Spectral decomposition of regulatory thresholds for climate-driven fluctuations in hydro- and wind power availability

• Climate-driven fluctuations in the runoff and potential energy of surface water are generally large in comparison to the capacity of hydropower regulation, particularly when hydropower is used to balance the electricity production from covarying renewable energy sources such as wind power. To define the bounds of reservoir storage capacity, we introduce a dedicated reservoir volume that aggregates the storage capacity of several reservoirs to handle runoff from specific watersheds. We show how the storage bounds can be related to a spectrum of the climate-driven modes of variability in water availability and to the covariation between water and wind availability. A regional case study of the entire hydropower system in Sweden indicates that the longest regulation period possible to consider spans from a few days of individual subwatersheds up to several years, with an average limit of a couple of months. Watershed damping of the runoff substantially increases the longest considered regulation period and capacity. The high covariance found between the potential energy of the surface water and wind energy significantly reduces the longest considered regulation period when hydropower is used to balance the fluctuating wind power. Plain Language Summary The availability of renewable energy fluctuates significantly with climate and needs to be regulated to be sufficient at all times. This regulation can be achieved by storing hydropower in water reservoirs, but is complicated by the vast spatial distribution of storage locations, size variations in reservoirs, the covariation of renewable energy, and the range of frequencies that need to be considered in climate variations. This study provides a new method of analysis that can provide estimates of the most effective use of hydropower reservoirs and the limits of their use for regulating renewable energy. Based on data from entire Sweden we show how the storage bounds can be related to a spectrum of the climate-driven modes of variability in water availability and to the covariation between water and wind availability. The high covariance found between the potential energy of the surface water and wind energy significantly reduces the longest considered regulation period when hydropower is used to balance the fluctuating wind power.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Naturresursteknik -- Havs- och vattendragsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Engineering -- Ocean and River Engineering (hsv//eng)

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)