Captura uses electrodialysis to remove carbon dioxide


An expansive aquatic facility is imagined to take over the ocean’s cleansing venture. The California Institute of Technology spin-off Captura plans to remove carbon emissions from the ocean by planting an aquatic facility in the heart of the sea and devising a mechanism where it purifies the water from carbon dioxide and spills it back into the ocean.


The design team states to only use renewable electricity and ocean water as inputs to minimize environmental impacts, and lets its readers in on its patented electrodialysis process that can generate a stream of pure CO2 that can then be sequestered or utilized to make other low-carbon products. The company’s mission lies in no purpose-built air contactors, no absorbents, and no by-products while enabling large-scale carbon removal at a lower cost.

captura carbon dioxide water ocean
images courtesy of Captura



planting the first ocean-based pilot facility


In the summer of 2022, Captura installed its first ocean-based, stand-alone pilot facility in Newport Beach, California where the use of a continuous flow of ocean water allowed the research team to measure system performance and implement system improvements. The company plans to increase its capacity by a factor of 100, eyeing to install the system at an ocean location in 2023.


In fact, Captura announced its collaboration with AltaSea at the Port of Los Angeles on May 4th, 2023. The latter is slated to house the former’s second direct Ocean Capture pilot system that can cleanse 100 tons of carbon dioxide from the ocean annually. ‘At AltaSea, our team will conduct a variety of technology development and ocean modeling work to further validate, scale, and improve our technology,’ says Captura.

captura carbon dioxide water ocean
Captura uses electrodialysis to capture carbon dioxide from water



acidic, decarbonized ocean water flow


Captura offers a facility dubbed to slow down the negative impacts of climate change through its gigaton-scalable Direct Ocean Capture (DOC) technology developed at Caltech. Captura explains that its electrodialysis technology begins by pulling a stream of filtered ocean water into the facility.


‘Less than 1% of this water is diverted and pre-processed to purify the ocean water into pure salt water. This salt water is then processed in Captura’s proprietary electrodialysis technology. Through dissociation, electrodialysis uses renewable electricity to split the salt and water into an acid and an alkali base,’ states Captura.


After the process, the acid created is added to the ocean water through the plant, triggering a chemical process that draws the CO2 out. ‘We accelerate this process using a gas-liquid contactor and vacuum pump,’ says Captura. The carbon dioxide is then collected as a purified stream, suitable for sequestration or usage, and this results in an acidic, decarbonized ocean water flow in the system.

captura carbon dioxide water ocean
the low-cost large-scale carbon removal facility runs on renewable energy source such as solar panels



alkaline base neutralizes the ocean water flow


The alkaline base is then added to neutralize the ocean water flow, which is subsequently returned to the ocean to absorb atmospheric carbon dioxide. ‘This decarbonized water then sits in the top layer of the ocean and will then react with the atmosphere to draw down an equivalent quantity of CO2,’ states Captura.


When the carbon dioxide-filtered seawater is returned to the ocean, it has the capacity to absorb the same quantity of CO2 from the air that was originally removed.


Through its technology, Captura believes it is able to deliver low-cost carbon removal with renewable energy and no absorbents. It can also produce a ‘pure, measurable, and verifiable stream of carbon dioxide for high-quality carbon credits. Alternatively, the CO2 stream can be used to make low-carbon products,’ states Captura.

captura carbon dioxide water ocean
electrodialysis uses renewable electricity to split the salt and water into an acid and an alkali base

captura carbon dioxide water ocean
Captura plans to develop a facility that can cleanse 100 tons of carbon dioxide from the ocean annually




project info:


name: Carbon removal facility

company: Captura