Planetary Technologies ($9M to sequester CO2 in seawater while producing green hydrogen)

Planetary Technologies (Planetary), a Canadian company founded in 2019, focuses on ocean-based carbon removal technology which works by producing magnesium hydroxide (Mg(OH)₂) from MgSiO₃ rocks through electrolysis technology and adding Mg(OH)₂ to seawater to speeds up the ocean’s natural carbon sequestration process and lowers ocean acidity. This process converts the dissolved carbon dioxide (CO₂) into a mineral salt, which will remain in that state for 100,000 years. Planetary aims to remove 1 billion tons of CO₂ from the atmosphere by 2045.

Challenges: Ocean-based carbon removal

CO₂ emissions

Since the early 1900s, carbon dioxide (CO₂) levels in the atmosphere have increased by 50% due to human activities. When fossil fuels (such as coal, oil, and natural gas) are burned for energy production, transportation, and industrial processes, CO₂ is released into the atmosphere. This excess CO₂ acts as a greenhouse gas, trapping heat and causing the air and ocean temperatures to rise. CO₂ emissions play a crucial role in driving climate change.

This warming effect has caused the global average temperature to rise by about 1.1 ºC since the pre-industrial period. This has led to rising in the frequency and intensity of extreme weather events, melting of polar ice caps and glaciers and rising sea levels, shifts in species ranges and increased risk of species extinction, agriculture and food security,  and ocean acidification.

To mitigate these impacts, the Paris Agreement aims to limit global warming to well below 2 ºC above pre-industrial levels. The Intergovernmental Panel on Climate Change (IPCC) estimates that a “carbon budget” of about 500 GtCO₂, which corresponds to about ten years at current emission rates, provides a 66% chance of limiting global warming to 1.5 ºC.

Ocean carbon sequestration

The oceans cover more than 70% of the earth’s surface. They store a lot of CO₂. They are the largest carbon sink on the planet, absorbing about 40% of the CO₂ emitted by human activities. They are an important buffer in climate change.

At its current average pH of 8.1, seawater contains 150 times more CO₂ than an equal volume of the air. The seawater locks the atmospheric CO₂ in the form of ions (HCO₃⁻ and CO₃²⁻) and solid precipitates (CaCO₃ and MgCO₃) according to the following reversible chemical reactions:

CO₂ + H₂O ⇆ H₂CO₃

H₂CO₃ ⇆ H⁺ + HCO₃⁻

HCO₃⁻ ⇆ H⁺ + CO₃²⁻

CO₃²⁻ + Ca²⁺ ⇆ CaCO₃↓

CO₃²⁻ + Mg²⁺ ⇆ MgCO₃↓

As CO₂ emissions increase, the ocean absorbs more CO₂, forming more carbonic acid and lowering the ocean’s pH, making it more acidic. As the oceans absorb more CO₂ than they can handle, it could lead to several potential consequences, such as ocean acidification. Ocean acidification can have negative effects on marine life, particularly organisms with calcium carbonate shells or skeletons, such as corals, mollusks, and some plankton species.

Ocean Alkalinity Enhancement

Ocean Alkalinity Enhancement (OAE) is a technical carbon removal approach that involves adding alkaline substances to seawater to enhance the ocean’s natural carbon sink. It is one of the important Negative emissions technologies (NETs). NETs are important because they can help companies, sectors, or countries remove more CO₂ from the atmosphere than they emit. According to climate models, a significant deployment of NETs will be needed to prevent catastrophic ocean acidification and global warming beyond 1.5 ºC.

By increasing the alkalinity of seawater, the above chemical reactions shift towards right, resulting in more dissolved CO₂ and converting more CO₂ to bicarbonates (HCO₃⁻), and carbonates (CO₃²⁻), according to the following chemical reactions:

CO₂ + OH⁻ → HCO₃⁻

HCO₃⁻ + OH⁻ → CO₃²⁻ + H₂O

Bicarbonates and carbonates are stable forms of carbon in the ocean. Therefore, the Ocean Alkalinity Enhancement process accelerates the ocean’s natural ability to sequester CO₂ from the atmosphere, helping to mitigate climate change and ocean acidification.

While OAE has the potential to remove significant amounts of CO₂ from the atmosphere, there are concerns about its environmental impacts, such as the effects on marine organisms and ecosystems. Further research is needed to fully understand the potential risks and benefits of OAE, as well as the feasibility, cost, and scalability of this approach.

Planetary Technology

How does Planetary technology work?

Planetary has developed an approach of Ocean Alkalinity Enhancement by electrochemically producing magnesium hydroxide (Mg(OH)₂) substance via an electrolyzer and safely adding Mg(OH)₂ to seawater by using a floating platform.

Planetary’s electrolyzer system electrolyzes sodium sulfate (Na₂SO₄) electrolyte to produce sulfuric acid (H₂SO₄) and sodium hydroxide (NaOH) base in order to convert MgSO₃ minerals into Mg(OH)₂. Due to its low toxicity to aquatic organisms and humans, Mg(OH)₂ is commonly used in wastewater treatment. Important aspect of Mg(OH)₂ is its sluggish dissolution, which limits its environmental impact. This prevents rapid pH rises at the outfall location, after which rapid dilution in the seawater maintains a pH well within safe limits.

Planetary has also developed a floating platform for safely dispersing Mg(OH)₂ in the ocean for carbon dioxide sequestering. The platform has a vessel for holding solid Mg(OH)₂ pellets and exposes them to a flow of seawater to create a Mg(OH)₂ solution with a safe pH level. The solution is released into the seawater, producing HCO₃⁻ or MgCO₃ solid, thus sequestering CO₂ present in seawater through chemical reactions:

Mg²⁺ + 2OH⁻ + 2CO₂ → Mg²⁺ + 2HCO₃⁻

Mg²⁺ + OH⁻ + HCO₃⁻ → MgCO₃↓ + H₂O

How does Planetary produce magnesium hydroxide?

The diagram below depicts Planetary’s electrolyzer system for producing Mg(OH)₂ from MgSiO₃ minerals and generating green hydrogen gas ( H₂) as a by-product, which could be used as a zero-carbon fuel.

Planetary Technologies electrolyzer system to produce Mg(OH)₂ for ocean-based carbon sequestration (ref. US20220170171A1).
Planetary Technologies electrolyzer system to produce Mg(OH)₂ for ocean-based carbon sequestration (ref. US20220170171A1).

The system mainly comprises an electrolyzer, a leaching tank, and a Mg(OH)₂ reactor.

  • Electrolyzer

The electrolyzer electrolyzes Na₂SO₄ electrolyte and produces H₂SO₄ and NaOH solutions. The acid solution is used to leach MgSO₃ minerals in a leaching tank, while the base solution is used to precipitate Mg(OH)₂ from the leaching solution in a separate Mg(OH)₂ reactor.

The electrolyzer uses two anion exchange membranes (AEMs) to create a three-chambered electrolytic container: an anode chamber, a cathode chamber, and a central chamber. The central chamber is supplied with Na₂SO₄ electrolyte recycled from the Mg(OH)₂ reactor, while the anode and cathode chambers are supplied with water to compensate for of water lost during electrolysis reactions.

When sufficient applied voltage on the anode and cathode, OH⁻ and H₂ are generated at the cathode according to the chemical reactions:

2H₂O + 2e⁻ → 2OH⁻ + H₂↑

Hydroxide ions transport to the central chamber, where they combine with sodium ions to form NaOH base solution. Hydrogen gas is removed and used as clean fuel.

On the anode, H₂O is electrically oxidized into oxygen gas (O₂) and protons (H⁺) via the chemical reaction:

2H₂O → 4e⁻ + 4H⁺ + O₂↑

The oxygen gas is removed. The protons combine with SO₄²⁻ ions that migrate from the central chamber via the anion exchange membrane to form H₂SO₄. The acid is introduced to the leaching tank to leach MgSO₃ minerals.

The overall chemical reaction occurs in the electrolyzer can be described below:

Na₂SO₄ + 3H₂O → H₂↑ +½ O₂↑ + H₂SO₄ +2NaOH  

  • Leaching tank

H₂SO₄ formed in the anode chamber is supplied to a separate leaching tank. The acid dissolved the MgSiO₃ mineral rocks in the tank according to the chemical reaction:

H₂SO₄ + MgSiO₃ rock (containing other metal silicates and oxides) → MgSO₄ + H₂O + SiO₂ + other metal compounds  

The leaching solution is processed by a cleanup unit. Silica (SiO₂) and other metal compounds are removed while the remaining MgSO₄ solution is delivered to the Mg(OH)₂ reactor.

  • Mg(OH)₂ reactor

In the Mg(OH)₂ reactor, MgSO₄ solution is mixed with NaOH solution from the central camber of the electrolyzer. Mg(OH)₂ is precipitated from the solution. The process can be described via the chemical reaction:

Mg²⁺ + SO₄²⁻ + 2Na⁺ + 2OH⁻ → 2Na⁺ + SO₄²⁻ + Mg(OH)₂↓

The Mg(OH)₂ precipitate is separated from the Na₂SO₄ solution via flocculation followed by settling-thickening filtration, centrifugation or other solid/liquid separation methods. The Na₂SO₄ solution is then recycled back into the central chamber of the electrolyzer to provide fresh electrolyte.

Planetary ocean-based carbon removal with floating platform

Adding Mg(OH)₂ into seawater causes an increase in initial pH levels around the outfall location. When the initial pH level at the outfall location exceeds 9, undesirable precipitation of CaCO₃ and generation of CO₂ occur according to the following chemical reaction:

Ca²⁺ + 2HCO₃⁺ → CaCO₃↓ + CO₂↑ + H₂O
In order to maximize CO₂ removal and storage, it is evident that the concentration of dissolved Mg(OH)₂ released to the ocean must be controlled in order to avoid the undesirable precipitation of CaCO₃. Planetary has performed MRV tests and concluded that the release rate of Mg(OH)₂ must be controlled so that seawater alkalinity concentrations do not exceed about 4 mmol/L.

Planetary has therefore developed a floating platform system, as shown in the diagram below, for the addition of Mg(OH)₂ solution to seawater in order to maintain seawater pH within safe environmental limits while maximizing CO₂-removal and sequestration and avoiding undesirable changes to seawater chemistry, including avoiding precipitation of CaCO₃.

Planetary Technologies floating platform system for adding Mg(OH)₂ solution into seawater for carbon sequestration (ref. US20220396503A1).
Planetary Technologies floating platform system for adding Mg(OH)₂ solution into seawater for carbon sequestration (ref. US20220396503A1).

The platform mainly comprises a Mg(OH)₂ stock container, sensors, pumps, and computer (not shown).

  • Mg(OH)₂ stock container

The container contains solid Mg(OH)₂ pellets or particles. A dispenser in the container is triggered by a sensor associated with the dispenser and releases the required amount of Mg(OH)₂ in the hull of the floating platform upon receiving the dispensing signal. The required quantity is calculated by the computer inside the floating platform.

  • Pumps

The floating platform has a pump for pumping seawater from the ocean into the hull to dissolve the Mg(OH)₂ pellets and dilute the Mg(OH)₂ solution. There is another pump for pumping the Mg(OH)₂ solution from the hull  to the ocean. Both pumps are controlled by the computer.

  • Sensors

The floating platform has a communication sensor controlled by the computer for sending a communication signal to outside entities for loading Mg(OH)₂ pellets in the container and relocating the floating platform to different locations in the ocean.

The floating platform has sensors for measuring pH of the solution in the hull and characteristics of the seawater surrounding the floating platform, such as pH and inorganic carbon.

Additionally, the floating platform has sensors for measuring lower and upper water levels inside the hull to ensure the water level is within a predetermined range.

Planetary Patent

  • US20210340681A1 Electrochemical system, apparatus and method to generate metal hydroxide in the presence of metal silicates
  • US20220396503A1 Method for sequestration of carbon dioxide using a body of water and a suspended platform therefor
  • US20220170171A1 Electrochemical method, apparatus and system with improved production efficiency and co2 sequestration
  • US20220002889A1 Method and system for co2 emission reduction in the production of chemical compounds

Planetary Technology Applications

  • CO₂ removal

Planetary has developed a method called Ocean Alkalinity Enhancement (OAE), which involves adding an antacid to seawater to capture CO₂ and reduce harmful ocean acidity. This process mimics the geologic capture of carbon but acts in months rather than millennia. The company’s OAE method uses naturally abundant materials that have been used in water treatment applications for decades. The treated water is then released into the ocean, resulting in the safe, permanent removal of CO₂, which helps to combat ocean acidification and climate change.

  • Hydrogen production

Planetary Technologies is also involved in the production of hydrogen via electrolysis, a process that uses electricity to split water into hydrogen and oxygen. This method of hydrogen production can result in zero greenhouse gas emissions, depending on the source of the electricity used.

  • Mining industry

Planetary Technologies is testing its carbon transition platform with Brazilian Nickel PLC, a UK-based sustainable nickel and cobalt mining company. The company is assisting Brazilian Nickel on its decarbonization path using its technology.

Planetary Products

Carbon offset credit market

The market value of carbon offset credits varies widely. In current carbon markets, the price of one carbon credit can range from a few cents per metric ton of CO₂ emissions to $15/mtCO₂e (metric tons of CO₂ equivalent) or even $20/mtCO₂e. However, the voluntary carbon offset market, which was worth about $2 billion in 2021, is projected to grow to $10-40 billion by 2030, transacting 0.5-1.5 billion tons of CO₂ equivalent, as opposed to the current 500 million tons. The total value of carbon credits produced and sold to help companies and individuals meet their de-carbonization goals could approach $1 trillion as soon as 2037.

Planetary science projects

Planetary has a small project in Cornwall that aims to determine if Planetary’s carbon removal technology can scale up safely and effectively. The project involves small and well-monitored trials in Hayle, UK, to remove carbon from the atmosphere while restoring marine ecosystems. Planetary has held two public consultations in the local area to hear from residents and those working hard to protect Cornwall and its environment. The company intends to update plans to account for local community feedback. All results from the test will be released publicly, in keeping with their Code of Conduct and integrity to their research and people.

Planetary Funding

Planetary has raised a total of $8.6M in funding over 6 rounds, including

Their latest funding was raised on Apr 22, 2022 from a Grant round.

The funding types of Planetary Technologies.
The funding types of Planetary Technologies.
The cumulative raised funding of Planetary Technologies.
The cumulative raised funding of Planetary Technologies.

Planetary Investors

Planetary is funded by 9 investors, including

XPRIZE and Apollo Projects are the most recent investors.

The funding rounds by investors of Planetary Technologies.
The funding rounds by investors of Planetary Technologies.

Planetary Founder

Mike Kelland, Greg Rau, and Brock Battochio are Co-Founders.

Planetary CEO

Mike Kelland is CEO.

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