Biotech/bioengineering has been a center of discussion for many years. Algae is considered one of the potent sources for oil production which you can also say as biodiesel. However, not only algae but other marine biomass also has the potential to produce massive amounts of energy.

On the behalf of the crown state, the Scottish association has published a recent report on marine science. The British monarchy held by a property holding organization explained the potential of marine biomass. They said that methane can be generated from marine biomass using anaerobic digestion. That samed methane can also be utilized for making heat and electricity and can also be used as CNG (Compressed Natural Gas) and as a fuel for transportation.
As marine biomass lacks the lignin and contains very small amounts of cellulose, it can be utilized for the production of cellulosic ethanol as well. The plus point is according to a report the marine biomass is also highly degradable.

http://biomassmagazine.com/articles/2298/marine-biomass-could-serve-as-power-source#:~:text=In%20addition%2C%20studies%20investigating%20the,as%20terrestrial%20sources%20of%20biomass.&text=According%20to%20the%20report%2C%20marine,30%20percent%20easily%20degradable%20carbohydrates.