An article posted last week by the Guardian and highlighted yesterday by Treehugger.com cites recent studies as well as data from maritime industry sources that the combination of quantity and quality of low-grade bunker fuel used in the massive engines of freight vessels may result in more emissions than all the cars in the world! I don't mean to wax sensationalist here, this is what is stated in the article. If the truth is anywhere near the statement, then the idea of hybrid-electric propulsion is more relevant to the design of freight and passenger ships than any personal automobile.
I admit that my daydreaming of sailboats using a mix of electric motors and a compact, efficient generator is a much more alluring topic for someone who loves to be on the water, but the emissions reporting above immediately shifted my focus to a more practical use for the technology. Hybrid-electric propulsion for ships is logical because it allows for significantly more efficient fuel burn since engines are set to optimum rpm and are decoupled from props. This also has an excellent side-effect of better prop control with electric motors whereas diesel engines, by design, have a minimum rpm (when engaged) that must be supplemented with thrusters. Captains love to minimize the number of moving parts that can fail in a ship, and Hybrid-electric systems have the potential to do so. Paired with a large battery array, such systems could potentially be charged with cleaner energy while in port to avoid the use of any fuel while within coastal waters, supporting impending laws such as the new low emissions shipping zone buffer announced recently by the USEPA.
Expanding further into the future, the idea of a return to sailing ships, or ships carried by trade winds using enormous kites, would further reduce or eliminate the need for fuel consumption at sea. Generating enough electricity from on-board solar panels or windmills is still technologically prohibitive for most ships, but there is still room for supplementing demand. And anyone with a course in logistics under his belt knows that once a shipping cycle is developed for a particular product, shipping time is not nearly as important as shipping frequency, particularly for just-in-time systems. There is a huge spectrum of solutions between bunker fuel and zero-emissions shipping. With every major economic interest involved and the lifeblood of globalization at the heart of the debate, finding an acceptable footing from which to begin the slow climb towards an emissions free shipping industry can be tricky. As we progress through the first step (acknowledging we have a problem), I hope the conversation turns to Hybrid-electric rather than other much less progressive options.