Large hydro refers to the conventional hydro power plant you and I have heard about – those large power plants with huge dams.
Some of the large hydro projects are really massive – the world’s largest hydro power project as of 2016 is the Three Gorges Dam that has a reported capacity of a humongous 22,000 MW (22 GW), giving us massive amounts of renewable power.
Renewable energy, it might be, but in most discussions on energy sources, you will not find large hydro power plants categorised as alternative energy.
Why is this so?
This is because large hydro power has been around for a long time (the 1300+ MW Hoover’s Dam in the US has been running since 1936), and large hydro already contributes to a significant share of the world’s electricity needs (over 15% as of 2016).
As a result, while large hydro power is indeed a renewable energy source, it cannot be considered an alternative energy source.
Any way, what’s there in a term!
By the way, you will be surprised to know that there are many who do not consider large hydro power even as a renewable source of energy. Why would this be, as surely, it is obviously a renewable source? Many do not wish to categorize it as a renewable energy source owing to the significant impact large hydro power projects have on the environment and the overall ecosystem of the region, as I have touched upon in this post.