This alternative fuel machine choice is preferred by many because it has relatively low environmental impact. This green fuel burns on average 35 percent cleaner than gas. Free of carbon build-up, propane engines can last 25 percent longer than gas models. There is less downtime and theft of the fuel is better controlled as it's stored in tanks vs. more mobile containers of gas. Going green has its challenges as large tool propane is less available than gas or diesel. That means stocking your own tanks or having ready access to a tank exchange. If you're intent on propane, consider using it to your competitive advantage by promoting your reduced carbon footprint.