有冇錯呀...我寫的..

not so bad.. your English & gammar sounds good.

1) But coal is also a type of fossil fuel.
Fossil fuel means all the energy materials extract from the land e.g. oil, coal etc.
2) the only solution ==> better use the only alternative
==> " solution" , it represents unclear power is to solve the problem for coal and pollution itself. But nuclear power is not a material/method to add to the fossil fuel and pollution itself.
" alternative"-- another way of performing.
==> Try to remember " using the least wording to express the ideal" is the key for good writing.


So,I prefer the following writing style:

Some people think nuclear power is the only alternative because of less harmful to the environment and more efficient than fossil fuel.

not bad but think about this, hope I can help you.

Some people SUPPORT this idea not only because they think nuclear power is less harmful to the environment, but also it is ( it is also) more efficient compared to coal and fossil fuel.



Some people think nuclear power is the only solution not only because it is less harmful to the environment, but IT IS ALSO more efficient when comparING WITH coal and fossil fuel.

2007-03-07 15:12:37 補充：
coal and fossil fuel should add an "OTHER" and make it coal and OTHER fossil fuel.

1st sentence:

This sentence is quite ok and I only
(a) change the word "suppose " to "support ", (b) add "that " before nuclear, (c) add "as " before compared, and (d) change "fuel " to "fuels ".

Some people support this idea not only because they think that nuclear power is less harmful to the environment, but also it is more efficient as compared to coal and fossil fuels.

But fossil fuels includes coal, so the sentence may be further improved to

Some people support this idea not only because they think that nuclear power is less harmful to the environment, but also it is more efficient as compared to fossil fuels such as coal.

2nd sentence:

Some people opine that nuclear power is the only solution to energy shortage because not only it is more environmentally friendly, but also more efficient when compared to fossil fuels such as coal.

Notes:
(a) I use "opine " rather than "think " in order to stress that an opinion is given.
(b) As pointed out by oakoakling, the problem (energy shortage) should be mentioned. There is no need to say "energy shortage problem " because everyone knows it is a problem.
(c) The word "only " before solution is retained to stress that there is only one solution.
(d) "because " is placed before "not only ", what follows is the reason why nuclear power is the only solution.
(e) I also change "less harmful to the environment " to "more environmentally friendly " to impress the readers.

Some people believe that nuclear power is the solution* to the energy problem** not only because it produces less pollution, but it also gives out much more power comparing to other fossil fuels***.

* better not to put "only" here
** you should mention the problem that needs a solution.
*** coal is a kind of fossil fuels.

The last clause is still kind of awkward. Some one may give u a better one.

suppose u have explain or suggest an idea in the pervious sentence:

Some people support this idea because they believe that the nuclear power is less harm to the environment. Also, it is powerful as compare to coal- and fossil fuel-power.

Some people believe that nuclear power is the only solution because it is less harm to the environment. Also, it is powerful as compare to coal- and fossil fuel-power.