Solar panels are mounted on the roof of the Los Angeles Convention Center on September 5. The state's governor has signed a landmark bill setting a goal of 100 percent clean energy for the state's electrical needs, by the year 2045. Mario Tama/Getty Images hide caption
Entering the control room at Three Mile Island Unit 1 is like stepping back in time. Except for a few digital screens and new counters, much of the equipment is original to 1974, when the plant began generating electricity. Jeff Brady/NPR hide caption
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
Warning signs adorn the fence surrounding the compound housing the Hornsdale Power Reserve, featuring the world's largest lithium ion battery made by Tesla, during the official launch near Jamestown, Australia, on Friday. David Gray/Reuters 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
Reinford Farms has 700 dairy cows. As you can imagine, they produce a lot of ... um... material to be converted into electricity. Dani Fresh for WHYY hide caption
Britain expects to go 24 hours without using coal to generate electricity Friday. It would be the first full day since the Industrial Revolution. David Davies/AP 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
