April 13, 2024

New electrochemical technology could deacidify the oceans – and even remove carbon dioxide in the process

In the effort to combat the catastrophic impacts of global warming, we must accelerate efforts to reduce carbon emissions and rapidly scale up strategies to remove carbon dioxide (CO2) from the atmosphere and oceans. Technologies to reduce our carbon emissions are mature; those that aim to remove carbon from the environment are not and require robust support from governments and the private sector.

Only 45% of carbon dioxide emissions remain in the atmosphere; the remainder is absorbed through two cycles: 1) the biological carbon cycle stores CO2 in plant matter and soils, and 2) the aqueous carbon cycle absorbs CO2 from the atmosphere into the oceans. Each of these cycles is responsible for 25% and 30% of the CO2 emitted, respectively.

CO2 that dissolves in the oceans reacts to form chemicals that increase the acidity of the oceans. The dissolution of minerals from rocks along the coast acts to counterbalance this acidity, in a process called geological weathering, but the extreme increase in the rate and volume of CO2 emissions, especially in the last 60 years, has far exceeded the rate of geological weathering, leading to a 30% increase in ocean acidity.

As the oceans acidify, millions of marine species and entire ecosystems—especially coral reefs—will be unable to adapt.

Read more: COP26 failed to address ocean acidification, but the law of the seas means states must protect the world’s oceans

We are overloading Earth’s natural rebalancing systems and harming its ecosystems in the process. Our recent work at McMaster University and the University of Toronto, supported by the Carbon to Sea Initiative, has attempted to address these challenges.

The challenge that lies ahead

The good news is that it is possible to rebalance the pH of the oceans using a process called ocean alkalinity augmentation (OAE). Furthermore, this rebalancing will also encourage additional absorption of CO2 from the atmosphere. By carefully and continuously restoring ocean alkalinity, ocean acidification and excessive atmospheric CO2 concentrations can be combatted simultaneously.

The most obvious approach would be to add finely ground alkaline minerals to the ocean to directly reduce the acidity of the water. However, the enormous scale at which these processes would have to be implemented is staggering.

For example, we estimate that about 8,000 Empire State Buildings’ worth of alkaline substances would have to be added to the oceans every year from mid-century onwards to meet IPCC emissions targets. It is clear that this technique cannot be the only solution.

Calcite is just one of the potential alkaline minerals that could be used to reduce ocean acidity.

We believe that an electrochemical approach powered by decarbonized energy is one of the best ways to combat ocean acidification. Using a process called bipolar membrane electrodialysis (BMED), the acidity of seawater is removed directly, without the addition of other substances. This technology only requires seawater, electricity and specialized membranes.

The simplicity and modularity inherent in BMED technology allows for a flexible, scalable and potentially cost-effective method of carbon dioxide removal.

Building to scale

In 2015 – with a team of researchers from Palo Alto Research Center and X Development – ​​we built and tested a small-scale BMED system. This system has performed well and shows great promise when combined with existing facilities such as desalination plants.

We identified its main technological limitations, but in 2015-2017, carbon credits and incentives for climate change technologies were insufficient and the project was shelved. Now the economic and physical climate has changed.

On the economic front, both tax credits granted by the Inflation Reduction Act (IRA) in the United States and the increasingly revenue-neutral carbon tax in Canada are reinforcing the economic viability of technologies. reducing carbon dioxide. Furthermore, the recent extreme weather events of the past year, from massive wildfires in Canada, to the hottest months on record, to the warmest sea temperatures ever measured, are shocking people into the stark reality of the changes. climate change and increasing the search for real solutions. BMED technology is one of these solutions.

BMED technology is limited in part by commercially available specialized membranes. Furthermore, these membranes represent a significant portion (around 30%) of the capital cost and have a short useful life, as they are susceptible to degradation.

A man walks between a network of pipes.
A worker walks over the pipeline carrying seawater to filters at Europe’s largest desalination plant, in Barcelona, ​​Spain, in May 2023. BMED systems could be easily integrated into existing seawater treatment facilities or in any system with an outflow pipe to the ocean.
(AP Photo/Emilio Morenatti)

Our work aims to develop ultrathin, scalable membranes for use in a modified BMED process, while identifying efficient operating conditions, optimal industrial couplings, and ideal global locations to implement this OAE technology in a cost-effective manner around the world.

The ultra-thin membranes will extract acidity more efficiently than existing commercial membranes, while their optimal manufacturing technique and use will drastically decrease your operational and production costs.

The development of cost-effective BMED systems will pave the way for economically viable OAEs.

Cautious optimism

Recently, several start-ups have been formed — such as Ebb Carbon, SeaO2 and Vesta — that aim to remove carbon dioxide from the oceans through EOA.

We encourage open communication about progress and challenges facing OAE with the public, research institutions, governments, and the private sector to accelerate solutions to OAE challenges.

In particular, we must assess the impact of readjusting seawater alkalinity on marine ecosystems while at the same time developing and implementing reliable systems to measure, report and verify the net amount of acidity and carbon removed.

Read more: Anthropocene or not, it is our current era that we should fight for

At the same time, we must also identify ideal large-scale implementation locations where OAE can be implemented safely and effectively.

These considerations are being investigated by several groups funded by the Carbon to Sea Initiative, but much more support is needed to quickly vet and scale this technology.

To overcome technological challenges and environmental uncertainties, government, industry, non-profit and venture capital support must be massively scaled and dedicated to the careful and responsible validation of large-scale implementation of OAE technologies around the world.

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