The field of renewable energy is hotly contested and often acrimonious, with the developers of each of the major forms of production (wind, solar and hydroelectric) battling for a larger slice of the limited investment budget.
While wind and solar power are making swift gains, and the efficiency of energy conversion is increasing every day, there are still those who argue that wind and solar are not yet efficient enough to provide an answer to our enormous hunger for power.
Hydroelectric power, on the other hand, is a proven technology that promises efficiency rates of up to 90%, far better than anything wind and solar power can offer. It’s seen by many as a solution to our energy demands that can be implemented right away. We can dam rivers, construct river barrages and install hydroelectric turbines that convert wave energy into power along our coastlines.
It seems like an ideal solution but, as with all forms of power, there are advantages and disadvantages of hydroelectric power that must be considered. With limited funding for renewable energy we must invest our resources wisely, so it’s important to consider all the facts before making plans for the future.
Advantages of Hydroelectric Power
It’s a Perfected Technology
Already today there are many countries that generate most or even all of their energy needs from hydroelectric. Paraguay, for instance, is fully water powered, and even has enough energy left over to allow them to export their surplus.
All in all around 20% of the global demand for energy is already met by hydroelectric power. This is a proven technology that doesn’t rely on further developments to increase its efficiency. We’ve been generating energy from water for centuries, and all we have to do to generate more is build more facilities.
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.
Cheap Costs of Hydroelectric Power
Thanks to the efficiency of energy production hydroelectric plants generate extremely cheap electricity. 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.
Disadvantages of Hydroelectric Power
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.
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.
Dams and Earthquake Risks
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.
Careful Construction is Key With 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.