In recent years, there has been more and more talk of a transition to renewable energy on the grounds of climate change, and an increasing range of public policies designed to move in this direction. Not only do advocates envisage, and suggest to custodians of the public purse, a future of 100% renewable energy, but they suggest that this can be achieved very rapidly, in perhaps a decade or two, if sufficient political will can be summoned. See for instance this 2009 Plan to Power 100 Percent of the Planet with Renewables:
A year ago former vice president Al Gore threw down a gauntlet: to repower America with 100 percent carbon-free electricity within 10 years. As the two of us started to evaluate the feasibility of such a change, we took on an even larger challenge: to determine how 100 percent of the world’s energy, for all purposes, could be supplied by wind, water and solar resources, by as early as 2030.