For at least 15 years in Norway I have read articles urging local ship companies to switch to greaner engines running on liquid gas or even electricity. The pro

For at least 15 years in Norway I have read articles urging local ship companies to switch to greaner engines running on liquid gas or even electricity. The progress has been made as occasionally I board an electrical ferry without unpleasant smell coming from the pipes. But it is very slow. And this is not surprising as ships are designed to run for 50 years or more and engine upgrades are very costly.