Large hydro projects represent an important source of renewable energy. Some of the large hydro projects are in excess of 500 MW capacity and with very good capacity utilization factors, providing a stable and large source of electricity.
In fact, hydro power has by far the largest renewable energy by contribution – as of 2016, large hydro capacity worldwide is about 1.1 TW (TW = terawatt = 1000 GW = 1000000 MW), slightly above 15% of the total installed electricity capacity globally!
In addition, hydro power projects are long lasting – many of these projects can last beyond 50 years, and with some replacements along the way, even longer!
At the same time, owing to their scale, large hydro projects also result in some not-so-environment friendly conditions:
- They require significant amounts of land, in many cases forest and environmentally sensitive land.
- As many large hydro-power projects are located in areas that are rich in wildlife, there have been serious concerns about the harm to wildlife that large hydro power projects bring. In fact, one of the reasons that many worldwide are even reluctant to call large hydro as a renewable energy source (even though it obviously is) is owing to the negative impact dams have on fisheries and water flows in that region.
- In quite a few cases, construction of large hydro projects have also has necessitated displacement of thousands of the native population. In countries like India, this has led to significant opposition by environmental and social activists (see Narmada Bachao Andolan).
On balance, it is a tough call to decide whether the net effect of large hydro projects is a plus or minus for the environment and the ecosystem!
Owing to their significant environment footprint, in the past few years, I have seen delays in implementation of some ambitious hydro power projects worldwide. While countries such as China have been able to push through some massive hydro projects (for instance, the Three Gorges Project, which is a mind numbing 22 GW in capacity), many other less authoritarian countries with an active civil society (India, for instance) have not been able to do so.