China has been relying heavily on coal (over 70%) and petroleum for energy to maintain its supercharged economic growth--it has plenty of the former, and now has to import nearly 50% of the latter. There have been continuous debates within the country to change China's energy mix to reduce dependence on foreign oil and the impacts of years of over and inefficient use of coal that has caused much environmental damage and social costs. Its 11th Five-Year Plan (2006-2010) unveiled in 2005 clearly articulated these goals and placed emphasis on efficiency in energy production and utilization as well as environmental protection; the plan specifically mentioned the development and increased use of natural gas and coalbed methane.
It is estimated that China's natural gas requirement will be 200 x 109 m3 (billion cubic meters) by 2020, 50% of them will have to be imported. Development of China's own CBM reserves will help bridge the gap between domestic supply and demand.
According to the latest data, China's total natural gas and coalbed methane reserves are about the same: the former is estimated to be round 36.7 x 1012 m3 trillion cubic meters) while the latter around 31.46 x 1012 m3 (less than 2,000 m deep); combined, they represent enormous amount of domestic energy source. The efficient use of China's methane resource will not only provide the country with badly needed energy without going overseas to maintain a sustainable double-digit growth, its use also will cause less environmental impacts.
PetroChina (PTR), one of the two partners China United Coalbed Methane (CUCBM), China's only coalbed methane company allowed to cooperate with foreign partners, decided to withdraw its 50% stake after 12 years. The transition is expected to be finalized the next few months and the company will become a wholly owned subsidiary of the China National Coal Group.
China's CBM Resources,
Methane occurs naturally in the coal coalification process over geologic time. Although it has always been associated with coal mining, methane occurs in non-coal mining as well. It is a clean form of energy, but unfortunately has notoriety in China because of the coal mining deaths as a result of methane ignitions (or explosions) triggering deadly coal-dust explosions. Until 2007, methane has always been the number one cause of coal mining deaths.
Coal's methane content is quite site-specific, but, in general, increases with coal rank (anthracite has the highest methane content of all, followed by bitumenous, etc.) and mining depth. Although commonly referred to as two forms of energy, natural gas and methane are basically the same thing that provides the same amount of heating content.
Two terms are also commonly used when referring to methane, coalbed methane (CBM) and coal mine methane (CMM): coal mine methane is gas released from coal or surrounding rock strata during coal mining (an emission reduction opportunity), while coal bed methane is an unconventional source of natural gas, not emitted to the atmosphere. These two terms have been used interchangeably.
Of the world's 74 countries with CBM resources, China ranks third in resource potential. Some 95% of the resources are situated in four gas-bearing regions: Ordos Basin and Junggar Basin (western and eastern Mongolia, respectively), Qinshui Basin (Shanxi Province), Tu-Ha Basin (Turpan-Hami Basin, Xinjiang Province) as well as the Yun-Gui region (Yunnan and Guizhou, in southwestern China), with each of these regions containing in excess of 1 trillion m3 in reserves. Of these four regions, Shanxi-Shaanxi-Inner Mongolia region has a bulk part totaling 17.25 x 1012 m3. Shanxi, specifically, accounts for approximately 27.2% or 1.0 x 1012 m3, mainly in Qinshui Basin and Hedong Coal Basin (He-dong means "east of Yellow River!").
According to recent (2003) a survey of 115 targeted regions, average methane content is 9.76 m3 per metric tonne at an average concentration of 90.6%, or averaging 115 million m3 per km2 with a gas content saturation of 41%. With increasing mining depths, this number is expected to increase as well.
Over the years, several major CBM producing districts have been established: Yangquan (Shanxi Province), Huainan (Anhui Province), Songzao (Sichuan Province), Fushun (Liaoning Province), and Pingdingshan (Henan Province). For example, Yangquan District (Shanxi Province) is China's largest CBM basin with 250 million m3 being extracted annually; other regions such as Huainan (Anhui Province), Fushun (Liaoning Province) and Songzao (Sichuan Province) each extracting in excess of 100 million m3 per year.
Methane Emissions from Coal Mines
Methane released to the atmosphere from gassy underground coal mine ventilation systems is a major source of greenhouse gas emissions. Operating and abandoned coal mines, post-mining coal processing, storage, and transportation are all sources of methane emissions in China, commonly referred to as ventilation air methane (VAM). The U.S. EPA estimates that they account for 95% of the emitted methane into the atmosphere, with remainder from CMM drainage systems. The exact number of China's operating coal mines are not known, numbers by the government range from 85,000 (in the early 2000s) to 29,500 (today); actual numbers are probably in the 40,000 to 50,000 range, almost exclusively underground operations. The U.S. EPA and China Coal Information Institute (CCII) put the total VAM emissions from these mines through ventilation airshafts into the atmosphere around 13 billion m3 annually. EPA data also show that China emits the greatest volume of VAM into the atmosphere, ranging from 45% (2001) to 48.7% (2002).
Based on U.N. data, approximately one-third or 19.4 billion m3 of methane produced during coal mining is vented directly into the atmosphere annually; nearly 100% of coal mining methane is vented.
Until recently, because of the very low methane concentration in this ventilation air (usually under 1%), coal operators had no technically proven options to recover this gas for its energy value. During the last decade, newly developed technologies in the United Kingdom, Australia, and the U.S. that offer means to economically recover most of these emissions at low cost. For example, the catalytic and thermal flow reversal reaction of VAM where up to 100% methane from the airshafts can be used, according to the manufacturer, Wisconsin-based MEGTEC. It's a typical example--just recognized by EPA--that enables VAM to be used as a primary energy-producing source.
China's CBM Industry
Some of the earliest methane drainage practice dates back the 17th century. In 1637 AD, in one of the earliest Chinese technical publications, Super Craftsmanship Open Volume (Tian Gong Kai Wu) described how bamboo was used to extract, and channel, methane from coal seams. Modern, systematic drainage has been practiced in Fushun and Tianfu (both in Liaoning Province), Yangquan and Tianfu (Sichuan Province) since the 1950s. But drainage operations in these regions were often driven by mine safety afternoon and performed by local mining bureaus, gas production was often limited in production, sporadic, and localized. More importantly, it was rarely financially successful.
Early systematic attempts in developing China's CBM industry were slow for several reasons. First of all, China's CBM reserves have very low permeability in many areas and are often situated in complex geological settings. It requires sophisticated drilling equipment and proven drilling methods unavailable at the time. A lack of systematic government financial support, proper policies and tax incentives also contributed to its slow development.
Encouraged by the successful development in CBM industry in the United States in the 1980s and early 1990s, China established the China United Coalbed Methane Corporation (CUCBM) in July 1996. It encompassed the former Ministry of Coal Industry (dissolved in the mid 1990s, most reorganized into current China national Coal Group), China National Petroleum Corporation (CNPC) and the former Ministry of Geology and Mineral Resources in a three equal partners arrangement. The mission of this agency includes exploration, development, production, transportation, sales and utilization of all of China's CBM resource; the agency was also given the exclusive rights to manage the exploration, development and production of CBM by foreign investors, becoming the fourth such entity in China besides CNPC, PetroChina Company, Ltd. (