In many of the least developed countries the energy security conundrum is how to provide affordable, safe and clean energy to a low income rural population. Household level generation of biogas from animal waste for both cooking and lighting, while producing high quality organic fertiliser, is increasingly proposed as a viable part of the solution for farming households. Since the early 1990s international development organisations – often in cooperation with the national government – have attempted to introduce biogas technologies in many least developed countries, but most initiatives failed. In this landscape of failed biogas development programmes the National Biodigester Programme (NBP) Cambodia started in 2006, with the aim to establish a permanent market oriented and self-financed biogas sector. The results show the development of a sustainable domestic biodigester sector, a rapid diffusion of biodigesters among poor rural households, but still ambivalences on financial independency from external funding and carbon finance. The conclusion is that a pure market model for biogas development in the rural area of the least developed countries will not easily work. Governmental regulation and coordination will remain needed, and carbon finance will not easily fully replace ODA and governmental financial support.