Natural gas does not have the same energy density as diesel. So in the past ng locomotives were ‘clean air gimmicks. Today Westport is working with all the large manufactures of truck, locomotives and even ships to move them to natural gas. Diesel is five or six times more expensive than natural gas. Diesel is the single most expensive item for rail road. Whether it is a combination of diesel and ng locomotives or locomotives that can use either or perhaps an ng locomotive that has a boost the switch will happen as quickly as possible. All the major truck fleets want to switch 1/3 of their fleets to ng. Most local commercial vehicles are switching over now. Despite sky high sailing rates there are plans to pull gas carriers into port to switch their engines from bunker fuel to the gas they carry. The savings are that great. Based on economics which is true efficiency, natural gas in America at five or six times less expensive while being 30% to 40% cleaner will drive rapid conversion from d.