage is the impact on the ecosystem caused by the dam and the flooding of the surrounding land.
For those reasons, research is currently focusing on making hydroelectric power more efficient in order to use smaller dams (with a fall of maximum twenty meters), or no dam at all, by simply using the natural height difference of rivers and tide flows.
In Italy, the traditional way to exploit hydroelectricity has reached its maximum development. The future is the so-called micro hydro, which uses the natural flow of rivers and can generate electric power for single families or small communities, with an environmental impact close to zero.