Gas fermentation, the process of producing protein from gases like carbon dioxide and hydrogen, presents a sustainable alternative to traditional protein production methods. Startups in this space, like Aerbio, are navigating challenges in demonstrating the market demand for novel proteins to partners and investors. Despite the recent setbacks in the industry, such as the closure of Arkeon, experts believe that gas fermentation technology can be commercially viable at scale. Aerbio, a Copenhagen-based startup, is developing a protein-rich bacterium fed on carbon dioxide, hydrogen, and other elements to produce high-quality protein ingredients. Dr. Rob Mansfield, the CTO of Aerbio, emphasizes the importance of achieving high protein yield, productivity, and cost efficiency in scaling up production. While sourcing green gases like hydrogen and carbon dioxide is crucial, current limitations in the availability and affordability of these inputs pose challenges for large-scale operations. Aerbio's process has been tested with various sources of carbon dioxide, including emissions from the Drax power station and Shell's Pernis refinery. The company is exploring different options for sourcing carbon dioxide geogenically and from direct air capture. Regarding hydrogen, Aerbio is considering regions with existing sources like blue hydrogen from natural gas as a transition strategy until green hydrogen becomes more widely available. The efficient transfer of gases into the bioreactor containing the protein-producing microbes is a key focus for optimizing the production process. Different bioreactor designs, such as horizontal and vertical systems, impact the efficiency and cost-effectiveness of gas fermentation. Aerbio aims to continue its journey towards sustainable protein production by addressing these technical and operational challenges.