Turbulent flows at high magnetic Reynolds numbers have been shown to act as efficient small-scale dynamos, with the magnetic energy predominantly on the same scale as the turbulent velocity, and with negligible magnetic energy at large scales. This poses a problem in cases such as the solar dynamo, which acts as a large-scale dynamo. Here we investigate an alternative dynamo mechanism, by considering whether flows susceptible to magnetic buoyancy instability can generate an electromotive force on the scales required. We consider a plane layer of fluid in a configuration unstable to the magnetic buoyancy instability and calculate the emf generated by the resulting flows. We show the variation of the electromotive force with latitude, rotation rate, field strength and field gradient.