Critics of the industry have claimed that in tropical areas of Brazil - which supplies more than 90% of its electricity from large dams - some reservoirs emit so much methane that their contribution to climate change is greater than an equivalent power station burning fossil fuels like coal or gas.Yikes! Who knew that hydro power lead to greenhouse gas emissions?
Methane is produced mainly by bacteria that break down organic matter where there is little or no oxygen, for example at the bottom of lakes and reservoirs.
Since intake pipes for hydroelectric turbines tend to be placed quite deep, methane-rich water is suddenly transferred from conditions of high-pressure to the open air.
How big is the impact?
A statistical analysis carried out by the INPE scientists has estimated that large dams could be responsible for worldwide annual emissions equivalent to some 800 million tonnes of carbon dioxide.That seems significant.
To put that in perspective, last year's total greenhouse gas emissions from the UK were around 660 million tonnes.
So what do you do when life gives you lemons? Make a little lemonade.
The INPE scientists are proposing that with relatively simple technology, this unwanted by-product of hydro-electric power generation could be turned into an extra source of clean, renewable electricity.Looks like instead of focusing on being a cow fart tycoon, I should have I have tried to be a dam fart tycoon.
They have estimated that some dams with an especially heavy methane load in the Amazon could increase their output by up to 50%.