The International Maritime Organization (IMO) has recently set aggressive emission targets to reduce global marine fuel sulfur content from the current 3.5% to 0.5% in 2020. Similarly, the California Air Resources Board (CARB) and other state agencies have established regulations limiting the sulfur content of fuel used in coastal regions (i.e., emission control areas or ECAs) to 0.1%. The main options for ships to comply with the low sulfur regulations include: 1) switching to low-sulfur bunker fuel, 2) installing onboard scrubbers, or 3) switching to liquefied natural gas. While the choice of adoption is primarily dependent on the vessel owner economic decisions, the global bunker fuel spec changes in 2020 will most likely force roughly 2.8 MM barrels per day of high sulfur fuel oil to switch to low sulfur fuel oil and distillates, possibly tightening the diesel market. Biomass-derived marine fuels offer potential synergistic benefits when blended with petroleum fuels by reducing the overall sulfur content, as well as improving overall lubricity and offering potentially lower ash and emission profiles. Biofuels derived from indirect liquefaction of biomass followed by Fisher-Tropsch (FT) synthesis can be cost competitive and environmentally sustainable. FT synthesis is considered a relatively mature conversion technology which involves the catalytic conversion of biomass-derived synthesis gas via indirect gasification into a mixture of reaction products which could be refined to synthetic fuels, lubricants, and petrochemicals. One of the important advantages that the FT process offers is its capability of producing liquid hydrocarbon fuels from synthesis gas, which are virtually free from sulfur and relatively low in aromatic content. This study evaluates the economic potential to utilize bio-derived marine fuels, as well as outlining further R&D needs and uncertainties associated with the integration of FT-derived hydrocarbon blendstock. With the increased availability of low-cost natural gas, this study also performs a scenario for the co-conversion of natural gas and biomass to marine fuels. Additionally, techno-economic assessment for marine fuels produced via hydrotreating of yellow grease will be presented and discussed.