Falling reservoir levels bode ill for hydro power generation this summer

Thanks to last year’s late monsoon, scanty winter rains and lack of snowfall, reservoir levels fell 17% from a year earlier to 73.29 billion cubic metres (bcm) on Thursday, data from the Central Water Commission (CWC) showed. The levels are also nearly 3.6 percentage points below the 10-year average of 76.06 bcm.

“Reservoir levels are very low currently; in case rainfall is deficient in the upcoming months, hydro power generation would be further impacted,” an official with a hydro power generation company said. “Last year, the monsoon was delayed and it hampered generation by hydro projects to a great extent. Govind Sagar, Indira Sagar and others are key reservoirs for hydro power projects,” the official said on condition of anonymity.

India has a hydro power capacity of 46.92 GW, which is 11% of the total capacity of 429.96 GW. Despite this small share, it has an outsized role in keeping the power grid stable, since its generation can be regulated when required, unlike other renewable energy sources like solar and wind which depend on wind and sunshine.

Most top reservoirs are running low on water levels compared to last year. Govind Sagar reservoir in Himachal Pradesh, which caters to a hydel capacity of 1.37 GW, currently is only 33% full, against 35% a year earlier. Koyna dam in Maharasthra, with a hydro power project of 1.9 GW, was 61% full, against 67% last year. Uttarakhand’s Tehri dam, which caters to 1 GW capacity, was at just 3%, against 37% the year before.

One exception is Indira Sagar dam in Madhya Pradesh, where storage has risen to 54% of its capacity from 40% last year, according to data from CWC. It has a hydro power capacity of 1 GW.

Until monsoon rains arrive, melting snow in the Himalayas is a key source of water for hydro power generation from March to June. However, there was little snow this time.

“This year, there was deficient winter rains compared to previous years. Usually, rains during winters in northern India coincides with snow formation in the upper reaches of the Himalayas. However, this winter, we witnessed only some scanty rains in late February and the formation of snow was also comparatively less, leading to no major source for snow melting and hydro power generation in the coming months. So, power generation may be impacted going ahead,” said A.K. Singh, general manager, NTPC, Hydro Headquarters.

Hydro power generation during April-January was already 17% lower at 121.28 billion units from the previous year’s 146.12 billion units, data from Central Electricity Authority (CEA) showed.

“Especially acute has been the September to December period, with generation in these months being on an average 29% lower than the same months of last year,” said Miren Lodha, director- research, Crisil Market Intelligence and Analytics. “This stems from uneven monsoons in fiscal 2024, coupled with unusually high temperatures seen since September of the fiscal prior to winters setting in.”

In India, thermal power has the highest share of 48% in installed capacity, while renewable power (excluding large hydro) has 31%. The likely fall in hydro power generation could put further pressure on thermal plants going ahead.

“Hydro power plays an important role in India’s energy sector, providing electricity at competitive rates along with flexibility in supply. Power generation from hydel power plants can be ramped up very quickly, unlike thermal power plants, where there are challenges in ramping up and down power generation beyond a certain level. In this context, the role of hydro power projects would remain prominent amid the increasing share of solar and wind power, which are intermittent in nature,” said Vikram V., vice-president & co-group head, corporate ratings, ICRA.

Given India’s net-zero ambitions, hydro power and pumped storage projects will play a much more important role going ahead, he said.

Further, with the anticipation of a warmer summer this year, power demand projection is also likely to grow, with increased cooling requirements. The India Meteorological Department (IMD) on Friday said India is likely to experience a warmer start to the summer season this year, with El Nino conditions predicted to continue through the season.

More heatwave days than normal are predicted over northeast peninsular India, including in Telangana, Andhra Pradesh and north interior Karnataka, and also in many parts of Maharashtra and Odisha.

“Based on IMD guidance for the upcoming summer months, normal to above normal temperatures are expected over most parts of the country during March-May 2024,” said Crisil’s Lodha. “This will be a key monitorable as it could lead to surge in power demand from cooling equipment along with irrigation, coupled with higher water consumption needs, eating into hydro generation resources where water sources are common. In the event of a similar monsoon as fiscal 2024, water levels in different regional pockets may also be a monitorable.”

Anticipating a surge in demand, the power ministry has already directed all thermal power generating companies to continue blending of 6% imported coal till June. Chairman of the Central Electricity Commission (CEC) Ghanshyam Prasad recently said that the peak power demand in the upcoming fiscal may touch a new record of 260 GW. The peak last year was 243 GW.