Dive into Ocean-based Negative Emissions Technologies (pun intended)

A summary of the state and feasibility of 5 ocean based NET's, and the largest opportunity for business to tackle.

39,000 GtC (gigatonnes of carbon) currently reside in the oceans, which is 16 times more than in the terrestrial biosphere (all plants, soils) and 50 times more than the atmosphere (Rackley, 2010). If we are to try to reach 1.5 °C, we need to explore more than just planting trees to remove carbon, and as shown above, the ocean has the potential to play an enormous role in helping to reduce our emissions. Here we will delve into the potential effectiveness, scalability, costs, and potential disbenefits of 5 Ocean Negative Emissions Technologies. All of these are relatively infant and require further scientific research to evaluate potential viability concretely, but here we try to identify what opportunities exist for businesses to tackle if the technologies become a widely-approved CO2 removal tool.

1. Blue Carbon

Restoring and increasing coastal vegetation involves ensuring the sustainability of mangroves, salt marshes and seagrass. Pound-for-pound, mangroves, for example, can sequester 10x more carbon than tropical rainforests. Not only this, but they help prevent the harmful effects of climate change, such as protecting coastal populations from rising sea levels and flooding. A 100-meter stretch of mangroves can reduce the height of waves by up to 66% (Menendez, 2020). This process appears to be the most ‘tried-and-tested’, however, it is expensive at $240, $30,000, and $7,800 per ton of CO2 (Gattuso, 2021) (for mangroves, salt marsh, and sea grass), and costs will need to come down to be more widely adopted.

Business issue to tackle: Lowering the cost of implementation

Startups tackling this:

Vlinder, Tenaka, Robocean, Tidal (Project X)

2. Sinking seaweed

This is the process of mass-growing seaweed and then sinking it into the deep ocean. Unlike restoring coastal vegetation, this is not restricted to coastlines, which means it is much more scalable and has a much larger carbon sequestration potential. Its cost alone is on the higher end, $610 per ton of CO2 (DeAngelo, 2022). Sinking seaweed has a large opportunity cost too, as not only can it can be used in human and plant feed (so sinking it is ethically questionable itself), but it can be used in a bunch of products:

Seaweeds can also deliver high-value molecules for pharma and food industries, replace carbon-intensive commodities like chemical fertilizers and synthetic plastics, or generate biochar and biofuels (Duarte et al 2022)

Furthermore, the is a lack of scientific evidence that this is fully feasible and effective and many of its environmental disbenefits are largely unknown (Ricart, 2022).

Business issue to tackle: Lower cost to commercially compete with other seaweed products

Startups tackling this:

Running Tide, Pull To Refresh, Seaweed Generation, Seafields

3. Marine BECCS

Marine bioenergy with carbon capture and storage is where marine biomass such as seaweed is converted into fuels and the CO2 emissions from these are captured and stored in the earth or embedded in long-lasting products. With lower area, water and nutrient requirements coming from microalgae (phytoplankton) and macroalgae (seaweed) vs land-based biomass options, Marine BECCS has the potential to become a long-term option. With further research and innovation to prove capacity and scalability, it is estimated to have the potential to be highly cost-effective at $26 per ton of CO2 (Gattuso, 2021).

Business issue to tackle: Building scalability

Startups tackling this:

Viridos, Manta Biofuel, Phycobloom

4. Ocean fertilisation

Enhancing open-ocean productivity is the process of increasing the drawdown of CO2 by phytoplankton, by fertilising areas where there is a low supply of nutrients. By directly adding macronutrients, such as phosphorus and nitrogen to the ocean, phytoplankton blooms can be spurred converting inorganic CO2 into biomass. Its cost appears to be relatively reasonable, at $20 per ton of CO2, however, the proposed scaling of this technique seems unrealistic (Williamson and Bodle, 2016).

Ocean Fertilization is considered to have negative consequences for 8 Sustainable Development Goals (SDGs), and a combination of both positive and negative consequences for 7 SDGs. (Honegger, 2020)

Business issue to tackle: Scaling nutrient harvesting and transportation

Startups tackling this:

Nitrocapt, Climos, Ocean Nourishment Corporation

5. Alkalinisation

Enhancing weathering and alkalinity is the addition of man-made alkalinity (e.g. olivine, basalt) to the ocean causing the sea to absorb more CO2 from the air. The cost potential is estimated to be $72–$159 per ton of CO2 (Gattuso, 2021), however, further research is required to understand the environmental co-benefits and disbenefits, and even if it appears net-beneficial, acquiring enough of these alkaline powders would be difficult. The required mining and grinding operations and distribution could have negative implications across a range of SDGs.

Business issue to tackle: Develop mining capabilities and mitigate disbenefits

Startups tackling this:

Planetary Technologies, KoBold metals, Bluejay mining, Vesta

Next time, let’s delve into the business models of the seaweed sinkers….

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