Ocean carbon dioxide removal is still a new topic in climate circles. What does it mean for us, the ecosystems, and the future of our warming planet?

Maria

<p><span style="font-weight: 400;">We&rsquo;ve all heard about DACS. But while the world is holding its breath for news from the Orca removal plant in Iceland, others are venturing into much less chartered waters. Ocean carbon dioxide removal is still a new topic in climate circles, yet it already has strong proponents and critics on both sides. What does it mean for us, the ecosystems, and the future of our warming planet?</span></p>
<h2><strong>The ultimate buffer</strong></h2>
<p><span style="font-weight: 400;">Since we started emitting unprecedented amounts of carbon dioxide around the time of the industrial revolution, the oceans have been doing the majority of the heavy lifting to keep us afloat. Only between 1994 and 2007, oceans absorbed 34 gigatonnes of carbon dioxide, or roughly 1/3rd of what humans put into the atmosphere during that period, according to a</span><a href="https://www.science.org/doi/10.1126/science.aau5153"><span style="font-weight: 400;"> Science study.</span></a><span style="font-weight: 400;"> Ocean ecosystems act as an ultimate buffer by permanently sequestering carbon in coastal soils and seabeds via primary producers such as mangroves, phytoplankton, and seaweed. </span></p>
<p><span style="font-weight: 400;">However, the growing concentration of CO</span><span style="font-weight: 400;">2</span><span style="font-weight: 400;"> means the pace with which they can continuously absorb it is slowing down. It also means the water is becoming increasingly acidic, which in turn threatens marine ecosystems such as coral reefs and shellfish.</span></p>
<h2><strong>Ocean&rsquo;s natural capacity fizzing out</strong></h2>
<p><span style="font-weight: 400;">This is where ocean carbon dioxide removal (CDR) comes in. The emerging technology relies on the principle called Henry&rsquo;s Law - the very reason why a bottle of a fizzy drink turns flat if left unattended. In line with Henry&rsquo;s law, the gas has a natural affinity to flow from higher concentrations to lower concentrations to achieve equilibrium. Up until now, the oceans absorbed CO</span><span style="font-weight: 400;">2</span><span style="font-weight: 400;"> as its concentration was lower than in the atmosphere - but as the </span><a href="https://www.ncei.noaa.gov/news/gulf-mexico-getting-warmer"><span style="font-weight: 400;">recent ocean data</span></a><span style="font-weight: 400;"> is telling us - this is not something we can rely on much for longer.</span></p>
<p><span style="font-weight: 400;">The science behind ocean CDR works by applying a voltage across a stack of membranes to split the seawater. This converts bicarbonates in the water to molecules of CO</span><span style="font-weight: 400;">2</span><span style="font-weight: 400;">, which can then be removed under a vacuum. A recent breakthrough method evolved by a </span><a href="https://news.mit.edu/2023/carbon-dioxide-out-seawater-ocean-decorbonization-0216#:~:text=The%20existing%20methods%20for%20removing,then%20be%20removed%20under%20vacuum"><span style="font-weight: 400;">team at MIT</span></a><span style="font-weight: 400;"> omits the use of costly membranes altogether and alternatively uses electrochemical cells to acidify and then alkalize the water molecules in a cyclic process. The output is valuable hydrogen or concentrated CO</span><span style="font-weight: 400;">2</span><span style="font-weight: 400;"> for industrial use or storage.&nbsp;</span></p>
<h2><strong>Localised silver bullet</strong></h2>
<p><span style="font-weight: 400;">According to Allan Hatton, a Ralph Landau Professor of MIT Chemical Engineering, a reinjection of the treated water could slowly counteract ocean acidification - at least locally. This could find its application in places like fish farms that acidify the nearby waters. When done in a controlled and dispersed manner, it would also pose minimal risks to the ecosystems.&nbsp;</span></p>
<p><span style="font-weight: 400;">As with all emerging CDR solutions, applications remain within the theoretical realm until they can breach the financing barrier. One of the front runners in the race is a&nbsp; Caltech startup </span><a href="https://capturacorp.com/"><span style="font-weight: 400;">Captura</span></a><span style="font-weight: 400;"> founded in 2021. The company is utilizing the&nbsp; $1 million from Elon Musk&rsquo;s XPrize competition to promote its most recent pilot project, AltaSea. Based on the Los Angeles Port,&nbsp; the pilot is 10 times bigger than the most recent prototype and should be able to take about 100 tons of CO</span><span style="font-weight: 400;">2</span><span style="font-weight: 400;"> out of the ocean a year.&nbsp; To put it in perspective, the tech is still in its infancy - a successful operation would be sucking out the equivalent of removing 22 cars off the road. And even that remains incredibly expensive.&nbsp;</span></p>
<h2><strong>The dark side of CDR</strong></h2>
<p><span style="font-weight: 400;">While some are drawing exponential graphs following the rapid scaling up of the technology to the N</span><span style="font-weight: 400;">th</span><span style="font-weight: 400;"> magnitude, others</span><a href="https://oceanfdn.org/wp-content/uploads/2021/04/Direct-Carbon-Removal-Strategies-TOF-v20Apr21.pdf"><span style="font-weight: 400;"> openly raise their concerns</span></a><span style="font-weight: 400;">. The biggest qualm is around making sure that the massive floating recovery facility is in no way harmful to the ocean. The water filtering system can pose a risk to smaller but vital plankton particles that form the basics of deep water ecosystems. Further up the food chain, the machinery and noise can further disrupt fish and marine life.&nbsp;</span></p>
<p><span style="font-weight: 400;">There are other reasons to be sceptical. The most generous backer behind the Captura project is Southern California Gas, the biggest gas utility in the US. Aramco and Equinor - oil and gas giants - are also among Captura&rsquo;s supporters.&nbsp;</span></p>
<blockquote>
<p><em><span style="font-weight: 400;">&ldquo;Across the board, the biggest backers [of carbon removal] are the fossil fuel industry and partners. It ends up being an industry scam or an industry distraction from real climate action, which is rapidly reducing fossil fuel extraction and use,&rdquo;</span></em><a href="https://www.theverge.com/2023/5/4/23711098/ocean-carbon-removal-california-captura-climate-change"><span style="font-weight: 400;"> says Shaye Wolf</span></a><span style="font-weight: 400;">, a climate science director at the Center for Biological Diversity.</span></p>
</blockquote>
<p><span style="font-weight: 400;">Whether ocean carbon dioxide removal proves a valuable asset in the portfolio of projects that have an actual chance of moving the needle is yet to be determined. What is certain though is that carbon removal should not be treated as a viable mitigation solution for climate change - but only relied upon in the case of industries that are hard to decarbonise completely. Regardless, boosting the ocean&rsquo;s ability to naturally absorb carbon dioxide can be further explored through solutions such as </span><a href="https://oursharedseas.com/demystifying-ocean-based-carbon-dioxide-removal-an-explainer/"><span style="font-weight: 400;">enhanced rock weathering and/or ocean alkalinity management</span></a><span style="font-weight: 400;">. In the face of the regenerative capacity of nature-based CDR approaches, Captura&rsquo;s early efforts remain a drop in the ocean.</span></p>
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<p><em>Future Thought Leaders is a democratic space presenting the thoughts and opinions of rising Sustainability &amp; Energy writers, their opinions do not necessarily represent those of illuminem.</em></p>
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Maria Zielinska

Maria Zielinska

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