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Cooking With Gas

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Max Chinnah, a 26-year old Nigerian inventor, has created a smokeless stove that could cook and charge phones.

The entire biogas production of the world was about 42 Giga cubic meters in 2008. In detail, the 35 countries of the Organization for Economic Co-operation and Development (OECD) have an annual production of 27 Giga cubic meters; non-OECD countries produce approximately 15 Giga cubic meters biogas a year. Some European countries like Germany represent the advanced level of biogas production in the world, not only in production amount, but also in technology and policy frameworks. The utilization of biogas shows a number of diverged functions and has achieved a high level of industrialization and commercialization in OECD countries, such as electricity production, biogas vehicles, and other transport systems. Recently, some crucial changes have happened in biogas production among those countries: some Central or East European countries including Poland, Hungary, Slovakia have made fast progress in biogas development; the number of biogas power stations continues to grow in a steady rate in Sweden, UK, and Denmark, but the biogas industries in Germany, Austria, and Italy have gradually stagnated in the past few years. As the biggest contributor in Europe, the stagnation of Germany’s biogas industry may have a strong influence on Europe as a whole. Thus, the European Biogas Association believes that the future is not bright for biogas development in Europe.

Biogas production in developing countries varies greatly. The data from the IEA show that only 36 % of the total biogas is produced by non-OECD countries. China produces 98.4% of biogas among the non-OECD countries in 2008.

The support and aid reached to 5000 million CNY in 2010, leading to a drastic rise of biogas users in the first decade of twenty-first century: from 11 million family users in 2003 to 43 million in 2013, and from 2300 biogas engineering projects in 2003 to nearly 10,000 projects in 2013 (calculated from data reported by MOA; several years used). Production capacity by household biogas digesters increased from only 4.5 Giga cubic meters in 2003 to 16 Giga cubic meters in 2013, amounting to 8000 Ktoe oil equivalent; total biogas production of large-scale biogas projects increased from 0.2 Giga to 2 Giga cubic meters during the 10 years, accounting for 12.4 % of natural gas consumption and 1000 Ktoe oil equivalent in 2013 (calculated from data reported by MOA 2013). After 2009, China has enhanced its support for biogas engineering projects by offering subsidies from 25 % to 45 % of the whole cost of projects, especially allocating more aid to Mid-Western areas and innovative projects, setting up policies similar to feed-in tariffs to promote power generation through biogas plants. Meanwhile, local biogas service systems were established by for improving the efficiency of biogas production and utilization. In 2014, central and local government still invested more than 2500 million CNY, of which the total biogas engineering construction accounting for 40 %, higher than the 18.4 % in 2008.

A long-term goal planned by China’s National Development and Reform Commission (NDRC) claims that the available biogas production in 2020 will be 44 Giga cubic meters, from which 30 Giga cubic meters biogas will be produced by household users and 14 Giga cubic meters biogas will be generated from biogas engineering projects (NDRC 2007). Another short-term goal on biogas development has been set up by China’s National Energy Administration (NEA): By 2015, the number of the biogas household users will reach 50 million with total biogas production of 19 Giga cubic meters. Large-scale biogas projects focused on agricultural and industrial (including municipal) wastes will produce 2.5 Giga and 0.5 Giga cubic meters of biogas, respectively, with more biogas being used to produce electricity production (NEA 2012).
As shown in Fig. 1, in general, biogas from rural household biogas digesters comprises the major proportion of total biogas production and shows a long and steady growth. However, according the updated data by the Ministry of Agriculture of China, in recent years, household biogas generation seems to have slowed down to a pre-2011 level, and probably has reached a peak in many provinces (calculated from MOA 1989–2014). In contrast, biogas from agriculture-based biogas engineering projects shows a dramatic growth trend with increasing proportion, and starts to play a more important role in the biogas production of China. Furthermore, biogas from industry-based biogas engineering projects rises gradually with some slight fluctuations, exceeded by agriculture sector after 2004 (calculated from MOA 1989–2014). In the past few decades, China has accelerated its reform pace in urbanization, industrialization, and even energy and agriculture transformation. Therefore, China’s biogas production is undertaking a dynamic and complicated transition, quite different from those of developed countries, and also different from those countries which rely on traditional agriculture or livestock husbandry.

Rural household biogas plants are the largest contributor to biogas production in China. As the earliest form of biogas digester, the round-shaped water-pressure biogas plant was once popular among farmers in China, and also welcomed by many developing countries with a name of “China-mode biogas” digester. Recently other types of technology have been developed in various areas of China. Strong back-flow biogas digesters have been introduced in Jiangxi province. The meandering-distribution biogas digester is a major type of digester in Yunnan province. The biogas digesters in Hunan province have separated gas storage with a floating cover. In the northwest region, biogas digesters with circumflex technology are applied to solve problems in resource updating and production efficiency. Household biogas-based systems in different areas also vary from each other, such as newly developed biogas-kitchen-farm-toilet model, pig-biogas-fruit model in South China, 4-in-1 biogas system in Northern China with a greenhouse, and 5-in-1 model in Northwest China with water and solar infrastructures.

Secondly, agriculture-based biogas engineering projects have been promoted in China since late 1990s by local and central governments, and the basic technology was introduced and fixed. As Fig. 2 presents, the system of agriculture-based biogas engineering consists of a fermentation tank, gas storage room, bioliquid storage room, gas purification system, biogas electricity generator, biogas transportation system and other related parts. Most of these biogas engineering projects use either the upflow solid reactor (USR) or the continuous stirred tank reactor (CSTR) as reactor technology, and these technologies have been used for more than 20 years. For these engineering projects, though climate condition is no longer the most important, enough raw materials should be guaranteed, and the project should be well maintained both technologically and financially. Biogas production involves many different stakeholders in this market-oriented model, far different from the model of the household biogas plant for families’ use.

There are increasing numbers of industry-based biogas projects in China that tackle rising industrial liquid and solid waste in paper making, food or liquor manufacturing, printing and dyeing, among other challenges. With regard to core regeneration technology of biogas production, the upflow anaerobic sludge blanket (UASB) technology is used in more than half of all biogas plants, followed by CSTR and USR. In addition, municipal sewage-cleaning biogas projects, landfill gas projects, and other biogas plants are small but non-neglected parts of the biogas industry in China, and part of biogas they produce is often reported together with the industry-based engineering projects.

Most of the high-level biogas engineering technology in China is introduced from OECD developed countries.

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