Hydropower Performance

Diminishing Returns from Large Hydropower projects in India

 Above: Graph showing how the power generation per MW installed Hydro Capacity has been doing down over the last two decades

As per the latest power generation figures just released by the Central Electricity Authority[1] the hydropower generation during the just concluded Financial Year 2014-15 was 4.25% lower than the previous year’s generation even though the installed capacity has gone up. Average generation per MW of hydro capacity in India in 2014-15 was over 20% less power than what our average generation was in 1993-94. More worryingly, the hydropower generated per MW installed capacity continues its downward slide, the downward slide has been going on for now over two decades.

The governments and power sector establishment in India have been pushing Large Hydro projects as if they are good in themselves. See the graph below that shows the rapid increase in installed capacity of large hydro projects in India[2]. A huge additional capacity of hydro capacity is under construction and various stages of approval and planning.

Increasing capacity of large hydropower projects in India
Increasing capacity of large hydropower projects in India

However, there has been no attempt at credible performance appraisal of hydropower projects in India. SANDRP has been doing performance appraisal of large hydropower projects of India for some years. In the graph given below we have plotted the Million Units (MU, one unit is equal of one kilowatt hour of power) power generated per Mega Watt (MW) installed capacity of all operating hydropower projects in India. We have done this based on the official data from Central Electricity Authority for total annual power generated by all existing operating large hydropower projects of India and total installed capacity of such projects, for each of the last 20 years from 1993-94. The total installed capacity of large (installed capacity over 25 MW) hydro projects in India as on March 31, 2015 is 40885 MW.

Diminishing generation from large hydropower projects in India
Diminishing generation from large hydropower projects in India

The graph also shows the trend line of power generation of Big Hydropower projects for the last 20 years, it is clear the trend-line shows diminishing generation from existing hydro power projects of India.

  • It shows that per MW generation in 2014-15 has dropped by over 20% from the generation figure for 1993-94. This should be a matter of serious concern, but the CEA, Power Ministry or none of the other bodies are doing such an analysis. Such an analysis can also help us try and understand why this is happening and what needs to be done to arrest or reverse this trend. The falling generation cannot be attributed to lower monsoon rainfall, since rainfall has been average or above average in most of the years under consideration.

Monsoon Rainfall What we can see (see Annexure 1 below) from these monsoon rainfall figures from India Meteorological Department[3] is that in 14 of the 22 years the rainfall was above or near normal (above 98% of normal), so one cannot say that the diminishing generation is due to below normal monsoon.

89% projects are underperforming A separate analysis showed that 89% of the projects generate at below the design or promised generation level at 90% dependability. Each large hydro project is given techno economic clearance by CEA based on a promise at appraisal stage that the project will generate certain amount of power in 90% of the years. When we compared that figure with the actual generation figure for the last 29 years for each of the operating projects, we found that 89% have been under-performing. And among the under performing projects, 50% were generating below the 50% of the promised power generation. And yet no questions are asked, no accountability fixed, in fact such an analysis is not even done by the official agencies. This means, for example that a lot of the projects that are being set up now are UNVIABLE projects or that the installed capacities are way above optimum levels.

The reasons There are many reasons why the generation per MW is dipping: unviable projects, unviable installed capacities, over-optimistic hydrological assumptions, over development (development beyond the carrying capacity of the basin), catchment degradation, high rates of sedimentation, inadequate Repair & Maintenance, Run of River projects (this phrase is a misnomer, these projects do not generate power from the run of the river but through a dam and a tunnel), changing monsoon patterns due to climate change, etc.

Here it should be added that the destruction of forests, rivers, fisheries, biodiversity and submergence of lands is also making the impact of  climate related disasters worse for the people and also for the hydropower projects, as could be seen during the June 2013 Uttarakhand disaster. All this needs to be part of our impact assessment and decision making process.

MONTHLY GENERATION The bar chart below provides monthly power generation from hydropower projects at all India level during the just concluded 2014-15. The chart shows that the maximum power in hydro sector (36.3% of annual generation) happens during three monsoon months of July-Sept. During six months of May-Oct, 63.7% generation happens and during the remaining six months, only about 36.3% generation happens, February has the lowest generation.

Monthly generation from Large Hydro Projects  during 2014-15
Monthly generation from Large Hydro Projects during 2014-15

Underperformers During 2014-15, central sector hydro capacity of 13576 MW generated 1% more power than 2013-14, and private sector capacity of 2728 MW generated 7.32% more power. It was the state sector capacity of 24582 MW that generated 8.1% lower power than the previous year. The biggest dip in generation was seen in the power generation at Sardar Sarovar Project’s 1450 MW capacity, which was a reduction of 50.31% compared to 2013-14. Among the central sector hydro organisations, NHDC (1520 MW capacity on Narmada river) saw the biggest dip of 35.9% compared to previous year generation. One of the reasons for the reduced power generation at SSP and upstream Narmada projects of NHDC was the unjustified depletion of the reservoir before the 2014 parliamentary elections[4].

There is no doubt that more detailed state wise, basin wise, type wise, age wise, etc analysis would help, some of which are available in “Hydropower Performance” section of SANDRP website[5]. However, to continue to push large hydro without such informed analysis would only lead to bad decisions, leading to avoidable social, environmental, economic and opportunity costs.

There are options Considering the diminishing returns from existing hydropower capacity and serious underperformance from 89% of existing projects, the first priority should be to optimise generation from existing projects instead of pushing for new large hydro projects. We are also not doing advance comprehensive project level and basin wide cumulative social and environmental impact assessments, nor getting public consent in upstream and downstream areas.

Even for ensuring power to those that do not have access to power now, there is also a huge potential of sub MW (less than 1 MW or KW scale) capacity hydro projects in most of the Himalayan and other mountain areas. These projects would have least costs, least impacts, and could be implemented in short time with full involvement of the benefiting local communities. Such projects should be a priority before taking up larger projects.

As global trends show, more solar and wind power based installed capacity is now being added than in any other sector. This is also likely to be the trend in India in future since cost of solar and wind based generation is going down. One of the obstacles in this regard is that the solar and wind power is only available during day time or wind hours and storage of surplus (over and above what the grid can consume) power generated during such time is costly and difficult to store. The pump storage hydro projects can provide an option in this regard even at existing dams. Thus surplus power during day time and wind hours can be used to pump water from lower (smaller) reservoir to upper (larger existing) reservoir of such projects. During night and off wind hours, this water than be released from upper to lower reservoir to turn the same turbines to generate power. This option needs to be explored.

No one is assessing peaking power from hydro projects One of the USPs (Unique Selling Propositions) of hydropower projects is that it can provide peak hour power, which coal based or nuclear power projects cannot provide. However, we do not have the necessary data to analyse what % of hydropower generation is providing peaking power. What is surprising however is that there is no agency in India that is doing such an analysis. Without such an analysis it is not even possible even start understanding and optimizing the peak hour power generation from hydro projects. Needless to add, such an analysis should also involve assessing the impacts of peaking power generation. Depending on site specific conditions, the currently under-utilised peaking power potential of existing hydropower projects can be substantially better utilised before going for new peaking projects. The question is, if we are neither monitoring nor trying to optimize peaking power generation, is there a case for pushing more hydro in the name of peaking power demands?

What about existing large dams? Lastly, it should be added that less than 3% of India’s large dams have hydropower component and most of the 97% large dams without hydropower component are irrigation projects. However, in these projects, the social, environmental and economic costs have already been paid. We need to at least assess the possibility of adding hydro component to some of these projects. But such an assessment is not happening at all. United States of America, whom we look up for many things, has been doing exactly that, assessing the possibility of adding hydro component at existing dams rather going for new hydro projects.

What all this means is that before we go for more large hydro projects at huge social, ecological and economic costs, we have a lot of options. We hope the questions raised in this analysis lead to changes in some of the directions indicated here.

Himanshu Thakkar (ht.sandrp@gmail.com)


[1] CEA is a Union Power Ministry’s premier technical body, see: http://cea.nic.in/monthly_gen.html

[2] The slight dip in installed capacity in 2010-11 is because in the capacity monitored by the Central Electricity Authority, the CEA that year excluded some of the small hydro projects (capacity below 25 MW) that were included in its monitoring matrix earlier.

[3] http://www.imd.gov.in/section/nhac/dynamic/Monsoon_frame.htm

[4] For details, see: https://sandrp.wordpress.com/2014/04/13/narmada-dams-levels-depleted-to-generate-more-electricity-threatening-water-security-for-gujarat-and-madhya-pradesh/

[5] https://sandrp.in/HEP_Performance/


Year Monsoon Rainfall
1993 101 %
1994 110 %
1995 100 %
1996 103 %
1997 102 %
1998 106 %
1999 96 %
2000 92 %
2001 92 %
2002 81 %
2003 102 %
2004 87 %
2005 99 %
2006 99 %
2007 106 %
2008 98 %
2009 78 %
2010 102 %
2011 102 %
2012 93 %
2013 106 %
2014 88 %

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