Solar Energy Perspectives - IEA

Solar Energy Perspectives: Testing the limits
Nuclear power has not been able to considerably expand its basis since the entry into force
of the UN Framework Convention on Climate Change in February 1995, despite its
recognised value in mitigating energy-related CO 2 emissions. It is not likely to perform much
better anytime soon in the post-Fukushima context, but over time it could recover and
expand significantly. If it did not, however, solar and wind and associated electricity storage
would together have to produce up to 11% more electricity than otherwise, not a considerable
change at a global level, if possibly very significant for some countries. Nuclear power as it
is now could be substituted by known and proven solar, wind and dispatchable technologies.
However, nuclear power might be developed to be more flexible through hydrogen
generation in high-temperature nuclear plants. If so, it could substitute economically for gasfired
balancing plants, and/or provide fuels for substituting fossil fuels or biomass in transport
and industry. Then it would actually enrich the menu of yet-unproven options for increasing
energy security and mitigating climate change, and partially substitute for CCS or solar fuels
if they fail to deliver.
In any case, the future will be different from what we can imagine today. History is full of
wrong predictions, and this chapter offers no prediction of any kind. It has no other ambition
than to illustrate one possible future, among many others. What remains, however, is that
a considerable expansion of renewable energy production would serve the goals of energy
security, economic stability and environmental sustainability (including climate change
mitigation) on a global scale through this century, a conclusion similar to that enunciated by
the IPCC Special Report on Renewable Energy (IPCC, 2011). Solar energy in its various forms
would likely form the backbone of renewable energy as it is the least limited resource,
followed by wind and biomass, then hydropower and others.
Defining primary energy needs
Various methods are used to report primary energy. While the accounting of
combustible sources, including all fossil energy forms and biomass, is unambiguous
and identical across the different methods, they feature different conventions on how
to calculate primary energy supplied by non-combustible energy sources, i.e. nuclear
energy and all renewable energy sources except biomass. In particular, the OECD,
the IEA and Eurostat use the physical energy content, while UN Statistics and the
IPCC use the direct equivalent method.
For non-combustible energy sources, the physical energy content method adopts the
principle that the primary energy form is the first energy form used downstream in
the production process for which multiple energy uses are practical. This leads to the
choice of the following primary energy forms:
• heat for nuclear, geothermal and solar thermal electricity;
• electricity for hydro, wind, tide/wave/ocean and solar PV.
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The direct equivalent method counts one unit of secondary energy provided from
non-combustible sources as one unit of primary energy, i.e. 1 kWh of electricity or
heat is accounted for as 1 kWh = 3.6 megajoules (MJ) of primary energy. This method
is mostly used in the long-term scenarios literature because it deals with fundamental
© OECD/IEA, 2011