What’s the greenest way to grill?  Earth911 decided to investigate.   When it comes to carbon footprint, propane and natural gas grills beat out charcoal as the most eco-friendly. Scientists in the United Kingdom conducted an Environmental Impact Assessment Review of the two types of grills in 2009 and found that a charcoal grill emitted 2,200 pounds of carbon dioxide over its lifetime – three times the carbon footprint of a natural gas grill, which is responsible for ...