Marine algae have the scale to make a meaningful difference: seasonal ocean blooms can transform thousands of square kilometres in a matter of days. Beneficial coastal algal blooms feed almost all fisheries on our planet and already contribute 20% to photosynthesis-based global atmospheric CO2 reduction, every year, more than all forests combined. By replicating these beneficial blooms year-round, prime in hot coastal deserts, they can significantly contribute to ‘new’ plant-based carbon fixation and storage without displacing existing agricultural land or ecosystem resources, at the gigaton scale.
Similar to trees, when the algae grow, they use photosynthesis to convert CO2 into biomass, which is then stored locked in the biomass for millennial storage.
Our approach combines the affordability of nature-based systems with the durability and measurability of engineered systems. By harnessing expansive deserts and unused seawater, we are given an extraordinary opportunity to draw down carbon from our atmosphere.
We use deep upwelled seawater that is pumped through a series of open, land-based ponds. Each day the algae double in biomass and move forward into the next, larger, pond where new seawater is added. At the end of the process, we then filter out the algae, to rapidly solar dry it and store them it underground at the same site.
Brilliant Planet cultivates locally sourced, wildtype, unmodified phytoplankton. Our algae are isolated from the beach in front of each site. Because the algae are local, they are resilient and readily accommodate natural environmental fluctuations, local pathogens and the composition of the intake seawater. Using wildtype strains allows us to cultivate the algae in open environments without posing a risk to the local environment.
An algal starter monoculture is grown in the lab, which gives us the ability to control environmental conditions and kick-start the ‘Bloom’ phase – a state in which they grow exponentially and divide more than once per day. Beneficial coastal algae blooms are responsible for 20% of the global carbon cycle and in terms of productivity makes them 10-50x more efficient at CO2 fixation than terrestrial plants per unit area.
After 10 days in the lab, the blooming algae are transferred into a greenhouse. This allows the organisms to acclimate to ambient desert conditions, so the cells can achieve maximum growth rate and density, while still growing in a controlled environment.
After the greenhouse we move the organisms into outdoor ponds, where they spend the remaining five days growing rapidly in the large outdoor production ponds. Due to the exponential growth, nearly 90% of the algae biomass is produced in these last 2 days.
The last pond is filtered out of the water by letting it flow over special screens that let the water through but retain the algae, forming a thick, algal slurry (think green smoothie) that is sent for drying. The seawater returns to the shallow ocean surface, is de-acidified and ready to promote biodiversity restoration.
We pump the biomass slurry produced at harvest up a drying tower, which sprays the mixture into the hot, dry desert air. This is a new drying method, where we mist the algal slurry similar to a snow-blower at a ski resort creating a fine powder. The particles rapidly dry as they float back to the ground.
The dried algae is collected, weighed, and put into specially lined landfill sites located above future sea level projections and away from watersheds. These locations are chosen to reduce the risk of water seeping in, and we use advanced tools to monitor the conditions inside these landfills. We are also careful to monitor for the formation of any unexpected gases or emissions at all stages.
These biolandfills, are designed to slowly remove any leftover moisture from the algae and salt mixture, and we keep a close watch on conditions like temperature, oxygen levels, and moisture inside.
Storing carbon in this way has several benefits: 1) the storage sites are co-located with our biomass production, so the transport of material is insignificant; 2) we follow well-established regulations set by the local authorities and US Environmental Protection Agency (EPA) to responsibly manage these landfill sites; 3) The biomass is available for straightforward physical verification, making it easy to demonstrate that the carbon-rich biomass is durable and has not leaked or degraded.
Half of the CO2 removed by system is taken directly from the atmosphere above the ponds. The rest is taken from the bicarbonate in the seawater that is used in the ponds. Our process does not change the seawater's alkalinity or chemistry. When the seawater is released back to the ocean, it quickly restores its bicarbonate pool, removing the second half of the CO2 from the atmosphere. 85% of this rebalancing takes place with four days, and we confirm it through direct measurements and computer modelling.
Monitoring our carbon removal is easy: every 600kg of algae we bury represents one ton of CO2 removed from the atmosphere.
To guarantee that the biomass that we store remains stable for over 1,000 years, we employ a ‘triple lock’ mechanism. The buried salt-biomass composite is >85% dry and it has a low water activity of 0.3 preventing absorption of water from the environment; it is extremely saline (with a salt content of 20-40% salt); and it is naturally acidic. Each of these properties alone is sufficient for high durability as they prevent microbes from growing by denying them the resources needed to break down the biomass. For each of these properties, long-term storage has been shown by naturally preserved biomass that has remained stable for thousands of years under these conditions. Their combined impact ensures the biomass is extremely resistant to degradation and can be stored in simple desert landfills, several meters below ground to protect the salt-biomass composite from erosion.
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