I just saw a post that suggested that 1 gallon of gas (6.3 lb) burned through a combustion engine generates 20+ lbs of CO2. I am sure they just missed a decimal or did not remember correctly what they saw or heard but
what would be some practical/military applications of being able to increase mass 3x by burning or performing some action on a substance? and
Are there any current processes that can be done on a substance that results in an increase in mass as the result?
I put this in world building because I was looking for a concept to build a story/world around. As the comments have shown, I was just missing all the mass inputs. I would still like to know if hand waving gave me more mass from energy somehow, what practical applications could come from it AND is there any process currently done or beautiful theory that can generate mass from energy so the hand waving would become unnecessary or significantly less?