It’s cheap, clean and reliable, so why is hydroelectric power so unfashionable?
This image from Fougères Castle in Brittany, France, shows one of its four waterwheels. Originally used to grind flour, it now produces electricity!
But unlike its fellow renewables, wind and solar, hydroelectricity is hardly ever mentioned as an option in the mad rush from fossil fuels to low-carbon energy.
Yet, in some countries, a few dams are enough to provide electricity to the majority of the population – and to do so all day, all year round.
Amazingly there are nearly fifteen thousand dams in Canada alone, together producing well over half of that country’s electricity. And thousands more in nuclear-friendly France – although only 750 are used for electricity production.
So why have we given up building dams and should we give hydro another shot?
History maybe gives some pointers.
Water power has been around for thousands of years - the Chinese were the first to harness water for grinding grain and crush ore as long ago as 200 BC.
In the second century, the Romans built a set of 16 watermills at Barbegal, in France, a feat that has been called the greatest known concentration of mechanical power in the ancient world! The mills were used to grind flour as well as serve unknown industrial purposes linked to the nearby harbours.
It is known, for example, than 84 waterwheels were owned by the abbey of Saint-Germain-des-Prés in France, one of the major abbeys owning lands between the Loire and the Rhine Rivers, by the ninth century. In 1086, after the Norman conquest of England, the Domesday Book identified no less than 5624 water mills in the country.
Industry was also the spur in England’s Derwent valley in 1771 when Richard Arkwright set up Cromford Mill to spin cotton using hydropower. However it was a French engineer, Benoit Fourneyron, who developed the first waterwheel of the kind we now call a turbine - capable of efficiently harnessing the energy in the water although not yet turning it into electricity. Finally, in 1849, the British–American engineer James Francis developed the first modern turbine – named after him – and this is the one used today for generating electricity.
None of this waterpower was used to generate electricity at the time though! Instead, this was a world of horse-driven carriages, coal fires and gas lights. The world’s first hydroelectric project had to wait until 1878, when a waterwheel was used – to power a single lamp in a Northumberland country house! But just four years later, the first plant to serve a system of private and commercial customers was opened in Wisconsin, USA. Unfortunately, as the generator was directly connected to the waterwheel and the water from the Fox River did not flow at a constant rate, the lights did not maintain constant brightness, sometimes dimming or worse - flaring up and burning out!
Nonetheless, by the turn of the century the technology was spreading round the globe. In 1895, the world’s largest hydroelectric development of the time, the Edward Dean Adams Power Plant, was created at Niagara Falls with ten turbines each rated at 5,000 horsepower.
Inventor Nikola Tesla said proudly of his achievement:
“We have many monuments to past ages; we have the palaces and pyramids, the temples of the Greek and the cathedrals of Christendom. But the monument at Niagara is worthy of our scientific age, a true monument of enlightenment and of peace. It signifies the subjugation of natural forces to the service of man.”
President Franklin Roosevelt enthusiastically embraced hydroelectric power as part of his New Deal in the 1930s and within a decade projects such as the Hoover and Grand Coulee dams accounted for nearly half of the country’s electricity!
Western Europe, the Soviet Union, and Japan all followed suit with hydroelectric power seen as low-cost and reliable. Brazil and China undertook huge projects, such as the 14,000 MW Itaipu Dam, straddling Brazil and Paraguay, and the Three Gorges Dam in China – which is rated at 22,500 MW or as much as twenty typical coal-fired power stations!
However these projects also produced new awareness of the environmental costs of hydroelectric and although hydropower is expected to remain the world’s largest source of renewable electricity for many years to come, policy makers started to turn away from it in favour of the “trendy” new technologies of solar and wind.
The first half of 2023 even saw a significant drop in hydroelectric power due to droughts, particularly in China. Worse still, some hydroelectric schemes were accused of contributing to earthquakes: one such, in China’s Sichuan Province that left 80,000 people dead, was linked to the Zipingpu Dam, located just meters from the fault that failed, five kilometers from the quake's epicenter.
Fortunately, earthquakes are very rare but every day, dams deprive areas downstream of vital water – harming animals and plant life. Even when water is released by operators, it can cause other problems as the water is typically flowing from the bottom of the reservoir - meaning that it too cold and lacking oxygen.
The most obvious problem with hydroelectricity, though, remains its appetite for previously dry land to use as a reservoir. One plant, built in a flat area of Brazil, flooded no less than 2,360 square kilometres - an area twice the size of Greater London! - and all this to provide a mere 250 MW of power generating capacity. That’s about a quarter of what a standard coal power station does or roughly the same as five hundred modern wind turbines!
Flooding land for a hydroelectric reservoir destroys forest, wildlife habitat, agricultural land, and occasionally, areas of great beauty too. Sometimes, entire communities have to be relocated to make way for reservoirs. And if dams fail - as happened just this month in Kenya - killing at least 45 people, it can result in people losing their lives.
Last but not least, hydroelectricity has been accused of having a relatively poor record on global warming, mostly because of the decomposition of vegetation in the reservoirs.
All of which means that in 2024, yes, hydroelectric power is a bit out of fashion. But fashions are superficial things - and another way to look at hydro is that, for now at least, it is by far our biggest source of sustainable electricity, generating 55% of the renewables total. That’s more than all the other methods put together! Not bad for a technology that’s over two thousand years old.
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