Opinion
Hydropower: Let pump dams fill gaps in India’s clean energy supply
Summary
- Adani’s mega investment in pumped storage hydropower (PSH) projects should be viewed in the context of India’s need to tackle wind and solar power intermittency for a smooth green transition. Unlike the usual renewables, PSH lets us ramp up or reduce output easily.
As India pushes forth with its transition to clean energy, storage is a challenge that confronts us. Windmills and solar panels serve well so long as the wind blows and sun shines. To fill in the gaps when they don’t and assure users a steady flow of electricity, we need to either store generated energy in chargeable batteries, which costs a lot, or create clean capacity with a control knob to raise or reduce output at will.
In this backdrop, the Adani Group’s latest investment plan is notable. According to a Mint report, Adani Green Energy Ltd plans to invest approximately ₹25,000-27,500 crore in pumped-storage hydropower (PSH) dams over the next five odd years, with PSH capacity of 5 gigawatts as its initial goal. Having already invested heavily in wind and solar projects, Adani expects to move fast on this, aiming to scale up its PSH capacity to 25GW eventually.
Players like Tata Power, JSW and the state-run NTPC also plan pump dams. Earlier this year, the Union environment ministry had cleared PSH projects worth over ₹80,000 crore, but Adani’s outlay is now the largest. Its entry will boost the country’s drive for sustainable power generation.
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What sets PSH units apart is that the power they generate can go by the sum of our needs rather than the vagaries of nature. This means they can be linked to grids to solve the problem of supply intermittency faced by other sources that do not use fossil fuels. Regular old dams hold water in vast lakes; by opening sluice gates to let it cascade onto watermills that rotate under its force to create electricity, they can vary their output, going full pep to maximum capacity if need be.
The same applies to PSH units, which are typically smaller but differ in a significant way. Their reservoirs, built as usual at some height, are self-fed with water that’s routinely pumped back up after use (using less power of course). Pumps relieve such dams of the need for natural water inflows. A steep hillside, for example, is all they need.
Also read: Mint Primer: Sikkim review: How safe are dams in India?
So, while PSH generators are capital intensive, they face fewer limitations of geography than classic river dams built in hilly regions. Spotting the appropriate topography to create a little lake is not short of its own challenges, but water recycling expands the country’s scope for hydropower manifold.
Although the basic idea has been around for long, technical advances in recent years are said to have given it better energy efficiency in terms of its input-output ratio.
To fully appreciate the value of a control knob to plug gaps in clean supply, consider India’s current scenario. Peak electricity demand this summer overshot our fossil-fuel capacity of around 237GW, and even though we have over 179GW of other capacity, large parts of India suffered outages.
While patchy grid link-ups explain much of this discrepancy between what we can produce and what users get to use, overall, what’s needed for us to rely on clean sources in the future—as we must—is a mission to back up renewable power with generators whose output is easy to vary. A robust network of PSH plants would fit the bill.
Also read: Mint Primer: Why India needs a new hydropower policy
Water-driven turbines only need large volumes of this fluid kept in reserve, with wind and sunlight conditions in no position to play spoilsport. Granted, pump dams are expensive—which is why their ideal role is as gap fillers. Of the 500GW that India is aiming for from non-fossil-fuel sources by 2030, more than just a sliver ought to be from pump dams. Seen from the sky, little lakes atop hills are the missing piece in our power puzzle.
