Climate-induced water stress is leading to frequent shutdowns at thermal and hydropower plants in summer, when electricity demand is high
Acute shortage of water in India, particularly following the years there is low rainfall during the monsoon season, has started hurting India’s energy production badly. Electricity generation in the country is heavily dependent on coal-fired thermal plants and hydropower projects, which require consistent supply of large volumes of water to operate at optimal levels. Any disruption in water supply affects production and leads to power outages.
For instance, water shortage related shutdowns in 2016 cost India roughly 14 terawatt-hours (TWh) of thermal electricity generation, enough to power neighbour Sri Lanka for an entire year, according to research by the World Resources Institute (WRI). The Washington-based research organisation compiled and analysed over 1,400 daily outage reports filed with India’s Central Electricity Authority between 2013 and 2016 to arrive at this conclusion.
The loss of generation has significantly increased over the past three years from 1,258 million units in 2014-15 to 4,989 million units in 2015-16 and to 5,870 million units between April 2016 and January 2017, Energy Minister Piyush Goyal told Parliament in March. See: Water scarcity stifles India’s thermal power
In 2016, as many as 18 thermal power plants had to lie idle for various lengths of time due to water shortages. If these plants had water supply during the shutdowns, they could have generated 14 TWh of electricity, about 1% of the country’s annual consumption, WRI’s analysis showed. During the four years from 2013 through 2016, India’s thermal power sector lost more than 30 TWh of potential electricity due to water scarcity, Tianyi Luo, Research Associate at WRI’s Water Programme, wrote in a recent report.
It is worrying that most of the shutdowns happened between March and September, the hottest months in South Asia when demand for electricity is high not only for domestic and industrial use but also to irrigate farms during the main cropping season. “In other words, electricity generation was the most hampered when people needed it the most,” Tianyi said.
Although India is taking big steps to expand its renewable energy capacity, the country’s power sector remains reliant mostly on thermal plants, which have a high water demand, mainly for washing coal and then for the boilers, from which the steam is funnelled to turn the power generation turbines. India depends on coal for about 60% of its energy needs and aims to double its output to 1.5 billion tonnes by 2020, according to Niti Aayog, the government’s policy think tank. It means that droughts, which last occurred in 2016, can lead to prolonged power outages, hamstringing the economy and endangering livelihoods.
Climate change is likely to increase the frequency and intensity of droughts, and socioeconomic development will intensify local water competition. “In the coming decades, we expect more water shortage-induced power shutdowns, unless steps are taken to reduce these risks,” WRI said.
Closed cycle systems
To reduce water requirement in thermal power plants, there has been a move to install closed cycle systems in new plants instead of the once-through cooling systems, the Energy Ministry has said. Existing thermal power plants can also reduce water risk by adopting less water-dependent cooling technologies, such as dry cooling.
Power plants are using other measures to conserve water such as installing ash water recirculation system, stopping discharge from ash pond effluents, adopting high and medium concentration ash slurry disposal systems, maintaining of high cycle of concentration in cooling towers and use of cooling tower blow down for disposal of bottom ash. These measures have helped bring down the total water requirement in a closed cycle system for a thermal power plant from 7 cubic metres per MWh to about 3 cubic metres.
But, considering the future water demand from upcoming thermal power plants and sectors like agriculture and domestic use, reducing water consumption in power plants will have only a short-term effect in improving overall water balance of the country, says a 2016 policy brief by The Energy and Resources Institute (TERI). Adopting a more comprehensive approach, thermal power plants must be asked to reduce the water footprints (rather than consumption) of their operations, said the brief titled Water Neutral Electricity Production in India: Avoiding the Unmanageable. “The concept of water neutrality must be made mandatory for power plants, which require them to return back an equivalent amount of water to the hydrological system as consumed by them,” TERI said.
To assess vulnerability of thermal power plants to droughts and water scarcity, there is need for detailed plant level water withdrawal and consumption data, says WRI, which is working on a methodology by using satellite imagery to develop a water usage database for the country’s thermal power plants, and provide a comprehensive risk assessment capacity that can support better planning for India’s water-stressed power sector. As demand for energy grows and climate change impacts water availability and timing, this kind of analysis will become vital for all countries, Tianyi said.