The process and system of the invention converts biomass materials into energy to power a large marine vessel without the problematic environmental releases of either liquids to the sea or greenhouse gases to the atmosphere. The biomass is conveyed to an on-board biomass storage facility and converted to synthesis gas in an on-board gasification unit to synthesis gas that is used as fuel for fuel cells to power the marine vessel. A portion of the biomass is sea biomass harvested from the sea and removed from the sea by on-board biomass removal means that strains the biomass from the sea water and flips the biomass into a holding bin before being conveyed to the biomass storage facility. A portion of the synthesis gas is converted to useful products. These products are partially used as fuel for the fuel cells. The remaining products are off-loaded at port facilities where biomass waste materials are loaded on-board and conveyed to the biomass storage to serve as the remaining portion of biomass.