So, what exactly is the flexibility of hydropower?
In short, hydropower's flexibility is provided by the properties it has to store energy, start and stop the power plants when it suits us, and to provide quick access to a lot of electricity at the same time (high power).
This means that hydropower can deliver flexibility in many different situations, both when a quick response time is required and when there is a need for storage over a longer period of time or large volumes.
Gigantic energy reserves in the mountains
An important reason why the hydropower system in Norway is so flexible is that we have taken advantage of the opportunity to store energy in water reservoirs in the mountains. This allows us to store water from the snow melt in the spring to produce energy in the winter when it does not rain.
In the future, water reservoirs and the possibilities they provide for storing large amounts of energy for periods from days to months will become even more important. With increased development of other renewable resources such as wind and solar energy in Norway and Europe, we will save water to a greater extent when there is a surplus from other energy sources and use more of the hydropower in periods when the wind and solar power plants are not producing.
Increased flexibility can also be achieved by filling and emptying the magazines more often. We can imagine that we fill them when we have access to excess energy from wind or solar power plants, and empty them when there is no wind and/or there is little sun available. This requires Norway to expand the possibility of pumping water up into the water reservoirs. In areas where there are already power plants with existing water reservoirs both upstream and downstream of the power plant, there is a question of installing pumps in existing power plants.
HydroCen has several projects related to this:
Upgrading of Hydropower Plants to Pumped Storage Plants: Tunnel System Hydraulics
Great potential for environmental design in water reservoirs
Conversion of hydropower plants to power plants and pumping stations
The morning shower affects the power system
In some periods, we need quick access to a lot of energy at the same time, and this means that the power output is large. This is typically early in the morning when everyone gets up, showers and makes breakfast, or when everyone has to cook and eat dinner at roughly the same time. Such peaks in consumption occur with a fairly regular pattern over days, weeks and years.
A more extreme case could be a storm in an area with a lot of wind power. Fosen district in Trøndelag is a good example of this. When the storm reaches wind speeds of approx. 30 m/s, then the wind turbines must stop to avoid damage. At Fosen, this could mean that access to as much as 1,000 MW falls out of the grid.
Then the hydropower plants must provide quick access to energy and it can be a matter of seconds in some cases. Let's imagine that Fosen Vind sells its energy to Hydro, which produces aluminium.
It would be a disaster if they lost access to energy. In such cases, it is very valuable that hydropower can contribute with quick access to power and energy.
Why do we need flexibility from hydropower?
History tells us that access to safe energy from hydropower has been a crucial prerequisite for building the industry that is the basis for the Norwegian welfare society.
Hydropower will continue to play this role in the future, but with an increased share of production from other renewable sources such as wind and solar power, hydropower will also have another important role. Energy from wind and sun cannot be stored, and must be produced when the resources are available, i.e. when it is windy and/or sunny.
Hydropower, on the other hand, is controllable to a much greater extent, and the new role of hydropower will therefore be to support the other energy resources so that we still have access to a safe and robust energy supply. Hydropower can provide access to energy and power when the wind is not blowing or when the sun is down, it can provide large amounts of power in a very short time, and it can store energy when there is a surplus from wind and solar.
But the change in how we use hydropower, from supplying energy to securing the system for variation in renewable energy production, could increase the need for the hydropower plants to start and stop the production of energy more often. In other words, the way the hydropower plants are operated will change, which in turn can lead to the tunnel, pipes, turbines, generators, etc. being exposed to much greater wear and tear than what they were designed for.
HydroCen has several research projects here:
Shall find the service life of hydroelectric tunnels (in norwegian)
Machine learning – fault detection in generators
Flow analysis and design of components for safer operation and increased performance in hydraulic turbines (in norwegian)
In a future with greater and more frequent rainfall, the reservoirs' flood-mitigating role will become even more important. We will probably also experience more frequent and longer dry periods in summer. That is why HydroCen is also researching environmental design in reservoirs.