绿色科技的大胆尝试：解决清洁能源难题的宏伟项目

Bold projects designed to solve clean energy's lingering challenges An aerial view of the Guoxin Salt Cave Compressed Air Energy Storage Project in Huai'an City, China CFOTO/Future Publishing via Getty Images Two decades ago renewable energy was a bit player on the world stage. Today renewables account for nearly half of all global electrical capacity, according to the International Renewable Energy Agency, and there's a lot more in the pipeline. It's a stunning surge showing that the renewable revolution appears unstoppable. Clean energy still faces challenges, though. To meet them, countries and companies are taking some big swings to push this revolution into a new phase—with ambitious projects that may or may not pan out. …