A recent report by REN21, the Paris-based global renewable energy coalition, documented that “the share of fossil fuels in final energy consumption has remained the same [since 2009], and global energy demand has expanded around 20%. Renewable energy meets just over 11% of global final energy demand – only a slight increase from around 9% a decade ago.”

This trend is concerning, given all the advances in renewable energies, including a massive drop in cost. Our World in Data provides a staggering analysis of how quickly and significantly renewable energies have become cost competitive. This also stands in contrast with Germany’s “Energiewende” (energy transition) weak results (Germany still has high energy prices plus a carbon-intense energy system). 

There is still a real-world gap between where the energy system is now, and how quickly we can decarbonize it, given climate impacts. Some are optimistic about this possibility – believing that the market and technological innovation will inevitably turn the tide. Others are far more skeptical. But the bottom line is, we need this revolution if we want to avoid the worst of climate change.

There are also physical constraints to consider: the question of how much energy it takes to develop and implement a system, compared to how much energy it gives us back. Charles Hall called this ratio EROI – energy return on investment. It also matters when, similarly to a financial cash flow, we invest in the energy compared to when we get it back (with renewables, energy investments happen at the onset, and returns are over time, while in oil extraction energy expenditures occur over time). Many researchers have concluded that an EROI under 4 is no longer viable to support energy intensive societies. Fossil fuel extraction started at an EROI of 100 and may now be closer to 10. Some renewable systems, like ethanol, may have an EROI as low as 1, making them unfit to scale. Well-placed wind power ranges from EROI 5 to 20.