Reducing Cement Plant Emissions via Algae Cultivation and Anaerobic Digestion

Abstract

Concrete is an essential aspect of modern infrastructure, and is a much-preferred construction material as it is a highly resistant and requires low maintenance. Concrete is produced through the creation of a paste comprised of cement and water that is mixed with aggregates such as sand and gravel. However, the concrete industry is one of the largest consumers of natural resources globally, and the emissions associated with its production are very high. Cement, one of the primary constituents of concrete, emits 0.93 pounds of CO₂ for every pound produced. Thus, concrete production is a major source of CO₂ emissions and accounts for approximately 8% of global carbon emissions. As the global demand for concrete continues to increase, it is evident that efforts must be made to reduce emissions associated with its production to mitigate climate change. This research proposes that the cultivation of algae can be integrated into the process of cement production so as to reduce the emissions associated with concrete. Algae uptake CO₂ through photosynthesis, having a CO₂ bio-fixation efficiency of 10-50 times higher than terrestrial plants. Algae have the ability to capture 1.8 kg of CO₂ per kilogram of algal biomass. Therefore, we hypothesize that, through the integration of algae cultivation and cement production, CO₂ can be effectively recycled through a closed-loop system. Algal biomass can be cultivated using the CO₂ emitted from cement flue gas. The cultivated algae can be harvested and used to produce methane gas (CH₄) via anaerobic digestion, which can in turn be used to power the cement plant, which will in turn produce more CO₂ to be captured through further algal cultivation.