Found an interesting company called Aquafuel who specialise in modifying engines to burn Glycerine. In 2008 world demand for glycerine was 0.9m tons but supply was 3.2m tons. Glycerol can be harvested from an Agae, Dunaliella salina, which lives in saline pools and produces glycerol to protect itself from osmosis. The more saline, the more glycerol up to a max of 85%. Clean burning and abundant, sounds good to me.
http://www.aquafuelresearch.com/uploads/9/7/3/7/973719/emissionimpossible.pdf
http://www.aquafuelresearch.com/uploads/9/7/3/7/973719/emissionimpossible.pdf