Aqualung has patented a hollow fiber polymeric membrane whose fiber has been coated with amine compounds that have high CO2 selectivity. This property essentially means that for the same flow of gases, Aqualung's membrane would require less energy than its competitors. The amines in the fiber work as a chemical initial step that passively pulls CO2 across the membrane via weak chemical bonds. This allows the system to work without the need of pressurization and improves the permeability, allowing more CO2 to migrate across the membrane per square centimeter, thereby reducing the footprint of the unit and its costs. The amine coating on the fiber has also the key feature of reacting positively with the water vapor present in the flue gas since it reacts with CO2 forming carbonate compounds. These molecules can also easily permeate through the membrane.

In a general process flow, the flue gas needs to be cooled down to 60 / 80°C (ideal operating temperature) and then it hits the first stage membrane system which upgrades the gas depending on the initial CO2 concentration from 10 to 40/50%. Then there is a highly selective stage being pulled across by a vacuum pump. This second membrane is the one that is fine-tuned to the needs of the customer. So, it is a two-stage typical membrane permeation. Depending on the inlet CO2 concentration, if it has high CO2 levels (30% or more), a one-stage membrane might be able to capture CO2 in 90%+ levels.

CASE STUDY

Commercial pilot

• Location: Magnolia, Arkansas • Source: flue gas from a gas-fired emission source. • CO2 Concentration: 4.5% • Size of Pilot: 700 CO2 ton/year • Delivery of Pilot: Q3 2022

R&D

• R&D test rig on a 250 kW diesel engine. • Source: Diesel Engine • CO2 Concentration: 11% • Pilot Size: 130 CO2 ton/year • Delivery of Pilot: Q2 2022

Cement installations

• Technology has been proven at 2 cement installations. • Source: Cement Kiln • CO2 Concentration: 11% • Size of Proposed Pilot: 20,000 tonnes of CO2 per year • Delivery of Pilot: Q3 2023

In terms of revenue flows:

• Aqualung would create a Special Purpose Vehicle (SPV) in which they would contribute the CO2 unit at cost, along with a 5% in exchange for tolling fee ($/ton) and net profit interest in SPV.

• The CO2 emitter or owner would drop the costs to buy the unit and the capital for the SPV. The emitter would also be paid back capital first and then net profit interest will be split based on ownership percentages.

• Denbury or other financial party could also step in to be the owner of the unit if the customer can't pay upfront.

• Aqualung is looking to partner with an O&M Maintenance company where they'd be educated on how to fix and operate the unit.

Aqualung has a strong partnership with Denbury Resources, they are their main investors and based on this partnership, the idea would be to capture CO2 and leverage Denbury to use their pipelines for transport and storage. For the time being, the business model will focus on developing CCS solutions within this pipeline network, though this doesn't mean that the company is not looking at opportunities in other geographies.

Another revenue possible for these type of projects is to sell carbon offsets from the avoided emissions. This would be possible in all those cases where the offset has a higher value than the tax that needs to be paid in each state, so it will highly depend on project location. In these cases, correct CO2 accounting is necessary to avoid double counting.

• Hollow fiber coated with amine layer enhances chemical potential to separate CO2 from flue gas.

• Lower membrane regeneration requirements.

• No need to pressurize the gas, the system can work at ambient pressures.

• No rotating equipment.

• Unit operates with water vapor present in the flue gases. When CO2 reacts with water, it forms carbonate compounds. The coated fiber has been tailored to have a high affinity for these compounds and that is how they are able to capture CO2 from flue gases without the need to dry the gas. This ultimately could also helps reduce costs.

• The membrane is a modification of the nitrogen / oxygen gas separation membrane and the core IP or tech is the coating layer (5 nm thickness). These type of technologies are commercially available and commoditized. This allows them to scale rapidly as they only need the coating and not the membrane.

Aqualung's technology is specially designed for post-combustion carbon capture or biogas separation. Post-combustion carbon capture is challenging technically and economically even at the largest scales (>1000 tpd). New technology that reduces capital costs could enable deployment at smaller scales, especially if operational challenges can be reduced.

The company's commercial containerized solution (40 foot container) can capture between 15 and 50 ktpa of CO2 from flue gases with concentrations ranging from 2% all the way to 30% and more (for the biogas sector). Current pilot rigs have sizes that range from 300 tpa to 4 ktpa. Both pilots are doing catch and release for the time being and have proven to be also at prices economically accessible.