Hydropower Energy

Did you know that 97 percent of renewable energy is just hydropower? Solar, wind, and geothermal only account for 3 percent. Learn more about this ancient energy source and the elegant designs that have allowed it to stand out as the most widely-used renewable energy source.

Where does Hydropower energy come from?



To say that hydropower comes from water would be an oversimplification. Really, hydropower comes from the volume and movement of water in rivers. Humans have been harnessing energy from the movement of water for centuries – even the ancient Greeks used water wheels to grind wheat into flour. But modern infrastructure allows us to harness energy from rivers regardless of water level or droughts.

How does it create energy?



Hydropower plants start with a dam beneath the river’s surface, raising the water level. When the water falls, it creates more energy – the further the water falls, the more energy it produces. The dam also allows the hydropower plant to control the water level. That way, even during times of drought, when the water level is lower, the plant still creates electricity. As the water falls past the damn, it spins the blades of a turbine. The movement of the turbine powers a generator above the river’s surface, creating electricity. Usually, the electricity gets carried away to buildings in the area along transmission lines aboveground.

Some hydropower plants, called pumped storage plants, store energy in the form of a water reservoir for later use. These setups contain an upper reservoir that a turbine fills using electricity from the power grid. In times of peak electricity demand, the pumped storage plants release water from the upper reservoir into a lower reservoir, spinning the turbine and generating more electricity.

What’s the environmental cost of Hydropower energy?



Hydropower doesn’t emit any greenhouse gases or other pollutants. However, like other sustainable fuels, it does affect the surrounding ecosystem. A hydropower plant may change the temperature of the river water, which can harm plant life and natural habitats around the river. The migration of fish through the river may also be interrupted. Newer hydropower plants are being designed in ways to mitigate these effects. For example, some are built with “fish ladders” through the dam to allow salmon through on their path to their spawning grounds.

What are its common uses?



Hydropower produces about 10 percent of the energy we use in the United States every year. Worldwide, the figure doubles to 20 percent. It’s so synonymous with electricity, it’s often called hydroelectric power. Farms, ranches, and other homes can generate and run on hydropower on their own if the homeowner prefers to operate outside the neighborhood’s power grid.

How much does Hydropower energy cost?



Hydropower is such a popular source of fuel because of how inexpensive it is. It’s a third of the cost of fossil fuels, and 90 percent efficient (that is, it converts 90 percent of available energy from its source into electricity). Because of the cost of building new infrastructure, only 2,400 of the 80,000 dams in the United States currently produce electricity.