Solar Energy Perspectives - IEA

Chapter 11: Testing the limits
transitions of energy systems that rely to a large extent on low-carbon, noncombustible
energy sources.
Using the direct equivalent method in a scenario with high-level penetration of
renewables other than combustible biomass allows comparing the high-level solar
“big picture” of this publication with the recent IPCC Special Report on Renewable
Energy (IPCC 2011).
Primary energy needs (direct equivalent method) would by 2060 – 2065 be of
about 165 000 TWh, under the assumptions of conversion efficiencies of 40% in
electricity generation from combustibles, 85% in heat from combustibles, and
60% in manufacturing biofuels, and accounting for losses in electricity storage and
in CCS. The contribution of solar energy to these primary energy needs would be
about 60 000 TWh 4 or 216 exajoules (Ej). With 36% of primary energy needs
(approximately the same share of final energy demand), the solar contribution
shown here is significantly higher than the estimates for direct solar energy by
2050 in the scenarios published before 2009 and analysed by the IPCC (2011),
though more recent analyses have stretched the possible contribution from solar
even higher.
Note that with ambient heat, derived mostly from solar energy (and some geothermal
heat), about 30 000 TWh of useful energy is neither taken into account in primary
energy needs nor in final energy demand. Taking ambient heat into account, primary
energy needs would have to be counted at 195 000 TWh for an overall final energy
use of 170 000 TWh. On both accounts, the contribution of solar energy would come
close to 50%.
The numbers in this chapter are enough to make one’s head spin and may seem unrealistic
to many. However, it is the sheer size of the energy system in 50 years from now that is
vertiginous. Without a very large application of renewables, the scale of the environmental
issues (not just climate change) associated with considerable use of fossil fuels during this
century raises the greatest concerns.
The economic burden of making the required energy resources available on such immense
scale is hardly less problematic. As the likely convergence of costs of various energy sources
around 2030 suggests, the size of the necessary investments, in solar plants, grids, storage
facilities, nuclear power plants, oil and gas wells, refineries, coal mines, and power plants,
would be roughly similar whatever path is followed.
The energy system of 2065 is almost entirely for us to build. In doing so, we face many
uncertainties, but some things are already clear. The future energy system will face many
constraints and challenges. In order to cope successfully, the system will need to be widely
diverse; no one technology can or should dominate. As it must, such a system will give
4. 20 000 TWh from PV (including storage losses), 25 000 TWh STE, 5 000 TWh th solar heat, 6 000 TWh th solar fuels, and 10% of
a total primary energy in biomass of 40 000 TWh.
213
© OECD/IEA, 2011