矿井通风煤矿瓦斯利用中英文对照外文翻译文献

中英文对照外文翻译

recovery is low methane concentrations in the gas mixture.

Safety regulations in Germany prohibit any utilization if the methane content is less than 25%. If the average recovery efficiency at German mines is to be increased, it will be necessary to adopt practices that will recover methane in a more concentrated form. 3 Barriers to decreasing coal mine methane emissions

There are several barriers to decreasing methane emissions by increasing coal mine methane use. Some are technical, such as low coal permeability, while others are Institutional, such as low gas prices. In a few cases, certain barriers are country orregion specific, but most cases, many of the same barriers exist in a number of countries. This section discusses obstacles to increased coal mine methane use, and potential ways to overcome these obstacles. 3.1 Technical issues

3.1.1 Low-permeability coals

Coal seams that exhibit low permeability pose special problems for developing

successful methane drainage and recovery systems. Methane desorbs and flows through natural pores and fractures until the gas reaches the mine face or borehole. Stimulation technology that enhances the flow of gases from the seam into a recovery system has been successfully used in the past several years. Early efforts to modify fracturing techniques for application in coal seams were largely unsuccessful （IEA, 1994） . The current practice of hydraulic stimulation in coals, however, minimizes roof damage while achieving

13

中英文对照外文翻译

extensive fracturing. Under ideal conditions, 60 to 70% of the methane contained in the coal seam can be removed using vertical degasification wells drilled more than 10 years in advance of mining. These efforts have been successful in the United States and other industrialized countries. Transfer of this technology to other countries can help increase coal mine methane recovery. 3.2 Economic and institutional issues

In addition to the technical obstacles described above, there are a variety of other issues that have prevented coal mine methane recovery from becoming more widespread.

These issues include lack of information, lack of capital, low natural gas prices and risks associated with foreign investment. Some issues are explored below.

The key strategy for overcoming informational barriers in the United States has been to develop outreach programs. Outreach programs work well when companies are shown that they can profit while at the same time reducing emissions or improving mine safety. Examples of outreach programs include the USEPA’s Coalbed Methane Outreach Program, which is conducted in the United States, and the Coalbed Methane Clearinghouses in Poland, China and Russia. These institutions distribute information and link together interested parties, provide technical training, and in some cases perform pre-feasibility assessments for specific projects. 3.2.1 Lack of information

In the United States and other countries, one of the problems that

14

中英文对照外文翻译

has slowed coal mine methane project development is that some coal mine operators do not have adequate information regarding coal mine methane projects. While much has been published on the subject, methane recovery is still seen as a relatively new concept to many coal operators. A related constraint is that some coal operators simply do not have the time or resources to investigate the potential to develop a profitable project at their own coal mine. 3.2.2 Lack of capital

Even when a pre-feasibility assessment has demonstrated that the economics of a coal mine methane project are attractive, a lack of financing may prevent projects from taking place. Coal companies often do not have surplus capital available to invest in coalbed methane recovery and use projects because available capital must be invested in their primary business of coal production. Additionally, some lending organizations may be unfamiliar with the relatively new concept of coal mine methane recovery and use, and project developers may thus be unable to secure the necessary up-front financing needed to cover the large capital investments required for such projects.

3.2.3 Low natural gas prices

In some countries natural gas prices are held at artificially low rates. Even in countries whose gas prices are at market levels, prices may be low due to low demand. In such cases, special types of incentives to encourage coal mine methane recovery could be implemented. For example, legislation could be enacted requiring local distribution

15

中英文对照外文翻译

companies to purchase recovered coal mine methane if it is sold at a competitive price. China has recently established preferential policies for projects which involve gas recovery and use from coal mines. The government has also passed a law exempting coalbed methane producers from royalties and land occupation fees for production of up to 2×109 m3 of methane per year. 4 Conclusions

As discussed above, coal mines worldwide emit large volumes of methane, much of which could be recovered and used as fuel. In many instances, countries whose mines emit large quantities of methane are in critical need of a domestic energy source, particularly one which is clean-burning. In countries whose economies are in transition, such as China, the former Soviet Union and the Eastern European nations, coal mine methane recovery offers economic benefits as a new industry that can help provide jobs for displaced coal miners or other workers. In countries whose economies are established, such as the United States, the United Kingdom and Australia, coal mine methane recovery may help increase the profit margin of mining enterprises.

The reduction of methane emissions can have a significant global impact, but incentives are needed to encourage more widespread recovery of coal mine methane. An incentive program offered on an international level would probably be the most effective means of stimulating development of the coal mine methane industry. Of the various options for international-level incentives, a system of tradeable permits for methane emissions would likely be the most cost effective.

16