In the Sahara desert along the Moroccan coast, more than 300 miles from the nearest town, a green pond now sits in the middle of the sand. This is a test site for shiny planeta startup that plans to fight climate change by growing large amounts of carbon-capturing algae in the world’s deserts.

“Per unit area, we can fix as much carbon – or more carbon, depending on where we are in the seasonality – as a rainforest,” says Raffael Jovine, co-founder and chief scientist of Brilliant Planet. “The difference is that when a tree in the rainforest falls, it sends 97% of the carbon back into the atmosphere, whereas we can sequester it all.” Production at the test site varies, as the company performs different tests. But when he builds the first commercial-scale factory, covering 1,000 acres, he expects to remove 40,000 tons of CO2 per year, or about the equivalent emissions to use 92,000 barrels of oil. Scaled to cover available desert land on the coasts, the system could hypothetically remove 2 gigatonnes of CO2 per year.

The company pumps seawater from the nearby coast into its facility, taking advantage of the fact that the water is filled with both nutrients the algae need to grow and CO2; the ocean absorbed tens of billions of tons of CO2 emissions over the past decades. As water flows through a series of containers and ponds, algae grow in the startup’s proprietary system and capture carbon. When the seaweed is ready to harvest – a process that takes between 18 and 30 days – it is filtered out of the water, which is returned to the ocean. (The process also makes the water less acidic, helping to resolve another problem caused by climate change.) Then the seaweed is dried and buried under the sand, where the carbon it captures can be permanently stored.

This is an example of something that climate science sees as necessary: ​​tackling climate change involves not only moving away from fossil fuels and eliminating other emissions, but also removing CO2 from the air. The latest IPCC report says that removing carbon, both through technology and through natural solutions like planting trees, is essential and will have to be developed massively so that the world has a chance of limiting global warming to 1.5 or 2 degrees Celsius.

Other companies growing algae, including failed biofuel startups in the past, have focused on a different approach, growing algae in expensive and complex-to-operate bioreactors. Jovine likens the old approach to growing in a test tube. “Instead of scaling a test tube, we’re scaling the ocean,” he says. “What that really means is that basically we took natural processes, natural algal blooms, which are the base of the food chain in the ocean. And we took them and brought them onto land on a very large scale.

In the ocean, large algal blooms occur seasonally, but the company has developed a process that can grow algae rapidly year-round. The system can capture CO2 at a much lower cost than direct air capture plants that suck carbon from the air. The algae plant costs less than $50 per ton of CO2 captured to operate; direct air capture can cost 10 times more. As with direct air capture plants, the company will sell carbon credits to companies that need to offset their carbon footprint. “The problem on the direct air capture side is just that it’s so expensive,” says CEO Adam Taylor. “There’s just an inherent amount of energy needed to separate CO2 from the atmosphere in such minute amounts.”

The approach also has advantages for removing carbon from nature: it is difficult to measure exactly how much CO2 a forest is storing or to know that trees might not be cut down or lost in a fire. . Another startup plans to grow kelp in the ocean and then sink it to capture the carbon, but will also face the challenge of showing that the carbon is permanently stored. Brilliant Planet will bury algae near the surface of the sand; due to the salty and dry environment, it will not decompose.

“It’s just a shallow burial, one or three meters underground,” Taylor explains. “So if anyone has already asked, did you really bury the seaweed?” Is it still there? Has it decomposed? You could kind of say, Well, there’s the GPS coordinates of where we were burying that day that we credited. Bring your shovel, and you are welcome to check it out.

Companies that aim to achieve net zero emissions or become “carbon negative”, such as Microsoft, are looking for high quality carbon credits to buy, permanent, scalable, affordable and proven solutions to add a new advantage rather than to double – count something that would have happened anyway. Brilliant Planet is currently considering the possibility of “pre-selling” one of its carbon credits to these companies. Full operation will begin soon.

The startup has operated its government-leased test site in Morocco for nearly five years to prove the system works, following earlier pilots in South Africa and Oman. Now, having raised $12 million in a Series A funding round, the company will begin construction of a larger demonstration facility in 2023; a commercial facility will be built in 2024.

There are half a million square kilometers (more than 300,000 square miles) of flat coastal desert land around the world – from Africa to South America to Australia – which the company says , could be perfectly suitable for this work. “One of the main advantages of this system is the enormous scalability, because we are using otherwise unused desert land that has no real agricultural alternative or agricultural or economic use,” says Taylor.