Center of Biogas Engineering and Technology and Yunnan Normal University
12/2011 – 07/2013
By the end of 2010 there were an estimated 40 million biogas digesters in China. However, according to some estimates, up to a quarter are significantly underused or do not fulfil their expected lifespans. This project set out to improve the long-term viability of domestic biogas as a sustainable technology for rural households in the Chinese province of Yunnan, by increasing the yields of functioning biogas digesters and reactivating those that are unused. It did so by tackling a range of aspects, which included raising awareness among users, improving the training of technicians, establishing a financially sustainable cooperative to carry out post-installation servicing and promoting additional value creation through the use of digestion residues and bio-slurry in farming.
Local biogas technicians were also approached as part of the baseline survey and this consultation revealed low incomes, lack of resources to carry out maintenance and varying standards of organisation across the region.
The establishment of a financially sustainable post-installation service to ensure the development of a strong biogas digester market was one of the most important goals of the project. This service took the shape of three biogas post-installation cooperatives established in three counties: Xinping, Eshan and Jiangchuan. Each cooperative brought together users and biogas technicians and maintained close links with the existing structures set up by local government (Rural Energy Stations).
The aim of the cooperatives was to actively improve the quality of maintenance and the efficiency of technicians, resulting in the re-activation of as many unused digesters as possible. Amongst other things, the cooperative established standards, membership fees and a rewards mechanism for best-practice. Every biogas user paid a membership fee of between 60 and 200 RMB (depending on services used) to join the cooperative.
Assistance in emptying the digestate from the digesters proved a fundamental way of reactivating unused biogas digesters. Members of the cooperative would pay a reduced price for the emptying service, which was carried out by specialised technicians using a suction truck provided by the local government. Moreover, training and awareness-raising were fundamental to the project.
In terms of environmental benefits, the project contributed to the reduction of GHG emissions by replacing traditional fuels with biogas for domestic uses (mainly cooking). Moreover, the carbon footprint related to biogasification has been reduced through improved management practices. For example, lower levels of methane from manure and residues waiting to be fed into the digesters are now emitted into the atmosphere. Lastly, the use of bio-slurry and bio-residues from digesters has replaced chemical fertilisers and pesticides. In this project, the cooperative’s assistance led to a higher number of households using biogas digestate for farming.
Outlays for chemical fertiliser and pesticides are also considerable. The project put strong emphasis on comprehensive biogas use, reaping the economic benefits of using bio-slurry and bio-residues as fertiliser and animal feed. Two households were selected to test the effects of residues on improving yields of the main crop in the region (bitter melon) and raising pigs. This practical demonstration enhanced the effectiveness of awareness-raising workshops.
A group of local biogas technicians also saw a measurable improvement in their income stability. Prior to the project, biogas technicians were employed by the government on temporary contracts. The cooperatives resulted in a larger work load and the training improved their capacity and motivation.
Regarding digester effluents that still remained unused in households, assistance from the cooperatives in their removal allowed for the effluents to be sold to other users, as well as ensuring their proper disposal.
Using biogas instead of traditional fuels for cooking can reduce indoor air pollution. In terms of gender, the respondents to the household survey shifted from a distribution of 90% male and 10% female in the baseline survey to 27% male and 73% female in the post-assessment survey.
Understanding the reasons why the biogas digesters had become dysfunctional was central to the project. This experience was shared during the project with government and civil society stakeholders, as well as with international experts.
In particular, the cooperatives can provide a model for the nationwide management of rural biogas. As a first step, this approach could be replicated in other areas of the Yunnan province, where there are an estimated 3 million dysfunctional bio-digesters.
Following two decades of emphasis on installing biogas digesters, the Chinese government is currently moving towards a focus on maintenance and management. This project provides important lessons for directing the financial and policy support from government. Key lessons have been learnt in terms of: