Does seaweed offer a solution for bioenergy with biological carbon capture and storage?

The concept of combining bioenergy with carbon capture and storage (BECCS) has been identified as one mechanism to achieve energy production with a net negative atmospheric carbon emission. Conventional geological carbon capture and storage involves large capital outlay and recurring expense. Therefore there is increased interest in coupling biological carbon capture and sequestration with biomass production. Systems such as low-input high-diversity native grasslands and biochar production have been heralded as carbon negative biofuels. Another potential production system for bioenergy with biological carbon capture and storage (BEBCCS) is the large-scale cultivation of seaweed (macroalgae) for biofuels. Marine biofuels offer considerable advantages over terrestrial first-generation biofuels in terms of their low land use, fresh water and fertilizer requirements. In addition, they also offer considerable potential in the field of BEBCCS. Macroalgae rapidly accumulate biomass and as part of this process, a significant proportion (estimates range up to 60%) of the carbon they fix photosynthetically is released into the water. A proportion of this released dissolved organic carbon (DOC) is highly labile and enters the bacterial loop and is rapidly remineralized back to CO2. However, a proportion is known to be resistant to biological degradation and enters the refractory DOC pool. The marine DOC pool is the largest organic carbon pool on the planet and the refractory component is known to have a turnover period of 100s-1000s years. The release of refractory DOC from macroalgae combined with biofuel production offers the potential for large scale carbon negative fuel production. © 2012 Society of Chemical Industry and John Wiley & Sons, Ltd