Hydropower, also known as hydroelectric power or water power, uses water to produce electricity. Generally, it captures the force and energy of fast-running water in rivers. Hydropower is considered a renewable and sustainable source of energy production. Although, hydropower stations are also known to disturb the natural environment.

Hydroelectric power is one of the oldest sources of renewable energy. It started about 2000 years ago as the energy of water was captured to turn the wheel in mills. Hence traditionally, hydropower was for powering machines.

Hydropower energy

Globally, hydropower stands for about one-sixth of the total electricity supply. Most energy comes from fossil fuels such as oil, coal and gas. According to Statista, China is the world’s largest hydroelectric power producer, followed by Canada, Brazil and the US. Some smaller nations with significant water sources are also at the top, such as Norway and Sweden. Although China is the biggest producer, hydropower only represents about 17 % of the nation’s total energy needs. At the same time, the source covers about 90 % of all power generated in, for instance, Norway. The country is the biggest producer of hydropower in Europe.

What is hydropower?

As mentioned, hydroelectric power captures the natural force and energy of fast-moving water in rivers. The source can be regulated, meaning electricity gets produced when needed. The most common hydropower stations stores water in a dam. Then, when the water gets released from the dam, the energy of that movement is captured. For example, by letting the water turn the blade of a turbine. Which then generates electricity.

There are three kinds of so-called hydroelectric energy plants. The one described above is known as an impoundment facility. Namely, when water is released from a dam to make a turbine spin, which then powers a generator. Another kind is called a diversion facility. It works by channelling water in a series of canals instead of a dam. The third type is a pumped-storage facility and gets used in combination with, for example, solar and wind power. It collects the energy from these sources to pump water uphill to a dam or pool. When electricity is needed, the water in the higher pool is released to turn a turbine.

How does hydropower affect the environment?

Hydropower is considered a sustainable source of energy. The benefits of hydropower are usually highlighted in the global debate on sustainability, as it uses the natural power of water. But also because it is the only renewable source that one can regulate. Solar and wind power only generate electricity when there is sun and wind. Although, the storage of these energy sources is getting better.

However, the enormous constructions required to build hydroelectric power stations disturb the environment. They drastically change landscapes and rivers. More so, they interfere with the natural movement of fish, as fish tend to move up and down the river. The ecosystems of rivers depend on this movement in a complex web. For example, fish also bring nutrition to the landscapes and animal life around the water source. Sometimes, this natural process gets considered by creating water passages. Yet, the facilities remain a blockage to the natural flows.

The disturbance of the hydropower constructions can negatively affect areas such as the Amazon rainforest. Not only environmentally but also socially. For example, new dam constructions tend to misplace people living by the rivers.

Furthermore, hydropower is usually known as a source that doesn’t release greenhouse gases. However, this is only partially correct. First of all, the construction of the facilities releases greenhouse gases. But most importantly, the facilities do release the potent greenhouse gas methane.

Future outlook

Overall, hydropower is a greener option than fossil fuels, yet, that does not necessarily imply that new constructions are good for the environment. Renewable sources also have complications and require lifecycle assessments. For example, before investing in an expansion of renewables, it is good to consider working with energy efficiency and lowering the energy demand.

Sources: National Geographic, The Guardian, Statkraft, Statista, Our World in Data.