CREW

The Approach

Wastewater treatment plants use microbes grown in treatment tanks, known as secondary treatment, to break down the organic waste entrained in the wastewater, which naturally produces biogenic CO2. CREW’s approach involves the addition of alkaline minerals to those tanks, which react with the CO2, capturing it as the more stable, aqueous bicarbonate ion.

CREW’s monitoring system deployed at the inlet and outlet of the plant allows for robust quantification of carbon dioxide captured within the treatment process. The resulting dissolved bicarbonate is then safely discharged to oceans, rivers, or the subsurface where it is stored for thousands of years.

The Case for CREW

This approach has a path to costing less than $100/ton. CREW’s approach takes advantage of existing wastewater treatment infrastructure that naturally channels biogenic CO2 into a closed system, reducing upfront capex. The CO2 in wastewater treatment tanks is much more concentrated than CO2 in the air (up to 10,000+ ppm vs. ~400ppm), minimizing energy needed. And the key ingredient, crushed limestone, is widely available and safe.

This approach is easily scaled and could reach over 500 million tons of CO2 removal per year. There are 100,000 wastewater treatment plants worldwide, and this approach requires little modification: the addition of a dosing system and CREW’s pioneering monitoring system. This approach can be done nearly anywhere there is a population center with wastewater treatment.

The MRV certainty is higher than for other alkalinity-based approaches. CO2 is removed within the bounds of the plant and can be measured on short time scales. Relative to other weathering and marine carbon removal approaches, this improves buyer confidence and overall cost of delivering a ton of carbon removal.

Wastewater treatment is key to keeping our waterways safe, and can contribute to removing CO2. CREW’s approach enables safe, optimized pH and alkalinity conditions for WWTPs, allowing them to achieve their mission of effectively treating wastewater while contributing to CO2 removal.

Pricing and Delivery

The total offtake amount from Frontier buyers is $32.2M for 71,878 tons of CO2 removed. The price accounts for both the removal itself as well as measuring, reporting and verifying (MRV) that each ton is safely and permanently stored.