Marine Carbon Removal: The Controversial Machine Sending CO2 To The Ocean And Making Hydrogen

by YOUxTalks | Dec 19, 2024 | Nature

As the world continues to grapple with climate change, scientists and researchers are exploring innovative ways to reduce carbon dioxide (CO₂) levels in the atmosphere. One such solution is marine carbon removal (MCR) technology, which involves using the ocean to capture and store CO₂, helping to mitigate the effects of global warming. But how does this process work, and why is it gaining attention?

What Is Marine Carbon Removal?

Marine carbon removal refers to a set of technologies that aim to remove CO₂ from the atmosphere and store it in the ocean. The process leverages natural oceanic mechanisms, enhanced by technology, to capture carbon and prevent it from contributing to climate change.

Step 1: Extracting CO₂ from the Atmosphere

The first step in marine carbon removal is to capture CO₂ from the air. Marine carbon removal technologies use various techniques to pull this carbon dioxide out of the atmosphere. Some methods focus on enhancing natural processes, such as increasing the growth of marine plants like phytoplankton, which absorb CO₂ during photosynthesis. Other methods, such as direct air capture (DAC), use machines that filter CO₂ directly from the air.

Step 2: Introducing CO₂ into Seawater

Once the CO₂ is captured, it is introduced into the ocean. The ocean naturally absorbs a significant amount of CO₂ from the atmosphere, and researchers are working to enhance this process. One of the primary ways this happens is through a reaction that occurs when CO₂ dissolves in seawater. The CO₂ reacts with water molecules, creating carbonic acid. This acid then dissociates into bicarbonate ions (HCO₃⁻), a stable form of carbon.

Step 3: Storing Carbon in Bicarbonate Form

The bicarbonate ions are a stable, long-lasting form of carbon that can remain in the ocean for thousands of years. This process effectively locks away carbon in the ocean, preventing it from re-entering the atmosphere and contributing to climate change. In this way, the ocean acts as a vast carbon sink, capturing and storing carbon for the long term.

Why Is Marine Carbon Removal Important?

Excess CO₂ in the atmosphere leads to rising temperatures, more extreme weather events, and rising sea levels. By enhancing the ocean’s natural ability to absorb and store CO₂, marine carbon removal could help slow down these effects.

The ocean covers about 71% of the Earth’s surface, making it a massive carbon sink. By tapping into the ocean’s natural ability to store carbon, marine carbon removal has the potential to make a significant impact on reducing atmospheric CO₂ levels.

Unlike some other carbon removal methods that only store carbon for a short period, the carbon stored in the ocean, in the form of bicarbonate ions, can remain locked away for thousands to millions of years.

Concerns and Challenges

While marine carbon removal holds great promise, there are some genuine concerns that need to be addressed:

Ecological Impact: Introducing CO₂ into the ocean could potentially affect marine ecosystems. There are concerns about the long-term impacts of altering the ocean’s chemistry, such as ocean acidification, which can harm marine life like corals and shellfish.
Scale and Feasibility: For marine carbon removal to make a real difference, it needs to be implemented on a massive scale. This raises questions about the costs, logistics, and the potential environmental impact of such large-scale operations.
Ethical and Governance Issues: Who controls the ocean? As marine carbon removal becomes more widespread, there will be challenges related to governance, ethics, and regulations. Others are concerned about the feasibility of marine carbon removal, and whether it could really put a significant dent in emissions.
Dependency on the Ocean: Some critics argue that relying on the ocean for carbon removal could lead to inadequate action on reducing emissions. While MCR can help address existing CO₂ in the atmosphere, it should not be seen as a substitute for cutting emissions and reducing our carbon footprint.

Marine carbon removal is a promising technology that could play a critical role in the fight against climate change. However, while it offers significant potential, it must be carefully monitored and scaled to ensure it is safe, effective, and sustainable.

Equatic’s carbon removal-hydrogen breakthrough

Equatic is among a wave of start-ups exploring how the ocean could be harnessed to capture and store carbon. But not everyone is sure it’s such a good idea. It is among companies exploring how the ocean could be used to store carbon in the long term, as an alternative to the more common proposal of injecting it into rocks below the Earth’s surface. It’s the only company, it says, which is also producing green hydrogen in the process.

Equatic is working towards the goal of achieving CO₂ removal at a cost of less than $100 (£79) per tonne by 2030. The company plans to sell credits from its Quebec plant for approximately $200 (£158) per tonne. However, it is believed that to properly stimulate market demand, pricing should eventually fall below $30 (£24) per tonne, although this target is expected to take several years to reach, likely not until the early 2030s.

The ocean has already been a vast and often unacknowledged ally in protecting humans from climate change. It has absorbed more than 90% of the heat generated from our greenhouse gas emissions and absorbs at least a quarter of our CO2 emissions.

How much more CO2 it will store naturally in the future is now a subject of intense scientific interest.