**6. Conclusions**

The sub and supercritical processing methods seems promising for the production of renew‐ able transportation fuels from various feed stocks. Supercritical alcohol processing provides much better path to produce biodiesel from cheap feed stocks such as animal fats and waste cooking oils. These feed stocks need very intensive pretreatments to produce biodiesel through catalytic transesterification. They can be directly processed using the supercritical alcohol method. At the same time the price of feed stock also plays a vital role to determining the sustainability of this process. Catalytic hydrothermolysis is being used by many corporate companies to demonstrate the possibility of producing high grade jet fuels and naval distil‐ lates. This technology is ready to deploy during certain critical political or environmental scenarios. Hydrothermal extraction and liquefaction is acquiring more interest in the research domain due to its ability to produce a wide variety of products. HT E & L processes are identified as the best possible techniques for the production of biofuels from algal biofuels. The current research is more focused on cultivation and recovery of byproducts from algal biomass though sequential HTL. The algae biofuel research is still in the research and devel‐ opment stage and may take a couple of years to be commercialized.
