Power systems must be actively managed to maintain a steady balance between supply
and demand. This is already a complex task as demand varies continually. But what
happens when supply becomes more variable and less certain, as with some renewable
sources of electricity like wind and solar PV that fluctuate with the weather? To
what extent can the resources that help power systems cope with the challenge of variability
in demand also be applied to variability of supply? How large are these resources?
And what share of electricity supply from variable renewables can they make possible?There
is no one-size-fits-all answer. The ways electricity is produced, transported and
consumed around the world exhibit great diversity. Grids can cross borders, requiring
co-ordinated international policy, or can be distinct within a single country or region.
And whether found in dispatchable power plants, storage facilities, interconnections
for trade or on the demand side, the flexible resource that ensures the provision
of reliable power in the face of uncertainty likewise differs enormously. Written
for decision makers, Harnessing Variable Renewables: a Guide to the Balancing Challenge
sheds light on managing power systems with large shares of variable renewables. It
presents a new, step-by-step approach developed by the IEA to assess the flexibility
of power systems, which identifies the already present resources that could help meet
the twin challenges of variability and uncertainty.