Hydropower’s role and significance in the Finnish electricity system has changed over time. When the Imatra hydropower plant was commissioned in 1929, it was Finland’s biggest hydropower plant – and it remains the biggest with its 192-megawatt capacity. Upon commissioning, it was believed that the Imatra hydropower plant was the only electricity production plant that would ever be needed in Finland. The dedication speech noted, among other things, that the power plant’s electricity production would be enough to supply Finland forever. Today, the Imatra hydropower plant’s production covers the annual electricity consumption of about 60,000 single-family homes heated with electricity. Imatra’s share of all electricity produced in Finland is about 1.5%, and hydropower produced in Finland covers only about 15% of electricity consumption in Finland. It should be noted that Finland is not self-sufficient in terms of electricity production; about one-fourth of all the electricity we use is imported.
Why is hydropower still so significant for our electricity system?
The primary global challenge of our time is the climate crisis. Global warming must be halted, and carbon neutrality must be achieved quickly, as was highlighted also in the recent IPCC report. Electrification will impact transportation, industrial processes, the heating of buildings, and more. To achieve this goal, we increasingly need wind and solar power. In addition to zero carbon emissions, hydropower has many other excellent characteristics, the most significant of which is its good balancing capacity compared to other production forms. In order to be able to connect renewable, weather-dependent production to our electricity system, the electricity system must have enough balancing power to balance the wind and solar production volumes to meet demand. In the electricity system, the production must be equal to the consumption at all times – every second and fraction of a second. Hydropower is at its best when balancing production with consumption.
How much balancing power is needed?
The Finnish transmission system operator Fingrid publishes on its website information about wind power production on an hourly level. The graph below presents Finland’s wind power production in March 2021. More than 2 gigawatts of wind power capacity has been built in Finland. Production fluctuates between the rated output and essentially zero output, depending on the wind conditions. The graph is an excellent illustration of the current situation. In March, wind power production fluctuated between 2,200 megawatts and under 200 megawatts on several occasions. Low wind-power production volumes can last several days or just a few hours, after which the production jumps to the other extreme. Is this fluctuation a lot or a little? The output of the upcoming Olkiluoto 3 reactor is 1,600 megawatts, so even the capacity of this huge nuclear power plant wouldn’t be enough to balance these production fluctuations.
Graph 1. Wind power production (MW) in Finland in March 2021 (Fingrid)
Hydropower’s balancing ability will be needed also in the future
These days, hydropower is to a significant extent responsible for producing the balancing power that is needed. A hydropower turbine typically has a wide control range, and the fuel has been stored in reservoirs, i.e. regulated lakes. Big water systems have so much stored energy that it’s possible to balance even longer-lasting fluctuations in wind power production. So far, no other energy production form has a similar ability as hydropower to store energy and produce balancing power. In fact, there currently aren’t many alternatives to hydropower, even though new solutions are constantly explored. In order to be successful in halting global warming, it is vital to enable the construction of renewable energy while securing hydropower’s position. According to a survey by the Finnish Wind Power Association, there are about 21,300 megawatts of public wind power projects in Finland, and about 3,400 megawatts of projects under construction will be commissioned within the next 2-3 years. So the demand for balancing power will be increasing even more.