A group of scientists is speaking out against what they call a new “BlueWashing” (a term used to describe misleading marketing that exaggerates a company’s commitment to responsible social practices), an emerging strategy that involves growing algae and then submerge them in the ocean, under the promise that they will capture excess CO2 and contribute significantly to the fight against climate change.
Despite its growing popularity and the significant investment it is attracting globally, experts warn of a lack of scientific evidence to support its effectiveness.
A study published in the magazine One Earth, authored by twenty scientists from various countries, calls for a pause and reconsideration of this increasingly widespread practice of submerging algal biomass in the ocean depths. This initiative, presented as a “nature-based solution” to carbon sequestration, lacks a solid scientific basis for its effectiveness.
The approach proposes the intensive cultivation of algae and its subsequent sinking to the seabed, seeking to take advantage of its ability to absorb carbon dioxide during its growth, in order to permanently sequester this greenhouse gas. However, science does not yet provide support for these claims.
Investments
The attention and financing that these types of projects have received, under the premise of carbon sequestration and compensation, has been notable. An industry report points to investments exceeding $375 million in seaweed over the past three years, a figure that likely underestimates the total investment given the scant detail available on some publicly traded companies.
The generation of carbon credits emerges as a strong incentive behind these proposals, promoting investment in projects that reduce greenhouse gases. These credits are an international instrument that allows companies and countries to offset carbon dioxide (CO2) emissions. How? Investing in projects that mitigate greenhouse gases, such as CO2 capture through algae cultivation. However, the value of these credits is questionable, and the economic logic behind growing and submerging algae to sequester carbon appears insufficient.
They could then sell these credits in the carbon markets to companies seeking to offset their emissions, thus providing an economic incentive to implement these types of projects. The reality is that the price of any carbon credit is negligible. For example, in Canada this is equivalent to $0.0145/kg of dried seaweed. Compared to the market price of algae, which can vary from a few dollars to more than $1,000/Kg depending on the application.
This last data is relevant, since at the COP28 held during 2023 it was reported that carbon credits vary between $0.01 and $154 dollars per ton, with an average of less than $20 dollars per ton, which places the value of Canadian carbon credits above average. Which shows how unattractive these proposals are to have a real impact or act as an incentive to mitigate the climate crisis.
Doubts
The doubts about the effectiveness and environmental sustainability of these projects are vast, ranging from the lack of understanding about the final fate of the submerged algae to the ecological impacts and the true carbon sequestration capacity.
According to Charles Yarish, co-author of the study, “dumping algae into the deep ocean is not a sustainable or ethical solution to mitigate climate change through carbon sequestration.”
Before considering the inclusion of algae in climate change mitigation strategies, it is crucial to address numerous barriers, from scalability and durability to conflicts with existing ocean uses and the adequacy of regulatory and economic frameworks. It is essential to develop advanced carbon accounting methods to accurately evaluate these projects, the study notes.
Intrinsic value
The use of algae as submerged waste is not only economically unviable but also a misguided strategy in the face of the current climate crisis. The algal industry offers enormous potential for innovative and profitable applications that can foster a more sustainable economy without resorting to disposal in the ocean, according to the study.
Regarding the potential of algae, Alejandro Buschmann, researcher at the Millennium Nucleus MASH and one of the authors of this study, comments “for more than a century, algae have been exploited to obtain polysaccharides with properties different from those normally found in plants. terrestrial”.
“For example, the agar obtained from some red algae has a very relevant use in microbiology and allows the cultivation and recognition of pathogenic bacteria in patients with infectious diseases. Carrageenan has multiple uses, especially to stabilize proteins in foods with high levels of them in dairy and meat products. Brown algae alginates have multiple uses from industrial, food and even in products used by dentists. To name a few of the many uses of algae. From our point of view this is more important than discarding this biomass and causing unknown environmental effects in practically unstudied ecosystems.”
Instead of focusing on trading carbon credits through seaweed submersion, experts suggest maximizing the ecosystem, bioeconomic and social benefits that seaweed can offer. Algae have the potential to transform value chains, promote decarbonization and mitigate excess nutrients and coastal acidification through ethical and beneficial uses, aligned with global sustainable development goals. This approach not only promises a real and positive environmental impact, but also recognizes the intrinsic value of algae beyond its use as a mere carbon offset instrument.
You can find the full article at the following link: Deep-ocean seaweed dumping for carbon sequestration: Questionable, risky, and not the best use of valuable biomass