Hydro in Europe: Powering Renewables - Full Report - Eurelectric

CASE STUDY 1 - Hydropower in the Nordic power system
Hydropower represents 55% of the 370 TWh of annual average electricity generation
in the Nordic Power System NORDEL, comprising Norway, Sweden, Finland and East
Denmark. 35 Hydropower plays a particular role in this system.
First of all, hydropower plants provide flexible generation capable of responding to
large load variations (day/night, low/high outside temperatures), since hydropower’s
storage capabilities in the NORDEL system are huge (120 TWh in a season). Thus,
hydropower plants in the NORDEL system are used for handling peak load.
Secondly, hydropower units make the power system more robust as they are capable
of handling sudden disturbances in transmission or large generation units. Hydropower
units are used for reserve needs in the system and are contracted by the TSOs to
provide reserve in case of disturbances such as extreme weather conditions, high load
demand, sudden loss of generation in a major nuclear plant, or technical faults in the
transmission system.
Several trends observed today will change the future demand of system services
provided by hydropower plants in the NORDEL system:
1. A large share of geographically distributed v-RES (here: large-scale wind) will
create a significant number of new and different load situations in the grid.
These totally new situations may trigger faults not discovered earlier or create
a major disturbance in the grid. This may cause an extra need of actions in the
power system and/or system services.
2. A fast growing share of v-RES in the system will increase the need to handle
power ramps, balancing services and capacity planning. The Swedish TSO
estimates that adding 4 GW of wind will require an additional 600 MW of
intraday balancing reserve and 900 MW capacity reserve to handle a no-wind
situation.
3. A growing intermittency in consumption patterns may add to the intermittency
from RES sources, especially for balancing intraday needs.
4. Climate change may increase the frequency of extreme weather situations such
as extreme temperatures, heavy storms or snow blizzards, which is why more
investments in the power system and prepared services for robustness will be
needed.
The hydropower plants in the NORDEL system still have a large remaining potential of
regulating capabilities of different kinds. First estimates indicate that this potential in
existing plants is double the capabilities present today. However, some of the potential
may be restricted due to transmission system bottlenecks. This may apply both within
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Nuclear and fossil energy sources represent 20% and 15%, respectively. 10% of electricity is generated from
renewable energy sources other than hydro.
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