Thermal power plants that run on natural gas, nuclear power, and coal accounted for 75% of global electricity generation in 2017. Asia in particular, is highly dependent on coal power for electricity supply, and demand is expected to grow in coming years. These plants, however, generally need water for cooling, which is increasingly constraining their electricity output because of low water availability or high intake water temperatures – sometimes both. Although some regional regulations attempt to address the environmental impacts of current and future coal-fired power plants by banning the use of groundwater for cooling, limiting the construction of new power plants, and mandating the use of wet cooling towers, there are still a large number of coal power plants in the region’s planning pipeline. This presents a problem, as population growth and economic development continue to drive both water scarcity and electricity demand in Asia. The effects of climate change are further exacerbating water shortages and increasing air and water temperatures, which has led experts to suggest that the usable capacity of thermal power generation could decrease globally by around 8–16% on average by the middle of the 21st century.
In their study published in the journal Energy and Environmental Science, researchers from IIASA, Ohio State University, the Institute for Integrated Energy Systems, and Utrecht University explored the extent to which current and future coal power plants in the region will be impacted by expected changes in the hydroclimate. This is the first study of this type and scale for the Asia region to use ultra-high-resolution hydrology to consider not only current, but also planned power plant capacity.
“We investigated the electricity planning problem in Developing Asia, where the rapid expansion of coal-fired power plants and low water availability co-exist with interdependencies that evolve with the makeup of the energy system and the climate. We used high-resolution hydro-climate simulations and datasets of the existing and planned power plants to quantify the water constraints on coal-fired electricity generation at the power-plant level under various climate and energy planning scenarios,” explains Yaoping Wang, who started her work on the topic as part of the 2017 IIASA Young Scientists Summer Program. Wang received a Peccei award for her work at IIASA and is currently an assistant research professor at the University of Tennessee.
The Institute for Integrated Energy Systems, and Utrecht University explored the extent to which current and future coal power plants in the region will be impacted by expected changes in the hydroclimate
To simulate future hydrological conditions, the study employed climate scenarios that correspond to a 1.5°C, 2°C, and 3°C increase in global temperature above pre-industrial levels. The 1.5°C and 2°C warming scenarios are consistent with the temperature and mitigation targets of the Paris Agreement, while 3°C (or higher) warming is likely to happen if the current trajectory of greenhouse gas emissions continues. The researchers further implemented different scenarios of cooling system choice, evolution of the power generation fleet, and the deployment of CO2 capture and storage (CCS) technologies, that are consistent with 1.5°C, 2°C, and 3°C warming to understand the potential impacts of adaptation to water scarcity and CO2 emissions mitigation.
The results revealed local and daily variations in water constraints on thermal power generation. Coal-fired power plants in Mongolia, Southeast Asia, and parts of India and China, for instance, are projected to confront substantially greater water constraints under current electricity sector expansion plans, regardless of the implementation of CO2 capture technology that requires even more water.
The analysis further shows that the planned electricity generation capacity is inconsistent with current international climate policy of limiting warming to 2.0°C. Ironically, large numbers of these plants, and subsequently parts of the entire electricity grid, have their reliability impacted due to changing water availability and air temperatures in a warming climate. Although not covered in this study, power plant outages, due to cooling water unavailability at large units such as coal power plants, are known to have serious implications for grid stability and can increase electricity prices. Climate-adaptation options to reduce reliance on water can also increase costs, which would ultimately be passed on to consumers.
The results revealed local and daily variations in water constraints on thermal power generation
According to the researchers, development and climate change pressures in Asia are immense in terms of the scale of development required for a third of the world’s population, who are mostly very vulnerable, and the severity of climate hazards that can be expected across Asia. This necessitates energy and water resource systems planning that can help mitigate the CO2 emissions from electricity generation that cause climate change and is also resilient to the already inevitable impacts of global warming that will occur at 1.5°C or 2.0°C of warming. The study highlights three possible strategies to mitigate water limitations namely, selectively reducing the existing/planned power plants in water-scarce regions; integrating electricity markets so that interregional electricity transmission can compensate for local water stress; and widely adopting dry cooling in northern Asia where the technology does not incur high losses in thermal efficiency.
“We know that coal power contributes significantly to global warming – more than almost any other electricity source, and what this study shows is that coal power development can expect reduced reliability in many locations across Asia. In addition to the other known negative impacts such as on air and water quality, this is further evidence of coal power’s increasingly recognized incompatibility with current international and national climate and sustainable development policy,” concludes study coauthor Edward Byers, a researcher with the IIASA Energy Program.