Wake Up to Hydropower’s Important Role in Integrating Renewables

  • 2018/11/28     Dresden, Germany


    Image: shutterstock/WeStudio

    By Huiyu Mo, Communications and Advocacy, and Stephan Hülsmann, Systems and Flux Analysis Considering Global Change Assessment

    Hydropower is a very popular renewable energy source which is widely used in the world. It is electricity generated from the energy of moving water. The World Energy Council (2016) reported that hydropower supplies 71% of all renewable electricity. Due to the rapid development of other renewables, how we integrate hydropower with other renewable technologies becomes a rising issue.

    In the UNU-FLORES policy brief “The Need for Water As Energy Storage for Better Integration of Renewables”, Hülsmann et al. (2015) discuss the need for energy storage, calling on the attention to the importance of reservoirs in energy balance management.

    The authors point out that we are facing new challenges in the energy system. Energy production generated from conventional sources such as coal, oil, and natural gas is steady and predictable. Renewables like wind and solar energy are clean and environmentally friendly, but they are neither stable nor fully predictable due to their dependence on the weather, which is beyond our control. Under favourable weather conditions, renewables can generate enough electricity or sometimes even supply more electricity than demanded; however, under unfavourable weather conditions, supply might not be able to match demand. With the vigorous development of clean energy, it is imperative to solve the problem of imbalance in power output and demand.

    In response to a growing proportion of variable wind and solar input, the authors cast their eyes on hydropower for its capacity to store energy.


    When electricity demand exceeds supply, water storage in a reservoir can provide a crucial support in the electricity grid. Releasing water behind a hydropower plant can compensate the variability of wind and solar energy, especially during peak times or when other renewables are in short supply.

    In parallel, when the generated energy goes beyond the required amount, pumping facilities can use the electricity to pump water from a low place to a high place, so that a reservoir will have enough water for generation when needed. This process consumes about 15% of the electricity, but it makes the electricity system much more balanced because the supply can meet the demand all the time.

    In short, hydropower is notably an ideal solution to meet storage and flexibility needs in energy systems with high/increasing contributions of wind and solar energy.

    Exploring the integration of hydropower and other renewables is not only a scientific task, but also one of governance. Linking scientific understanding with policymaking is vital; the authors provide several policy recommendations.

    Policy Recommendations

    1. The role of reservoir hydropower and pumped storage in the energy system should be acknowledged. They can help to keep the system reliable via storing and regulating energy. This aspect needs to be considered while developing pathways towards a decarbonised energy supply system.
    2. Reservoirs and pumped storage are ideal backup energy supplements to wind and solar energy at multiple time scales. Careful further development of such systems is required, considering other needs and services.
    3. Reservoir infrastructure can provide a full range of water services, including providing domestic and industry water, managing flood and droughts and storing energy, and so on. Integrated management in the sense of a Nexus Approach is needed in a dynamic and adaptive way, and policy has to provide the framework and incentives to implement it.

    See policy brief for more policy recommendations

    Hydropower’s important role in the energy system has to be considered as part of the water-energy nexus. It emphasises the interconnections and interdependencies of water and energy, for example, water can be used to generate energy (and for many other uses), while energy is required for water treatment and transportation. To achieve sustainable environmental management, a comprehensive understanding of the water-energy nexus is crucial. When water is placed at the heart of energy discussions, it can bring us closer to a resource-wise world. Large opportunities are documented in various case studies and are particularly evident in areas with high hydropower potential (e.g., Bullock and Hülsmann 2015).


    Bullock, Andrew, and Stephan Hülsmann. 2015. Strategic Opportunities for Hydropower within the Water-Energy-Food Nexus in Mozambique. Vol. 4. Working Paper. Dresden: UNU-FLORES.

    Hülsmann, Stephan, Atle Harby, and Richard Taylor. 2015. The Need for Water as Energy Storage for Better Integration of Renewables. Policy Brief. Dresden: UNU-FLORES.

    World Energy Council. 2016. “Hydropower World Energy Resources 2016.” World Energy Resources 2016. London: World Energy Council.