0 not harmful to the environment, especially because of not making climate change worse by producing carbon dioxide:
Engineers hope to perfect a clean-coal technology that could provide climate-friendly energy at modest cost.
The report calls for aggressive measures to encourage climate-friendly cities.
Americans can help make their national parks more climate-friendly by using bikes and trains to access them.
"Taking the bus is one of the most climate-friendly ways to get to work," said a spokeswoman.
