How much energy do marine organisms store?

It is estimated that if all the phytoplankton produced in the ocean in a year were transformed into energy, it could be consumed by all of humanity. In addition to the phytoplankton present in the ocean, benthic algae are also very important sources of energy, like macroalgae. After harvesting the macroalgae, biogas can be obtained by fermentation, which constitutes a good source of energy. The United States has been growing and using algae since 1978, with the help of the Navy, and has had good results. It is estimated that growing 4 square kilometers of macroalgae can produce 100,000 kilowatts of energy per year, making it one of the most promising energy sources.