Hydropower

Moving water can make power.

Fast water or falling water makes energy. This energy can make electricity.

People use big dams to hold water. The water flows through a channel. It spins a wheel called a turbine. This spinning makes power for homes.

Long ago, people used water wheels. They used them to grind flour. They also used them to cut wood. Water power is a great way to help.

Hydropower is a way to make power from water.

It uses falling water or fast water. This can make electricity for our homes.

One way to do this is with a dam. A dam holds water in a big lake. This is called a reservoir. When we need power, water flows through a channel. It spins a machine called a turbine. The turbine is linked to a generator. The generator makes electricity.

Another way is a run-of-river plant. These do not use a big reservoir. They use the natural flow of the river. These plants depend on how fast the river moves. In the rainy season, they make more power. In the dry season, they make less.

Hydropower is a clean way to make energy. It does not make carbon dioxide. But, dams can change the river. They can stop animals from traveling upstream. Large dams also take up a lot of space. Some people must move if a dam is built near them.

This tool was used in old gardens too.

Hydropower is a way to make energy using falling or fast-running water.

This method is a sustainable way to produce power. It is an attractive alternative to fossil fuels because it does not directly produce carbon dioxide. It also does not create other pollutants that go into the air. Hydropower provides a relatively consistent source of energy for many people. Today, it is mostly used to create electricity for our world.

There are different ways this energy works. One way uses a dam to hold water in a reservoir. The water is available on demand to create power. When the water flows through a channel, it spins a turbine. This turbine is connected to a generator that makes electricity.

Another way is a run-of-river plant. These plants do not use a reservoir but use a barrage to control the flow. They depend on the continuous flow of the river. This means they make more power during the rainy season.

People have used water power since ancient times. Evidence shows the basics of hydropower come from ancient Greek civilization. Waterwheels also appeared in China around that same time.

In the past, watermills were used for many jobs. They helped with irrigation and ran machines like sawmills or textile mills. They even powered dock cranes and ore mills. A device called a trompe can even make compressed air from falling water. In 1910, a facility like this was built at Ragged Shutes in Ontario. It supplied 5,000 horsepower to nearby mines.

Hydropower is a huge part of how we get electricity today. In 2021, the global capacity for hydropower reached almost 1,400 GW. This is the highest amount among all renewable energy technologies. Hydroelectricity provides at least 50% of the total electricity for more than 35 countries. It also generates about 15% of the electricity used around the world.

Some systems use pumped-storage to save energy. They pump water uphill to a reservoir when demand is low. They then release it to make power when demand is high.

Even though it is helpful, hydropower has some downsides. Building large dams can change river ecosystems. It can stop animals from traveling upstream or change the water's oxygen levels.

Large reservoirs can also cause greenhouse gas emissions from rotting plants underwater. This process can produce methane. Sometimes, people living near a site must move because of construction. Designers must also plan for the "probable maximum flood" to keep the dam safe. They use spillways to route extra flood water around the dam.

Hydropower is the use of falling or fast-running water to produce electricity or mechanical power.

This process works by converting the gravitational potential energy or kinetic energy of a water source into usable power. Potential energy is stored energy based on an object's height, while kinetic energy is the energy of motion. Hydropower is considered a sustainable method of energy production. It serves as an attractive alternative to fossil fuels because it does not directly release carbon dioxide. It also provides a relatively consistent source of power for many societies.

To understand how much power a site can provide, engineers look at the hydraulic head and the volumetric flow rate. The hydraulic head is the energy per unit weight of the water. There are two types of head: static head and dynamic head. Static head is proportional to the vertical height through which the water falls. Dynamic head relates to the velocity of the moving water. The total available power depends on the flow rate, water density, the height of the fall, and local gravity. For example, a turbine that is 85% efficient with a flow rate of 80 cubic meters per second and a specific head can produce about 97 megawatts.

There are several distinct ways to harvest this energy. One common method uses a dam and a reservoir to store water. This allows operators to release water on demand to spin a turbine. A second method is called a run-of-river plant. These plants use a barrage to control water flow without a large reservoir. They rely on the continuous flow of the river, which means they produce more electricity during rainy seasons. Some systems also use pumped-storage hydroelectricity. This is an energy storage system where water is pumped uphill during low demand. The water is then released to generate power when demand is high.

Humanity has utilized water power since ancient times. Evidence suggests the fundamentals of hydropower began in ancient Greek civilization. Around the same period, waterwheels emerged independently in China.

In the past, watermills were used for irrigation and mechanical tasks. These included operating gristmills, sawmills, textile mills, and even dock cranes. Some specialized machines, like the trompe, used falling water to produce compressed air. In 1910, a facility using this principle was built at Ragged Shutes in Ontario. It supplied 5,000 horsepower to nearby mines.

Today, the scale of hydropower is massive. In 2021, global installed hydropower capacity reached almost 1,400 GW. This is the highest capacity among all renewable energy technologies. Hydroelectricity generates about 15% of the world's electricity. It also provides at least 50% of the total electricity supply for more than 35 countries. Large-scale plants can supply power to an entire nation. Even small-scale systems, known as micro hydro, exist to provide localized power.

Despite its benefits, hydropower has significant environmental and social downsides. Building large dams can cause habitat loss for aquatic species. It can prevent animals from traveling upstream and change the oxygen levels in the water. Reservoirs can also cause greenhouse gas emissions. This happens when organic matter rots underwater in low-oxygen conditions, releasing methane.

Additionally, construction can displace people living near the site. Engineers must also design dams to handle the "probable maximum flood" to prevent catastrophic failures. They often include spillways to route these extreme flood flows around the structure.

Scientists are even exploring new frontiers like "rain power." This involves capturing the energy from falling raindrops. One method uses piezoelectric devices, which generate power when they move. Another approach uses microturbines to capture water from rooftop rain gutters. While these technologies are in early stages, they represent the ongoing search for new ways to use water's energy. Hydropower remains a central pillar of the global transition toward low-carbon economic development.