THE REGENTS OF THE UNIVERSITY OF COLORADO NEW HESTIA AWARD CONTROL NUMBER: 2625-1532 TITLE: A PHOTOSYNTHETIC ROUTE TO CARBON-NEGATIVE PORTLAND LIMESTONE CEMENT PRODUCTION THE OVERARCHING GOAL OF THIS PROJECT IS TO MANUFACTURE AND COMMERCIALIZE A NET-CO2-STORING PORTLAND LIMESTONE CEMENT USING BIOGENIC LIMESTONE (CACO3) PRODUCED FROM CALCIFYING MICROALGAE. MOST CEMENT-RELATED CO2 EMISSIONS ARE CAUSED BY HEATING CACO3 TO PRODUCE CAO, WHICH RELEASES CO2 IN THE PROCESS. THE TECHNICAL PREMISE OF THE PROPOSED TECHNOLOGY IS TO PRODUCE BIOGENIC CACO3 USING COCCOLITHOPHORES, CALCAREOUS MICROALGAE, THAT SEQUESTER AND STORE CO2 IN MINERAL AND ORGANIC POLYMER FORM THROUGH BIOLOGICAL DIRECT AIR CAPTURE VIA PHOTOSYNTHESIS AND CALCIFICATION.