Biogas Technology in China
History of Biogas Technology in China
The first household biogas plants were installed by well-off families in the 1930s. Biogas was not propagated or promoted extensively until around 1970. After a phase of massive campaigns about seven million biogas plants were constructed. However, these only functioned to a minor extent due to technical defects. The same approach was pursued as during the time of the Great Leap Forward (1958 to 1961): Quantity was pursued over quality of the digesters and little attention was given to training and maintenance.
A focal point of biogas dissemination was the province of Sichuan, and here especially the area around Mienyang. Due to climatic conditions, biogas only played a less significant role in Northern China. Biogas plants spread most rapidly in areas where politicians particularly devoted themselves to this task and in areas whose traffic infrastructure was well developed and which and were not, in fact, among the poorest of regions.
In 1975, moving beyond the pilot stage, biogas technology was promoted on a mass scale and biogas was included in the National Economy Program. Part of this promotion effort was the training of technicians, the manufacturing of appliances and equipment, and experimentation with different digester designs.
The interaction of the three levels, state, cooperative and household was a favourable atmosphere for the dissemination of biogas in periods of a strongly socialist tendency. The state provided the skeleton conditions, the cooperatives or communes provided material and paid for the labour for the otherwise private biogas plants. On the user side also there was hardly any coalition of interests between communes and cooperatives. This very interesting interaction of varying levels has ceased since the introduction of privatisation. For example, since privatisation straw is far less frequently used in the biogas plants as emptying of the plants involving a high work input no longer becomes necessary because the digested straw no longer has to be provided for use on communal fields as it had to be during times of communal management.
Since 1982 obligatory standards have been prescribed and applied in the construction of biogas plants. At the same time, the aggressive dissemination strategy has been cut back, scientific research has been intensified and direct subsidies have been reduced from two-thirds to just one-third of the costs. After the subsidies were abolished the number of plants built annually declined sharply. Beside these improvements in the diffusion strategy, many problems and high rates of failure persisted during the 1980s. Country-wide about five million household digesters were in good working order. By 1992, Sichuan had around 1.7 million biogas plants in operation. During the 1990s, investment has increased dramatically. Over the Ninth Five-Year plan period, Chinese government has invested six billion Yuan for biogas development. By the end of the 1990s, there were 9.8 million household digesters in operation throughout China.
In the 2000s, the two central policies to promote biogas technology are the “National Rural Biogas Construction Plan 2003-2010”, developed in 2003 by the Ministry of Agriculture, and the “Medium and Long-Term Development Plan for Renewable Energy”, published in 2007 by the National Development and Reform Commission (NDRC). They both formulate the goals and methods of biogas promotion. The goal for the year 2010 was that 40 million (about 16% of all rural households) households will be using biogas and their number is to double to 80 million by 2020. By 2008, about 28 million household digesters were in operation, which makes 40 million digesters a very ambitious goal.
Biogas is also part of several strategies for China’s rural development. The Eleventh Five-Year Plan (2006-2010) and the policy of “Building a New Socialist Countryside” (shèhuìzhǔyì xīn nóngcūn jiànshè) aim to modernize rural China while mitigating the negative impact of intensified agriculture on the environment. Renewable energy, biogas in particular, has the potential to assist this goal. The Chinese government also promotes biogas systems as part of campaigns and policies like “Three Rural Issues” (sān nóng), “Circular Economy Policy” (xúnhuán jīngjì) and “Ecological Garden Projects” (shēngtài yuánlín jiànshè). It aims to combine biogas technology with agricultural production and environmental protection. Since the end of 2008, rural biogas has been included in the national package plan that addressed the international financial crisis, and had the goal to expanded domestic demand and revive the economy.
Since 2009, substantial progress has been made in the development of rural biogas CDM projects. A CDM methodology was developed independently by Chinese experts: “Methane recovery methodology in agricultural activities of peasant households/small scale farms” and has been recognized by CDM Executive Council. In February 2009, the household biogas CDM project in Enshi (Hubei Province) was successfully registered. Covering 33,000 households in eight counties, the estimated annual emission reduction will be 58,400 tonnes CO2 equivalent. The biogas users will receive 60% from the emission reduction (about RMB 100 Yuan annually for 10 years), 18% will be used to provide technical service, and 22% will be used to conduct supervision and management of the project.
Recent Developments in Yunnan Province
In Yunnan Province, biogas technology has been promoted since the 1970s and has been a focus of rural energy development since the Ninth Five-Year Plan (1996-2000). This plan established guidelines for sustainable development, ecological agriculture and renewable energy. Further affecting the promotion of biogas digesters in Yunnan was the “New and Renewable Energy Development Program” (1996-2010). The ongoing program aims to develop renewable energy and to increase its share in the overall energy mix. In 2010, three million households, about 36% of all rural households, are estimated to own a biogas digester.
In 2003, about 224,000 new digesters were built in Yunnan, achieving the highest increase countrywide. With 1,043,700 digesters owned, but not necessarily used, by 4.2 million people, Yunnan Province ranked fourth at the end of the year. One reason for the high increase was the “National Rural Biogas Construction Plan 2003-2010”. The plan set the national as well as the provincial targets for biogas digesters and increased the support from the central government to 1,000 Yuan per unit. Despite this success, the share of biogas in total energy consumption was only 1.79% in 2003.
The Renewable Energy Law provides unprecedented policy support for the development and utilization of biogas systems. The local governments above county level are instructed to prepare a plan to develop and fund renewable energy, considering local economic and social development, ecological protection, and health issues.
The 2007 “Yunnan Provincial Climate Change Program” intends to develop biogas technology while accommodating local conditions and paying special attention to the comprehensive utilization of manure.
Biogas policies are implemented primarily through the Agricultural Department, the Forest Department and the Rural Energy Offices (REO) on different administrative levels.
At the local level, the REOs, in conjunction with the Rural Energy Service Stations (below county level), are an important part of the biogas technology promotion and service system. Their main task is to distribute government subsidies at the village level and to provide technical assistance, such as installation services, training and maintenance, to the households. They are the one of the major reference points for farmers. It is here where they receive advice and where they can commission the biogas plant. Many REOs suffer from three main problems: First, the offices are understaffed and the staff’s qualification and general education is insufficient. Second, office equipment is often either outdated or inadequate. Last, there are significant efficiency losses between the REOs and other responsible institutions, administrative levels and policies.
In 2007, the National Development and Reform Commission published the “Medium and Long-Term Development Plan for Renewable Energy”. The plan sets the government subsidy at 1,000 Yuan (about 110 Euro) per household biogas digester. This covers about one-third of the total costs of a biogas system. On the local level the actual amount of subsidy can vary (e.g. 800 Yuan are paid in Hunan Province and households can receive up to 2,000 Yuan in Yunnan Province).
The subsidy is issued in the form of building material (1,400-1,600 Yuan), equipment, expertise and the assistance of technicians. Households primarily have to provide labor, which would cost between 800-1,500 Yuan (for 20-30 working days). Yet, often households choose to build the digester themselves. In some cases households also have to buy certain construction materials.
Types of Biogas Plants and Systems
Rural Energy Offices offer four sizes of standardised plants; the most frequently built are plants with 6 m3 digester volume. Though the trend is to bigger digesters. These are fixed-dome plants which are either made out of concrete or built of bricks, depending on the availability of local materials. The pipe connected to the compensation chamber is at medium height. Such details and similar matters have been scientifically investigated over many years and finally standardised.
Different site layouts have also emerged that are adapted to the requirements of local conditions and thus designed to provide more benefits to the users. There are two popular kinds of biogas system: the ecological “pig-biogas-fruit” system and the ecological courtyard system.
The ecological “pig-biogas-fruit” system, or “three-in-one” (sān wèi yītǐ), is popular in southern China. This layout has been widely used since the 1970s and became the standard design in many regions in the 2000s. The pigsty and toilet are connected to the digester. The input material automatically flows into the digester, saving a considerable amount of work and time. Otherwise the biomass has to be collected and added to the digester manually. The slurry is used as fertilizer, for fruit trees in particular.
The second system is the ecological courtyard system in northern China, which is also referred to as “four-in-one” (sì wèi yītǐ). The system is more adapted to colder climates. The layout consists of a biogas digester, a toilet, and a pigsty, which is located inside a greenhouse on top of the digester. This arrangement creates mutually beneficial conditions for plants, animals and gas output.
Other biogas layouts, beside the two mentioned, can include a solar water heater (“four combinations”), a new bathroom and/or a new kitchen. Some combine biogas digesters with fishponds, using the slurry as feed.
Strategy of Biogas Dissemination
According to high-level biogas officials, the strategy of biogas dissemination is based on the recognition that biogas plants are important in saving energy, in improving agriculture and sanitation, as well as in protecting the environment. However, it is assumed that these overriding objectives are of secondary significance for the potential owner of the plant in his decision to invest.
It is for this reason that an increase in income, by intelligently integrating the biogas plant in the production process, is emphasised as the incentive for investment. The greater role here is played by the utilisation of slurry. Consequently, production processes involving the use of the slurry for the cultivation of edible fungi, for fish farming, pest control or as pig food are propagated which thus increase the value of the subsequent products. The use of human nightsoil as substrate is, of course, a condition of this, and in fact, it is practised in 80% of all cases.
Many of these more advanced uses of the slurry are often not part of the training the government provides for the users. There is also the problem that in some regions the majority of farmers do not value the slurry and thus do not use it.
In several regions, non-governmental organizations support and supplement the government program. Some focus on providing additional training and after-sale services, others built digesters themselves, while organisations offer know-how and support regarding additional income generating methods, such as organic farming.
- An interesting case study by Hu Qichun on the rural district of Xindu describes, in addition to many details, the drastic decline in demand in the 1980s: Hu, Qichun (1991) "Systematical study on biogas technology application in Xindu rural area, China". Bangkok : Asian Institute of Technology.
- Case study concerning biogas technology diffusion in Hainan Province: Bi, Lei/Haight, Murray (2006): “On the Way Towards Eco-Villages: Upgrading Energy Systems in Rural Hainan”. China Environment Series. 8, 148-152. www.wilsoncenter.org (pdf).
- Case study analyzing the role of the community in the diffusion of domestic biogas: Greenhouse, Benjamin (2006): "Community Characteristics and Their Influence on Community Renewable Energy Projects: A Case Study of Cang Dong Village, Hainan, China". Master of Environmental Studies Thesis, Environmental Studies in Environment and Resource Studies, University of Waterloo, Waterloo. etd.uwaterloo.ca (pdf)
- Extensive case study in Liaoning and Yunnan Province: Byrne, John et al. (2004): “Health, Ecological, Energy and Economic Impacts of Integrated Agricultural Bioenergy Systems in China and Institutional Strategies for Their Successful Diffusion”. Center for Energy and Environmental Policy. report.pdf http://ceep.udel.edu
- A case study in Yunnan Province of an INGO (The Nature Conservancy) biogas project: Kuss, Benjamin (2006): “Community-Based Rural Development and Participatory Communication: A Case Study of the Nature Conservancy in Lijiang, Yunnan Province, China”. orestry.msu.edu (pdf)
- A case study in Yunnan Province of an INGO (The Nature Conservancy) biogas project. Here, the focus lies on their credit scheme: Pei, Yanhui (2006): “Energy Consumer and Income Generation Credit Scheme – Its Impact on the Promotion of Renewable Energy in the Rural North-West of Yunnan Province, China”. University of Flensburg, Germany. www.iim.uni-flensburg.de/ sesam/community/files_dis/1146090795.pdf.
- A small case study in Yunnan Province of an NGO (Yunnan Eco Network) biogas project: Lee, Amanda (2008): “Renewable Energy and Agriculture: Promoting Biogas in the Rural Communities of the Lashihai Wetland Nature Reserve”. ISP Collection. Paper 60. digitalcollections.sit.edu
- A small case study comparing the impact of government and NGO biogas programs: Harter, Julia (2010) “The Diffusion of Biogas Technology and its Impact on Sustainable Rural Development in China”. Diploma in Regional Studies of East Asia. University of Duisburg-Essen. dl.dropbox.com (pdf)
- A case study regarding the Livestock-biogas-fruit system in Guangdong Province: Chen, Rongjun (1997): "Livestock-Biogas-Fruit Systems in South China". Ecological Engineering Vol 8 (1): 19-29. www.sciencedirect.com
- Biogas Portal on energypedia
- Types of Biogas Digesters and Plants
- A summary on the technical development is given by Cao Guoqiang: "Overview on Biodigester Development in China". BIOGAS FORUM No. 48.
- An overview over history as well as policies and promotion is provided by: Li, Jingming (2006): “Rural Biogas Development in China”. methanetomarkets.org (pdf)
- Study on Biogas Plant Performance in China Baseline Study on Biogas Plant Performance in China