1.   But how do they compare with the damage caused by other energy sources?

2.   Down on the factory floor, automatic control had the expected virtue of moderating high-powered energy sources as mentioned earlier.

3.   Environmentalists would like to see fossil fuels replaced by renewable energy sources.

4.   Gas will become, along with hydro-electricity, the largest single energy source.

5.   He asserted that nuclear power was a safe and non-polluting energy source.

6.   However, I found the short section on conservation and alternative energy sources disappointing.

7.   Iceland possesses sufficient quantities of clean energy sources that it does not need to rely on fossil fuels.