Seaweed as biofuel


On March 22, a group of Japanese scientists released details of an ambitious proposal calling for the large-scale production of bioethanol made from cultivated seaweed.
Researchers from Tokyo University of Marine Science and Technology, Mitsubishi Research Institute, Mitsubishi Heavy Industries and several other private-sector firms envision a 10,000 square kilometer (3,860 square mile) seaweed farm at Yamatotai, a shallow fishing area in the middle of the Sea of Japan. They claim a farm of this scale could produce about 20 million kiloliters (5.3 billion gallons) of bioethanol per year, which is equivalent to one-third the 60 million kiloliters (16 billion gallons) of gasoline that Japan consumes each year.
Seaweed has long been discussed as a potential source of bioethanol, which is typically made from crops such as sugar cane and corn, but the idea has never been brought to fruition. According to the proposal, giant nets used in nori and wakame seaweed cultivation would be laid out to cultivate sargasso seaweed (hondawara), which grows rapidly. Floating bioreactors — special facilities that use enzymes to break the seaweed down into sugars — would prepare the seaweed for conversion into ethanol, which would also be done at sea. Tankers would then transport the ethanol to land.
The main components of seaweed are fucoidan and alginic acid. While an enzyme for breaking down fucoidan has already been discovered, the scientists are looking for an enzyme that breaks down alginic acid. They are also looking at the possibility of using genetic modification technology.
The group is also conducting research on how to develop the production plants and attract investment. Other participants in the project include NEC Toshiba Space Systems, Mitsubishi Electric, IHI, Sumitomo Electric Industries, Shimizu Corporation, Toa Corporation, Kanto Natural Gas Development Co., Ltd., and the Japan Agency for Marine-Earth Science and Technology (JAMSTEC).
The researchers claim that in addition to serving as a source of fuel, the seaweed would help clean up the Sea of Japan. According to Professor Masahiro Notoya from Tokyo University of Marine Science and Technology, the seaweed would work to remove some of the excess nutrient salts that flow into the sea from the surrounding land masses.
Professor Notoya will formally present the proposal at the International Seaweed Symposium, which is set to begin on March 26 in Kobe, Japan.