Chinas Use of Biogas - Chapter 2

Biogas in Rural China

• Chapter-1
• Chapter-2
• Chapter-3

Chapter 2 – The strengths of biogas technology over other technologies

The term “renewable energy” by and large refers to alternative energy sources from the sun, wind, water, and the Earth’s internal heat. Up until a few years ago, these alternative energy sources were viewed as being simply “pet projects for ‘bearded vegetarians in sandals’[1]”. Whilst these are often still viewed as unconventional, in recent years they have received more credibility and function. In China, three state agencies, the Ministry of Science and Technology (MOST), the State Development and Planning Commission (SDPC), and the State Economic and Trade Commission (SETC) have in cooperation established a ‘Program on New and Renewable Energy Development in China (1996-2010)[2]. Energy development in China, under the guidelines of the Development of New and Renewable Energy, follows the initiatives of saving energy, increasing its utilization efficiency and utilizing more clean energy as an alternative to high-carbon-containing mineral fuels. Chinese energy development has made sure to encompass civil society, supporting the local populations under the format of ‘self-reliance’, ‘self-construction’, ‘self-management’, and ‘self-consumption’.

This section offers a review of the development of renewable energy sources in China. The first half of this section will discuss renewable energy sources other than biogas. It will analyse their theoretical benefits and detriments, their potential in China, as well as the actual realisation of their use. The second half will cover biogas technology in more depth. It will compare biogas to the other renewable energy sources being developed, as well as explore the various benefits of the technology.
Types of renewable energy and their development in China

One ‘alternative’ source of energy is wind power which works by converting the energy of moving air into electricity. Electricity generation from wind creates no air pollution and solid wastes, and is able to produce electricity using a locally available and free resource. Wind power may be cheap and efficient, but energy generation is totally dependent on when the wind is blowing, and thus inherently extremely site-specific. Wind power technology has developed rapidly on a global-scale. In 1992, the “global installed capacity of wind power reached 2.7 million kilowatts with the generating capacity of 4.7 billion kilowatt hours”.[3] China is still in the process of developing its wind power potential. In the 1980s, 50 to 200 watt turbines were developed and put into production in areas such as Inner Mongolia, Xinjiang, Qinghai and other coastal areas lacking grid connection. This technology is owed for supplying power for lighting for herdsmen and fishermen in these areas. Development is now being concentrated on smaller-scale turbines (1 to 20 kilowatt) as well as the creation of 14 wind turbine farms. China New Energy estimates that the total installed capacity of wind power generation in China is 26,000 kilowatts. Progress has been made in the fields of investigation into wind energy, performance testing, basic theory and with the introduction of technology.[4]
A second option is solar energy, in the form of passive solar design, Solar Thermal Energy and Photovoltaics. Passive solar design involves building and designing buildings to take advantage of reliable daytime light and heat, and solar thermal energy involves simply using the heat from the sun directly. Whilst both of these are useful for heating or lighting, they offer little in the form of electricity generation or transfer into other energy types. Photovoltaic cells, on the other hand, involve turning sunlight directly into electricity with solar cells. This technology was a product of the “Space Race”[5] and involves light striking a silicon and trace element surface of a photovoltaic cell; it then bumps a negatively charged electron out of its orbit around the positively charged nucleus. The ‘pulling’ of these electrons sets up an electric flow that is harnessed by the photovoltaic cell. Whilst, this works well in producing energy it does need further development, and like many renewable sources of energy is quite expensive and therefore not competitive. In short, it is in need of a price fall and more efficiency to become more widely used. However, the world annual production of photovoltaic cells has reached more than 60 MW with the conversion efficiency of fifteen per cent. The cost has indeed gone down (though perhaps not sufficiently) by four dollars per crest watt and 25 cents per kilowatt-hour correspondingly.

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China has developed passive solar design and solar thermal energy as well as photovoltaic cells. The development of passive solar design and solar thermal energy requires very little research or advancement as they are simple technologies. The designs and concepts were diffused throughout the country, and in ten years it is thought that they have essentially reached a good standard. Three particular models have become popular: domestically made solar energy water heaters, passive-type solar houses, and solar stoves. These models are thought to save a huge amount of energy: the solar energy water heater can save 100 to 150 kilograms of coal per year, a passive type solar house can save 20 to 40 kilograms of coal per square meter of floor space per year, and a solar stove can save 500 to 700 kilograms of straw or wood per year. With regard to photovoltaic cells, between 1983 and 1987 China launched solar-cell production lines from the United States and Canada, increasing the yearly solar-cell production capacity from 200 kilowatts in 1984 to 4.5 megawatts in 1988.[9] Solar power is still being actively pursued – “with over 60 per cent of the country’s landmass experiencing more than 2,000 hours of sunlight per year, solar power – the cleanest and most plentiful of all renewable energy sources – has tremendous potential”. [10]
Hydropower is a source of renewable energy that utilises the energy in falling water. Typically a dam is created or used to produce and abrupt drop and the amount of energy that can be secured depends on the vertical distance between water behind the dam and free water downstream.[11] Hydropower can also be captured through wave power, tidal power, and ocean thermal energy. Whilst it is a non-polluting and efficient energy source, its impact on fish, wildlife and local communities has been adverse and highly debated. The Chinese have significantly utilised small hydropower generation, particularly for rural areas. 109 counties have achieved electrification through hydropower, and another 200 counties are currently being developed. [12]
Whilst there are clearly a lot of options for alternate sources of energy, there are a variety of constraints that have impeded these technologies from being more widely used. First, because of the costs involved in research and development, many of these technologies are quite expensive, and doomed to be uncompetitive. Second, many of the technologies are extremely site-specific, which is significant in that they may have a lot to offer in some areas, and nothing at all in others. The Program on New and Renewable Energy Development in China has calculated the quantity of energy that is likely to be exploited in China from each source of renewable energy. The calculations are as follows: the hydropower potential is about 378 million kilowatts, of which about 11 per cent has been developed; the potential for development of solar power is huge but difficult to quantify, but China’s 9.6 million square kilometres, receiving on average a little more than 600,000 joules of solar radiant per square centimetre, are an indication of the massive potential of solar energy; the total wind energy potential is estimated at 1.6 billion kilowatts, of which about 10 per cent is currently being exploited. Biogas, on the other hand, is already a massive contributor to China’s energy consumption. The Program for New and Renewable Energy in China estimates that biomass (including stalks, firewood, and other varieties of organic waste) provides 70 per cent of domestic energy consumption in the rural areas, and 50 per cent of the total energy consumption of the country.[13] Accessible immediately with no immediate need for additional advancement as with other unconventional energy options [14], biogas also has diversity as its advantage, “both in the kind of energy produced and in its resource base”. [15]
A History of Biogas
Biogas is essentially one of the products of the anaerobic (without air) digestion of any biomass (living matter). It is a mixture of methane and carbon dioxide which can be used as an energy. Biogas (from sewage and human wastes) began to be used for lighting in the late nineteenth century, and was developed through the last century. However, biogas did not advance much as coal and oil were easily available as inexpensive sources of energy. Some countries did, however, begin to develop their biogas potential: it has been in use in India since 1923, and in China for nearly 70 years.[16] European interest in biogas technology was shortly rekindled during World War II, but coal and oil have always remained more important. Nonetheless, since the 1960s biogas has once again been acquiring popularity as an energy source[17] for a variety of reasons that are outlined below. In short, “biomass energy offers what no other conventional fuels offer – increased supply with a positive environmental impact”.[18] Nonetheless, the “approximately 2.5 million people (about half the world’s population) rely on biomass for almost all their cooking, heating and lighting needs”[19] are more likely to do it for survival than out of concern for the environment. The production of methane to be used as an energy source is key to the process of anaerobic digestion. This raises issues to do with global warming, as methane is one the “greenhouse gases” thought to be responsible for this phenomenon. When light energy comes through the atmosphere it is absorbed by the Earth’s surface and converted to heat energy that is then radiated back up through the atmosphere. “Greenhouse gases” that are naturally present, like Carbon Dioxide, absorb some of the infrared radiation and reradiate it back towards the earth’s surface, insulating the earth and preventing the loss of heat to space. However, if too many gases are anthropologically added to the assortment, too much reradiation will occur and heat will stop escaping to the sun. Methane is a very powerful and effective greenhouse gas, and thus concern is warranted. However, when biogas is used, the effect is to convert a powerful greenhouse gas (methane) to a much less damaging one (carbon dioxide). For example, it has been estimated that “using the landfill gas in the UK instead of letting it leak away is equivalent to reducing the carbon dioxide reaching the atmosphere by between 38 and 55 million tonnes a year – 10% of present UK carbon dioxide emissions”.[20] By using livestock manure as a resource for anaerobic digestion, methane emissions from livestock manure are reduced.[21] Additionally, in contrast to the burning of fossil fuels, in biogas production the carbon inherent in organic matter is recycled. This explains why there is fairly little air pollution – “the combustion of plant matter releases no more carbon dioxide than is absorbed by its growth, so the net contribution to greenhouse gases is zero”[22]. All of this is extremely important, especially when put into the context of China as a “greenhouse giant”.[23] China is the world’s second largest producer of greenhouse gases, after only the United States.[24] According to predictions by the National Committee of the Chinese People’s Political Consultative Conference (CPPCC), China will be the world’s primary energy consumer by 2050, getting through 3.8 billion tons of standard coal per year – three times the amount for 2000.[25] As Hertsgaard states “[w]ith its immense coal reserves, huge population, and booming economic growth, China is very likely to triple its greenhouse emissions by 2020”.[26] Put into this context, the importance of an energy resource that avoids contributing to greenhouse gas emissions is clearly extremely important.
With regard to another important environmental concern, biogas can be instrumental in avoiding deforestation. As people turn to biogas for cooking and lighting instead of firewood, less firewood will need to be used. This will, however, require cautious planning. At the moment, there are some concerns that there is a positive correlation between biogas production and deforestation and that “energy cropping” is occurring. There are concerns that biomass developers will damage forests by harvesting faster than they replant, or by targeting old-growth forests.[27] There has also been some fear surrounding the use of “energy farms”, or concern that biogas resources will compete with food production.[28] There are a few responses to this: first, where the resources used are human or animal wastes there need be no concern over deforestation; second, the variety of sources for biomass are vast and energy cropping is not necessary. The concern over deforestation illustrates the fact that biogas may be an extremely problematic resource to manage. As Cole and Skerret concur, “if it is not managed carefully … increasing biomass’ contribution to our energy mix could damage forests, erode cropland, and do little to ease air pollution”. [29]
The products of anaerobic digestion are both biogas and slurry – a slurry that can be used as a compost or fertiliser in agricultural application. In this sense, biogas technology creates not only energy but also a valuable fodder substitute or organic fertiliser. It also recycles nutrients back into the earth, as opposed to losing them completely as happens when wastes are burnt. Where the slurry is used as a fertiliser, the nutrients (nitrogen, phosphorous, potassium and other micro-nutrients) are returned to the ecosystem.[30] The slurry makes an effective fertiliser that is also lower leaching than manufactured nitrate fertilisers. It may also be used as a cheap cattle feed. [31]
Biogas technology is also beneficial for the disposal of waste and for sanitation purposes. Depositing human and animal wastes, as well as other waste, into a sealed digester is a very effective way of getting rid of odours. The process of anaerobic digestion alters the odour-causing substances in organic matter into methane and carbon dioxide, which are unscented.[32] This can be very important, as some argue that people who are exposed to these odours have “less vigour and more tension, anger depression, fatigue, and confusion”[33]. The digestion of these wastes can decrease the parasitic and pathogenic counts by over ninety per cent.[34] Rahman et al concur that “during digestion inside a digester, the majority of the harmful microbes present in the feed sticks are inactivated and killed and at the same time the wastes are stabilised to a significant extent”.[35] Biogas also offers an additional derived benefit by preventing the use of firewood for cooking as the smoke brought about by this can have very serious health implications.
Making use of the biogas also stops human and animal wastes from being discharged into freshwater ecosystems. The use of these wastes can be instrumental in preventing eutrophication, the process by which excess nutrients entering an ecosystem leads to an increase in algae and microscopic organisms that prevent light infiltration and oxygen absorption. This can lead to the death of many organisms and biogas makes other use of these nutrients and in turn can help to prevent this process. For example, the application of raw organic wastes on occasion causes acute shortages of oxygen in fish ponds, but the use of biogas fertiliser reduces this problem by preserving the dissolved oxygen in the fish ponds.[36] Biogas is also thought to reduce local water and groundwater pollution by 70-90 per cent.[37] Most importantly, even if thebenefits of energy production are ignored, biogas is useful purely as a disposal method. The process of anaerobic digestion itself produces heat, but sometimes the biogas itself must be used to provide heat for the process. In an extreme case, all the gas might be needed for this purpose, creating a net energy output of zero. Nonetheless, the plant may still pay for itself because money will be saved on the fossil fuels that would have been required to deal with these wastes.
This section has reviewed the various alternative and renewable energy sources that are available, and that are being developed, in China. It has also outlined the variety of benefits encompassed by biogas technology. The Development of New and Renewable Energy in China is indeed making significant steps with solar-, wind- and hydro- power in addition to biogas, and it is clear that biogas is the ‘green’ technology that is most widely used, and (perhaps) the technology with the most potential. This section has discussed thebenefits and detriments of biogas technology, and the following sections will examine how and why biogas technology has been harnessed in China, as well as how it could be developed further.

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