Solar Energy Perspectives - IEA

Solar Energy Perspectives: Solar electricity
Another IEA study (Inage, 2009) confirms that in this range (10% to 12%) of penetration, PV
does not significantly increase the need for electricity storage. The BLUE Map Scenario for
Western Europe of ETP 2008 put the contribution of wind power at 27%. The assumed net
wind power variability would require electricity storage capacities of 39.8 GW by 2020.
Adding 12% PV in Western Europe by 2020, as originally suggested by the Solar Europe
Industry Initiative (SEII) and considered in the High Ren Scenario of ETP 2010 would raise
the requirement for storage only slightly to 42.8 GW.
Harnessing variable renewables
In Harnessing Variable Renewables: A guide to the balancing challenge, the IEA
(2011c ) studied a range of quite different power systems and showed how different
the potential flexibility might be from one system to another, which is greater than
usually thought. Similarly, the existing technical potential for flexibility is often much
greater than the available potential – due to various barriers, which can be partially
or totally removed (Figure 3.6).
Drivers to make best use of existing flexible resources include strong and smart grids
and flexible markets, but optimisation strategies would vary from place to place.
Contrary to common belief, the introduction of variable renewable generating
capacities does not require a “megawatt for megawatt” back-up, but rather holistic
planning of flexible resources to cover net system variability. The addition of more
flexible generating capacities as back-up might still be needed, but it is important to
realise that such capacities will be run only rarely, and this is what makes building
them fully compatible with low GHG emission scenarios.
In addition, significant current capacities, especially of flexible gas, will remain
online in the coming decades, notably in industrialised countries (e.g. Italy, Japan,
Spain, and the United States). Their capacity factor will decrease, either from now on
or later (including after an increase as older coal plants are closed). To be kept alive,
and ready as spinning reserves, flexible capacity might require some specific
incentives, but in many cases there will be no or little need to build greenfield fossilfuelled
plants for backup.
This study shows that the variability of PV, which matches demand peaks better than
wind power and is relatively predictable, is unlikely to raise substantive issues for
managing grids. This is assuming PV generation achieves the levels considered in
several scenarios of about 10% to 12% – although at different dates for different
scenarios.
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There will be, for sure, balancing costs for grid operators. In some areas, the total
of distributed small-scale capacities can be greater than local demand could
absorb at peak times. This means that the distribution and transport grids would
have to work both ways. Most existing transformers allow only one-way
conversions of high voltage (for transport) to lower voltage (for distribution).
However, these costs will remain limited and not likely to prevent PV’s 10% to
12% share.
© OECD/IEA, 2011