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article imageHeatwaves and the reliability of EU power plants

By Karen Graham     Aug 12, 2019 in Environment
Across the world, heatwaves have been blamed for hundreds of deaths and power outages due to higher power demand. In Europe, heatwaves are affecting the supply of water, which is essential for cooling power plants and the production of hydropower.
The European Union's Joint Research Center (JRC) published an interesting analysis of the recent heatwaves to hit Europe - along with some proposed actions for addressing the problems that could arise in EU energy and water policies.
It was discovered that in July 2019, several nuclear power plants were temporarily closed in various parts of Europe due to high water temperatures. These thermal nuclear power plants require large quantities of cooling water to function. Added to the problem with water, hydropower output was also affected in France, Spain, the Balkans, and in Scandinavia.
"July 2019 was the warmest month on record. Rising temperatures have an impact on the energy and the water systems – two systems which are very dependent on one another. The energy industry is heavily dependent on the availability of water, but also the water sector depends on energy to be able to collect, pump, treat and desalinate water", said JRC researcher Davide Magagna, one of the authors of the study.
France is the world's most nuclear-dependent country  with 58 reactors providing 75 percent of ...
France is the world's most nuclear-dependent country, with 58 reactors providing 75 percent of its electricity
PHILIPPE DESMAZES, AFP/File
Water temperature can be critical
According to the World Nuclear Association, the amount of cooling required by any steam-cycle power plant (of a given size) is determined by its thermal efficiency. It actually has nothing to do with whether it is fuelled by coal, gas or uranium. However, currently operating nuclear plants often do have slightly lower thermal efficiency than coal counterparts of a similar age, and coal plants discharge some waste heat with combustion gases, whereas nuclear plants rely on water.
In Europe (especially Scandinavia) low water temperature is an important criterion for power plant location. And this strong interdependency between water and energy systems is being described by the JRC researchers as a "critical uncertainty". Any nuclear or coal-fired plant that is normally cooled by drawing water from a river or lake will have limits imposed on the temperature of the returned water (typically 30°C) and/or on the temperature differential between inlet and discharge.
This problem between inlet and discharge temperatures becomes a concern during summer months and critical during a heatwave. In mid 2010 the TVA had to reduce power at its three Browns Ferry units in Alabama to 50 percent in order to keep river water temperatures below 32°C, at a cost of some $50 million to customers.
Duke Energy s Oconee Nuclear Station  Unit 1
Duke Energy's Oconee Nuclear Station, Unit 1
NRC
"Until recently, the strong link between the water and energy sectors was not considered a major issue. But with the rising temperatures, it is quickly becoming a critical one. Although we are now using more and more renewable energy, the energy sector and even some forms of renewable energy require a lot of water. But our freshwater resources are limited and vulnerable to the effects of climate change", explains Davide.
Solutions and actions
With everything going forward as planned, by 2050, overall water withdrawn and consumed by the energy sector will decrease, but even so, water may still be at a premium. The climate crisis will have a negative impact on water availability and water scarcity could lead to more frequent power generation problems in different locations around the globe.
"Climate models suggest that the disruptions observed during the summer of 2018 will become more common and harsher. Water scarcity will be felt across Europe, affecting at least 90 million Europeans. And this will not only occur in the Mediterranean regions but also in other countries such as Poland, Czechia, and Germany", said JRC researcher Giovanni Bidoglio, another of the study's authors.
Alto Lindoso hydro-power dam in Portugal  part of the country s renewable energy mix.
Alto Lindoso hydro-power dam in Portugal, part of the country's renewable energy mix.
Wikimedia Commons
One option for reducing the need for so much water is transitioning to renewables like wind and solar. "Opting for renewable energy forms which are not water-intensive, such as wind or solar power, would further reduce the water requirements of the EU energy system, thus making it also more secure", Davide Magagna explains.
Smart meters are also mentioned in the report, along with the development of energy efficiency indicators and targets for the water sector, as well as boosting research activities on innovative water- and energy-saving technologies.
More about heatwaves, Thermal power stations, water for cooling, Hydropower, Renewables
 
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