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Domestic biogas technology helps to foster sustainable development in different ways. It is particularly important in countries like Ethiopia where about 80% of the population lives in rural areas, and more than 90% of the households use solid biomass for cooking. In light of this, the Government of Ethiopia has launched a National Biogas Programme in 2008. The Programme, now in its third phase, has successfully installed tens of thousands of biogas digesters. This paper aims to give a macroeconomic insight on the role of the biogas sector in Ethiopia. The annual gross value of biogas outputs reached USD 7.7 million in 2015/16. Installing biogas digesters contributes USD 1.4 million each year to the construction industry. Results of the study indicate that the micro and macroeconomic contributions of biogas sector partly rely on the effective utilization of its co-product (i.e., the slurry) as fertilizer. Agricultural policies of the country should therefore highlight and link domestic biogas production with the extension services.

Abstract This article explores the potential of producing domestic, home-scale biogas using anaerobic digestion in the suburbs of the developed world – an urban context where currently biogas production is almost non-existent. The current status of food waste management across the globe shows that internationally, cities are increasingly using anaerobic digestion as a central technology at commercial scale to treat food waste and decarbonise through the recovery of energy and nutrients. However, in order to achieve this, it is preferable to separate organic waste such as food waste from other waste streams. Australia currently does not offer any schemes that support source separation of household food waste. Notwithstanding this, there are upwards of five large-scale plants currently treating commercial food waste and substantial scope exists to increase this provided appropriate waste management strategies are put in place. Nevertheless, the absence of food waste management schemes in developed countries may provide an impetus for individuals in urban landscapes to explore the potential of home-style biogas systems to produce energy and biofertiliser using food waste derived from households. This article provides a novel case study of one operator's experience using a domestic system, the 'HomeBiogas 1.0' unit, in the suburbs of Melbourne, Australia. A critical analysis of the system was performed, including a cost benefit analysis of the recently released 'HomeBiogas 2.0' unit. The cost benefit analysis indicated that the system could pay for itself in 4.45 years if simply mitigating the cost of natural gas. This payback period is likely to be reduced if the value of fertiliser were included or if use of a HomeBiogas unit allows for disconnection from the gas grid (avoiding service fees), as it did in this case study. The paper concludes by identifying barriers from a technical, regulatory and education perspective. Highlights • The potential for domestic scale biogas in urban landscapes was examined. • A unit located in the suburbs of an Australian capital city was assessed. • Cost benefit analysis resulted in an approximate payback period of 4.45 years. • Barriers from a technical, regulatory and education perspective were identified. [ABSTRACT FROM AUTHOR]

The operation of household scale anaerobic digesters is typically based on diluted animal dung, requiring stabled livestock and adequate water availability. This excludes many rural households in low-income countries from the benefits of a domestic biogas digester. Solid state anaerobic digestion (SSAD) can be operated with low process water demands, but the technology involves operational challenges, as e.g., risk of process acidification or low degradation rates. This study aimed at developing simple methods to perform SSAD of yam peelings in low-tech applications by testing different inoculation strategies and evaluating the necessity of dung addition as a supportive biomass. In initial lab scale trials 143 ± 4 mL CH4/g VS (volatile solids) were obtained from a mixture of yam peelings and dung digested in a multi-layer-inoculated batch reactor. In a consecutive incubation cycle in which adapted inoculum was applied, bottom inoculated digesters loaded without dung reached a yield of 140 ± 16 mL CH4/g VS. This indicates that SSAD of yam peelings is possible with simple inoculation methods and dung addition is unnecessary after microbial adaptation. A comparison with a conventional fixed dome digester indicated that SSAD can reduce process water demand and the digester volume necessary to supply a given biogas demand.

Accelerating the diffusion of domestic biogas is considered to be a promising option for reaching the goal of universal access to energy by 2030, particularly for the provision of cooking energy for rural populations in developing countries. The aim of this study is to develop a systematic account of the factors that influence the diffusion of domestic biogas technologies. To achieve this objective, a three step analysis approach is applied. In the first step, a conceptual model is built based on insights from scholars that have been studying the diffusion of energy innovations in rural contexts. In the next step, a qualitative content analysis of scientific literature is undertaken to test and refine the categories proposed by the conceptual model and to systematically organise the empirical evidence of the factors that influence the diffusion of domestic biogas in developing and emerging countries. The systemised evidence is used to identify the components and interactions between the household configurations and socio-economic context that determine both the adoption process at household level and the overall technology diffusion. Finally, in the last step, we reflect on the implications of the resultant systematic conceptualisation regarding the purpose and design of programmes promoting the dissemination of domestic biogas technologies. [ABSTRACT FROM AUTHOR]

Ethiopia experiences an energy and environmental crisis due to the sustained reliance on woody biomass to satisfy its energy needs. This situation could be improved by using biogas. This paper analyses the current status of the domestic biogas sector in Ethiopia and identifies barriers and drivers that influence its development and further growth. The analytical framework used for the analysis combines the Multi-Level Perspective (MLP) and Strategic Niche Management (SNM). The information sources are: desk study through literature and internet research, online interviews and questionnaires with Ethiopian stakeholders, and an extensive field study including a large number of interviews with stakeholders inside and outside Ethiopia. The biogas sector in Ethiopia started with the launch of the National Domestic Biogas (NBPE) programme in 2008, which has led to the dissemination of over 8000 biodigesters so far, about 60% of what was initially intended. The use of domestic biogas has been triggered by the energy crisis in Ethiopia and the suitability of the technology with the physical geography. However, the dissemination has been affected by factors such as economic instability, poverty and illiteracy. Also, many Ethiopian farmers are trapped in a lock-in, where due to their limited purchasing power they cannot afford the niche technology; at least in the way it is being disseminated. Within the emerging biogas sector, the NBPE designated a diverse set of actors to contribute to the implementation of the niche technology. However, their alignment is poor and the private sector is not involved. Expectations have had to be lowered because targets were not met. Also, learning processes are not optimal. The paper is innovative because it provides an up-to-date review of status of and bottlenecks and drivers in the biogas sector in Ethiopia and it provides more insight in the applicability of the SNM and MLP frameworks to a sustainable innovation in a developing country. [ABSTRACT FROM AUTHOR]

The operation of household scale anaerobic digesters is typically based on diluted animal dung, requiring stabled livestock and adequate water availability. This excludes many rural households in low-income countries from the benefits of a domestic biogas digester. Solid state anaerobic digestion (SSAD) can be operated with low process water demands, but the technology involves operational challenges, as e.g., risk of process acidification or low degradation rates. This study aimed at developing simple methods to perform SSAD of yam peelings in low-tech applications by testing different inoculation strategies and evaluating the necessity of dung addition as a supportive biomass. In initial lab scale trials 143 ± 4 mL CH4/g VS (volatile solids) were obtained from a mixture of yam peelings and dung digested in a multi-layer-inoculated batch reactor. In a consecutive incubation cycle in which adapted inoculum was applied, bottom inoculated digesters loaded without dung reached a yield of 140 ± 16 mL CH4/g VS. This indicates that SSAD of yam peelings is possible with simple inoculation methods and dung addition is unnecessary after microbial adaptation. A comparison with a conventional fixed dome digester indicated that SSAD can reduce process water demand and the digester volume necessary to supply a given biogas demand. [ABSTRACT FROM AUTHOR]