When you say "there is no..." then you are making a very definite rule. It is fine to use "except" only if you are making an exception to that rule.
In your first example of scientists - there are probably quite a few scientists that are renowned, or well known - Einstein, Newton, Hubble, to name a few that I know of and I do not work in the field of science. Still, if you intend to declare one scientist the most renowned, then speak in the singular:
There is no scientist
who is as renowned as Einstein except Stephen Hawkings.
If on the other hand, you wish to acknowledge that there is more than one renowned scientist then obviously use the plural:
There are few scientists
who are as renowned as Einstein, but Stephen Hawkings is among them.
You can see I haven't used "except" in this second example because I am not making an exception to any "rule". I have not said that Einstein is the only renowned scientist, and so Hawkings is not a single exception, he is simply joining the ranks of those renowned scientists I alluded to.
Also, you will notice I have scored out some unnecessary words - you don't need to say "are, are", or "is is".
In your second example about books, it is more a case of what question you are answering. If someone asked you "which books do you have", then you would reply the same way, that you have "no books except this red one". On the other hand, if they asked you "do you have the green book?" there is an assumption you only have one book, so you could answer "I have no book except this red one".