Planetary Hydrogen has patented an Ocean Air Capture (OAC) technology that boosts the ocean’s natural ability to capture and permanently store atmospheric carbon dioxide while producing ‘green’ hydrogen.
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The Earth’s Natural Cycle
The earth’s geologic carbon cycle is one way in which carbon dioxide is naturally consumed and captured, where excess carbon dioxide is removed from the atmosphere via rock weathering.
Rainwater is acidified by the excess carbon dioxide in the atmosphere. Surface rocks are dissolved when contacted with this rainwater, producing dissolved alkaline molecules that are washed into the ocean. Through this natural process, dissolved carbon dioxide is chemically converted into bicarbonate and carbonate forms. But while effective, this process will need hundreds of thousands of years before the current levels of atmospheric carbon dioxide are reduced to pre-industrial levels.
Planetary Hydrogen seeks to accelerate this slow geological process with its innovative OAC technology.
The SeaOH2 Process
Planetary Hydrogen’s OAC process, called SeaOH2, uses electricity from renewable sources to carry out water electrolysis. In addition to green hydrogen production, a mineral base is generated as a by-product when mineral salt is added to the process.
When the mineral hydroxide is added to seawater, using the ocean’s surface as an air contactor, carbon dioxide is converted into bicarbonate, which is likened to an “ocean antacid”. The SeaOH2 process promotes carbon capture and utilizes the ‘antacid’ by-product to counteract ocean acidification, partially caused by the excessive absorption of atmospheric carbon dioxide.
By using renewable energy, negative emissions hydrogen – described as “super green” – can be generated using this technology, as the process also produces a chemical that actively consumes excess carbon dioxide from the atmosphere. By introducing carbon dioxide to the oceans in the form of bicarbonate or carbonate, this process mirrors slower naturally occurring rock weathering.
Scaling Up
Planetary Hydrogen has committed to larger-scale testing and experiments with a pilot plant due to be operational in 2022. A research project will be carried out simultaneously in the same region to determine the impacts of increased ocean alkalinity.
The aim of the pilot plant is to produce up to 50 kg of hydrogen per day and capture 1-1.5 tons of carbon dioxide over the same period.
Following a successful pilot phase, the next step would involve building a 10 MW facility in 2024/2025 to sequester up to 25,000 tons of carbon dioxide per year while producing approximately 600 tons of green hydrogen at 85% of capacity.
One of Planetary Hydrogen’s ambitious scale-up targets, to be achieved by 2035, will involve partnering with several organizations worldwide to deploy solutions aimed at removing around 1 billion tons of carbon dioxide from the atmosphere every year.
Potential Environmental Concerns
To avoid the need to mine mineral salts, Planetary Hydrogen is investigating other existing processes that generate waste streams, which contain these salts. One potential avenue is to utilize the waste streams from mining, where sodium sulfate is commonly found.
If the process reaches global scales and salt supplies become a concern, the option of using seawater as the electrolyte could be explored. Even though seawater is described as the “holy grail” that would enable a cheaper and more scalable process, sodium chloride electrolytes will typically result in the generation of chlorine during electrolysis, which must be used and handled carefully.
Planetary Hydrogen’s OAC process currently utilizes deionized water, which avoids the challenges associated with the generation of chlorine, as oxygen is generated instead.
Another potential environmental concern is the impact of the added carbon dioxides, in the form of bicarbonates and carbonates, could have on the ocean’s chemistry and ecosystems. The oceans already contain approximately 38,000 billion tons of carbon dioxide, with few studies carried out on the alkalinization of the ocean. The environmental benefits of alkalinity addition have yet to be fully validated in real-life settings.
To address these concerns, Planetary Hydrogen is working with several partners to better understand the benefits and impacts of alkalinity addition on the ocean’s marine life and chemistry.
Theoretical Potential of Ocean Air Capture Technology
Planetary Hydrogen’s negative emissions technology delivers on a number of fronts: large quantities of excess carbon dioxide can be absorbed from the atmosphere and safely stored in the ocean at an accelerated rate, valuable green hydrogen is produced as part of the process, and the issue of ocean acidification is addressed. With mounting global efforts to combat climate change and its impacts, the theoretical potential of this technology cannot be overstated.
Planetary Hydrogen’s unique application of electrochemistry may be the key to producing enough mineral hydroxides to sequester large quantities of atmospheric carbon dioxide. However, important questions relating to scale, environmental benefits, and costs need to be resolved before large-scale deployment can be considered.
References and Further Reading
Planetary Hydrogen (n.d.) Technology. [Online] Planetary Hydrogen. Available at: https://www.planetarytech.com/ [Accessed on 21 Jun 2021].
Doyle, A. (2021) Producing Hydrogen While Storing CO2 in the Oceans. [Online] The Chemical Engineer. Available at: https://www.thechemicalengineer.com/features/producing-hydrogen-while-storing-co2-in-the-oceans/ [Accessed on 21 Jun 2021].
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