Imatra hydropower plant

General information about hydropower

​Hydropower is the most important form of renewable energy production in the Nordic countries. Additionally, hydropower has a special role in the functionality and reliability of the energy system because of its flexibility.

Hydropower is a domestic, carbon dioxide-free and renewable electricity production form. It is based on the natural cycle of water. Hydropower plants utilise the difference in height between the dammed water and the water’s outflow; this difference is called the head. The dammed water is released through the power plant to the outflow. The energy harnessed from the water flow rotates a turbine that drives a generator. The generator converts the water’s energy into electricity.

The important role of hydropower

By regulating water levels in lakes and reservoirs, the electricity production can be matched with the demand. That is why hydropower plays a key role in balancing electricity production and consumption in the Nordic countries. Power plant start-ups, output adjustments, and shutdowns are quickly implemented, and the water in reservoirs is used to even out fluctuations in demand.
One of the advantages of hydropower is that water can be stored in lakes and then used when there are spikes in electricity consumption. However, hydropower production is dependent on weather conditions. In years with low precipitation or little snowmelt, there could be a shortage of water to be stored.

Good efficiency

The water systems in Finland typically have a high fluctuation in flow rates. By storing energy and by regulating water systems, electricity production can be timed to better meet the demand. Spring flood waters can be stored in lakes and reservoirs for the use in dry seasons. This simultaneously accomplishes flood protection in regulated water systems. Hydropower efficiency is high and hydropower plant maintenance and operating costs are low. Hydropower production can be adjusted quickly. For this reason, fast changes in electricity demand are met primarily with hydropower. Hydropower plants start-ups, output adjustments, and shutdowns are implemented more quickly than with other power plants.

Hydropower production is dependent on weather conditions. There could be a shortage of water to be stored, in years with low precipitation. Hydropower’s role in balancing production and consumption will be emphasised in the future when an increasingly bigger share of electricity is produced with e.g. wind and solar energy.