The production of biodiesel from single-celled microalgae has been receiving renewed research attention, as evidenced by a growth spurt in publications on microalgal biofuel this year. Meanwhile, Scottish researchers working on the Biomara project argue that coastal temperate regions should make fuel from macroalgae (seaweed) instead.

In a recent article published in Biotechnology for Biofuels, Adam Hughes and colleagues review the technological advances and requirements for cultivation of seaweed, for anaerobic conversion into biogas, principally methane. Seaweed culture techniques have been advancing in China in the last 50 years, to the point that seaweed grown for food and other high-value bio-products is now China’s biggest aquaculture business.

The main advantages of marine based seaweed cultivation for biofuel are lack of competition for arable land and zero requirement for freshwater. The idea is not without major caveats, since wild harvest or in-shore cultivation of seaweed on a large scale could easily destroy a coastal ecosystem. However, mass cultivation and selective breeding could be made feasible, using vertical rope growing systems, stationed offshore.

Pilot scale fuel production from seaweed is gaining global momentum and earlier this year, Austrian firm See Algae technology announced the first commercial scale seaweed plant in Brazil, to be completed in 2013. The Brazilian venture will explore ways to use macroalgal culture to mop up excess CO₂ from an existing biofuel plant, that is already producing ethanol from sugar cane.