Why we are using Seaweed to Fight Climate change

 Seaweed is a photosynthetic macroalgae that produces energy through the assimilation of carbon dioxide. Some species are so productive that they can grow more than 50 cm a day, which is more than 30x faster than land plants. The high productivity of seaweed means that more carbon dioxide will be assimilated from the atmosphere, increasing our capacity to mitigate greenhouse gas emissions. We have identified one such species, Giant Kelp (Macrocystis pyrifera), that is native to Tasmanian waters as being ideal for this purpose. 

We have identified two methods for the long-term storage of carbon in seaweed tissue. Our first strategy is to produce biochar, an inert form of carbon. Biochar is created by the combustion of seaweed biomass in the absence of oxygen. Biochar is a particularly useful product itself, as it can be applied to soils to increase fertility [2]. 

Our second strategy is to utilise natural oceanic pathways whereby kelp is transported to the deep ocean (> 1,000 m) and can no longer exchange with the atmosphere [3, 4].  Both methods have almost zero chance of subsequent carbon release back into the atmosphere in the short (<10 years) or medium (<100 years) terms once implemented correctly.

 There are many coastal regions around Australia where forests of Giant Kelp have been degraded, due to a combination of human harvesting and changing oceanic conditions. We will work towards the active reforestation of these areas, as this will increase the standing stock of carbon in solid form (similar to a stand of trees), while also providing new habitat for other coastal species. Furthermore, seaweed grows by absorbing nutrients from the surrounding water and can contribute to the restoration of eutrophic water bodies. The ecosystem services that seaweed provides results in a highly restorative style of ocean farming! 

References

1. Leung, D.Y.C., G. Caramanna, and M.M. Maroto-Valer, An overview of current status of carbon dioxide capture and storage technologies. Renewable and Sustainable Energy Reviews, 2014. 39: p. 426-443.

2. Bird, M.I., et al., Algal biochar: effects and applications.GCB Bioenergy, 2012. 4(1): p. 61-69.

3. Froehlich, H.E., et al., Blue Growth Potential to Mitigate Climate Change through Seaweed Offsetting. Current Biology, 2019. 29(18): p. 3087-3093.

4. Krause-Jensen, D. and C.M. Duarte, Substantial role of macroalgae in marine carbon sequestration. Nature Geoscience, 2016. 9(10): p. 737-742.