The law would encourage companies to switch from coal to cleaner fuels.

法律会鼓励各公司从用煤转向使用更清洁的燃料。

《柯林斯英汉双解大词典》

Under the new rule, by 2015, existing boilers must switch from No. 6 oil to a low-sulfur version of the No. 4 heating oil or to an equivalent cleaner fuel.

按照这项新法规，截止2015年，现存锅炉必须由6号燃料油换成4号低硫型燃料油或与之相当的较为清洁的燃料。

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At times the carbon price has made it worth power companies' while to switch from dirty fuels to cleaner gas.

有时碳价格会让电力公司感觉花时间把肮脏燃料转换为清洁空气是值得的。

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Similarly, when Margaret Thatcher broke the British coal miners' unions in 1985, Britain was able to switch to cleaner-burning natural gas.

CNN: Hot Air In Kyoto

The gradual switch to cleaner sources of energy has contributed to a 13% decline in carbon emissions from 2007 to 2012, the report said.

FORBES: Report: Clean Power Is Moving (Gradually) Into Americans' Homes

The fuel that powered the U.S. from the industrial revolution into the iPhone era is being pushed aside as utilities switch to cleaner and cheaper alternatives.

MSN: Coal producers find themselves in a hard place