What is biogas?

Biogas is a mixture of gases — mostly methane and carbon dioxide — released when bacteria break down organic material in an oxygen-free environment. The same process happens naturally in wetlands and in the digestive systems of livestock.

In a digester, that process is contained and controlled. Feedstock goes in, the tank is kept at a stable temperature, and gas collects at the top. The remaining material, called digestate, comes out the other end as a soil amendment.

Raw biogas is usable directly in a burner or an adapted engine. Turning it into vehicle fuel means removing water, hydrogen sulphide and carbon dioxide, then compressing what is left. That step is where the cost and the regulation live.