论另类非常规天然气——生物天然气的开发

A discussion on the exploitation of biogas: Another kind of unconventional natural gas resources

非常规天然气目前已成为热门话题,在调研分析的基础上,论述了又一种已经初露锋芒、但在我国还远远未被重视的非常规天然气——生物天然气。任何有机物在无氧条件下,都可发生微生物厌氧发酵而产生沼气,再经过净化和提纯,就成为与常规天然气完全同质的生物天然气(Bio-Natural Gas),又称生物甲烷(Biomethane)。其实质是将需要几亿年地质过程才能完成产生天然气的过程,压缩到几个月乃至更短的时间。在最近不到20年内,生物天然气在欧盟国家已发展成具相当规模的产业。与页岩气和煤层气相比,其技术成熟度和经济可行性更为优越:能够大量地提供任何可再生能源均无法提供的实物态车用燃料和燃气,而且是碳"零排放"乃至"负排放"的。我国生物天然气的资源非常丰富,近中期内有年产1 500×108 m3以上的潜力,但迄未引起足够的重视。创建若干个1 0×108 m3级的生物天然气"绿色气田",对从根本上破除对产业沼气的偏见、大幅度减少温室气体排放量以及提高能源自给率都具有重大现实意义。

Unconventional natural gas has been a hot topic at present. On the basis of a deep investigation and thorough analysis, this paper makes a discussion on biogas, another kind of unconventional natural gas resources, which started to show its prospect but still has not yet been concerned so far in China. The bio-natural gas also called biomethane is a naturally occurring gas which is produced by the so-called anaerobic digestion of organic matter; after being purified and refined, its quality is absolutely as same as that of conventional natural gas. The essence is that the time of several hundred millions years needed for the formation of conventional natural gas can be shortened to be a few months or even much faster than that for the production of biomethane. Over the past nearly two decades, bio natural gas has been developed as an industry to a certain scale in some EU countries. Biomethane is superior over shale gas or coalbed methane gas in terms of the maturity of technologies and economic feasibility. Besides, unlike any other renewable energy sources, biomethane can be supplied in a huge amount as a green source of energy in a physical state for vehicle-used fuel or fueled gas to help achieve zero or even negative emissions. There are extremely rich bio-natural gas resources in China and its annual productivity will be expec- ted to be over 150 billion m3 in the short and moderate term. However, up till now this has not aroused enough concern yet. The proposal of building a few bio-natural gas fields, the so-called green gas fields, with the annual productivity of at least one billion m3 , will not only break with any prejudice to the industrial production of biogas, but substantially cut down the emissions of greenhouse gases. And this will be also of practical significance to improve the self-sufficiency rate of energy sources.