http://www.reuters.com/article/2012/07/02/us-usa-navy-greenfleet-idUSBRE86106X20120702 The US Navy now has an aircraft carrier task group that runs only off of biomass fuel. Check out the article, the pros and cons are interesting.
And more expensive. The Biomass fuel they're using costs like 20 dollars to the gallon or something insane like that. And we're talking about millions of gallons for just a month of exercising or something.
It's a new technology, of course it's going to start out expensive. As with all new technologies, as it become more common the industry will grow(hopefully this green fleet jump starts the process), making the fuel cheaper to produce, thus prices will drop.
