I hold an Egyptian passport and it's currently at the USA embassy in order to obtain a business visa.
I have a business trip to Spain in few days and I’ll need to travel before I receive back my passport. Is it enough to travel from Germany to Barcelona with my permanent Residence Permit?
It depends totally on the Airline. They generally ask you to present the passport when you are flying from one Schengen country to the other. You will have to contact the airline and ask them about the official list of documents.
In some cases they allow you to travel if you present your residence permit along with the letter from the embassy stating that your passport is with them (just talking from the personal experience).
Regardless of whether or not you are able to travel, note that in Spain you are supposed to carry ID at all times. If the police ask you to identify yourself (perhaps because you're a victim or witness of a crime, or because you got too near to a protest) they are not required to consider that your German residence card is sufficient ID. (As I understand it, even the German police don't consider it ID). A certified copy of your passport may be sufficient, depending on who certified it.
