**2.2 Challenges of biogas development**

The technology for producing biogas from biomass is currently fully developed, but there are several obstacles preventing its adoption. The obstacles include general ignorance about biogas and its application among the very people who can benefit most and lack of a regulatory framework to support the installation of biodigesters and lack of necessary incentives [75, 76]. Statistics show that many biogas digesters are underutilized, with some even laying unused soon after being built [74]. Lack of technical management skills, together with economic and cultural factors, contributes to this. In 2002, during the World Summit on Sustainable Development, it was acknowledged that many countries may benefit from using renewable energy to alleviate poverty [2, 77].

The global biogas production capacity by volume is over 59 billion m3 biogas or about 35 billion m3 methane equivalent, but the European Union alone accounts for about half of the total capacity. This shows that many developing and some developed countries have unsatisfactory contribution and have a long way to go in biogas production and use compared with developed counterparts [76]. The biggest barrier to the widespread use of biogas technology is the high expenses incurred in digester operation and maintenance. Complex biogas digester designs and a lack of technical knowledge are further obstacles [67, 78]. The key issues with the adoption of technology of biogas are discussed below:

#### i.Poor maintenance and management

The efficient operation of a biogas system requires the adoption of suitable management practices for the digester and zero grazing units for animals to achieve maximum efficiency. However, there are a few competing zero grazing management standards that make it difficult to manage the digester effectively. Farmers typically place more importance on the health of their farms than on keeping the digester well maintained. Due to this situation, there is a restricted amount of biogas produced, which may make it more difficult for the farmer to return his costs [67]. Studies show that lack of knowledge on digester maintenance is a leading challenge for biogas production in rural China and other countries, and technical training and availability of technicians would help alleviate the challenge [2].

#### ii.Lack or low technological awareness

There is a significant knowledge gap among biogas users in terms of technology and feasible applications. It is challenging to run, maintain, and service the biogas digesters and biogas energy systems because of the widespread lack of knowledge and skills. When the needs for biogas are not met to their full potential, production suffers [2, 78].

#### iii.Lack of feedstock

Studies also show that there is pervasive perception that biogas technology is only ideal for people having sufficient animal and agricultural waste for them to venture into biogas energy production. Therefore, lack of existing supply chain for biogas feedstock limits some small-scale farmers from investing in biogas production. The provision of reliable information on potential feedstock may assist potential investors in decision making [75].
