Solar Energy Perspectives - IEA

Chapter 3: Solar electricity
Figure 3.6 Present variable RE potential in various systems
PVP (present VRE Penetration Potential of gross electricity demand)
100%
90%
Height of bar shows deployment potential
80%
based on technical flexible resource
70% 63%
Colour gradient highlights that flexible resource
60%
will not be fully available (see lower part of figure)
50%
48%
45%
40%
37%
31% 29%
30%
27%
20%
19%
10%
0%
Denmark Nordic
market
United States
West (2017)
NBSO area
(of Canada)
Mexico
Japan
Great Britain
and Ireland
Spain and
Portugal
Grid
Market
Score:
High Medium Low
Note: NBSO stands for New-Brunswick System Operator.
Source: IEA, 2011c .
Key point
All electric systems already can handle some variable generation.
Storage options
Currently almost all global large-scale electricity storage capacities are in pumped-hydro
storage, with about 150 GW in service and about 50 GW under construction. Water is
pumped from a lower body of water to an upper one when excess electricity is available, and
sent to the turbines when electricity is needed (Figure 3.7). Pumped hydro stations can be
part of natural hydraulic systems, in which case they are both hydropower plants fed from
natural waters, and pumped hydro plants. They can also be completely artificial and
independent from natural rivers. The round-trip efficiency ranges from 70% to 85% – higher
in more recent plants. Nevertheless, 80% efficiency means that 100 MWh of electrical output
first requires the absorption of 125 MWh from the grid.
These plants were typically conceived to add some flexibility in electricity systems dominated
by generating capacities with little economic flexibility. In France, for example, pumpedhydro
storage stations are used to absorb nuclear power at night and generate electricity
during demand peaks. Most of the plants worldwide are used on a daily basis, some only on
a weekly basis.
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© OECD/IEA, 2011