It is possible to use the field to generate work; however, in most cases this is not viable. This is because almost everything you observe around you is macroscopically neutral.

I suppose a simpler way to store and generate energy would be to use the gravitational field - such as one of [these][1].

As for the example you mentioned - the voltage across the two ends terminals is indeed sufficient, but you lack a source of electrons. A battery does not only provide voltage, but it also provides a source and a sink of electrons.


  [1]: http://www.stratosolar.com/gravity-energy-storage.html