Verdox Captures $80M to Develop Novel Electric Carbon Capture Technology.

Company to Commercialize Patented Electrochemical Capture System to Remove Carbon Dioxide from Atmosphere and Industrial Emission Sources

BOSTON Feb 2, 2022 – Bill Gates led Breakthrough Energy Ventures (BEV), Prelude Ventures, and Lowercarbon Finance have invested $80 million in capital to Verdox, an electric carbon capture and removal startup. The funds will be used to help the company develop and deploy its innovative electrochemical carbon capture technology.

“Combating climate change requires the world to prevent further increases in atmospheric carbon dioxide concentrations and eventually return them to pre-industrial levels,” according to Dr. Brian Baynes, Founder and CEO of Verdox. “Many industries, however, still lack a plan for complete decarbonization, because of the high cost and energy consumption of currently available capture technologies. Unlike these predecessors, Verdox’s technology has the potential to capture carbon from any industrial source or the air – and at up to 70% relative energy savings, giving us the ability to intervene completely.”

Last year, atmospheric carbon dioxide concentrations hit a new high of 420 parts per million, putting us on track to comfortably surpass the IPCC’s anticipated 2°C warming threshold of 450 parts per million. This level would be reached in the next 10 to 20 years, based on current yearly carbon dioxide emissions of about 40 billion metric tonnes. The demand for a reduction in emissions is so great that it necessitates a multi-pronged approach that includes both natural and technological solutions, as well as capture from emission sources and the atmosphere.

Verdox Logo
Verdox Logo

“The high energy efficiency and scalability of Verdox’s technology could enable the company to play a major role in addressing the carbon removal challenge,” says Carmichael Roberts from BEV. “This innovation has provided a paradigm change for both industrial and air capture – and the Verdox team has made great strides to reduce the concept to economical commercial practice.”

Prof. T. Alan Hatton and Dr. Sahag Voskian of the Massachusetts Institute of Technology developed Verdox’s fundamental technology (MIT). Dr. Voskian is the company’s CTO, while Prof. Hatton presently serves on the Scientific Advisory Board. Prof. Hatton and Dr. Voskian rethought carbon removal by combining electrochemistry’s efficiency with organic chemistry’s tunability. This one-of-a-kind combination enables the precise utilization of electrical energy to absorb and release carbon dioxide at any concentration with unrivaled selectivity. This method eliminates the need for the massive amounts of heat and water that are now used in carbon dioxide removal solutions.

The technology breakthrough was first published in 2019 in Energy & Environmental Science: “Faradaic electro-swing reactive adsorption for CO2 capture.”

Electrochemical Cell Design
Electrochemical Cell Design. Image from MIT News

As per an article published by MIT, Carbon dioxide (CO2) emissions from human activities must be reduced as part of any climate change mitigation strategy. CO2 capture equipment has been installed in several power stations to capture CO2 from their exhaust. However, those systems are each the size of a chemical plant, cost hundreds of millions of dollars, consume a lot of energy to function, and only work on CO2-rich exhaust streams. In a nutshell, they aren’t a viable alternative for airplanes, home heating systems, or automobiles.

Worse, collecting CO2 emissions from all anthropogenic sources may not be enough to address the climate crisis. “We’d still have to do something about the quantity of CO2 in the air if we’re going to restore preindustrial atmospheric levels at a rate relevant to mankind,” says Sahag Voskian SM ’15, Ph.D. ’19, co-founder and chief technology officer at Verdox, Inc. And designing a device that can absorb CO2 in the air is a particularly difficult task, partly due to the low amounts of CO2.

The CO2 capture challenge

Finding a “sorbent” that will pick up CO2 in a stream of gas and then release it so that the sorbent is clean and suitable for reuse and the released CO2 stream may be used or delivered to a sequestration site for long-term storage is a fundamental difficulty with CO2 collection. The majority of research has concentrated on sorbent materials, which are microscopic particles with “active sites” on their surfaces that trap CO2 through a process known as adsorption. CO2 attaches to particle surfaces when the system temperature (or pressure) is decreased. CO2 is released when the temperature is raised (or the pressure is dropped). However, generating those temperatures or pressure “swings” takes a lot of effort, partly because it involves treating the entire mixture, not just the CO2-bearing sorbent.

Voskian, a Ph.D. candidate in chemical engineering at the time, and T. Alan Hatton, the Ralph Landau Professor of Chemical Engineering and co-director of the MIT Energy Initiative’s Low-Carbon Energy Center for Carbon Capture, Utilization, and Storage, began looking into the temperature- and pressure-swing approach in 2015.

“We wondered if we could get by with using only a renewable resource — like renewably sourced electricity — rather than heat or pressure,” says Hatton. 

Electricity had been used to elicit the chemical reactions required for CO2 capture and conversion for decades, but Hatton and Voskian had a fresh perspective on how to design a more efficient adsorption system.

Their research is focused on quinones, a type of chemical. When quinone molecules are pushed to accept extra electrons, they become negatively charged and have a strong chemical affinity for CO2 molecules, snatching any that pass by. When the extra electrons are removed from the quinone molecules, the molecules’ chemical affinity for CO2 vanishes almost instantaneously, and the CO2 is released.

Quinones and an electrolyte have been used in a number of electrochemical devices by others. The devices usually have two electrodes: a negative one that activates the dissolved quinone for CO2 capture and a positive one that deactivates it for CO2 release. Moving the solution from one electrode to the other, on the other hand, necessitates elaborate flow and pumping systems that are big and take up a lot of room, restricting the devices’ applications.

Hatton and Voskian came up with the idea of using the quinone as a solid electrode and varying the electrical charge of the electrode itself to activate and deactivate the quinone by providing what Hatton terms “a modest variation in voltage.” There would be no need to move fluids or adjust temperature or pressure in such a configuration, and the CO2 would end up as an easy-to-separate attachment on the solid quinone electrode. Their concept was dubbed “electro-swing adsorption.”

Verdox Carbon Capture System Electrodes
Verdox Carbon Capture System Electrodes

The electro-swing cell

The researchers created the electrochemical cell depicted in the two schematics in Figure 1 of the slideshow above to put their theory into practice. They doubled the geometric capacity for CO2 capture by placing two quinone electrodes on the outside of the cell to enhance exposure. They required a component that could feed electrons and then take them back to turn the quinone on and off. To avoid short circuits, they employed a single ferrocene electrode placed between the two quinone electrodes but separated by electrolyte membrane separators. They used the circuit of wires at the top to connect both quinone electrodes to the ferrocene electrode, as well as a power source along the way.

The power source generates a voltage that causes electrons to flow across the wires from the ferrocene to the quinone. The quinone has now taken on a negative charge. When CO2-containing air or exhaust is blasted through these electrodes, the quinone will absorb the CO2 molecules until all of the active sites on its surface have been filled. The direction of the cell’s voltage is reversed during the discharge cycle, and electrons flow from the quinone back to the ferrocene. Because the quinone is no longer negatively charged, it no longer has a chemical attraction to CO2. A stream of purge gas releases the CO2 molecules and sweeps them out of the system for later usage or disposal. The quinone is now regenerated and ready to capture more CO2.

Two further elements are necessary for a successful procedure. The first is an electrolyte, in this case, a liquid salt, which supplies positive and negative ions to the cell (electrically charged particles). Because electrons can only flow through the external wires, charged ions must go within the cell from one electrode to the other to complete the circuit.

Carbon nanotubes are the second unique constituent. Both quinone and ferrocene are present as coatings on the surfaces of carbon nanotubes in the electrodes. Nanotubes provide good support and serve as an effective conduit for electrons moving into and out of the quinone and ferrocene since they are both strong and highly conductive.

To make a cell, scientists first make a polymer-based on a quinone or ferrocene, such as polyanthraquinone or polyvinylferrocene. They then combine the polymer with carbon nanotubes in a solvent to create “ink.” The polymer wraps around the nanotubes almost instantly, forming a fundamental bond with them.

They use a non-woven carbon fiber mat as a substrate for the electrode. They dip the mat into the ink, let it dry gently, and then dip it again, repeating the process until the substrate is covered with a homogeneous layer of composite. The technique produces a porous mesh with a large surface area of active sites and simple paths for CO2 molecules to enter and exit.

The researchers assemble the electrochemical cell by laminating the pieces in the correct order — the quinone electrode, the electrolyte separator, the ferrocene electrode, another separator, and the second quinone electrode — after they have made the quinone and ferrocene electrodes. Finally, they use their liquid salt electrolyte to wet the assembled cell.

Verdox Carbon Capture
Verdox Carbon Capture

Experimental results

The researchers placed a single electrochemical cell within a custom-made, sealed box and wired it for power input to evaluate the behavior of their device. The voltage was then cycled, and the device’s essential responses and capabilities were monitored. The amount of CO2 adsorbed increases as the quinone electrode is negatively charged, according to the simultaneous trends in charge density injected into the cell and CO2 adsorption per mole of quinone. CO2 adsorption decreases when the charge is reversed.

Full capture units — open-ended modules in which a few cells were lined up one beside the other, with gaps between them where CO2-containing gases may move, passing the quinone surfaces of nearby cells — were also built for testing under more realistic conditions.

The researchers tested both experimental systems with CO2 concentrations ranging from 10% to 0.6 percent in the input streams. The former is characteristic of power plant exhaust, whereas the latter is closer to ambient indoor air concentrations. The efficiency of capture remained fairly consistent at around 90% regardless of concentration. (A 100 percent efficiency would mean that one molecule of CO2 was collected for every electron transported, which Hatton deems “extremely implausible” because other parasitic processes could be occurring at the same time.) The system consumed around 1 gigajoule of energy for every tonne of CO2 captured. Depending on the CO2 content of the incoming gases, other technologies consume between 1 and 10 gigajoules per tonne. Finally, the system proved extremely long-lasting. Its CO2 capture capacity declined by only 30% during 7,000 charge-discharge cycles, according to the researchers, a loss that may easily be overcome with further electrode preparation modifications.

The remarkable performance of their system stems from what Voskian calls the “binary nature of the affinity of quinone to CO2. The quinone has either a high affinity or no affinity at all.

“The result of that binary affinity is that our system should be equally effective at treating fossil fuel combustion flue gases and confined or ambient air,” he says. 

Read the complete article on MIT News here.

Sahag Voskian SM ’15, PhD ’19 (left) and Professor T. Alan Hatton have developed an electrochemical cell that can capture and release carbon dioxide with just a small change in voltage.
Sahag Voskian SM ’15, PhD ’19 (left) and Professor T. Alan Hatton have developed an electrochemical cell that can capture and release carbon dioxide with just a small change in voltage.

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