I am interesting in a electric type piston mechanism (if there is one)
that I can use for paper compaction.  I plan on putting underneath
(sideways) an industrial paper shredder and using it to push shredded
paper that falls from blades into a large container.  This is similar
to a baler application however, I don't want to use a baler.  The
concept is similar to this mechanism
(http://www.orwak.us/little_elephant/models/tlp80.htm) however, I
thought there might be something else.  Any help would be appreciated.

Regards,
Paul

I think you can do whatever you want.

There are linear motors. 

There are screw type electric acuators. 

There electrically driven sealed hydraulic units.

There are fans.

The cost and the amount force required. The amonunt of paper being crushed.
And the degree.
The size of the bin. 

Your proposed application is vauge.  But if  you can use air you can electric.

Home type trash compactors were being sold 20 years ago. Perhaps some
of the old units can be purchased cheap. Their design may give you
clues as to why they were unsucessful, and ideas on improvements.  
Neil