According to the German government’s plans, by 2050 Germany should be able to obtain its energy primarily from renewable sources such as solar energy, wind power, hydropower, geothermal energy or renewable raw materials. Nine research institutions, including the Ruhr University Bochum (RUB) and the University of Kassel, have now joined forces with various companies to investigate the extent to which the water available worldwide has an influence on the spread of renewable energy. Together they have launched the collaborative project “Water Resources as a Significant Factor in the Energy Transition at Local and Global Levels – WANDEL” (the German acronym means “change”). In this three-year project, they examined, for example, the “water footprint” of different energy systems and developed tools for water management. The project, which ended at the end of 2020, was funded by the German Federal Ministry of Education and Research.
Water is of great importance in energy generation – and by no means only in hydropower plants. For example, water is used for cooling in thermal power plants. River flows are also regulated for hydropower utilization, which in turn has an impact on local water and environmental systems at the power plant site. Depending on the energy system, water consumption is more or less significant. But there are also other, indirect impacts on water resources that are less talked about, such as in regions where coal or copper is mined.
In the WANDEL project, the researchers examined four different energy scenarios and their impact on water resources: a coal-fired power plant with water cooling on the Weser River, a chain of six run-of-river power plants on the Danube, a solar thermal power plant in Morocco, and the use of sugarcane biomass to generate electricity in Brazil.
Varying water footprints for different energy systems
The project results show “that strategies for transforming the energy system in the context of the energy transition should not only consider the reduction of greenhouse gas emissions, but also water consumption,” the scientists explain. For example, scenarios that set a low-carbon energy system as their goal would not automatically also lead to lower water consumption worldwide. Quite the opposite is true. The total amount of water consumed worldwide for thermal power plants to produce electricity would actually continue to rise. Consumption could only be reduced if the efficiency of power plants and cooling technology increased. As a result, thermal power production would become increasingly vulnerable to the increasing water scarcity that is expected to result from climate change.
The water footprint analysis the team conducted included both local and remote water demand along the entire energy supply chain. They compared the consumption per unit of energy produced for different energy systems and the result showed that consumption was very high for renewable resources, for example. On the other hand, however, the water footprint of this type of energy production would be much lower if systems that use waste materials were integrated, such as sugarcane biomass.
“Risk and sustainability analyses show that energy supply becomes more vulnerable with increasingly frequent water scarcity and drought under climate change conditions,” the researchers point out. Particularly in regions where water is scarce, such as desert and steppe regions, water shortages are already a problem for economic growth and agricultural production. In these areas, the lack of water endangers both human health and ecosystems and, as a consequence, sustainable energy production. Because hydropower use impacts freshwater megafauna, the scientists say that “biodiversity should also be considered when evaluating strategies for the transition to low-carbon energy.”
To address all of these issues, the project partners developed several water management tools and a simulator to train power plant personnel. This would allow dams and reservoirs to be operated optimally, also increasing the efficiency and safety of waterways and “dam-controlled watercourses.” The so-called “Environmental Sustainability Assessment” improves environmental impact assessment and can evaluate the sustainability of man-made processes with upstream supply chains. “A set of indicators to determine the vulnerability of energy systems and water resources helps decision-makers assess the sustainability of actions taken in the context of energy and water security,” the project partners write.
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