The X PRIZE Carbon Removal is a $100 million global competition aimed at tackling climate change and rebalancing Earth’s carbon cycle. Funded by Elon Musk and the Musk Foundation, this competition is the largest incentive prize in history. The competition seeks to incentivize the development of carbon removal solutions that can achieve net negative emissions, including nature-based, direct air capture, ocean-based, mineralization, and other approaches. The goal is to develop efficient solutions that can collectively achieve the 10-gigaton-per-year carbon removal target by 2050.
The X PRIZE Carbon Removal competition will run for four years, from April 22, 2021 (Earth Day) to Earth Day 2025. The grand prize winner must demonstrate that their innovation is capable of removing 1,000 metric tons of carbon dioxide from the atmosphere or oceans and storing it in a safe, cost-effective way.
While there isn’t a specific X PRIZE focused solely on ocean-based carbon removal, ocean-based solutions are included in the broader X PRIZE Carbon Removal competition. Ocean-based carbon removal technologies have significant potential due to the vast size of the oceans and their ability to absorb large amounts of carbon dioxide. In this article, we introduce some X PRIZE Carbon Removal companies who specialize in ocean-based carbon removal technology.
Planetary Technologies 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
Equatic has developed a transformative electrolytic method for CO₂ removal that leverages the high concentration of CO₂ in seawater and the enormous abundance of Ca²⁺ and Mg²⁺ cations. The in-situ alkalization of seawater in electrolytic flow reactors forces CO₂ mineralization via reactions between dissolved CO₂ and Ca²⁺ and Mg²⁺ to permanently lock CO₂ as stable carbonate solids and/or as aqueous bicarbonates. The process also produces green hydrogen (H₂) that can be used to fuel the process during intermittency or sold to generate revenue.
Ebb Carbon has developed an automated ocean alkalinity enhancement (OAE) system that uses renewable energy and electrodialysis stack to produce alkaline saltwater from the seawater. The alkaline saltwater is returned to the ocean in a safe manner and increases the pH of the seawater in a safe manner, thereby creating a natural chemical reaction that captures CO₂ from the air. Ebb Carbon’s approach accelerates the natural process of ocean alkalization, which happens over millions of years, so atmospheric carbon can be safely removed fast enough to counteract climate change. The company’s solution also reduces the acidity of seawater, which can benefit marine life like shellfish and coral reefs.
Captura has developed an ocean-based carbon removal technology that uses renewable energy and the well-established electrodialysis technology. The electrodialysis uses seawater to produce hydrochloric acid (HCl) and sodium hydroxide (NaOH) base solutions. The acid solution is used to acidify the seawater in a tank, causing HCO₃⁻ and CO₃²⁻ ions to decompose into CO₂ gas. CO₂ is then captured and stored. The base solution is used to neutralize the acidified decarbonized seawater to a pH level that is safe for reintroduction to the oceans.
SeaO2 has developed an ocean-based carbon removal approach based on the well-established electrodialysis technology. The electrodialysis uses seawater to produce acid and base solutions. The acid solution is used to acidify the seawater in a tank, causing HCO₃⁻ and CO₃²⁻ ions to decompose into CO₂ gas. CO₂ is then captured and stored. The base solution is used to neutralize the acidified decarbonized seawater to a pH level that is safe for reintroduction to the oceans. Note that the technologies between SeaO2 and Captura are very similar. The Founders of both companies have close collaborations on the research of ocean-based carbon removal technologies based on electrochemical processes.
What do you think about the technologies of the above companies for carbon removal? Do you know any other promising carbon removal tech startups?