Although conventional wisdom continues to support charcoal grills, which are not an entirely bad choice; the truth is that both propane and biogas are more eco-friendly. David Wardle of the Swedish University of Agricultural Science, in a study about the limitations of charcoal, stated that charcoal and wood tend to be inexpensive, but wood burns dirty and charcoal grills are messy and typically have fewer amenities than other types of grills.
Charcoal is traditionally considered to be the least eco-friendly mode for grilling. A report in Elsevier’s Environment Impact Assessment Review states that charcoal grilling is less eco-friendly than propane grilling. The article further reports that in the United Kingdom carbon outcome from charcoal grilling is almost three times higher than carbon emissions from propane gas grilling. The study also states that propane gas grills are more energy efficient when compared to charcoal grills, are more efficient in production costs and carbon expenses, and eventually they are more efficient in cooking, too.
Charcoal grilling is done by heating the wood in an open furnace, and their commercial yields are around the 20-30% range, i.e. the rest of the wood is converted into gas and eliminated in the environment. By contrast propane gas is in about the 90% range. Moreover the charcoal grill emits around 12 pounds of carbon dioxide in a hour, compared to similar size gas grills that emit around 5 pounds. Ultimately, charcoal is the least efficient alternative to propane.
But contrast to this to what Department of Energy Oak’s Ridge National Laboratory researcher Tris West says. She states that make using of charcoal will give a long-run advantage:
Charcoal is made from wood. It is a renewable energy source, which means once that CO2 is emitted into the atmosphere, forests are then regrown wherever they were cut down and they take up CO2 from the atmosphere. There's a carbon cycle. We release it and then it's taken back up by the trees.
There is going to be twice as much carbon released from your charcoal grill as there is from your propane grill. When we consider the total carbon cycle and the charcoal as a renewable energy source because it's from wood, the story is completely flipped and you have more emissions from natural gas because emissions from charcoal are net zero.