1.   Although it burns cleaner than ordinary gasoline, ethanol also produces less energy per gallon and requires frequent refueling.

2.   Besides reducing the reliance on imported oil, which is refined into gasoline, the alternative fuels also generally burn cleaner.

3.   A new burner not only will burn cleaner, producing less fumes and odor, but it would be more efficient.

4.   Advocates argue that ethanol burns cleaner than gasoline, and studies show that it does reduce certain pollutants.

5.   Air-quality experts disagree, saying nothing burns cleaner than alternative fuels.

6.   Britain gets to sell oil, which pollutes, to other countries and keep natural gas, which burns cleaner, as a substitute for coal.

7.   Ethanol, which is combined with gasoline to create gasohol for vehicles, also burns much cleaner than fossil fuels.

8.   Gas-fired burners generally burn cleaner than oil burners so a tuneup is needed only every other year.

9.   Gas-fired equipment burns cleaner and should be serviced every other year.

10.   The prototype runs on natural gas, which burns cleaner than diesel fuel.