Run-of-the-river hydropower systems use the natural flow of a river to turn turbines and generate electricity, without the need for a dam or reservoir.

Pumped-storage hydropower systems store energy by pumping water uphill during off-peak periods, then releasing it downhill through turbines to generate electricity during peak demand periods.

Impoundment hydropower systems use a dam to create a reservoir of water, which is then released through turbines to generate electricity.

Tidal hydropower systems can generate electricity 24 hours a day, as long as there is a tidal flow.

China is the largest producer of hydropower in the world, accounting for over 30% of global hydropower production.

Hydropower systems can have a number of environmental impacts, including greenhouse gas emissions, water pollution, and habitat destruction.

There are a number of ways to minimize the environmental impacts of hydropower systems, including using run-of-the-river systems instead of impoundment systems, building fish ladders and other fish passage structures, and releasing water downstream to maintain natural river flows.

Hydropower is expected to continue to grow as a major source of renewable energy, as it is a reliable and cost-effective way to generate electricity.

Wave hydropower systems use the energy of waves to generate electricity.

Wave hydropower systems can generate electricity 24 hours a day, as long as there are waves.

Portugal is the largest producer of wave hydropower in the world.

Wave hydropower systems can have a negative impact on marine life, as they can disrupt natural wave patterns and destroy habitats.

There are a number of ways to minimize the environmental impacts of wave hydropower systems, including using wave energy converters that are designed to minimize noise and vibration, siting wave energy converters in areas with low marine life activity, and monitoring the environmental impacts of wave energy converters and taking steps to mitigate any negative effects.

Wave hydropower is expected to continue to grow as a major source of renewable energy, as it is a reliable and cost-effective way to generate electricity.