The article delves into the importance of understanding the fuel used in hydrogen fuel cells and hydrogen internal combustion engines (H2-ICE) to impact performance and fleet sustainability. It discusses the various terms and categorizations used to identify hydrogen based on carbon intensity or color codes like green, blue, grey, and pink. The article highlights that the source of hydrogen, whether from water, methane, or oil, impacts production methods and energy needs, with cleaner energy sources leading to better carbon profiles. It emphasizes the significance of evaluating hydrogen through color codes and carbon intensity scores to slash emissions in medium and heavy-duty trucking. Industry experts, including Tom Swenson and Isabel Castro from Cummins, stress the importance of using color codes and carbon intensity values to evaluate hydrogen production methods for environmental impact and performance in fuel cells. The article explains how contaminants in hydrogen can affect fuel cell performance and the importance of maintaining a pure fuel for optimum operation. The article provides insights into various colors of hydrogen production, such as green, yellow, grey, blue, turquoise, pink, brown, black, and white, each obtained through different processes with varying environmental impacts. It highlights the DOE's approach of focusing on carbon intensity values rather than color codes to define hydrogen in efforts to enable clean hydrogen production. Overall, the article underscores the need for stakeholders to understand the diverse production methods and environmental impacts of hydrogen to achieve sustainable fleet management and meet ESG goals.