Hydropower fell out of favor in the late twentieth century due to nuclear power and exceptionally cheap electricity costs. Today, however, hydropower is unquestionably the best source of renewable energy. It is the most commonly utilized carbon-free energy source, accounting for 15% of the world’s electricity production.
Image Credit: ©2024 Eric Buche for EPFL
In Switzerland, it makes up about 53% of our renewable energy mix. Furthermore, hydropower has the potential to contribute significantly to reaching net-zero energy supply. However, the International Energy Agency estimates that output would need to double by 2050 from its current level (1,400 GW).
The most significant advantage of hydropower is its versatility. Hydropower plants might not only create electricity on demand, but they can also absorb electricity generated by other renewable energy sources and store it in pumped-storage facilities.
With hydropower, we can increase our production and storage capacity for other renewables—and therefore build more solar and wind farms.
Elena Vagnoni, Project Head, Technology Platform for Hydraulic Machines, EPFL
This research and development platform was founded in 1969 and has since become a center of excellence in its field, with world-class experience in hydraulic equipment testing and certification.
A Paradigm Shift
At first, hydropower plants were designed for optimal efficiency and not to provide flexibility to power grids. But now we’re undergoing a paradigm shift, which means we need to completely rethink the way equipment is designed and used. That said, we obviously can’t tear down all our existing plants and build new ones. So, we have to find ways to retrofit existing equipment, in addition to designing next-generation systems.”
Mario Paolone, Head, Technology Platform for Hydraulic Machines, EPFL
EPFL conducted the EU’s largest hydropower research and development initiative, XFLEX Hydro, which just concluded.
Vagnoni added, “We developed a range of technology for improving the flexibility of hydropower systems without increasing their installation and maintenance costs.”
The initiative involved examining how to make better use of existing equipment, assessing the stresses on equipment in highly dynamic working situations at hydropower facilities, and doing research on fluid mechanics and flow control systems.
Gaining Megawatts
Pumps and hydroelectric turbines, for example, are connected in series in pumped-storage systems. That is, the turbines revolve to create power, and the pumps use that electricity to move water into a reservoir at a higher elevation, storing any excess energy. When plant operators desire to change the order of activities, the plant must be shut down for at least ten minutes.
To address this issue, researchers have developed what they call hydraulic short circuits, or devices that allow pumps and turbines to run concurrently.
“This mechanism lets plant operators reverse the process instantly, like what happens inside a battery. We have already tested it successfully at several hydropower plants in Europe,” Paolone added.
The engineers are also investigating strategies for increasing the production of hydropower plants.
Vagnoni further stated, “It is always better to rely on a carbon-free source of energy.”
They are looking into a variety of options, including increasing a plant’s energy storage capacity by installing more pumps, installing microturbines within pipes to supply power to small villages, addressing system fatigue, dealing with sediment more effectively, implementing digital processes for monitoring, maintenance, and production schedules, mapping out more granular production schedules, and getting knowledge on still-obscure physical phenomena.
Preserving the environment is vital as well.
“We are looking at how we can renovate hydropower plants to reduce their impact on plant and animal life and make them more resistant to the fluctuations in water levels being caused by global warming,” Vagnoni concluded.