Abstract

CO2 in the atmosphere is a major driver of global warming, trapping heat in the atmosphere. Much CO2 release and the resultant increases in global warming have been attributed to widespread human use of fossil fuels. Keeping CO2 from the atmosphere is called sequestration, and specifically focusing on power plants, which generate 33% of US carbon dioxide emissions, current methods involve using liquid amine scrubbers to purify CO2 from coal flue gas, and then injecting it into mile deep underground sites.

This method is inefficient, logistically and financially, to deploy en masse to global powerplants. This project aims to find a better method to sequester CO2, through biochemical reactions. The enzyme carbonic anhydrase, catalyzes interconversion of CO2 and water to carbonic acid, around a million times per second in ideal conditions. Carbonic acid is then reacted with calcium hydroxide(a base) to form calcium carbonate, a precipitate with many industrial uses.

Proof of concept was provided through testing four 15 min. trials of 4 different millimolar concentrations of carbonic anhydrase in a prototype bucket with a 200 micron polypropylene mesh, simulating a reaction chamber with high CO2 concentration(10 g of CO2 and water, 20 g of calcium hydroxide); measured for efficiency and cost to effect ratio, through a 100% CO2 sensor. The 5 micromolar concentration was best in cost to efficiency, 50 micromolar was best in total sequestration. At industrial scale, this could sequester 1 ton of CO2 in 12 hours at a cost of $3,800 dollars.