It is highly unlikely the world can be powered by renewable energy sources alone by 2050. This is one of the conclusions of the IPCC’s often cited but rarely read Special Report on Renewable Energy Sources and Climate Change Mitigation, or SRREN.
Published in 2011, it reviewed 164 energy scenarios that focus on the role of renewable energy in the world energy supply. While the report finds that the maximum “technical potential” of renewable energy sources is indeed large, these scenarios – which attempted to take into account at least some economic and other practical limitations as well – found that their realizable potential is probably much less.
The above graph sums up the results. Not one of those 164 scenarios could deliver, in 2050, even the amount of energy used in the world in 2010. Even the most positive outlier, based on Greenpeace’s Energy [R]evolution study (which in turn was largely based on data from renewable industry lobbyists) delivered only 428 exajoules per year. The average of all scenarios was much less, only 186 exajoules per year.
The SRREN report was by no means overly critical of renewables. As several commentators noted after the report’s release, it downplayed or even omitted discussion about several problems with high renewables scenarios. For example, the feasibility of different scenarios was not really assessed: they may be technically possible, but can the world politics put them to practice?
And even if the most optimistic of those 164 scenarios is put into practice and runs into no unforeseen difficulties, the world energy demand needs to drop drastically while world population grows to 9 or 10 billion.
Let’s suppose we’re building a bridge and order 164 engineering analyses of the proposed structure’s soundness. Every single one of these analyses suggests that the bridge will be unlikely to withstand current traffic, much less the likely increase in the future. We proceed with the plans anyway, and even declare that our plan is the only one worth mentioning. Are these the words of a responsible designer?
Are the words of Greenpeace – and others who advocate for zero nuclear energy – responsible, or are they a gamble with the climate?