European hydro power is currently well-developed. Although European hydro power electricity generation will increase in absolute terms, its share of total electricity generation will decrease slightly. The capacity of hydro power to store energy and act as balancing power will be increasingly important as renewable but intermittent types of energy, such as solar and wind, gain significance.
Global potential for small-scale hydro power
Small-scale hydro power plants have a great potential. Like large-scale hydro power, electricity generation in small-scale plants is renewable and inexpensive. However, these plants also have an impact on the surrounding natural environment. The disadvantage of small-scale as compared to large-scale hydro power plants is that they do not offer the same level of security of supply, since they often lack regulation or storage capabilities and therefore cannot be used as balancing power.
At present, however, several regulatory obstacles must be resolved before a more comprehensive expansion of small-scale hydro power plants can be achieved.
Pumping power increases system reliability
Hydro pump storage plants fill an important role in the energy system as a way of storing energy and equalising electricity supply and demand. When electricity generation is high and consumption is low (for example at night or during the summer months) the surplus is used to pump water into a higher reservoir. When electricity demand is higher than generation (for example during the day or in winter) the water is released from the higher reservoir and electricity is produced as in a conventional hydro power plant. However, hydro pump storage plants are net energy consumers, meaning that on average they consume more energy than they produce.
Combining hydro pump storage plants with solar power stations and wind turbines offers both security of supply and an even generation rate regardless of weather conditions. This method utilises the renewable energy generated by wind and solar power and combines it with the pump storage plant's capacity to store energy. In combination, the power stations become a net energy producer. However, these efforts are still in the developmental phase.
New technologies on the way
Although new technologies such as wave, tidal and osmotic power have great potential, they are still under development. Their significance in future energy systems is hard to predict.