Europe went dark on March 20. As the moon swept across its face, the sun was hidden for about three hours in an eclipse that allowed only 20 percent of its usual light to reach the Earth. It's a reminder that, in the drive to switch more of the world to renewable energy sources, solar panels don't light up when it's dark, and turbines don't rotate when the wind doesn't blow. The sea, though, is constant, reliable — and scandalously underutilized.
Europe has also been swift to adopt wind power, with sufficient capacity to meet more than 10 percent of the region's energy needs, according to the European Wind Energy Association. That reflects a global embrace of turbines, which has seen the world's wind capacity double since 2009, according to the Global Wind Energy Council:
"Wave and tidal energy, though, remain negligible contributors to renewable energy output. Marine power companies raised just $74 million last year by selling shares or taking investments from venture-capital and private-equity companies, according to Bloomberg New Energy Finance. While that's double the 2013 total, it's down from a peak of $271 million in 2007."