Area III Agricultural Mechanization Exam 2026 – Complete Study Resource

When a fuel mixture can burn, methane is the part that provides the energy for combustion. CO2 and other inert components in biogas dilute the mixture, lowering flame speed and overall energy content. Because of that dilution, there’s a practical lower limit to how much methane the biogas must contain for reliable ignition and stable burning in typical equipment. In practice, you need about two-thirds methane by volume to ensure the mixture will ignite and sustain combustion even with the CO2 present. Below this, the energy and flame stability become insufficient. Above this threshold, combustion remains possible, but that isn’t the minimum. So the minimum methane content is roughly two-thirds, about 65%.