renewable energy

Denver's newest skyscraper (center) followed new building codes for energy efficiency. The city wants to reduce greenhouse gas emissions 80 percent by 2050. Dan Boyce for NPR hide caption

Belinda Batten of Oregon State University stands in front of a wave energy generator prototype. Jeff Brady/NPR hide caption

Solar cells sit in the sun at the Desert Sunlight Solar Farm in Desert Center, Calif. The people who run California's electric grid expect the solar power output to be cut roughly in half during the eclipse. Marcus Yam/LA Times via Getty Images hide caption

A view of the newly-erected wind turbine on Tilos, Greece, part of a microgrid that, along with a solar park and a renewable battery system, will power the island. Joanna Kakissis for NPR hide caption

Jayme Orrack oversees Xcel Energy's new wind farm in Courtenay, N.D. The wind farm started generating electricity late last year with 100 turbines that collectively generate 200 megawatts of electricity. Amy Sisk/Prairie Public Broadcasting hide caption

Kevin Butt, Toyota's regional environmental sustainability director, at a facility that uses methane to generate clean electricity to help run Toyota's auto plant in central Kentucky. Jennifer Ludden/NPR hide caption

Part of one of the world's biggest renewable energy systems, wind turbines dot the landscape on the edge of Sweetwater, Texas, along with a pump jack pulling up oil. Ari Shapiro/NPR hide caption

About a quarter of California's electricity comes from renewable sources, like this wind farm outside San Diego. Lauren Sommer/KQED hide caption

A car drives by a Switch data center in Las Vegas on Sept. 9, 2015. In 2013, data centers consumed 2 percent of all U.S. power — triple what they used in 2000. John Locher/AP hide caption

Logger Greg Hemmerich and his crew feed low-value trees into a wood chipper, before bringing the chips to ReEnergy Holdings' biomass plant in Lyonsdale, N.Y. David Sommerstein/NCPR hide caption