Subject: Is there a generator which uses CO2 phases to make electricity?

My sister and her husband have been (in the wake of Y2K-mania) asked to 
invest in a company that produces what she said they call "CO2 generators" 
that produce electricity from the energy in "phase shifts" of CO2 (ie. 
liquid-gas).  I didn't think there was much energy in CO2 bonds.  Are they 
being led down the primrose path?  The company claims that these will be 
sold for $200 each and can be used to run an entire household.  As a 
biologist, I am also a skeptic.  Should they zip their purses and run?

Re: Is there a generator which uses CO2 phases to make electricity?