Ebb Carbon is a climate tech startup that develops a new method of carbon removal using well-established electrodialysis technology to enhance the ocean’s natural ability to safely store carbon dioxide (CO₂) while reducing ocean acidity. The electrodialysis system uses renewable energy and the seawater to produce alkalinity solution with a safe pH >8 and inject it back into the ocean, thereby creating a natural chemical reaction that removes CO₂ from the air.
Challenges: climate change and ocean acidification
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.
The Paris Agreement is a 2015 international agreement to combat climate change. It aims to limit global warming to well below 2 ºC above pre-industrial levels and to pursue efforts to limit the temperature rise to 1.5 ºC. The average global temperature has already risen by between 0.8 ºC and 1.2 ºC. 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 acidification
The ocean is the largest carbon sink on the planet, absorbing about 40% of the CO₂ emitted by human activities. As the CO₂ concentration in the atmosphere increases, the ocean absorbs more CO₂. As the oceans absorb more CO₂ than they can handle, it could lead to several potential consequences, such as ocean acidification and its negative impacts on marine life and ecosystems. One concern with ocean acidification is that the decreased seawater pH can lead to the decreased survival of shellfish and other aquatic life having calcium carbonate shells, as well as some other physiological challenges for marine organisms.
Negative emissions technologies
Negative emissions technology (NET) is important because it 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. NETs include methods of Direct Air Capture (DAC) and Indirect Ocean Capture (IOC).
DAC methods directly extract CO₂ from the atmosphere. They fall into two main categories:
- engineered solutions, such as DAC and Bioenergy with Carbon Capture and Storage (BECCS); and
- natural climate solutions, such as reforestation.
IOC methods offset CO₂ emissions by enhancing the ocean’s ability to absorb atmospheric CO₂ using various natural and/or technological processes, such as Ocean Alkalinity Enhancement. Ocean Alkalinity Enhancement involves adding solid alkaline substances to the seawater to enhance the ocean’s natural carbon sink function.
Direct Air Capture
DAC methods extract CO₂ directly from the atmosphere and can permanently store CO₂ in deep geological formations to achieve carbon removal. DAC approaches will only be climate-relevant if they swiftly reach gigaton scale by the middle of the year 2030, due to the amount of carbon that will likely need to be removed. However, the dominant DAC technologies of today are too expensive for large-scale deployment.
Bioenergy with Carbon Capture and Storage
Bioenergy with Carbon Capture and Storage (BECCS) technology produces bioenergy using biomass while capturing and storing CO₂. BECCS provides energy, as opposed to other carbon removal methods such as DAC, which require energy. BECCS has many different pathways for converting biomass to heat, electricity, or liquid or gas fuels, and the carbon emissions from this bioenergy conversion are sequestered in geological formations. However, BECCS has some challenges, such as the availability of biomass, the energy required to produce and transport biomass, and the cost of carbon capture and storage.
Forestry and Soil Carbon Sequestration
Forestry and Soil Carbon Sequestration captures and stores CO₂ in tree biomass and forest soil. Forests currently offset about 10% of the U.S. greenhouse gas emissions, and reforestation can lead to soil carbon sequestration. Carbon sequestration in forests and soils is an important strategy for mitigating climate change.
Ocean Alkalinity Enhancement
Ocean Alkalinity Enhancement involves the addition of alkaline substances to seawater to enhance the ocean’s natural carbon sink. Adding minerals such as olivine or pulverized silicate or carbonate rock to seawater increases the water’s alkalinity and helps to deacidify the ocean. The process accelerates the ocean’s natural carbon cycle by transforming dissolved CO₂ into bicarbonate ions (HCO₃⁻), which can mitigate the effects of ocean acidification and climate change. However, environmental impacts and species sensitivities to alkalinity enhancement are a concern.
Ebb Carbon Technology
Ebb Carbon has developed an automated ocean alkalinity enhancement (OAE) system that uses renewable energy and seawater to produce alkaline saltwater. 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.
Ebb Carbon carbon removal system
The diagram below depicts Ebb Carbon’s carbon removal system, which captures CO₂ from the atmosphere and mitigates ocean acidification by generating and supplying an alkalinity product with a pH >8 to seawater at an outfall location.
The system uses renewable energy sources like wind turbines and solar cell panels to power its components. The system has a modular container that contains an ocean alkalinity enhancement system. The modular container protects the ocean alkalinity enhancement system and facilitates its transport and placement near the water.
The alkalinity enhancement system uses renewable electricity and electrochemically dissociates seawater to produce hydroxide (OH⁻) and sodium ions (Na⁺), which combine to produce NaOH base solution. The base solution can be added directly and safely to the ocean through a transfer pipe to a designated outfall location.
Alternately, the base solution is mixed with seawater to produce an alkalinity product with a pH value (pH range between 8.0 and 9.0) higher than that of ocean seawater. After verifying that the alkalinity product is within the target pH range, the electrochemical device supplies the alkalinity product to the ocean through a transfer pipe to a designated outfall location.
Controlling the generation and supply of alkalinity products can prevent harm to sea life caused by dangerously high seawater pH levels near outfall location, which may occur if the base substance in alkalinity product is supplied into seawater in an uncontrolled manner.
The increased alkalinity of seawater at the outfall location reduces ocean acidification and increases the ocean’s ability to absorb atmospheric CO₂ according to the chemical reaction:
OH⁻ + CO₂ → HCO₃⁻
Ebb Carbon modular ocean alkalinity enhancement system
The diagram below depicts the modular ocean alkalinity enhancement system. The system comprises a bipolar electrodialysis stack, a control circuit, and a power distribution circuit.
- Bipolar electrodialysis stack
The structure of a bipolar electrodialysis stack is described below. The bipolar electrodialysis stack electrochemically processes seawater to generate a base solution comprising fully dissolved NaOH salt. The base solution can be added directly to the ocean in a controlled and risk-free manner. Alternately, the base solution is combined with seawater to create an alkalinity product with the desired pH level.
- Control circuit
The control circuit monitors input data received from sensors and regulates operations of the bipolar electrodialysis stack such that the alkalinity product is only supplied to the ocean when
- sufficient low/zero-carbon electricity is available to operably power the base substance generation and supply operations performed by the bipolar electrodialysis stack;
- the bipolar electrodialysis stack performs the generation and supply operations safely; and
- supplying the alkalinity product will not endanger sea life adjacent to the outfall location.
When all three conditions are concurrently satisfied, the control circuit can restrict base substance supplying operations to maximize the energy efficiency. When low/zero-carbon electricity is available and the base-generating device is capable of safely conducting the automated maintenance cycles, but when supplying the base substance may endanger sea life, the control circuit performs automated maintenance cycles.
- Optional power distribution circuit
Optional power distribution circuit supplies the bipolar electrodialysis stack with externally supplied electrical power. When the control algorithm determines that the aforementioned three conditions are satisfied, the control circuit can assert control signal. In the absence of low/zero-carbon power, the power distribution circuit can supply alternative power to the control circuit and the bipolar electrodialysis stack to facilitate specific operations.
How does Ebb Carbon’s technology work?
The bipolar electrodialysis stack is an established water purification technology. The diagram below depicts the structure of the bipolar electrodialysis stack for the ocean alkalinity enhancement system.
The electrodialysis stack comprises a series of salt, acid and base chambers that are respectively separated by ion-permeable membranes. Each salt chamber is separated from each adjacent acid chamber and base chamber by an anion-exchange membrane and a cation-exchange membrane, respectively. The adjacent acid and base chambers are separated by a bipolar membrane. The electrodialysis stack also includes electrodes that apply an electric field across the salt, acid and base chambers and cause ions to pass through the ion-exchange membranes.
During operation, the flow control system directs a salt stream from the salt buffering tank (not shown) through the salt chambers. Similarly, the flow control system directs an acid stream from the acid buffering tank through the acid chambers and a base stream from the base buffering tank through the base chamber.
The diagram below illustrates the ionic transport and production of acid and base during the electrodialysis stack’s operation.
The applied electric field causes chloride ions (Cl⁻) to pass from the salt chambers through the anion-exchange membranes into the acid chambers, and also causes sodium ions (Na⁺) to pass from the salt chambers through the cation-exchange membranes into the base chambers. In the bipolar membrane that separates adjacent acid and base chamber, water is dissociated into protons (H⁺) and hydroxide ions (OH⁻). H⁺ transfers into the acid chamber, where it combines with Cl⁻ to form acid (HCl), while OH⁻ transfers to the base chamber, where it combines with Na⁺ to form base (NaOH).
Consequently, the concentrations of acid (HCl) in the acid stream and base (NaOH) in the base stream increase. In other words, the acid and base streams leaving the electrodialysis stack have a higher concentration of acid and base substance, respectively, than the acid and base streams entering the stack. Therefore, the properties of concentration and pH change as each acid/base fluid stream passes through the electrodialysis stack.
The acid can be utilized for a variety of commercial purposes. The base is used as an alkalinity product for enhancing ocean alkalinity.
Ebb Carbon Patent
- US11629067B1 Ocean alkalinity system and method for capturing atmospheric carbon dioxide
Ebb Carbon Products
The market for negative emissions technologies is still in its early stages, but it is expected to grow as more countries, cities, and companies commit to achieving net-zero emissions. According to a report commissioned by the UN-supported Principles of Responsible Investment, NETs could create trillion-dollar upside opportunities for investors. NETs are the next frontier, and removing harmful greenhouse gasses (GHGs) from the atmosphere is a necessary step. However, the political economy of negative emissions technologies is complex, and there are still many challenges to overcome, including high costs, technological limitations, and regulatory barriers.
Ebb Carbon is developing automated ocean alkalinity enhancement systems to enhance the ocean’s natural ability to safely store CO₂ while reducing ocean acidity. The image below shows their modular and scalable ocean alkalinity enhancement system. Their first installation is rated at 100 tons of carbon removal per year. They plan to deploy a megaton (1 million tons) of carbon removal systems over the next five years.
Ebb Carbon Funding
Ebb Carbon has raised a total of $23M in funding over 2 rounds, including
Their latest funding was raised on Apr 20, 2023 from a Series A round.
Ebb Carbon Investors
Ebb Carbon is funded by 5 investors, including
Incite.org and Congruent Ventures are the most recent investors.
Ebb Carbon Founder
Ben Tarbell, Matthew Eisaman, Dave Hegeman, and Todd Pelman are Co-Founder.
Ebb Carbon CEO
Ben Tarbell is CEO.
