sentence: Renewable resources are usually much cleaner.
sentences_before: A problem with fossil fuels is the pollution and global warming gases they produce.
sentences_after: But they can also cost more. New technology for renewable resources is helping to make them cheaper. And now even fossil fuels are becoming harder to find and more expensive. This combination means that renewable resources are making more sense than ever, and this is a growing field. From 2008 to 2012, the U.S. doubled renewable generation from wind, solar, and geothermal sources, and America is now home to some of the largest wind and solar farms in the world.
concept_name: renewable resource
headings: Renewable resource
categories: Energy Materials Economics