Advantages and Disadvantages of Hydroelectric Power

By Clint Ouma

While wind and solar get all the attention, there's a quiet achiever doing big things in the background... Hydro!

Here we'll explore the advantages and disadvantages of hydroelectric power... and how it fits into the clean energy puzzle.

Hydro is widely accepted as a solution that can be implemented right away. We can dam rivers, construct river barrages and convert ocean waves into power.

While hydro power has exciting advantages, we must consider the DISADVANTAGES... and how the pros and cons can be managed.

Advantages of Hydroelectric Power

1. Hydroelectric Technology Development is well established

Many countries already rely heavily on hydroelectric power plants. For example, Paraguay is fully hydro powered, and even exports a surplus.

All in all around 20% of the global demand for energy is already met by hydroelectric power.

Hydroelectric has been refined over decades, unlike other solutions that are in the mid stages of development.

2. Hydroelectricity Can Provide Constant Power

While the wind can fall and the sun can be hidden in cloud, hydroelectric power enjoys constant capacity for power generation. Only in times of extreme drought will a dammed river be unable to produce power, and hydroelectric plants are only built in locations where a dry river is not an issue.

Out to sea the flow of 'fuel' is even more assured. Wave power relies on the tides themselves, one of the few natural processes that are guaranteed to continue unabated as long as the moon orbits the earth. In short, hydroelectric power is by far the most dependable form of renewable energy production.

3. Cheap Costs of Hydroelectric Power

A typical plant will pay for its own construction in 5-8 years, after that producing what amounts to free energy, and since a hydroelectric plant can be expected to operate for anything up to 100 years a single plant could generate enough revenue to pay for itself 20 times over.

While this means little from an environmental point of view it counts for a great deal to the developers of power plants. A 2000% return on investment presents an attractive prospect, making the construction of many more hydroelectric facilities much more likely. Conversely, the high initial cost of solar and wind energy production facilities holds back investment.

4. Hydropower Is Extremely Efficient

Efficiency is a big factor of measuring energy technologies.

"Efficiency" means the ability to use or "capture" the energy... and the loss that occurs in the process.

Solar has efficiency levels of around 22%, and wind around 45% maximum. According to the US department of the Interior, hydroelectric power plants can have efficiency rates of up to 90%.

Disadvantages of Hydroelectric Power

1. Environmental Problems of Hydroelectric Dams

The problem with hydroelectric plants - or, at least, those that require a river to be dammed - is that the river behind the dam will swell and flood the surrounding area.

Many miles of riverside including towns, villages and valuable habitats will be inundated, and considering that riversides are popular locations for human settlements this can force the relocation of large numbers of people.

China's Three Gorges Dam, the world's largest hydroelectric facility, displaced at least 1.2 million people from 13 cities, 140 towns and 1,350 villages. The 600km resevoir created by the dam disrupted the environment to an unprecedented degree.

On smaller scales the disruption need not be a fraction as severe, but wherever a dam is built there will be at least some measure of damage caused to the upstream environment.

2. Wildlife is Affected by Hydroelectricity

While most dams include slipways to allow fish and other river life to pass, building a dam will always disrupt the fragile ecosystem of a river. Migratory routes are disrupted, sediment flow rates are changed and the river life will be affected in ways that will not always be predictable.

The problem with this is that the disruption often extends far beyond the river. Ecosystems are complex and interlinked, and any change can be disastrous. The loss of a species of fish may affect the populations of species downstream that depend on it for food. This may have a knock on effect to yet more species, destroying the fragile balance of habitats surrounding the river.

3. Dams and Earthquake Risks of Hydroelectricity

We rarely consider the weight of water, but if you've ever tried to lift it in any quantity you'll know that it's heavy.

Artificially altering the flow of a river by creating a reservoir places extreme strain on the bedrock beneath.
In most cases this will not cause problems, but in tectonically active regions the stress can be so severe that it causes earthquakes.

Many experts believe that the Sichuan earthquake of 2008, which caused the deaths of 70,000 people, was caused or exacerbated by the presence of the Zipingpu Dam, a hydroelectric plant that created a reservoir holding 315 million tonnes of water.

Construction Considerations for Hydroelectric Power

The development differences between the various forms of renewable energy are clear. Solar and wind power are still developing technologies, while hydroelectric has already proved successful for many years.

However, while the advantages of hydroelectric power plants is that they can generate enormous amounts of energy - enough to meet the energy demands of a large proportion of the global population - there are clear environmental disadvantages that must be taken into account.

Hydroelectric power can offer us a lot, but it's clear that we must carefully consider the location of new plants before forging ahead.

Conclusion - Hydroelectric power plants as a piece of the energy puzzle

With limited funding for renewable energy, we must invest our resources wisely. It's important to consider all the facts before making plans for the future, and see hydro as a "piece of the puzzle"... alongside solar, wind, and improved efficiency.

First published October 6, 2012
Last updated February 5, 2021

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