Why isn’t human waste in cities centralized for fermentation to produce biogas? 

Why can’t cities transport human waste to a giant biogas plant to generate biogas for energy?

In fact, biogas is produced through fermentation by microorganisms that decompose organic matter and generate methane. The activity of these microorganisms depends on factors such as organic matter concentration, temperature, humidity, pressure, light, and the concentration of toxic substances. This means that in order to generate biogas, the requirements for the biogas digester are quite high. Moreover, relying on microorganisms to decompose human waste is a slow process. While “scaling up” might seem like a solution, do you know how much human waste a city produces every day? While biogas production capacity might increase, have you considered how large the biogas digester would need to be to accommodate such a huge amount of waste? A digester of that size, if something went wrong, could easily be triggered by even a small spark, potentially causing an explosion! Even if we are fortunate enough to avoid casualties, the entire city would be overwhelmed with waste, creating an extremely negative impact.

Addressing this issue involves not only technical challenges but also requires careful consideration of safety, scale, and the social consequences.