Ever since the oil shocks of the 1970s, and the early emergence of commercial wind turbines, solar hot water heaters, and the first solar PV panels, there has been speculation about what it would take to completely wean ourselves from fossil fuels. As far back as 1975 Danish physicist Bent Sørensen published a paper looking at a 100% renewable energy system for Denmark. The visionary Dr. Amory Lovins came up with the term ‘soft energy path’ in 1976 to describe a future where energy efficiency and renewables gradually replace a centralized energy system based on fossil fuels and nuclear power.
After the emergence of the threat of human-induced climate change in the late 1980s, the discussion got a bit more serious. Both solar and wind technologies had progressed somewhat during the intervening decade and a half, but were still expensive and small. The first fossil fuel free energy scenario was published by Greenpeace and the Stockholm Environmental Institute in 1993.