Using Microalgae to Convert Brewery Carbon Gas Emissions into Valuable Bioproducts

Abstract

The brewing industry is a major part of the agri-food sector, but its fermentation processes contribute significantly to global CO2 emissions, exacerbating the greenhouse gas crisis. Achieving net-zero emissions requires innovative solutions, and this study explored one such solution by using microalgae to capture CO2 from a brewery while simultaneously generating valuable bioproducts. Two microalgae species, Tetradesmus obliquus and Limnospira maxima, were cultivated in a 1000 L raceway and a 400 L tubular photobioreactor, both powered by the brewery’s CO2 waste gas. The specific growth rates reached 0.3 in the raceway and 0.4–0.5 in the photobioreactor for both species. Notably, L. maxima showed higher productivity, achieving up to 0.80 g L−1 day−1 in the photobioreactor and 0.5 g L−1 day−1 in the raceway. Operating across 300 brewing days per year, a single module (1400 L) of this system could reduce a brewery’s CO2 emissions by 29%. These low-maintenance systems are modular, allowing for easy scaling and operation. The harvested biomass was nutritionally valuable; L. maxima contained up to 55% protein and 3% phycocyanin, while T. obliquus was rich in carbohydrates (36%) and lipids (12%), levels suitable for feeds and fertilizers. A cost-benefit analysis suggests that coupling CO2 removal with bioproduct generation supports a sustainable circular economy while offering financial returns.

Keywords

• brewery
• CO₂ emissions
• algal cultivation
• greenhouse gas crisis
• high-value products
• circular bioeconomy