JUST KEEP TRIPLING:

After decades of incipient growth, it seems that wind and solar power are finally ready for prime time. These two renewable energy resources are growing rapidly and are beginning to move the needle in global energy supplies.

Renewable energy's growth has been fueled for years by deployment subsidies and other support policies -- feed-in tariffs, tax credits, portfolio standards, and the like -- exactly the kind of proactive public policies that the Breakthrough Institute (where one of us worked and the other still does) has supported since its inception.

While we have both called for reforms to improve the efficacy and sustainability of dominant approaches to deployment policies, we also recognize the tremendously important role deployment policies -- however imperfect -- have played in driving nascent industries. Just as government investment in research development and demonstration and subsidies for early deployment were central to unlocking the shale gas revolution or giving rise to the modern nuclear power sector, public investment in renewable energy adoption has taken the wind and solar industries a long way.

How far have we come exactly? In 2013, wind turbines generated almost three times as much electricity globally as they did in 2008. Solar generation grew by more than a factor of 10. Together, wind and solar increased from 1.1 percent to 3.3 percent of global electricity over that same period, not an inconsiderable feat as overall global electricity demand simultaneously expanded 14 percent. Of the 6,340.1 terawatt-hours (TWh) of power generation growth between 2003 and 2013, 10.9 percent came from wind (564.8 TWh) and solar (122.8 TWh).

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