By Paul Homewood
h/t Joe Public
Wind contributes just over 8%, with hydropower contributing 14% making it the largest source of clean energy.
https://www.bbc.co.uk/news/articles/cq80ygdd3zlo
While the BBC is bragging that 14% of the world’s electricity comes from “clean” hydropower, they seem to have forgotten what they wrote previously:
Dams and reservoirs around the world are an underappreciated source of methane. Now start-ups want to capture that gas as a source of power.
It takes just one second for four Olympic-sized swimming pools-worth of water to charge through the turbines at the Tucuruí dam in northern Brazil. The rush of water here at one of the largest hydroelectric reservoirs in the Amazon region is deafening, but it’s what makes the dam the fifth largest power plant in the world.
As the water churns through a series of 25 turbines and spillways of the dam, however, something else is happening – it’s emitting greenhouse gases.
Often regarded as one of the oldest forms of renewable energy, hydroelectric dams and their reservoirs are responsible for the release the equivalent of almost one billion tonnes of carbon dioxide into the atmosphere (with much of these greenhouse gas emissions in the form of methane) as water approaches and then tumbles its way through the turbines that generate electricity. Methane is a greenhouse gas that’s more than 80 times more potent than carbon dioxide over a 20-year lifespan, but it also breaks down faster in the atmosphere than CO2.
These hidden emissions mean that hydroelectricity is perhaps not as clean as it first seems.
The reason is that it’s not just water passing through the turbines – a lot of dissolved greenhouse gases flow through them too. Just as carbon dioxide dissolves in our fizzy water while under pressure, so too does methane gas dissolve in large bodies of water under certain conditions.
Now imagine you’re holding a bottle of sparkling water. Before opening it, you don’t see any bubbles inside because the carbon dioxide gas stays dissolved. As you open the lid, you hear a fizzing sound as the pressure is released and bubbles of carbon dioxide rise up. Shake that water first, and this effervescent "degassing" will most probably make your carbonated drink explode everywhere.
Something similar happens to the methane dissolved in the water from lakes when it is churned.
Sounds as if hydro power is not quite as clean as the BBC would like you to believe!