To deal with increasingly critical air pollution, Chongqing municipality is carrying out the project of changing coal into coal gas, known as city clean energy action.

为解决日益严重的大气污染，重庆市实施了清洁能源行动之煤改气项目。

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Based on In-pipe clearing ash robot in exhaust gas pipeline of metal smeltery object, the scheme of in-pipe clearing ash robot with track to clean out ash in pipe is put forward.

分析了火电厂灰水管道结垢的原因 ，介绍了目前采用和研究的几种清洗技术 ，并对几种清洗技术进行了比较。

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In its update yesterday, McMoran says it is injecting a barite solvent to clean out the perforations, or holes in the drill pipe, through which the gas will flow.

FORBES: Updated 11:30 Central.

The wind industry has largely been out-competed by natural gas, which has proved to be a clean, reliable and cheap power source for the future without subsidies or even venture-capital funding.

WSJ: Patrick Jenevein: Wind-Power Subsidies? No Thanks.

The more people who point out that natural gas is a bridge fuel to nowhere, the closer we get to a clean energy future.

CNN: Don't let America get 'fracked'