Research topics  /  The flexibility of hydropower

The flexibility of hydropower 

Hydropower has provided Norway with secure access to energy for more than a hundred years. Globally, hydropower remains the largest producer of renewable energy. At the same time, a lot is being invested in the development of solar and wind power, which means that in the future we will be increasingly dependent on utilizing hydropower to get reliable and stable access to renewable energy. This requires us to utilize the flexibility of hydropower to a much greater extent than we do today.

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.

FACTS ABOUT HYDROPOWER PRODUCTION IN NORWAY

  • At the start of 2021, Norway's annual energy production from 1,682 hydropower plants was approximately 137 TWh (Terrawatt hours). That's 137 billion kilowatt hours. Installed power was 33011 MW (Megawatt).

For example, a coffee maker draws around 1-1.5 kW of power, so that means we can run more than 22 million coffee makers at once! (If we do nothing else).

    • The hydropower plants contribute over 90% of electrical energy in Norway.
    • Hydropower produces 34% of electrical energy in Europe and approx. 17% in the world.

    What happens if we do not have access to flexibility from hydropower and/or other energy sources?

    If this happens, it will in the worst case cause us to lose access to electricity. In less extreme cases, we can get unstable access to energy. This means that the frequency and/or the voltage changes, which can lead to more power outages, and that electronic devices such as TVs, PCs and other machines do not work or break down.

    FACTS ABOUT ENERGY AND POWER

    To better understand what role hydropower will have in a renewable energy system, we should be aware of the difference between energy and power.

    We can simply say that energy is how much electicity we have available, while power is how much electricity we can use at the same time.

    When we cut down on the use of fossil sources such as coal and gas, the energy-needs can be met by developing more solar and wind power. But to maintain the needed power in the system, it is crucial that the energy sources can be turned off and on exactly when it is needed.

    This is where the hydropower comes in. Hydropower can both store energy and deliver power when it is needed.

    • If we compare it to a car, for example, energy is the amount of fuel in the tank, while power is the size of the engine. So, you can have enough energy to drive from Trondheim to Tromsø if the road is completely flat, but to get up and over Saltfjellet you also need to have a high-power engine just when you need it.

    Power is how much energy you can deliver at the moment. The unit of measurement is Watt (symbol W).

    Energy is how much power is used over time, which can be measured in kilowatt hours (kW).

    • If you leave a heater with an output of 1 kilowatt on for a period of one hour, you have, for example, used one kilowatt-hour (kWh) of energy.

    The unique thing about hydropower compared to other renewable sources is that we can store energy, as water in reservoirs. Hydropower can then balance the energy system when wind and solar energy are not available.

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    About HydroCen

    We are a research center for environmentally friendly energy.

    Researchers will deliver knowledge and innovative solutions to Norwegian hydropower.

    The goal is for the research to contribute to Norwegian hydropower being able to meet complex challenges and opportunities in the future's renewable energy system.

    Norwegian University of Science and technology (NTNU) is the host institution and main research partner in HydroCen together with SINTEF Energy and the Norwegian Institute for Natural Research (NINA). HydroCen has around 50 national and international partners from research, industry and administration.

    About the Knowledge Hub

    The goal of the Knowledge Hub is to collect and make available the knowledge from the research in HydroCen so that the results can be used directly by the hydropower industry or in further research, thereby helping to ensure value creation and societal benefit.

    Newsletter from HydroCen

    We regularly send out newsletters with research results and news. Please register here:

    CONTACT

    RESEARCH RESULTS

    HANDBOOKS AND TOOLS

    PUBLICATIONS

    MORE RELEVANT TOPICS

    About HydroCen

    We are a research center for environmentally friendly energy.

    Researchers will deliver knowledge and innovative solutions to Norwegian hydropower.

    The goal is for the research to contribute to Norwegian hydropower being able to meet complex challenges and opportunities in the future's renewable energy system.

    Norwegian University of Science and technology (NTNU) is the host institution and main research partner in HydroCen together with SINTEF Energy and the Norwegian Institute for Natural Research (NINA). HydroCen has around 50 national and international partners from research, industry and administration.

    About the Knowledge Hub

    The goal of the Knowledge Hub is to collect and make available the knowledge from the research in HydroCen so that the results can be used directly by the hydropower industry or in further research, thereby helping to ensure value creation and societal benefit.

    Newsletter from HydroCen

    We regularly send out newsletters with research results and news. Please register here:

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