Sunday, October 28, 2012

Energy Generation: Waste Seaweed as Biomass

Japanese researchers have developed a biomass fermentation system that uses seaweed dredged from the shore to produce fuel for generating electricity. Seaweed is one of the few untapped sources of biomass energy that is easily obtainable in Japan, and the plan calls for the research stage to be wrapped up no later than March 2007, with full-fledged electricity generation to begin later in the year. The goal is to create the first power plant in the world to run off of seaweed.

Fresh seaweed is commonly eaten in Japanese dishes like sushi and miso soup, but the seaweed that washes up on the shore can rot and begin to smell, and it is unsightly as well. Collection and disposal of it is a major burden for local governments along the coast. At the same time, seaweed absorbs carbon dioxide as it grows, so using it as biomass could be an effective means of combating global warming as well as conserving oil resources. This is why Tokyo Gas Co. teamed up with the New Energy and Industrial Technology Development Organization (NEDO) in 2002 to begin work on a project to use seaweed as a source of biomass for energy production.

A test facility constructed in Yokohama first crushes large amounts of seaweed into a sludge-like state. After using micro-organisms to break down this semi-liquid material, the methane gas that results from this process is used as fuel for a gas engine that produces electricity. In the tests to date, one ton of seaweed has been processed per day, allowing the collection of 20 kiloliters of methane gas. In order to boost efficiency, this is blended with natural gas and converted into 10 kilowatts of electricity per hour. At present production levels, this is enough energy to power 20 households, and this energy is currently used to power lighting in offices at the plant, among other things.

Tokyo Gas Co. aims to complete research by March 2007 and then consider how the system can be put to larger-scale commercial use. The company has studied the optimal conditions for fermenting kelp, sea lettuce, and other types of seaweed and has determined that the system is feasible. There are hopes that the local governments and maritime companies that have struggled to dispose of seaweed in the past can be enlisted into this effort, which is both good for local communities and good for the global environment

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