Should we sink seaweed for CDR?
First and foremost let’s be clear, with current growing practices it is totally unviable to sink healthy cultivated seaweed that could be made into any number of valuable products. There are over 11,000 types of seaweed, and each should be used for the highest possible value use case. Given the small-scale, high cost, labour intensive nature of seaweed farming, Carbon Dioxide Removal (CDR) would not currently be viable.
While there’s lots of excitement about the potential of seaweed, the growing methods are not developed enough to grow these amazing organisms reliably and at scale. If done responsibly and sustainably, seaweed aquaculture offers the chance to not only develop a valuable industry but also help remediate the damage done to our oceans with both carbon capture and biodiversity benefits.
We, and other forward-thinking companies, are working to rectify this, and indications are that demand for seaweed derivatives will continue to grow as the world looks for fossil fuel alternatives. Right now, it makes no sense to sink high-cost and valuable biomass.
What does make sense is to sink excess, waste and, in our case, problematic biomass that (through human action) has grown to such a scale that natural environmental processes can’t deal with it. Sargassum has no commercially viable, scalable, and sustainable use case. Our Chief Science Officer, Professor Mike Allen, has spent >9 years trying to find one.
Sargassum inundations from The Great Atlantic Sargassum Belt (distinct from the Sargasso Sea) cause environmental, social and economic disruption across the Caribbean, Central US and West African regions. Massive influxes of seaweed wash ashore and rot, releasing not just the absorbed CO2 but hydrogen sulphide gases, decimating fragile coastal ecosystems including mangroves and seagrass meadows and killing countless marine animals.
Finding a solution to this is paramount, and sinking it represents a clear opportunity to make use of Sargassum’s most redeeming feature - its carbon capture capabilities.
Of course (given the impact human activity has already had on our planet), we need to tread carefully, ensuring biomass placed in the deep ocean does not have any negative impacts or implications on the surrounding environment and organisms. But we know Sargassum that naturally dies and sinks, has already been reported in deep sea trenches around Japan, in the guts of deep sea crustaceans, and is often found on the seafloor in the Atlantic underneath the Sargasso Sea.
No one in this field is asserting that seaweed should be sunk without deep sea observation beforehand. The hostile environment presented by great depths means we currently have a limited understanding of our ocean floors. If we want to map the deep ocean and understand it better, CDR (and the associated need for monitoring, verification and reporting) is actually a huge opportunity to do so.
Yes, there are deep ocean ecologies that are still being discovered, these are rather unusual though. The vast majority of deep ocean ecology is soft mud with microbes the dominant life forms. The Sargasso sea is a notable expectation with its unique oceanographic characteristics and natural falling Sargassum impacting its productivity and biodiversity. The constant delivery of Sargassum material over thousands of years has created a thriving environment that harbours life forms which are dependent on Sargassum detritus, not threatened by it. You can see an example of this in this video.
For some Scientists this indicates that sinking extra biomass may in fact stimulate deep ocean ecology, perhaps compensating for the biodiversity loss caused by warming waters and subsequent decreases in marine snow. One of the bonuses of our approach is that we and other scientists will be able to use our monitoring program to find out more about the deep sea.
But let’s not get ahead of ourselves, we can’t assume either a positive or negative impact to sinking Sargassum, so a cautious pathway and detailed monitoring has been built into our approach. The scale of our operations are such that we can measure any change to the ocean environment on the surface, mid or deep ocean. Right now, and for the next few years our operations are literally a drop in the ocean (or a teaspoon of Sargassum per m2).
The deep ocean contains 38,000 GtC. All of human emissions since the industrial revolution are estimated to be 1,500 GtC. So adding the carbon equivalent of all human emissions to the deep ocean would be just 4%.
We desperately need carbon removal solutions, now more than ever. The world has officially entered a time of Climate Boiling, according to the UN. This is the most important problem that humanity has ever faced.
The IPCC, which is the world’s largest body of scientific minds, has been very clear that we need to be able to remove (not offset, remove) 10 billion tonnes of carbon a year from the atmosphere by 2050 to have a hope of avoiding utter catastrophe for all people and all earth life. If we don’t manage to make this happen, we will see war, famine, mass migration and suffering on a scale that we cannot even currently comprehend. Carbon Dioxide Removal will need to be the largest industry by annual volume that the world has ever seen. Bigger than oil and gas, bigger than fashion, bigger than food.
CDR is currently a market in its infancy, but with projections of this size it’s inevitably attracting investor interest. There are lots of approaches out there - Direct Air Capture, Enhanced Weathering, Biochar, Afforestation to name a few. The truth is, we’ll need all of these to even make a dent in the IPCC’s removal goals. But very few approaches have the scalability, additionality, durability, low cost and biodiversity benefits of seaweed.
We know the amazing economic and environmental potential that cultivated seaweed has to create a myriad of thriving industries. But to do that, it needs investment, and to get investment, it needs an unequivocally large end market to point towards. The very real need for a huge and robust CDR market, gives companies in the fledgling world of seaweed the chance to gain investment and develop the technologies needed to crack the seaweed market wide open.
At Seaweed Generation, we have never been afraid to talk about that. On the way to unlocking the huge potential of ocean based CDR using automated robotics, all other use cases for cultivated seaweed will be unlocked, by making seaweed cultivation commercially viable for so many other climate positive applications.