So the question is whether we can power today’s world, or, more accurately, the world in 2040 or 2050, with renewable energy. The world in 2050, with a population exceeding 9 billion people and a greater proportion having achieved modern living standards, will almost certainly require at least twice as much energy as the world today, and more than 50 times more energy than was required to power the pre-industrial world when we last depended primarily on renewable energy sources.³

It depends on what you count. For some consumers in some places, the cost of electricity from rooftop solar photovoltaic panels is comparable to the retail cost of grid electricity. But that doesn’t reflect the full costs. Like In the United States, the federal investment tax credit subsidizes about one-third of the cost of buying and installing solar panels.²³ Other subsidies at the state level frequently augment that subsidy. Net metering policies in many states provide even more subsidies, requiring utilities to buy back power from solar producers at several times the effective rate at which they could purchase power on the wholesale market.²⁴