Very interesting reading:

Zero-point energy is the energy that remains when all other energy is removed from a system. This behaviour is demonstrated by, for example, liquid helium. As the temperature is lowered to absolute zero, helium remains a liquid, rather than freezing to a solid, owing to the irremovable zero-point energy of its atomic motions. (Increasing the pressure to 25 atmospheres will cause helium to freeze.)
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From this line of reasoning, quantum physics predicts that all of space must be filled with electromagnetic zero-point fluctuations (also called the zero-point field) creating a universal sea of zero-point energy. The density of this energy depends critically on where in frequency the zero-point fluctuations cease. Since space itself is thought to break up into a kind of quantum foam at a tiny distance scale called the Planck scale (10-33 cm), it is argued that the zero point fluctuations must cease at a corresponding Planck frequency (1043 Hz). If that is the case, the zero-point energy density would be 110 orders of magnitude greater than the radiant energy at the center of the Sun.

As to whether zero-point energy may become a source of usable energy, this is considered extremely unlikely by most physicists, and none of the claimed devices are taken seriously by the mainstream science community. An experiment to test a prediction of SED theory that would have some bearing on the ontology of zero-point energy is in a preliminary phase at the University of Colorado (as of June 2006).


Calphysics Institute: Introduction to Zero-Point Energy

Lots more there, DARK ENERGY and STOCHASTIC ELECTRODYNAMICS THEORY are interesting. I'm checking that out.

I'm very skeptical that we can harness enough of these kinds of "energies" or forces to do something like say run a car. Would be very much less effective than say trying to do so with even SOLAR panels.