Solar Energy Perspectives - IEA

Chapter 11: Testing the limits
Figure 11.3 Seasonal variations of the European electricity demand and of the electricity
generation from solar, wind, and a 60%-wind 40%-PV generation mix
Normalised power
Normalised power
1.6 1.3
1.4 1.2
1.2 1.1
1.0
0.8
0.6
2000 2002 2004 2006 2008
Seasonal variations of solar
electricity generation
Seasonal variations of wind
electricity generation
1.0
0.9
0.8
2000 2002 2004 2006 2008
Generation from a 60%-wind
power and 40%-PV
Seasonal variations of the demand for
electricity in EU-27 around the average
Note: The average values are normalised to 1.
Source: Heide et al. 2010.
Key point
Wind power is abundant in winter; PV electricity is abundant in summer.
Daily variations in the generation of electricity from both PV and wind are important to
consider. Large penetration rates of wind power and PV would likely require large storage
capacities, on top of the flexibility factors considered in Chapter 3 (see Box: Harnessing
Variable RE on page 41). Electricity storage would have two related, but somewhat distinct
objectives: i) to minimise curtailment of renewable electricity; and ii) to help meet demand
peaks. Although electricity shortages do not have to be avoided at any cost, the history of
shortages suggests there is a significant value in avoiding them. By contrast, some curtailment
of either wind power or PV power might be acceptable as long as the economic losses it
entails are lower than the marginal costs of additional storage capabilities only rarely needed,
such as in the rare event of simultaneous large PV and large wind power generation.
To assess storage needs, one must make some assumptions relative to generating
capacities other than solar. For example, one may consider a global generation of 25 000
TWh from wind power. Wind power has very large technical potential and its costs will
likely be lower than, or similar to, most alternatives, i.e. in a range of USD 50/MWh to
USD 100/MWh in the long run, depending on the shares of on-shore and offshore wind
farms and the actual learning curve of offshore wind power. Hydropower and geothermal
electricity are more limited by geography. It is assumed that hydropower plus tidal and
other marine energies would provide 10 000 TWh/year of electricity. Another 2 000 TWh
would come from burning natural gas in balancing plants (blended with the 2 000 TWh
of solar hydrogen). The remaining 10 000 TWh would come from a mix of base load,
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© OECD/IEA, 2011