For the post-independence leaders of Egypt and Ghana in the 1950s, hydroelectricity and sovereignty were inextricably linked. Building vast irrigation and electricity projects across the Nile and the Volta was a prerequisite if they were to catch up with their former colonial masters. That association still holds: four of the six biggest users of hydro today are Brazil, Russia, India and China, the Bric nations synonymous with the idea of rapid economic development.
That may be changing, however. The rise of data centres mining cryptocurrencies and training AI models is providing a new market for the vast volumes of electricity produced by hydro. That risks destroying the maths that for decades has made dams an essential tool of development.
Poor people and crypto miners typically want the same thing: the cheapest electricity on the planet. The former group use it to power lights, fans and chargers for mobile phones that can connect them to the world - and later textile mills, garment factories, manufacturing plants and all the other energy needs of a fast-developing economy.
Crypto miners, on the other hand, use it to solve mathematical puzzles so they can win tokens on the blockchain as a reward, an activity that's the basis of most digital currencies such as bitcoin and that consumes about the same amount of electricity as Australia. Hydro has been particularly popular in recent years as crypto enthusiasts, stung by criticism of the industry's rapidly growing carbon footprint, have sought a source of power that's cheap, reliable and green.
In Laos, dubbed the "battery of Southeast Asia" thanks to its abundance of hydro power, the region's cheapest grid power has sparked a boom in crypto mining, which now consumes more electricity than all of the country's households. That led to power outages last year, when erratic rainfall in the rapidly developing Mekong basin caused hydro generation to dip.