Hydroelectricity: An attractive foundation for sustainable and clean energy

hydroelectricity - cleanbuild

Hydroelectricity: An attractive foundation for sustainable and clean energy

The history of hydroelectricity dates back to the Grecian period over two thousand years ago. Then, the ancient Greeks channeled the force of moving water to turn the wheel of their mill in grinding wheat into flour.

Beyond its use in food processing in the ancient world, our modern era has witnessed the use of hydropower to generate electricity.

In Africa, hydroelectric energy is one of the most relied upon methods that countries leverage to bring affordable electricity to their territories. It is a form of renewable energy that harnesses the power of moving water to produce electricity.

Hydroelectric power plants are composed of three major parts- a reservoir of water, a gate or valve to control how much water flows out of the reservoir, and an outlet through which the water ends up after flowing downstream.

As water gains potential energy just before it spills over the top of a dam, the energy is converted into kinetic energy as water flows downhill. Through the use of a generator, the water that is being forced to move by a turbine shaft is converted to electricity.

Hydroelectricity can be generated using any of the three main hydropower generating systems:

  • Flowing river technology
  • Dams
  • Pumped water system
Flowing river technology

This is the most environmentally friendly form of electricity generation that basically relies on the flow of a river. From an elevated angle, water flows downwards by the power of gravity through a turbine generator.


This system of power generation uses the potential energy from the stored water in dams. Power is generated when water from one or more dams flows from an elevated level through a turbine generator located at a lower level.

Pumped water system

This is the only system of power generation that produces a non-renewable form of hydroelectricity. It employs a two-dam system where one dam is placed at a higher level than the other.

At times when electricity cost is low, water from the lower dam is pumped upwards using power from the electricity grid. When electricity is high, water from the higher dam is allowed to flow downwards to generate electricity.

While hydroelectricity is the only mature renewable power generation system that is flexible and cheap compared to coal-produced electricity, its process of power generation is not perfect for the environment.

What are some of the risks associated with hydropower generation? They include:

Land loss

It requires lots of land to build dams. This has led to the displacement of communities and has caused the disruption of ecosystems.

Greenhouse gas

The pumped water system, though a renewable energy source, is not neutral to greenhouse gas. Water that is reserved in the dam produces methane which is more potent than carbon dioxide (CO2).

Methane in the dam is formed when organic matter, which comprises plant and soil debris which have collected in the dam, decays in the absence of oxygen.

Water loss

Due to the high surface area of dams, water loss is inevitable because of evaporation. This poses a great threat to dry areas.

We recommend careful planning to curb community displacement and ecosystems disruption, and pumping water with energy from the sun and wind instead of electricity grids.

The future of renewable energy sources surely looks bright. We just need to explore the many options nature has given us and use them to our advantage.

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